WB8NBS

NBS
This Blog will document projects I have
in progress or completed. You can search for my
handle on Flickr, Facebook, YouTube, or Picasa
for photos. I will link some of those here.

Toastmasters Timing Light

There was a post on the Workshop88 mailing list asking for someone to construct a small manual light box for use by the timer at Toastmasters meetings. The specification was, a switched Green LED, switched Yellow LED, switched Red LED, and a fourth switch to blink all the LEDs at a 1 hz rate. The actual timing is done by a human with a stopwatch, the box just signals the speaker. The Toastmasters’ existing setup uses 110 volt incandescent lamps and is not very portable.

Much discussion ensued on the mailing list about what could be done with a Raspberry PI or Arduino, LCD screen, etc. etc. but in the end, I agreed to design and build something simple according to the original manual spec. Ultra bright LEDs could be used with a 555 timer to do the blinking. A standard MN1604 9 volt battery would easily power the LEDs for 8 – 12 hours. And I could use the standard Arduino style enclosure: and Altoids tin.

I’ve built two of these boxes. The photos on this page are from the second – but first came a prototype on a solderless breadboard.

Breadboarded Timer

Breadboarded Timer

 

On the breadboard the timer circuit was checked for reasonableness and LED illumination tested. I found with a nine volt battery I could put two LEDs in series, and with a 200 ohm limiting resistor the Red LEDs drew 15 milliamps, the Yellow 20 Ma, and a pair of Greens 12 Ma. The Red and Green were very bright, Yellow not so much. Later I checked the spec sheet on the Yellow LEDs and found they would take 50 milliamps.  I lowered the Yellow limiting resistor to 130 ohms which brought the Yellow current up to 35 Ma and then all three pairs were similarly bright.

These Ultra Bright LEDs have a clear plastic envelope with a lens formed in the end which directs most of the light straight up.  I sawed the tip of each LED off at a 45 degree angle to remove the lens. This directs more light to the front and reflects much more to the rear.

Original and Faceted LED

Original and Faceted LED

 

Here is the final schematic. This is slightly revised from the first model, the timing person wanted a separate power switch, and also wanted the blink cycle to start with LEDs on rather than LEDs off.

Toastmaster Timer Schematic

Toastmasters Timer Schematic

 

The original breadboard had all three of the grounds at the bottom of the 555 chip connected together, a switch from there to power negative activated the 555. In that configuration, the 10 microfarad capacitor started out in a discharged state which resulted in LEDs off.  Splitting that capacitor off and hard grounding it causes it to start in a charged state which turns the LEDs on. Switching the 555 pin 1 to ground starts the blinker.

I constructed the 555 module on a bit of perf board with copper pads on one side. A six hole by seven hole piece holds all the parts. This is the layout sketch I used.

Toastmaster Timer Blinker Module

Toastmasters Timer Blinker Module

 

Here is an assembled module. It measures 3/4″ by 5/8″.

Blinker Module

Blinker Module

 

With the blinker built and tested, I turned to physical construction of the box. Everything should fit in the lid.  I made an aluminum template for drilling the ten holes. In this photo, the four switches have been mounted and there are small holes drilled above the nut for the anti-rotation washer.

Altoids Lid Drilled and Template

Altoids Lid Drilled and Template

 

The LEDs don’t have any formal mounting hardware. To get maximum exposure, they are just inserted in the holes until they bottom out on the shoulder. Then a narrow strip of FR4 perf board is threaded over the leads and tacked down with bits of bent paper clip soldered to the tin lid. That paper clip in the center had to be moved later because it interfered with the battery. Soldering the LED leads in the perf board creates a very rigid assembly. I soldered the current limiting resistors between the LED pairs.

Switches Mounted and LED Dropping Resistors

Switches Mounted and LED Dropping Resistors

 

Spacing between the switches and the LED retaining strip is critical because the nine volt battery has to fit there, but not rattle around. A large paper clip was straightened out, then bent to capture the battery. A paper clip has just enough spring to hold the weight of the battery. This photo shows the battery clip soldered onto the lid. White arrows point to the four Z shaped wires holding the LED retaining strip in place. Ground leads are soldered to each switch and each has been cabled to it’s assigned LED pair.

Pins Holding LED Board

Pins Holding LED Board

 

Here is a photo with a battery installed in the clip. You have to be careful not to short the terminals on the lid lip.

Fitting the Battery

Fitting the Battery

 

At this point the lid is ready to receive the 555 timer blink module. It is mounted with two more bits of soldered paper clip, this time bent into an L shape. One clip is soldered into the ground hole of the perf board, the second in a vacant hole. White arrows in this photo point out the two module mounting clips also three of the LED restraining strip clips. Note the two retaining strip clips nearest the rim are bent parallel to the lid edge. This is to give clearance for the box bottom.

Blinker Module Installed

Blinker Module Installed

 

The last piece of hardware installed was the power switch. I used a small slide switch as that type will be less likely to accidentally turn on in somebody’s pocket.  Two eighth inch holes were drilled, then squared up with a small file. I soldered the ears of the switch to the inside of the box.

Power Switch Soldered In

Power Switch Soldered In

 

Finally the wires for power were added, everything tested, and all loose wires laced up with waxed dental floss. A bit of foam tape was added to the bottom to help make sure the battery clip doesn’t come loose. There’s a small paper clip loop soldered next to the power switch to take up strain on the wires there.

Internal View

Internal View

 

Here is the finished box with all three LED strings lit.  Note this is not a normal condition, only one color at a time should be on, mostly the Green which only draws 12 Ma (but is so bright it hurts your eyes). Blinking will draw about 60 Ma half the time. Duracell’s data sheet shows a useful life greater than 8 hours with a 50 milliamp draw so I expect this application to last considerably more than that.

Completed Toastmaster Timer

Completed Toastmasters Timer

 

This has been an interesting project that was well received by the users.  There is a short video on Dropbox.

Home Made Iambic Paddles

I have two homemade paddles to use with the Iambic Keyer Project.

This first example was made in the late 70s or early 80s, can’t remember exactly. I mentioned to a friend who worked in maintenance at a steel mill that I was looking for a heavy piece of metal to make paddles that wouldn’t scoot around on the desk.  We discussed some ideas and a few days later he produced the frame (all the blue parts) you see in the photo. It weighs over five pounds, it only moves if you want it to.

The arms are plexiglass fastened to short pieces of tubing. The tubing is flared at each end and each flare receives a bearing ball. Cup tipped Allen screws in the top frame and in the base capture the balls. With careful adjustment leaving a small amount of play, these bearings work well.

The rest of the paddle hardware is made of scraps from my junk box. Simple contacts made from machine screws work, but are noisy. Noise however does not bother the keyer much, as once an element is started, the paddle input is effectively debounced by dot/dash timing in the software.

Paddles Home Made About 1978

Paddles Home Made About 1978

 

My second example was made recently. I decided the blue paddles were not portable enough so I made something smaller. This set has a base of two inch steel Aux Bar scrounged from a telco installation project. The next photo shows the first iteration.

For pivot bearings I used brass thread inserts from Woodcraft. They have a 1/4-20 inside thread and a very coarse outside thread, intended to screw into a woodworking project. I filed the coarse threads off two sides of the inserts and soldered them to a strip of PC board material to form the paddle arms. The bearing for the arms is then the threads of the screws which go into threaded holes in the base plate.  Contacts are bent paper clips screwed to half inch nylon standoffs.  This works but has a terrible feel due to slop in the 1/4-20 threads.

I put a square of sticky silicone mat under the base and it stays put pretty well. The square was cut from a large mat intended to hold a wood work piece in place while you use a router on it’s edges.

Paddles Home Made February 2015

Paddles Home Made February 2015

 

The second iteration of the Aux Bar paddle is an attempt to remove some of the annoying backlash in the screw thread pivot bearings. I thought longer threads would help and got two threaded sleeves from the hardware store. These are made for joining two lengths of threaded rod. They have a #10 thread and are about an inch long. Two new paddle arms were constructed, this time with the bearings on the outside of the PC board as the sleeves are larger than the brass inserts used in the first model.

I inserted three sets of small screws into the arms to capture the tension spring which allows some adjustment. The spring shown in the photo is from an old IBM keyboard. If you part out one of those old Model M’s you have enough springs to last a lifetime. A second spring directly between the pivot points takes up some of the backlash remaining in the threads. Also the two #10 pivot screws are epoxyed into the base to eliminate that small bit of wobble. At the back of each arm where the paper clip touches, I added a drop of silver containing solder to make a better electrical contact.

This iteration has a very light touch but still too much slop in the bearings. I think with some tuning of the springs it will be very usable.

Paddles Home Made March 2015

Paddles Home Made March 2015

 

 Update 5/11/2015

Added a spring directly centered between the two pivot points. This spring is stronger than the small one separating the paddle arms, and it’s function is to take up backlash in the sloppy threads on the cheap pivot screws. I soldered cut down copper carpet tacks to the inside of the paddle arms to keep the new spring in place. The spring force is directly between the pivot points, so it does not contribute to the effort required to close the paddles unless you press hard enough to overcome it’s higher tension. It improved the feel of the Aux Bar paddles a lot.

Pivot Spring Added

Pivot Spring Added

Fun With Direct Digital Synthesis

You know that good feeling you get when a project comes together? Thats what I felt when I saw this sine wave on my oscilloscope.  It’s a Pulse Width Modulation (PWM) signal generated by an Arduino using a Direct Digital Synthesis (DDS) technique and a lookup table of amplitude values. It was the result of searching for a way to improve the tone quality of a morse code keyer project and I had gotten half wave, then quarter sine wave symmetry working in a demonstration sketch.

Quarter Wave Symmetry

Quarter Wave Symmetry
1000 Hz 256 Step Table

 

Digital to Analog Conversion is best done with optimized precision circuits. The relatively simple processor in an Arduino does not have a DAC device but it can do Pulse Width Modulation which can, in most cases, do the job adequately.

Pulse Width Modulation is widely documented. Basically it is a technique for generating an analog voltage from a digital signal. The device generates a high speed pulse train with varying pulse widths.  This is fed through a filter circuit which averages the energy in the pulses.  Fat pulses average to a higher voltage, skinny pulses average to a low voltage. By changing the pulse width over time, digital software can create a good analog representation of an arbitrary periodic signal. Other interesting applications are possible.

An Arduino generates PWM by setting up a timer. This is a counter with a circuit to trigger an interrupt at a specified count. The counter is incremented by the processor clock or, through a prescaler, a submultiple of the processor clock.  PWM is achieved by the Interrupt Processing Routine (ISR) manipulating the specified count at which the timer fires. DDS applications synthesize an arbitrary waveform by using a lookup table of values that the ISR accesses sequentially to change the terminal count.

Common non-DDS applications might be dimming an LED , feeding an RC servo, or controlling the speed of a motor, and the Arduino environment has a convenient analogWrite() function that handles all the details for you. Hybrid cars use PWM to control the traction motors.

I found many articles on generating DDS sound using the Arduino platform. I picked one from KO7M as a base to learn more about the method. Read Jeff’s weblog entry with source code here. His sketch sets up timer 2 for PWM with a 32 KHz base frequency.  Timer 2 is normally used by the Arduino for the tone() function and since my aim is to supersede the tone() function with something better, his example was a perfect starting point. In this article, I will only describe the changes I made in Jeff’s Interrupt Service Routine (ISR) and in the tables. Details of setting up the timers are covered in the source code and in many Internet sources. Here is a drawing of the Arduino connections:

Schematic for DDS Demo

Schematic for DDS Demo

Only five external parts needed including a button switch that stops and starts the sweep.

My test bed started out simple but it grew some (gruesome?).

Test Bed

Test Bed

Part 0: Analyzing and Parting Out the KO7M Sketch

After confirming that the sketch actually worked, I added code to sweep the frequency range from 50 to 2000 HZ so I could hear what it would sound like, and observe fidelity on my oscilloscope. Later I also added lines to generate a pulse at the start of the sine wave on a different pin. Using this pulse as an external sync source allowed the scope to display a steady waveform. I removed the sync code in the examples in this post for clarity.

This is the ISR from the original sketch (with small changes by me). TuningWord is the only parameter passed from the main part of the program. It is adjusted to set the particular PWM output frequency desired:

ISR(TIMER2_OVF_vect) {
  byte sine_table_index;
  static uint32_t phase_accumulator;
  
  // Update phase accumulator and extract the sine table index from it
  phase_accumulator += tuning_word;
  sine_table_index = phase_accumulator >> 24;  // Use upper 8 bits as index

  // Set current amplitude value for the sine wave being constructed.
  OCR2A = pgm_read_byte_near(sine256 + sine_table_index); 
}

Note Jeff is storing his sine table in flash memory. If you’re not familiar with that technique, read this tutorial. It is a good method for reducing the RAM footprint of an Arduino sketch. You can find my version of Jeff’s sketch here.  This is the 1000 Hz output from the original sketch with floating point math:

Original Floating Point

Original Floating Point
1000 Hz 256 Table

Part 1: Integer Conversion and Multiple Sine Tables

At this time, all floating point math in the example was converted to integer. To my surprise, it still works. There is more jitter on the waveforms due to integer truncation, but for keyer sidetone it is acceptable and the sketch sized dropped by about half.

I wanted to experiment with multiple lookup tables to get an idea of the minimum memory footprint possible while still producing acceptable sound. Libre Office Calc easily produced data with a 0-255 range for tables of length 256, 128, 64, 32 and 16 samples. See my spreadsheet here. Calc could also graph the tables to show how rough the waveform might be.  It was a simple matter to paste a table column into VI and join the values into C style  statements. These lines of data were inserted into the sketch and wrapped with #ifdef and #endif statements. At the top of the sketch is this code:

// Table sizes. Uncomment one and only one
//#define Table256
//#define Table128
#define Table64
//#define Table32
//#define Table16

Which allows me to choose a table size to evaluate at compile time. The wrapped tables look like:

#ifdef Table16
// 16 samples per period
#define Bits 12               // # of bits to shift 
PROGMEM prog_uchar sineTable[16] = {
  128,177,218,245,255,245,218,177,
  127,79,38,11,1,11,38,79
};
#endif // Table16

Bits is a constant definition that controls how far the ISR has to right shift the phase accumulator variable so the number that remains does not exceed the sine table size.

The interrupt handler changed little and looks like this:

ISR(TIMER2_OVF_vect) {
byte sineTableindex;
static unsigned int phaseAccumulator;

  // Update phase accumulator and extract the sine table index from it
  phaseAccumulator += tuningWord;
se
  // Right shift because we're only using the most significant bits of the INT
  sineTableindex = phaseAccumulator >> Bits;

  // Look up current amplitude value for the sine wave being constructed.
  OCR2A = pgm_read_byte_near(sineTable + sineTableindex);
}

Code for this full table sketch is here. These are waveforms from the Integer version:

Integer Version

Integer Version
Three Table Sizes

Part 2: Using Half Wave Symmetry of Sine Waves to Reduce Table Size

During my Google research I found articles pointing out that the size of the sine table could be reduced by a factor of two or four if you exploited the symmetry of a sine wave. Several pages described how to do this in FPGA hardware but I could not find a good example of symmetry use in C code and nothing at all for an Arduino. I tackled symmetry in two stages.

For half wave symmetry it is only necessary to duplicate the first half of the wave for the second half, inverting the second half as it is generated. First you need to know which half is being processed during the interrupt. The Most Signifigant Bit (MSB) of the phase accumulator variable has that information. It will be zero in the first half of the sine wave, one in the second half. I added a variable to record this bit and use a mask of 0x8000 to extract the bit. Then a new constant MSBMask was created inside the table definitions to turn off the high order MSB during table lookup. The tables now look like this example:

#ifdef Table16
// 16 samples per period
#define Bits 12
#define MSBMask 0x07
PROGMEM prog_uchar sineTable[8] = {
 128,177,218,245,255,245,218,177
};
#endif // Table16

Note the table sizes are half the original. This 16 stepe per period table is now only 8 bytes long.  The modified ISR with half wave symmetry now looks like:

ISR(TIMER2_OVF_vect) {
byte sineTableindex;                     // calculated index into sine table     
static unsigned int phaseAccumulator;    // running total of phase offset
unsigned int whichHalf;                  // for sine symmetry switching

  // Update phase accumulator and extract the sine table index from it
  phaseAccumulator += tuningWord;
  whichHalf = phaseAccumulator & 0x8000; // record which half of wave

  // Right shift because we're only using the most significant bits
  // of the INT. Leave only enough bits for one half table range
  sineTableindex = (phaseAccumulator >> Bits) & MSBMask;

  // Set current amplitude value for the sine wave being constructed.
  OCR2A = pgm_read_byte_near(sineTable + sineTableindex);

  // invert the second half of sine wave
  if(whichHalf) OCR2A = 255 - OCR2A;
}

The only additions to the ISR were the whichHalf variable, MSBMask which is defined with the sine table to remove the MSB, and the if statement at the end which does the actual inversion.

Code for the half wave symmetry version is here. These photos are from the half wave version:

Half Wave Symmetry Version

Half Wave Symmetry Version
Three Table Sizes

 

Part 3: Using Quarter Wave Sine Symmetry to Reduce Table Size

Exploiting quarter wave symmetry is more complicated. It is a left/right symmetry while half wave symmetry is up/down. First you have to know which quarter of the wave is being generated. The second most significant bit in the phase accumulator variable has this information. It will be 0 if in the first or third quarter, 1 if second or fourth. A new state variable and a mask of 0x4000 records this bit.  Since we are using less of the lookup tables, the MSBMask is smaller, it now needs to discard two MSB bits. The tables now look like:

#ifdef Table16
// 16 samples per period
#define Bits 12
#define MSBMask 0x03
PROGMEM prog_uchar sineTable[5] = {
  128, 177, 218, 245, 255
};
#endif // Table16

Note that the sixteen sample table has been reduced to five (not four) bytes. The 256 level table is only 65 bytes long! The odd byte at the end was necessary to work around a glitch – the table read from flash would look up the same value twice at the beginning and end of the even quadrant. Adding one to the index and one extra table byte solves that issue. The ISR now looks like this:

ISR(TIMER2_OVF_vect) {
byte sineTableindex;                     // calculated index into sine table     
static unsigned int phaseAccumulator;    // running total of phase offset
unsigned int whichHalf;                  // for sine symmetry
unsigned int whichQtr;                   // for sine symmetry
static boolean pulsed;                   // for unique scope sync

  // Update phase accumulator and extract the sine table index from it
  phaseAccumulator += tuningWord;
  whichHalf = phaseAccumulator & 0x8000; // record which half of wave
  whichQtr =  phaseAccumulator & 0x4000; // record which quarter of wave

  // Right shift because we're only using the most significant bits
  // of the INT. Leave only enough bits for one quarter table range
  sineTableindex = (phaseAccumulator >> Bits) & MSBMask;

  // Look up current amplitude value for the sine wave being constructed.
  if(whichQtr) {                         // in second or fourth quarter
  // +1 works around a glitch where same data at the quarter 
  // transitions was looked up twice in a row
    OCR2A = pgm_read_byte_near(sineTable + (MSBMask - sineTableindex + 1));
  } 
  else {                                 // in first or third quarter
    OCR2A = pgm_read_byte_near(sineTable + sineTableindex);
  }
  // invert the second half of sine wave
  if(whichHalf) OCR2A = 255 - OCR2A;
}

This code does quarter wave symmetry first, then wraps half wave symmetry around that for the final output.  The changes to add quarter wave are the whichQtr variable and it’s masking line, and the if(whichQtr) statement which inverts the table lookup left to right. MSBMask in in the byte read statement because it is the number of steps that exactly form a quarter of the wave form.

Code for the quarter wave symmetry sketch is here. Here are scope traces of the quarter wave symmetry version:

Quarter Wave Symmetry Version

Quarter Wave Symmetry Version
Three Table Sizes

 

Conclusion:

These changes to the original Interrupt Service Routine allowed the table sizes to be reduced by a factor of four with hopefully, not too much additional overhead. Any ISR overhead added is executed 32000 every second so you have to be conservative.  CPU time in the ISR is traded for a smaller program.

All three of these sketches can be useful for arbitrary waveform synthesis by constructing an appropriate table.  The base sketch would work for any periodic waveform, including those that have no symmetry either up/down or left/right. A sawtooth wave for example.  Half wave symmetry would be good for representing an underdamped or overdamped square wave.  Quarter wave symmetry works for sine waves, as shown here, or a triangle wave.

The oscilloscope traces are interesting by themselves. These sketches and a scope could be used to demonstrate microcontroller techniques at your local science fair. My scope is an 80’s vintage Tektronix clone. On the screen you can see the generated sine waves and by zooming in, see the artifacts of PWM happening at a 32 KHz rate. Use the coarse 16 step table and the staircase model of DDS is clear. You can view the raw PWM by simply disconnecting the 0.1 Ufd integrating capacitor from the scope input. Interesting though, disconnecting the filter capacitor does not affect the audio much because your ears can’t respond to 32 Khz sound.

DDS quantization is most visible at low frequencies, using the smaller tables. Here you can clearly see the 16 steps and 32Khz fuzz on the trace.

50 Hz 16 Step Waveforms

50 Hz 16 Step Waveforms

 

Footnote:

The 64 step sine synthesizer with quarter wave symmetry was successfully added to my keyer project.  I see no degradation of the morse timing at 50 WPM.  A brief video is here.  Also I recorded MP3s of the tone before and after.  The tone produced by the stock Ardino tone() function is here.  The tone from the 64 step (16 values) DDS function is here.

 

Arduino Based Iambic Keyer(s)

Version 1.0 – ATTiny85 Port

Richard Chapman KC4IFB published an article in the Sep/Oct 2009 QEX magazine (subscription required) for constructing an Iambic Keyer on the Arduino platform. I downloaded his code from the QEX web site (ARRL membership required) and found it worked well.  I have not been active in Ham Radio for years and my morse code is seriously rusty, so I decided to build a keyer for practice purposes and maybe to use on a real radio some day when I figure out how to get an antenna up on this small lot.  I have a WB4VVF Accu-Keyer I used with my homemade paddles long ago.  I bought the PC board from WB4VVF himself at the Dayton Hamvention.  Chapman’s keyer implementation on the Arduino Uno felt exactly the same and I had no problem getting used to it.

I wanted to see if this code would run on an ATtiny85 chip. These are beautiful little microcontrollers in an 8 pin DIP package. They have 8K of internal flash memory and with a minor bit of library downloading, are programmable via the Arduino IDE.  There is a catch though, tiny85 does not normally have bootloader code like a formal Arduino does so you need additional circuitry to burn your sketch onto the little chip. In July 2013 Jim Williams from Workshop 88 in Glen Ellyn conducted a class in tiny85 programming which I attended. At the end of the class we all had our own Arduino ISP adapter board and could burn a tiny85 by using an Arduino UNO as an intermediary.

I amped up my ISP adapter by adding a ZIF socket. It also can program the ATMega328 chips by moving five jumpers.

ISP programmer for ATtiny85 and ATMEGA328 microcontrollers

ISP programmer for ATtiny85 and ATMEGA328 microcontrollers

With the ISP programmer working, I was ready to work on the tiny85 port.  I found Chapman’s code worked but there was no side tone generated.  After a few hours debugging I noticed Chapman’s code was turning the tone on in every iteration of loop(). The tiny85 did not like that. I just added a flag so tone was turned on once, then left on, and the tiny85 port was working 100%. In the end, a very minor change.

I wanted SMALL so I added code to eliminate the speed potentiometer. In my version, you hold both paddles closed for 5 seconds and it goes into speed set mode. Dots increase the speed and dashes decrease.  Another five second Iambic squeeze and it goes back to normal mode.  Also I added a Straight Key mode. If a two conductor instead of a three conductor plug is inserted in the paddle jack it will just beep out what it sees on the dot paddle.  Good for code practice with my J38 if I can remember where I put it.

Source code for the ATtiny85 port is here. This is the finished Keyer in the mandatory Altoids enclosure (but note SMALL Altoids):

Atmel ATtiny85 based Iambic Keyer

It was a challenge to get everything in there and still have the lid close.  The speaker is from a defunct greeting card but rest of the parts were purchased from Jameco. In the end, the most expensive single component was the Altoids mints from the drug store.  The ATtiny85 chips are less than a dollar if you buy ten.

There are these few parts required:

  • speaker and 22 ohm resistor
  • 2032 battery and holder
  • two 3.5 mm jacks, one output, one paddles
  • three bypass capacitors
  • Dropping resistor and LED
  • Power switch
  • ATtiny85 chip and 8 pin socket
Interior of ATtiny85 Iambic Keyer.

Interior of ATtiny85 Iambic Keyer.

There is a short video of the keyer in action here.  So now if I spend a few minutes every day practicing I might get back to the 13 WPM I had to do to get my current license.

Version 2.0 – ATMega328 with Memories

Richard’s QEX article suggested several possible enhancements. I thought adding memories would make the device much more useful so began another journey into Arduino programming. Yes, I know there are already Arduino keyers out there. The K3NG implementation has a ridiculous number of options, but I wanted to do my own based on Chapman’s sketch in the most efficient manner possible. A schematic drawing of my completed keyer is available, and I have written a description of the functions. Source code for the sketch is here.

The PS2 keyboard requires +5 volts so I designed around a five volt Sparkfun Pro Mini board. Only ten bucks! Available here or here. The Pro Mini has an on board 150 milliamp capacity 5 volt regulator if you use a 7-12 volt power supply.

Features in the keyer sketch now include:

  1. Memory or keyboard characters are buffered in an asynchronous circular queue so memory buttons or keyboard characters can be “typed ahead”.
  2. PS2 and serial terminal keyboards supported.
  3. Paddle generated morse is interpreted and printed as ASCII letters on the serial terminal.
  4. Four programmable memories with 50 character capacity each.
  5. Memories programmable from the keyboards or from the paddles.
  6. Random code practice modes, letters, letters and numbers, letters, numbers, and punctuation.
  7. Sending speed settable 10 to 45 WPM. Limits can be changed by recompiling.
  8. Sidetone frequency settable 100 to 1500 hz. Limits easily changed by recompiling.
  9. Commonly changed default settings are in a separate header file (Canned.h).
  10. Message strings, sending speed, and sidetone frequency are stored in EEPROM and easily reset to defaults.

The sketch requires five I/O connectors:

  1. A 3 conductor jack for the paddle or straight key. Connect dot paddle to tip, dash paddle to ring. Use a 2 conductor plug for a straight key in the same jack.
  2. A 3 conductor jack for transmitter keying. A 2N2222 open collector output is on the tip. Line level sidetone is connected through a 5k resistor to the ring so you can connect an external amplifier if you need louder audio.
  3. A power jack for either a 5 volt or 7 -12 volt wall wart supply. Consult the Sparkfun documentation for which Pro Mini pin to use for power.
  4. A six conductor mini DIN connector for the PS2 keyboard. See Canned.h for information on the four leads needed.
  5. A connection for programming, and TTL serial terminal through an FTDI adapter. This can also power the unit instead of the wall wart.

There are six push button switches and a volume control needed:

  1. A reset button for the Arduino.
  2. A Function button.
  3. Four push buttons to activate individual memories.
  4. The volume control feeds a one transistor buffer for the internal speaker. It does not affect the level on the line output connection.

Operation:

Pressing reset momentarily has different effects depending on what other switches are closed. A processor reset normally takes a few seconds, when finished three mid tone beeps will be heard.

  • Press the reset button alone to restart the Arduino. This is also the only way to exit code practice mode.
  • Press the reset button while holding the function button down until three low tone beeps sound will restore the four message memories and code speed to defaults. Default messages, speed, and sidetone frequency are set at compile time from the file canned.h. You must do this action when loading the sketch for the first time into a new Arduino to initialize the EEPROM.
  • Press the reset button with a 2 conductor straight key plug inserted and the keyer enters straight key mode where the sketch generates tone and output simply follows the key closures.
  • Press the reset button while holding down one of the memory buttons starts random code practice. Characters will be generated in five character groups and echoed on the serial port.
  1. Memory 1: letters only
  2. Memory 2: letters and numbers
  3. Memory 3: letters and numbers
  • Pressing reset while holding Memory 4 enters sidetone frequency set mode. The dot paddle increases frequency, dash paddle decreases. Press M4 again to exit set mode.

The function button has three duties:

  • Reset to default messages as mentioned above. You must hold the function button down until you hear 3 low tone beeps.
  • Holding function alone down triggers speed change mode. While function is held, the dot paddle increases speed, dash paddle decreases speed.
  • Holding function down and then momentarily pressing a memory button allows programming that memory. After programming, press function again to return to normal.

New memory messages may be entered from the PS2 keyboard, the serial port keyboard, or from the paddles.

Pressing a memory button by itself transmits the programmed message.

Serial or PS2 keyboards have a command mode, entered by typing a back slash followed by a single character. Commands implemented are:

  1. \+ increase sending speed one Word Per Minute
  2. \- decrease sending speed one Word Per Minute
  3. \u increase sidetone frequency by 5%
  4. \d decrease sidetone frequency by 5%
  5. \w save current sidetone frequency and WPM to EEPROM memory
  6. \1, \2, \3, \4 send a message as though a memory button was pressed.

The keyboard translation table (AtoM.h) includes all the characters shown in the Wikipedia article on Morse Code except the underscore and the dollar sign. Typing an unsupported character echos “x” on the serial port and will be ignored by the morse interpreter.

Version 2.0 Hardware Implementation

Here is a photo of my 2.0 construction. There are three jacks on the left for power, paddles and transmitter keying. PS2 keyboard jack on the right, small volume control and send monitor LED on the front. Not visible is the six pin serial connector on the rear.

On the lid of the S.A.E. you can see a small speaker through the holes around the center. Round holes were made with a heavy duty paper punch. For buttons, I used 6 mm square through hole PCB mount switches with four pins, the kind everybody uses on their solderless breadboard. I bent the pins on one side back so they could be soldered directly to the Altoids lid. Quarter inch square holes for the buttons were punched with a hollow chisel mortiser bit which worked quite well.  I made labels by placing the lid in a scanner, adding text to the scan in GIMP, then printing a 1:1 image of the labeled lid on photo paper. I cut the letters out and glued them to the Altoids lid. This technique produces text labels with the original Altoids artwork underneath. I coated each label with clear nail polish for protection.

Arduino Memory Keyer Exterior

Arduino Memory Keyer Exterior

With the box opened you can see the small Sparkfun Pro Mini board. It is mounted by a pair of L shaped wires cut from a paper clip. These are soldered in the Mini’s two ground pins and then soldered to the Altoids tin. A rectangular hole in the back of the tin provides access to the six pin serial connector. All the in use Arduino inputs have 9.8 k pull up resistors added, and are bypassed at the switch with a small capacitor. The outer end of the pullup resistors are soldered to a narrow bit of PC material wired to Vcc.

Three jacks on the left are epoxyed in place. The PS2 jack on the right, which was salvaged from a defunct USB-PS2 adaptor, is held by a narrow copper strap soldered to the jack and to the Altoids tin. A small perf board at the front holds most of the ancillary components for keying and the audio control. I mounted the perf board using more stiff wire cut from the paper clip.

There is a strip of thin PC material laid across the button switches to add more physical support. The two switch pins not soldered to the Altoids lid are bent over the strip and soldered. Notches filed in strategic places across the copper isolate each switch, and I added the necessary 0.1 uFd capacitors at this point.  The speaker is tucked under one of the PC strips and epoxyed in a couple of places. A short piece of flexible solder wick bonds the box lid to the bottom.

Arduino Memory Keyer Interior

Arduino Memory Keyer Interior

Future Enhancements

Add a FTDI USB to Serial adapter inside the box. It would allow a more graceful connection to a host computer running a serial communication program. Or build another unit with a USB integrated chip.

Add a 16×2 LCD display. Code would be trivial, but will probably have to find a bigger box.

Expand to six or eight memories. My sketch is compiling in about 13 k of flash, and has over 1500 bytes of ram free plus the Pro Mini has eight analog inputs so easily done. But how many memory messages can the average ham keep track of? I think four is a good number and I love the Altoids tin paradigm.

 

Credits

Many thanks to Richard Chapman KC4IFB whose February 2009 QEX article provided the inspiration and base for this sketch. His iambic keyer sketch feels exactly like my original WB4VVF Accukeyer. A version of his sketch with instrumentation added so you can see the state changes is here. Also see Rarons Blog  for a discussion of the tree method for decoding and encoding morse characters. Would you believe 300 WPM full duplex?  I did not use his library but his work was very helpful in building efficient translation tables. The circular queue was implemented with help from examples from the Embedded Systems Journal.

 

Revision History

V2.0.0 Initial coding to implement fully asynchronous event loop.
All delay() and spin waits removed from the main loop path.
Remove numbers only practice. Change eeprom order. Add change sidetone.
https://dl.dropboxusercontent.com/u/40929640/ArduinoMorseCode/MemoryKeyerV2.0.zip

V2.0.1 Minor tuning space generation in doIambic.
https://dl.dropboxusercontent.com/u/40929640/ArduinoMorseCode/MemoryKeyerV2.0.1.zip

V2.0.2 Converted sidetone generation to DDS/PWM sine wave with help from
http://ko7m.blogspot.com/2014/08/direct-digital-synthesis-dds.html

https://dl.dropboxusercontent.com/u/40929640/ArduinoMorseCode/MemoryKeyerV2.0.2.zip

Quarter Wave Symmetry

Quarter Wave Symmetry
1000 Hz 256 Step Table

V2.0.3 Changed sine table to half step offset. Saves one byte.
https://dl.dropboxusercontent.com/u/40929640/ArduinoMorseCode/MemoryKeyerV2.0.3.zip

V2.0.4 Added sidetone envelope shaping. Required several other changes.
https://dl.dropboxusercontent.com/u/40929640/ArduinoMorseCode/MemoryKeyerV2.0.4.zip

Shaped Dits at 45 WPM

Shaped Dits at 45 WPM

V2.0.4.1 Bug fix was dropping dits on a long string of upper case “H”s. Disable interrupt while changing sine tables.
https://dl.dropboxusercontent.com/u/40929640/ArduinoMorseCode/MemoryKeyerV2.0.4.1.zip

V2.0.5  Changed AtoM table from prog_uint16_t to char to save memory, which created bug where setup does gratuitous write to A6 and A7. Fixed problems when compiling under Arduino IDE 1.6.1, did not accept typedefs in pgmspace.h. Fixed bug in initByte, 1.6.1 did not like  aaByte = aByte -= 0x20;  Compiled size is 2k smaller in 1.6.1 and no more bogus compiler warnings!
https://dl.dropboxusercontent.com/u/40929640/ArduinoMorseCode/MemoryKeyerV2.0.5.zip

April 30 – Have not changed the V2.0.5 sketch but did redo the audio section of the Altoids keyer. I found the single transistor audio buffer was not satisfactory, distorting badly when driven by a sine wave. Also it was drawing 50 milliamps at idle. I removed the transistor and connected an LM386 amplifier – much better sound and very little current draw when idle. A revised schematic is at:
https://dl.dropboxusercontent.com/u/40929640/ArduinoMorseCode/MemoryKeyerV2.0.5Schematics.zip

Notes

20 March 2015  —  The keyer sketch was developed with Arduino 1.0.6. Recently I downloaded the latest Arduino IDE 1.6.1 and discovered the keyer sketch will not compile. It appears the newer version of GCC will not accept the typedefs used in the pgmspace.h library. I will upload a 1.6.1 release as soon as I figure out what’s going on. FIXED see V2.0.5 above.

24 March 2015  — Was shopping in Frys and bought an inexpensive (< $3) adaptor, is USB A female to PS2 male, is about the same size as the two connectors placed end to end.  It was made by Shaxon Industries in guess where. To my complete surprise it works. Using the adaptor I can connect any USB keyboard to the keyer which is good news, as PS2 keyboards especially compact ones, are getting hard to find. I measured power supply current with the adaptor, it does not add significant drain over the 25 Ma the keyer itself draws. The small USB keyboard I tried added only about 3 milliamps when not typing. I did find the transistor I used to buffer the speaker draws 25 milliamps itself, will have to find a more efficient amplifier.

Offset Flip Top Table

This article describes a two foot square mobile cabinet, with a pivoting top so two tools can be supported. These are known as “Flip Top Tables” but my version uses an offset pivot point so a much taller drill press sits lower when it is rotated up.

Cost was about $130.

My design was featured in “Americas Best Home Workshops 2009″, a Wood Magazine publication.

 

The Problem

In early 2008 I upgraded a generic 10 inch drill press to a new Delta DP300 benchtop version. The Delta took up about a quarter of my work area. It is 34 inches tall and weighs about 80 pounds. Not exactly portable.

Drill Press

New Drill Press

 

Later that spring, an Ebay opportunity resulted in acquiring this DeWalt 733  planer.

Planer

New Dewalt 733

 

But my shop is in one corner of a garage and I didn’t have a place to store the planer. It is 21 inches tall and weighs about 84 pounds.

 

The Solution

Put the planer and the drill press in the same space.

Table

Flip Top Table

 

A few hours of sketching and arithmetic showed that my drill press on a conventional flip top pivoting at the table surface would put the table 42 inches from the floor. The press chuck would be above eye level, too high for comfortable work.

So after many paper designs, I had the idea of making the top as a tray, with pivot points offset four inches vertically from the tray surface. This allows the drill press to sit eight inches lower when it is rotated up.

Since this tray style design obviously cannot have a solid pivot axle from side to side as most fliptops use, I made sturdy hinges from 1/4 inch plate and half inch carriage bolts. There is a short length of 3/8 pipe slipped around the bolt that acts as a spacer and also forms the pivot bearing surface with the smaller steel plate.

Pivot Prototype

Assembled Pivot Hinge

 

Here is the prototype hinge mounted in scrap plywood. It proved to be extremely rigid and easily handles the bending moment of the loaded tray.

Hinge

Prototype Hinge

 

This photo shows the drill press attached to the finished pivoting tray. I added two small bolts at the rear of the cast iron foot as I thought the strain of supporting the drill press head might be too much when the machine was leaned over.

One of the four bolts holding the planer to the other surface is visible.

Press Mounting

Drill Press Mounting

 

There is a lock screw at either side of the tray at front. They are big star knobs with 3/8″ threaded shafts running through to T-nuts inset in the cabinet side.

Front Tray Lock

Front Tray Lock

 

Note how the front edge of the tray is cut away around the cabinet support gussets. When the top begins to pivot, the cut away allows clearance for the tray to rotate.

Tray at Start of Pivot

Tray at Start of Pivot

 

The next detail shows the rear of the tray as it begins to pivot. The back is *not* cut away around the gussets, instead the gussets form a positive stop for the rear structure. Thus the tray will only pivot in one direction, and only 180 degrees.

There are T-nuts installed at the rear of the cabinet sides for the lock bolts when the planer is rotated up.

Rear View

Tray at Start of Pivot – Rear View

 

I used 3 inch casters to make the cabinet mobile. The bottom plate is a double layer of 3/4 plywood and there is an additional 3/4 block at each corner where the casters bolt through.

The entire cabinet is screwed together. I was going to do a dry fit, take it apart and glue everything, but it is very rigid as is, I don’t think glue is necessary.

Caster Mounting

Caster Mounting

 

This shows the table with drill press up.  Note the base of the press is now 4 inches below the pivot points.

Drill Press Proud

Drill Press Proud

 

I was surprised to find that the planer and drill press balance each other very well.  It takes only one hand to rotate the tray, which is carrying over 160 pounds.  I did not think this would be the case as the drill carries most of it’s mass at the top, but the 4 inch offset evens out the weight distribution nicely.

Table Rotating

Table Rotating

 

This shows the table with planer up. The rear face of the tray is now sitting on the front gussets which positively stop the rotation.

Planer Proud

Planer Proud

 

This shows the rear of the cabinet. I had to cut away the rear gussets to clear the planer handles. I could have mounted the planer sideways for more clearance, or removed the handles. Also you can see a section of plywood added across the bottom for lateral stiffness.

Note in this position, the top is four inches above the pivot point. The planer is a bit high for a large, heavy board but at least it has a home, and I use the drill press a lot more than the planer.

The lock knobs have been inserted at the rear in this picture.

Planer Locked

Cabinet Rear View

 

Here is a rough drawing of the cabinet. The dimensions are for my build, if you decide to make a table like this, you will need to work out sizes for the tools you plan to mount. The limiting measurement for my table was the height of the tallest tool, the drill press.

Basic Dimensions

Basic Dimensions

Basic Dimensions

Basic Dimensions

 

There is a short video on YouTube.

My offset cabinet has been very successful. I generally wheel it out in the driveway to use the planer, my dust collection consists of a broom and a leaf blower. It takes only about a minute to stow the drill press cord and lamp and then flip the top.

Portable Planing Board

Lately I’ve gotten much more interested in using hand tools. I don’t have a real bench though, just an old office desk and there is not a good way to hold a board down flat to work on it. Holdfasts just don’t work well with an office desk, and the desk doesn’t have any structure to support a tail vise.

So I made an 11×48 inch planing board. It clamps easily in the bench front vise, or in a Work Mate out in the driveway. The bed is made of 5/8 Birch plywood, with 3/4 inch holes every 2 inches down a rigid spine, and there is a wide stop screwed to the left end. I researched several different methods of constraining a board. The most promising was the Veritas “Wonder Pup” but it looks awkward to tighten, is 3/4 inch tall, made of plane blade unfriendly metal, and is not cheap.

I worked out a cam arrangement to secure the work but found it takes a pair of cams to cover the 2 inch range.

In this photo the larger cam is lying on the bench at rear along with the plywood spanner wrench used to torque the cams. A pine board is locked by the smaller of the two cams which has a range of 1 to 2 1/4 inches.  The larger cam has a range of 2 to 3 1/4 inches.

Planing Board

The Planing Board on the Bench

 

In the next photo, you see the small cam locking a board. There is an aluminum follower that slides underneath.  A tapered wood wedge is screwed to the face of the follower which helps to keep the cam from loosening.

I initially thought I could just use the cam against the work piece. It would tighten (with some difficulty), but if the work wiggled even slightly the cam would rotate and release. Next I made the aluminum cam follower captured by the central peg, which worked better but still loosened too easily. Finally I added a ramp to the follower. It changes the point of contact so clamping force tends to tighten rather than loosen the cam. This works much better, though the thickness of the follower does add a bit to the half inch height of the cam.

The spanner wrench is just quarter inch dowels in a bit of scrap. The wrench has two sets of pins at 90 degrees to each other because the cams have about a 225 degree swing.

The Cam Lock

The Cam Lock

 

I don’t have to use the left end planing stop, I can put a 3/4″ peg in any one of the holes and pin the work with the cam.  The next photo shows a board locked cross grain using the larger cam.

One problem is the large cam overhangs the edge in some situations, possibly interfering with the plane. If I had to do it over, I would build the spine an inch closer to the sled center. I have also added many more holes for additional short pegs, see later photos.

Large Cam Working Against a Pin

Large Cam Working Against a Pin

 

Showing the whole planing board. I spent a lot of time drilling holes, then sunk a 2 inch screw between every pair of holes for strength. It is quite rigid when the vise is snugged up, and more importantly, FLAT.

A Board Pegged in the Sled

A Board Pegged in the Planing Board

 

Here you can see the cam follower, large cam upside down, spanner wrench, small cam, and a peg in one of the holes. I made two sets of cams, one works clockwise, the other counterclockwise. This photo shows the counterclockwise set but I mostly use the clockwise arrangement. Sometimes switching the cam sense will work around a plane interference problem.

Peg holes are 3/4 inch blind drilled 2 inches deep, then 1/2 inch drilled through.  This stops the pegs but lets shavings fall through. You can also stick a screwdriver up through the half inch hole to push out a stubborn peg.

The Parts

The Parts

 

This is a picture of the clockwise cams, the profile was refined using this spreadsheet: Cam. If you decide to build a board like mine, you can scale and print this as a pattern. Shape and size are not critical as long as there is sufficient range (> one inch) between smallest and largest radials.  The range of the two cams overlap a small amount.

Cams

Large and Small Cam
Large Cam 5 3/4″ x 4 5/8″
Small Cam 3 7/8″ x 2 7/8″

 

And here is a photo of the clockwise cam follower. It is made of aluminum cut from a box lid from my junk pile.  the two legs are 3/4″ apart, they straddle the cam dowel so the follower is constrained to move mostly in the direction of the work but can still angle a bit to conform to a board that isn’t square.

Cam Folower

Cam Follower
2 3/4″ x 5″

 

Here you can see how the plywood wedge attached to the follower works. It moves the point of contact between cam and follower to a point just past the centerline. Back pressure from the work then tends to rotate the cam in the direction that tightens. If the wedge was not there, the point of contact, because of the spiral shape of the cam, would be just before the centerline and the cam would tend to loosen from back pressure.  Also there is a fair amount of friction between the cam dowel and spine holes which helps keep the cam in place

Cam and Follower

Showing Cam Follower Offset

 

The fixed planing stop protrudes 3/8 inch above the sled surface at the left end. It is held with screws and can be moved to the right end if necessary. To plane stock thinner than 3/8″, I put hard board spacers underneath the work.

The Planing Stop

The Planing Stop

 

In this bottom up photo, you can see the spine made of two 2 inch strips of 5/8″ thick plywood laminated together.  It provides overall rigidity, meat around the peg holes, and gives something for the bench vise to hold on to.  The spine is fastened 2 inches back from the edge to allow room to set clamps.

The small bit of darker wood at rear is a spacer the same width of the inside vise jaw so the board bears directly on the edge of the bench, which helps keep the far end from wiggling.

Bottom of the Sled

Bottom of the Sled

 

Since I made the planing board, several improvements have been implemented. The first was, I drilled a bunch more peg holes, and cut a handful of 3/4″ pegs in various lengths to fit the job. This photo shows the bottom of the board.

Planing Board Bottom

Planing Board Bottom

 

Each added hole has a slot routed in the bottom to accommodate a steel pin screwed into these short pegs. The pin helps keep the peg from wobbling in the relatively thin plywood. For most jobs though, it is sufficient to insert a peg in the top of the board. Note I have planed a flat spot in the side of each peg and the steel pins align the flat.

Pinned Pegs

Pinned Pegs

 

Planing along a board edge was a problem because the larger cam sticks out far enough and high enough to interfere with the tool.  I can raise a work piece by putting spacers underneath, but my Stanley 45 fence hit the protruding cam. The solution was to provide a long, thin spacer between the cam and the work. This is made of a half thickness of maple flooring, with a milled slot that accepts a carriage bolt. I loosely fit the bolt through one of the spine holes and it keeps the spacer from buckling.  Planes now have plenty of clearance.

Spacer in Use

Spacer in Use

 

This photo shows a work piece locked in by the large cam using the hardwood spacer.

The Cam Spacer

The Cam Spacer

 

A close view of the spacer. The slot is wide enough for the carriage bolt head but has a narrower bottom so the bolt won’t spin when tightening the wing nut.

Spacer Componants

Spacer Components

 

In the four years since it was constructed, I have used this planing board a lot. I consider it one of my more successful projects. Nowhere was it used more than the Eleven Grooved Box project. Every piece goes on the board for smoothing and grooving.

This photo shows stock for the box sides getting the last of three grooves. The Stanley 45 has to reference it’s fence against the vertical edge of the work which I have aligned with the edge of the planing board. You can see how the long spacer block just behind my left hand keeps the cam far enough behind the plane fence that they don’t interfere.

Groove three

Groove three

 

Here, the thin board which forms the top or bottom of an Eleven Grooved Box is getting rabbited so it fits into it’s eighth inch groove. I could not do this operation without clamping in the planing board. Again, using the spacer block so the cam doesn’t interfere with the fillister plane.

Rabbit end grain edges to 1/8 inch

Rabbit end grain edges to 1/8 inch

 

Finally, this is an interesting use of the board. The edges of the thin Eleven Grooved Box lip strip have to be planed down until the strip fits tightly in it’s groove. I stick several pegs in the planing board and weave the strip through them. The strip stays put and planing the edge square is easy with a big Stanley number six. It’s very quick to pop out the strip to test it’s fit.

Preparing to trim lip strip

Preparing to trim lip strip

House for a Homeless Stanley

This page documents a White Oak box I constructed in early 2011 to house a Stanley 45. It features a hard wood spine designed to hold the plane securely in place which I will describe in detail.

As far as I can tell, this particular 45 dates from the late 50s. Almost new!  It was a Christmas present to myself. Actually, I already had a 45 but dropped it onto the concrete garage floor. In a fit of despair, I bid on this 45 on EBay and won.  Meanwhile I was able to repair the cracked main stock on the first 45 so now I have two of them working.

Neither came with an original box which was likely cardboard anyway. Hence this project.  Guess I will have to build two of them.

The first photo shows the plane side of the spine. The peg at left hooks the front of the skate on the 45. The plane then is lowered till the skate sits on the horizontal wooden ledge. Three magnets grab the main stock skate while the bottom of the wooden fence sits on a thin strip of Oak underneath the spine.

Finished Box Spine

Finished Box Spine

 

A Stanley 45 has sort of a turned up nose on the skates. That fits under the peg.  The flat strip of Oak under the Rosewood fence is necessary and is cut away at the front because the front tip of the fence pivots down a bit while hooking the plane under the peg, and needs additional clearance there.

Hooking the Skate Under the Peg

Hooking the Skate Under the Peg

 

The main stock side of the oak spine has to be relieved to accommodate the slitter stop and the depth gauge and there was minor chiseling near the dowel to get everything to fit.

It was my goal to not have to disturb the plane’s settings just to put it away in the box. Usually that succeeds, though the fence does have to be close in and in the higher of it’s two positions.

Main Stock Side of the Spine

Main Stock Side of the Spine

 

This is the “new” Stanley 45 plane nestled in it’s docked position. It’s snug and the magnets hold it down pretty well.

On this plane, the tote and fence are Rosewood but not the fence knob.  Stanley stopped using Rosewood about 1960, so this plane was probably made during that transition. The 45 was not made after 1962. I have not yet attempted to de-rust or otherwise clean this plane. Its clean enough to use. I’ve made a lot of Eleven Grooved Boxes with the two 45s.

Docked

Docked

 

Box joints for this project were cut with my lead screw box joint fixture, which is documented elsewhere on this Blog.  Grooves for the top and bottom pieces were cut with a Lee Valley Box Slotting bit  which works really slick.  It cuts a 1/8″ slot so needs two passes to get the 3/16″ groove I needed.  The July 2008 issue of  “Wood” magazine had an article (“Box-Slotting Bits”, Page 24) on using this bit, but unfortunately, it does not seem to be accessible on line. You just set up the slotting bit in a router table, dry fit the box with strap clamps, then set the box over the bit and run it all around the inside.

The next photo shows completed sides and bottom with inside components attached. There is a double grooved block on the bottom which holds the longer set of rods. Button magnets keep the rods in place and there will be more button magnets inset in the bottom to retain the two removable depth stops, and the cam. I made seperate thin sided boxes to hold the cutters, these are screwed in place along the sides.

Box Dry Fit

Box Dry Fit

 

And this is the Stanley 45 nestled in its new home.  I should have made the box a quarter inch longer, had to relieve the panel on the right side to allow the tote to seat all the way. The sliding top fits well enough that the plane can’t move much once the box is closed.

Dry Fit with Stanley

Dry Fit With Stanley

 

I did the glue up in the house as the garage was so cold that PVA wouldnt work.

About 120 box joint pins have to be coated with glue and the whole thing assembled at one time. I use Titebond 3 extend which has a long open time. You get at up to 15 minutes but that still means careful preparation and rehearsal is needed to get the thing together before the glue sets up. 15 minutes is used up very quickly.

I did stain all the interior surfaces prior to glue up as it would be difficult to get into all the corners later. Also liberal use of masking tape inside and out to control glue squeeze out.

On removing the clamps I noticed the box had racked a bit.  Next time I will use strap clamps with corner cauls on the panels. It will be much easier to check for and correct errors.

Clamp Time

Clamp Time

 

The box is finished and assembled.  It has had one coat of straight Minwax Golden Oak stain, two coats of 50/50 Golden Oak and Watco Natural, and a final coat of Watco Natural alone. After the Watco cures, everything gets several coats of paste wax.

You can see the cutters inserted in the two side boxes, long rods stowed at bottom left.  The cam and one of the depth stops are tucked away at top left, and the tongue stop stuck to a magnet at bottom right. Button magnets work well to control those little parts.

Finish Applied

Finish Applied

 

This is the docked position of the plane.  One of the medium width cutters is installed to check the fit and you can see the skates hooked under the dowel at the front.  Later I learned to store the cutters pointed end down. Please don’t ask how I learned that.

Stanley in New Home

Stanley in New Home

 

All the White Oak material was obtained from inch thick cutoffs. It was resawn on my table saw, thicknessed to 3/8″ using a lunchbox planer, and glued up into panels.

The lid slides in a 3/16″ groove which was made with the box-slotting bit. There is a 3/8″ inch radius sanded on the rear corners of the top plate to match the size of the slotting bit  A small lip at the front of the lid gives a better purchase for the brass latch.  The box bottom has a similar design.

That brass latch was way more trouble that it was worth….

All the Parts

All the Parts

 

The box can now be considered finished.  I let the finish cure for a few days then applied several coats of  Butchers Bowling Alley Wax.

Final dimensions are 6 3/4″ x 7 1/4″ x 11 1/2″.

The Money Shot

The Money Shot

 

It’s now May 2012 and I  finished a box for my second Stanley 45.  This one is made of Jatoba – a hard tropical wood with twisty grain which makes it a real pain to smooth out.

Jatoba Box

Jatoba Box

 

The second box is pretty much identical to the first but is 3/8 inch longer.  Please Don’t Ask Me Why the first box is shorter.  Also I made the cutter holders longer on the right side, and used more magnets in the long rod holder.

Second Stanley At Home

Second Stanley At Home

 

This Family Shot shows the new Jatoba box next to it’s older White Oak brother.

Two Stanley 45 Boxes

Two Stanley 45 Boxes

 

The following photos have dimensions added.  Most of my projects are Ad Hoc and if you build something based on these, make sure it fits your tools. I have noticed the two 45s I own are slightly different.

Outside Dimensions

Outside Dimensions

 

The spine has cutouts for the main and slitter depth stops. Two button magnets and a magnet from an old hard drive inset.

Spine Details

Spine Details

 

At the nose end, the spine has an extra piece glued on. The peg that constrains the hook on the front of the skates is inset in that piece.  This is a critical part and needs to be positioned so the skate has enough clearance to hook underneath but is captured securely.

Spine End

Spine End

 

There is a thin spacer underneath the spine. It has a cutaway at the nose end to allow clearance for the fence when the plane is hooked under the dowel.

Spine End

Bottom Spacer

 

Finally, a close up of the dowel in the spine. You can see where I had to remove material to clear parts of the plane body.

Box Spine Nose Close Up

Box Spine Nose Close Up

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