These WordPress pages document my method of constructing a frame and raised panel door. I need to make a pair of these about 30″ x 18″ each to replace an ugly entrance to the crawl space in my home. Each door will be a single solid Pine panel, the frame will be about 2 inches wide with molding on the inside edge.
I have a small panel raising plane. It is unusual in that it has an adjustable fence, there is no nicker and no flat area near the fence, the cut is beveled all the way to the edge of the work. It may have had some other use in the past but it works for panel raising. I have since added brass strips at the main wear points.
Making a cabinet door usually proceeds by constructing the outside frame to fit the target opening, then creating a panel to fit the frame. I have a number of frames made as practice exercises for a real job closing off the crawl space in my house. These were all based on square blanks cut from a length of 1×8 select pine from Home Depot. I used up all the spare lumber so for this weblog post I glued up some scraps and trimmed to 7 1/4 square.
The panel will have a quarter inch tenon all around the edges that seats inside a groove plowed around the inside edges of the frame. The first step is to define this tenon edge by measuring the frame face to groove distance so the panel will be flush with the frame. Subsequent operations will remove wood down to these lines. I darken the marked lines with pencil.
The panel raising plane fence has been set to an “about here looks right” distance from the cutter tip. I’m measuring this horizontal distance carefully, maintaining the angle of the bevel.
I will be defining the inside line of the raised area using a cutting gauge. This is necessary, especially on the cross grain sides because the plane does not have a nicker. Here I transfer the measurement from the previous step to the gauge.
Cut the gauge lines deeply into all four sides of the panel blank.
Here I have darkened the lines with pencil.
One hand tool principle I have learned well is to remove as much material as you can with the blade that is easiest to sharpen. I block plane off wood down to about 1/16 inch from my two lines.
Removing waste wood
Now the panel raising plane does it’s work, starting with the cross grain edges. This plane works well across the grain because it has a steeply skewed blade. Which also means it is hard to sharpen.
Raising the center creates a shadow line which makes the panel look a bit smaller and lighter.
The final step is rabbiting the back of the panel to the line. This M-F 85 has the fence set to cut a quarter inch wide relief and the depth stop set to stop at my line. Since the raised portion of the panel is angled, the edge tenon is tapered so I will make this a little less than a quarter inch thick to make it easier to fit the frame groove.
The finished panel came out fairly well though I had trouble with the panel raising plane. I believe the blade is not bedding flat inside the body which causes the blade to flex slightly and chatter. The wedge also loosens too easily which causes the blade to fall out. I’m working on it.
And it does fit the frame. See how all those shadow lines make the panel look like something other than a flat board.
These two WordPress pages document my method of constructing a frame and raised panel door. I need to make a pair of these about 30″ x 18″ to replace an ugly entrance to the crawl space in my home. Each door will be a single solid Pine panel, the frame will be about 2 inches wide with an Ovolo molding on the inside edge. An Ovolo is a quarter round with a small step. It creates a shadow line around the inside of the frame which softens the edge visually.
Another goal is to, as much as possible, use only hand tools in the project. A few years ago I acquired a small panel raising plane at an estate sale and it’s time to put it to work. This photo shows some of the tools used in creating a frame.
Three episodes of “The Woodwright’s Shop” contributed to my techniques.
“Raising Panel-Zona” describes several methods of making a raised panel.
“Painless Panel Doors” where Roy constructs a mortise and tenon frame.
“Simple Sash Restoration” shows how to join a frame with molding around the inside.
To understand and practice the procedure I’ve made several small framed raised panels. These will find their way into a box or maybe a lamp sometime in the future. This procedure builds a frame to house a pre-constructed panel though usually the frame will be built first, made to fit an existing opening, then a panel constructed to fit.
This, the second page of my frame and panel series describes the frame construction. It turns out that making the frame, with a molded inside edge, is harder than building the raised panel.
My practice raised panels were cut from 1×8 pine, resulting in a 7 1/4″ square panel. The frame begins with two 10 3/4″ rails and two 11″ stiles cut from a pine 1×4 ripped down the middle.The stiles are longer than needed to make them more likely to survive the mortise chisel.
The raised panels have a centerline mark so the first step is to mark a centerline as an alignment reference on the frame pieces.
The stiles and rails are inspected. the best sides marked as face, and a position in the frame picked and marked.
The panel with grain vertical, and both rails are turned bottom up and aligned with the center marks. Four tenon shoulders must be located on the rails. These are aligned with the inside edge of the panel back rabbit but an allowance should be made for the panel expanding across the grain in humid conditions. I use a thick steel ruler as a spacer which results in about 1/32 inch extra. The 12 inch ruler is flexible and bent down so it butts up tight against the rabbit. Both left and right side tenon shoulders are marked on the rails. They are knifed later.
On the face side, the tenon shoulder is a quarter inch farther out to allow for coping the molded edge. Here the back side line has been extended up the rails side and I used a 1/4″ brass spacer to locate the face side shoulder.
This shows the offset shoulder laid out. The face and rear shoulder lines will be knifed to help with accurate sawing, the short side lines are not knifed.
My practice raised panels varied a bit in depth so here I am checking the distance between panel top surface and the bottom of the rear rabbit. Ideally the distance between the top surface of the panel and the bottom of the rear rabbit groove will be 9/16″ which will allow 1/4″ panel raise, 1/4″ panel edge thickness, and 1/16″ for the Ovolo molding.
Set the mortise gauge outside pin to exactly the depth measured above. The separation between the two pins is set to exactly the width of my quarter inch mortise chisel.
Tenons are marked with the mortise gauge then penciled in lightly. Note here the face side line is scratched shorter that the rear side because of the offset shoulder.
Now to cut the tenon cheeks. As Roy shows, part from one side, part from the other, then clamp the rail vertical and saw down to the shoulder line.
Before the tenon shoulders are cut free, a groove to receive the panel is cut with a plow plane. The depth stop is set for 5/16″ a little deeper than the panel rabbit, we don’t want it to bottom out. he plane fence is carefully adjusted so the groove runs right down the center of the tenon.
Once the groove is done it’s checked for depth with vernier calipers. A dry fit of the raised panel confirms the groove.
Next the tenon shoulders are cut off. A bench hook supports the rail while sawing.
The frame groove defines the inside extent of the tenon but the outside is marked 3/8″ in from the edge. The cut will not go all the way to the offset tenon shoulder, it stops about 1/8 inch from the shoulder to create a haunch. The haunch fills excess space in the stile groove and it will be trimmed later to fit exactly.
I’m using a fine tooth dovetail saw to cut the outside of the tenon. It is important that the inside and outside edges be parallel but precise width is not critical. Saw in at the haunch then cut vertically on the line.
With the outside wood removed, these start to look like real tenons. In this photo you can see the offset top shoulder and the short haunch left.
Nobody’s perfect and my tenon sawing technique needs a lot more practice. In the meantime I made a jig so I could true up the sawn surfaces with a router plane. I cleaned each face until the tenons measured exactly 1/4″ with my calipers. This also ensures that all four tenons are the same depth from the rail faces. The jig is just two pieces of 3/4″ MDF clamped to the table top with a machine screw. They support the router plane while it’s doing it’s thing.
Now the completed tenon outlines have to be transferred to the rails to define the matching mortises. I dry fit the grooved rails to the panel and lay that assembly on the rails. Everything is rear side up in this photo and the rails are aligned with the panel using the center line marks.
The tenons lay flat on the blank rails making it easy to mark where the mortise edges will go.
Here you can see both tenon edges are traced on to the rails.
I use an engineering square to bring the marked mortise edge lines around to the sides of the stiles. Then the mortise gauge defines the sides.
Pencil in the gauge lines and the stiles are ready for the mortise chisel.
My mortise chopping technique is straight from Roy’s video. Chop from the far end to near going deeper with each eighth inch increment, reverse the chisel and chop back near end to far. Straighten the edges and in this soft pine you will be half way through. Turn the stile over and repeat, chopping all the way through.
I use an engineers square to check for true inside edges. Trim with the mortise chisel if not.
Once the mortises are cut and dry fit successfully, I plow a groove in the stile. If all measurements were good, the groove will go through the center of both mortises.
This is a face side dry fit of all four joints. It’s looking like a real frame now. If the tenon shoulders were carefully cut, it will be square.
Molding the inside edges starts with cutting a thin rabbit on the inside edge. I use a Miller Falls 85 for this with the fence set to a quarter inch width and the depth stop is set to 1/16″. This should leave a quarter inch square shoulder on the inside which will be rounded over.
It took about a dozen strokes with the rabbit plane to make the 1/16 inch step.
In this photo you can see the shadow line created by the small rabbit.
To begin the Ovolo round over, I chamfer the edge with a block plane. This makes it easier for the molding plane as much of the wood is already removed. It’s a woodworking principle to always use the tool with an easily sharpened blade first.
I have this small hollow plane, it has a 5/16 cutter. The round edge is smaller so it takes some fussing and finally a few swipes with sandpaper to get the curve correct.
When all four pieces are molded, the frame is dry fitted and the edge of the rails Ovolo step carefully transferred to the stile. I also transfer the outside edge of the rail to the stile but since the end (horn) of the stile will ultimately be cut off, that’s not really necessary. The molded edge between the two marks is removed.
I carefully chisel out the molding of the stile between the marks. The rail’s longer tenon shoulder will fit into this recess.
The next step is to cope the rounded molding on the rail. It will fit over the stile molding and give the illusion of a 45 degree miter. This procedure is right out of “Simple Sash Restoration” and begins by using a template to precisely miter the corner of the rail molding.
A close up of the mitered rail molding.
Now the mitered bit is coped. a small scribing gouge is used to remove the wood visible when you look straight down at the miter. This gouge is a little too big for this job but it’s all I have.
This photo shows the coped corner.
The coped joint is dry fit and trimmed to fit closely. Trimming might require fine tuning the cope, planing one of the tenon shoulders, and trimming the haunch. Sometimes it helps to undercut the shoulders a bit. If the shoulders were planed, check the assembly for square afterwards.
Success is a dry fit of all four joints with no gaps.
With the panel inserted you can see what the final product will look like. Since the whole reason for separate frame and panel construction is to allow the panel to move a bit, the panel must be finished before the assembly is glued up. Finishing the glued up frame would be easier but would risk an unfinished line appearing at the panel’s long grain edges in dry weather.
The back side doesn’t show anyway but the rear of the assembled frame and panel should be flat if everything was done correctly. The protruding horns on the stiles and tenon stubs will be sawn off and planed smooth after the final glue up.
Parts one and two of this series showed construction of a small frame and panel assembly. I made a half dozen of those as learning exercises for the final project, rebuilding the entrance to the crawl space in my tri-level home. This may be way over engineered but the old doors are truly ugly, made from thin paneling covered with contact paper, and besides, I wanted to learn how to make raised panels with hand tools.
Most of the techniques I used came from the Woodwright’s Shop episodes mentioned in part 2, this part 3 will document differences needed to complete the larger scale crawl space entrance.
I built a new outer frame from 2 inch pine to fit the existing opening. I have to admit not using hand tools for that as I recently acquired a Kreg K2 jig and wanted to try it out. Also the rails on a butt jointed frame would be four inches shorter than a mitered corner frame which worked out much better with the 72″ stock I had.
The outside dimension of the doors is determined by the inside edges of the outer frame so I propped up the outer frame and centered the stile pieces leaving about 1/16″ gap at the sides.
Each pair of stiles was checked for parallel with pinch rods. Everything came out OK with very little tweaking. Stiles were marked top and bottom where they touched the outer frame. Then I centered the rail blanks on the stiles and marked where they touched the rails left and right. Those four lines define the dimensions of the doors.
Here you can see tenons laid out on the four rails. These were sawn, tuned, and outlines transfered to the stiles as in part 2. Mortising the stiles, then grooving and molding the inside of each piece proceeded as in part 2.
I glued up two panels a couple months ago but had to square them for fitting in the frames. Could not hold the panel steady against the miter gauge so I built a miter gauge helper from a piece of heavy aluminum angle and a toggle clamp, should have done that years ago. The panel surfaces were planed with a Stanley 4 1/2.
Each completed door frame was laid over the square glued up stock. I aligned left and bottom panel edges with the inside of the frame, marked the top and right edges of the inside opening on the panel stock, then ruled a line one half inch farther out on the top and right. This allows room for a 1/4″ tenon all around the finished panel. I then trimmed the panel top to my ruled line on the table saw using the miter gauge as in the previous photo.
Next, the panels had to be trimmed to width. They are too tall to use the miter gauge, so I got out my standard homemade saw fence, a four inch oak timber. I used the line on the cut off top piece to adjust the fence to the proper width.
A deep breath moment. I had been putting off cutting these panels to exact size because I was afraid of screwing up the measurements. In the end, they fit well.
As in part 1, I struck a line with a cutting gauge to define the panel step, then removed wood with a block plane to 1/16″ of the line. Raising the panel actually means lowering the edge. It depends on your point of view. In this photo, the cross grain ends have been lowered and I’m ready to work the long grain edges.
The panel raising plane lowered the bevel to the edge line and created the top step as in part 1. This took a while as the panel raising plane was acting up and I took time to tune it. I believe the bed under the blade is not flat so the blade doesn’t fit properly.
There were a LOT more shavings than in part 1. Working the two panels took most of an afternoon.
The last operation on the panels is creating a rabbit all the way around the rear side. Always cut the cross grain ends first then the long sides. Knifing the cut line with the gauge is mandatory on the ends, the spur on this MF 85 sticks out way too far. I also used a sharp knife to relieve the wood at the left end of the rabbit before planing to reduce tearout there. There was a small amount of fuzz which I cleaned up with the wooden shoulder plane.
I had more trouble with the sides than the ends, the grain was not with me. Home Depot pine does not have a strong grain pattern and it’s hard to see how it’s running. Waxing the plane about every fifth stroke helped.
Checking the tongue for fit in one of the rail piece grooves. I want a good fit to keep the panel from rattling around if it shrinks. I found a web site that calculates wood movement, these 14 inch wide panels could move with humidity variations as much as an eighth of an inch.
Finally, the completed panels fit with very little tuning. I sawed off the frame horns and am happy with the results. This photo shows the back side of the assembled doors.
And this is the raised panel side.
The sawn off horns were rough so I converted my workbench and planing fixture into a shooting board.
Checking the frame and panel doors for fit in the frame is awkward as I don’t have an area in the garage that I trust to be flat. I had to trim 1/16″ from the left bottom, the rest fit well. There will be a final tweaking after the hinges are installed, and a final-final tweak after the glue up, and a final-final-final after it’s nailed onto the crawl space.
Hinge position is somewhat arbitrary. I used the bottom of the panel field as a reference. A steel ruler is held against the raised line and the outer frame marked. This sets the outer edge of the hinge gain.
Laying the hinge on the marked frame defines the inside of the hinge pocket. Both marks were squared across the inside with a knife and deepened with a chisel. I chiseled every quarter inch along the area to be removed then used a Stanley 71 to remove wood. Clamping boards to the sides gives the router plane has something to sit on. A Stanley 71 1/2 that doesn’t have the wide gap at the front would work better for this.
The hinge plate measured .060″, I cut the pockets to about .080″deep to narrow the gap between door and outer frame.
I use a small Vix bit to establish the hinge screw position then pilot each hole with a 1/16″ drill so the screw doesn’t wander in this soft pine grain.
All four hinge gains were cut in the outer frame, hinges screwed in, then the doors were re-inserted and marked where the hinges touched. Those marks were knifed square across the outer stiles and incised with a chisel.
I was able to clamp my router support fixture on the doors. It forms a reference surface for the router plane and also furnishes a square outer edge to locate the hinge.
Here the hinges are seated and the doors dry fitted back in the outer frame. The doors closed OK with a small amount of planing on the inside vertical edge. There will be a final fitting after the door frames are finished and glued up.
Tenon cheek cutoffs are perfect for trying out different finishes and I have 16 of them. I made several samples using Minwax Jacobean, Dark Walnut, and English Chestnut stains plus a few samples with various mixtures. I also experimented with Minwax Pre-Stain Conditioner which produced much more even results. Most of the wood in the house near the crawl space entrance is very dark and I thought the Jacobean would be the best match, but the wife overruled and picked the English Chestnut sample which is much warmer.
The doors were removed and completely disassembled for staining. A raised panel can not be finished in place because if it shrinks, an unfinished area would appear at the edge. So at least the stain has to go on with the panels outside the frames. I did separately the door frames, then the panels, then the outer frame as I did not want to let the stain set too long without wiping off. The Chestnut stain did not color evenly though the conditioner did help. This photo shows the two door frames, one of the panels and the outer frame.
With every frame piece stained and both panels stained all the way to their edges, it was finally time to glue up the doors. I dry fitted the everything together again, reattaching the doors to the outer frame with the four hinges for a final fitting. I noticed the hinge screws were loosening up after being removed three or four times so following a tip in a recent magazine, I drizzled super glue into the screw holes. It seems to help quite a bit.
I propped one door open, removed the center stile, pulled out one rail at a time, applied liquid hide glue to the hinge side tenon and plugged the rail back into the hinged stile. Because I did one rail at a time, the panel could remain in place. Both rails then got the inside tenon buttered with LHG, and the inside stile installed.
Since the doors were still hinged to the outer frame I could check for racking before the glue set up. I clamped the doors in the outer frame, using thin wedge shims inserted under the hinges to even the pressure. After 2 hours for the glue setting, I did the second door the same way.
The next day, I removed the doors yet again and took the outer frame to the crawl space for a fitting around the opening. A little dry wall trimming was all that was necessary. Minwax semi-gloss poly was next, two coats applied to each door and to the outer frame.
Check out the shadow lines in this photo.
There were a bunch of cutoffs from ripping original stock down to two inches. I planed, stained, and varnished some of them. These will form a lip around the inside of the crawl space opening. One of the original specifications was that the doors be insect proof.
Finally it was time to install the frame and assemble the doors. There are only four 8d finishing nails, one at each hinge, holding the frame on in this photo. I may put more nails in the top and bottom rails after the wood acclimates but for now the doors close without rubbing anywhere. One of the finished strips was screwed to the inside edge of the left door with a quarter inch protrusion, so the right door holds the left door closed and theres no visible gap. The old doors had two magnetic catches, I reused one at the bottom of the right door.
This is what it used to look like.
This has been a four month long project with much of the time spent learning how to use hand tools to create the raised panels. I couldn’t have begun without inspiration and education from Roy Underhill. Three episodes of “The Woodwright’s Shop” contributed to the project.
“Raising Panel-Zona” describes several methods of making a raised panel.
“Painless Panel Doors” where Roy constructs a mortise and tenon frame.
“Simple Sash Restoration” shows how to join a frame with molding around the inside.
If you don’t know what a router plane is, you probably don’t need one.
I have a couple of Stanley 71 router planes. The cutters are difficult to sharpen because the bevel is blocked by the shaft that connects the foot with the plane. Last weekend, at a Midwest Tool Collectors show, I acquired a Stanley 271 which is similar to the 71 but only about a third of the size.
The small cutter in the 271 is even more difficult to sharpen that a 71 blade and this one had significant rust pitting to grind out.
The foot (business end) bottom side of these cutters is flat and ground at an angle to the plane base to provide a relief area behind the cutting edge. Flat surfaces can be ground and polished on stones in the conventional manner, I have a coarse diamond plate and with sufficient elbow grease was able to flatten and remove all rust pitting on the bottom of the 271 cutter. That little guy is hard steel!
But the bevel did not yield as easily. An internet search showed people holding the cutters upside down with the bevel on the edge of a stone. I could not hold the small cutter at a consistent angle and I was rounding over the bevel, a no-no on a plane blade. So I did what any red blooded woodworker would do. I took a nap. When I woke up I had an idea. I have a saw sharpening jig that combines a saw vise with a flat reference plate which stabilizes the triangular file. If I could create a similar reference plate parallel to the router plane blade bevel, I could use that to guide a diamond file. And this method would work just as well on a Stanley 71 cutter.
In the junk pile I found a bit of aluminum bent at a 90 degree angle. It probably was a rack spacer in a previous life. This would do as a reference.
Sandwiching the cutter between the machinists vise jaw and the reference surface was easy. I propped up the back end of the reference plate with wood blocks.
Now to align the surface of the bevel to the reference surface. The bevel angle on the cutter is thirty degrees. To that must be added the six degrees of the flat bottom relief angle. So the bevel is thirty six degrees from the shaft axis. I marked a 36 degree line on a plastic template and eyeballed the shaft angle.
Next, the height of the bevel above the reference surface has to be set. I am using a ruler to support the far end of the diamond file so the bevel surface must be exactly one ruler thickness above the reference.
After fussing back and forth checking the shaft angle and the bevel face altitude several times, I was ready to grind. A drop of oil went on the reference plate so the ruler would slide easily. Then hold the ruler with two fingers and press the diamond paddle tight to the ruler with another finger then slide the whole thing down the surface and back. It was easier than it sounds. I actually started with a much coarser diamond file just to get the bevel initially flat and rust free.
This photo shows how raising the cutter bevel to the proper height makes the paddle parallel to the reference surface.
Did not take long at all to get through the four diamond grits I have available and now a nice even shine on the cutter bevel. No more dubbed over.
I touched up the flat bottom of the cutter to polish and remove any burr.
And it works! Many times I could have used one of these little routers and now I own one. Thanks MWTCA.
In a Chicago winter it’s way too cold in the garage for woodworking, so I turn to coding to pass the time. In 2014 I built an ATTINY85 Morse Code keyer in an Altoids Small box and in 2015 I expanded that with an Arduino Pro Mini based keyer in a regular Altoids tin. It was a lot of fun and consumed pretty much the whole winter. I’ve written down a few ideas for enhancements and in this year’s model some of those are implemented. The hardware wish list (so far):
Batteries and LCD won’t fit in an Altoids tin. I found a metal Crayola box at Tuesday Morning. It was made by the Tin Box Company, who produce many designs that would make interesting project enclosures. It is 3″ x 5″ x 1.5″, about three times the volume of an Altoids box, the metal is slightly sturdier than Altoids but still flimsy enough to be difficult to work without distortion. I found the inside surface was coated with a thin layer of something which repelled solder unless sanded a bit first. I don’t see this particular box available any more but there is a slightly larger version. My experience indicates that the time to complete a project is inversely proportional to the size of the enclosure (maybe to the fourth power).
These days “Arduinos” come in many shapes and varieties. The latest official 1.6.7 IDE is almost 100 megabytes, expanded to accommodate different versions. I wanted to try processors other than the standard ATMEGA328, so last summer bought a Teensy2.0 (32u4) and a TeensyLC (ARM Cortex M0) made by PJRC. Both promise built in USB client support. The PJ in PJRC is Paul Stoffregan, who has contributed a great deal to the Arduino community. There’s an IDE add-on “Teensyduino” that must be downloaded from the PJRC site to use Teensy boards. Teensyduino installation is dead simple and includes Teensy versions of most familiar Arduino libraries plus a few useful additions from Paul.
Last summer I worked with the Teensy2.0 a bit, wanted to see if the DDS sine wave generation function I used in the 2015 design would work. The port was successful, the 32u4 required only a few minor tweaks, and I even got Fast PWM working as described in Atmel’s documentation. PJRC has a forum where you can brag about your accomplishments so I wrote something on the 32u4 DDS sketch thinking it might be useful to others. Paul Stoffregan replied suggesting I consider a Teensy3.2 as it has an integrated Digital-Analog Converter which would produce a cleaner waveform. I fired up the similar TeensyLC and used Paul’s suggested method. DDS on the TeensyLC was also successful so I built a breadboard version of last years keyer using the LC. Everything worked with PJRC’s libraries including DDS side tone, the PS2 keyboard, and lcd.prints added for the display.
The small module at the upper left of the breadboard is an Adafruit PAM8302 audio amplifier. Last year I struggled with a 1 transistor class A amp for the speaker, gave up on that and built an LM386 design. The PAM8302 amp at only four bucks is clearly a winning choice. The only problem I had was later on I discovered the Output side did not like being grounded and I had to insulate the external speaker jack.
TeensyLC has one serious limitation for my application. Because the ARM chip handles flash differently than the MEGA328, TeensyLC has only 128 bytes of emulated EEPROM. That meant limiting stored button memory to four messages only 30 characters each. At that time I was thinking about adding a Real Time Clock so looked at getting Adafruit’s FRAM breakout and their DS1307 RTC. But for less money than these two modules plus a TeensyLC I could get a Teensy3.2 module with a Cortex-M4, lots of memory, built in RTC, and 5 volt tolerant inputs. I sent off an order to Adafruit (10% off if you watch “Ask An Engineer”).
Teensys have lots of I/O pins, same spacing as the LCD modules, so I elected to mount the Teensy board directly on the LCD. One 3 pin header and one four pin header is needed. In the next photo you can see the headers with two short gray spacers to separate the PC boards. I had to flatten one of the LCD bezel mounting tabs for clearance but the mount is very compact and rigid. Note to self: make sure you don’t need any more connections to the bottom of the board before soldering down the headers.
I had the idea to use a software driven flashing LCD back light to indicate a flat battery. ARM I/O pins are limited to 9 milliamps each, not enough for an LCD back light so a 2n2222 transistor was glued in to act as back light current switch. The trim pot on the right is for adjusting LCD contrast. It is across the back light LED pads, did not work out well, as later in development I am PWMing the 2n2222 to get adjustable back lighting. So the trim pot has been moved up on the LCD board, epoxied in place, and hard wired to ground and +3.3 volts.
The two wires leading off the right end of the Teensy go to a CR2032 backup battery for the Real Time Clock, and you can just see the Adafruit 32KHz crystal added on the bottom of the Teensy. With this minimal configuration I was able to test and experiment with the built in RTC using the example program furnished with the PJRC Time library, modified with LCD prints. Initially setting the clock was a problem, you need to send a “T” followed by Unix time (seconds since 1970) into the serial port. I worked out this Linux incantation to get the proper format for Central Standard Time:
echo T$[`date +%s` – 6 * 3600]
Then copy “T1453151560” and paste into the Arduino serial window. Once the clock has been set it takes care of itself though I’m not sure how. I believe it reads and sets time from code uploaded from the compiler. The Time library is more than a little obscure.
Of course many wires have to be added to interface Teensy with the rest of the keyer. It’s not so neat looking now, I’m using nearly every I/O pin plus power from the built in 3.3 volt regulator. I use mostly 24 gauge wire, solid if connecting to other points on the lid, stranded if routing to points below. I have an old Ungar fine tipped soldering iron plugged into a Variac set to about 70 percent.
There are three auxiliary perf boards in the design, One mounts seven memory switches, another holds volume control, transmit LED, and the Function button, the third has clock battery and an optoisolator for transmitter keying. These boards were carefully laid out on paper, then cut out and marked up so mounting holes could be located. Working with a hinged lid box you have to be careful to leave extra clearance for the lid to close. I did have to file a bit off the button board and the speaker.
The box needs a couple dozen holes to mount parts. Blue tape was applied to all surfaces, a layout drawn on the tape, then all holes center punched. I start with my smallest drill bit in a drill press then enlarge 1/64 at a time to final size. A few holes required fine tuning with a tapered reamer. I made a rectangular cutout for the LCD bezel by using a wooden template screwed to the lid, then cutting with a 3/16 carbide router bit surrounded by a 1/4″ collar. Mounting hardware is mostly 2-56 with a few 4-40 spacers.
I had a pair of paralleled 18650 cells taken from a cell phone charging pack. These are fastened in the box by a strip of tin can metal soldered in, and restrained by an angle bracket soldered at one end. The small speaker was taken from a defunct IPod dock. In the next photo, most of the lid components are mounted. The small audio amp board goes on the two screws at right center of the lid, mounted mezzanine style.
Next is a close up of the batteries with 2 amp fuses soldered in both plus and ground leads. Also see three stereo jacks at the right side for Key/Audio Out, External Speaker, and Paddles In. You can see in the bottom three long #2 screws for mounting the third perf board and Adafruit boost/charger. Most board mounting screws have three nuts; one to secure the screw, one to support the bottom of the board at the proper height, and a third to secure the board against the second. Thank heaven I still have a Heathkit nut starter.
At the right side of the box there is a power switch, PS2 jack, and a micro USB jack breakout. The power switch does not actually switch power, it grounds the Enable pin on the charger board which turns off the boost converter. That allows charging to continue while the rest of the unit is off. Later in debugging the hardware, I added bypass capacitors to that switch and a separate wire to the Enable pin on the audio amplifier which suppresses a weird sequence of sounds from the speaker on powering off. The PS2 jack leads wouldn’t reach the processor board so they route to the third perf board and get jumpered there to stranded wire headed for the Teensy. It’s getting hard to find a real PS2 keyboard but the software works fine with a USB keyboard plugged into a USB/PS2 adaptor.
This is a good place to register a complaint. I bought the Adafruit PowerBoost 500 board to manage the battery. It charges from 5 volt USB in and boosts from the 3 volt battery, seamlessly switching sources when you pull the USB connection. It does NOT however pass through or even break out the two USB data pins from the micro USB input jack. The only way to actually use USB while charging the battery is to wire out the D+ and D- leads outside the board. Adafruit support suggested doing this by cutting up a USB cable. I was able to route the micro USB breakout data leads (Green in the next photo) to the processor and the incoming positive and negative supply leads to the PowerBoost using a plug from an Adafruit micro USB connector (red and black in the photo). An extra $2.50 in parts that wouldn’t have been needed if Adafruit had only provided pads on the PowerBoost for D+ and D- or better, added two traces to route the data signals from the input connector to the output connector.
One more issue with the PowerBoost. It has a nice pair of status LEDs (where it says CHRG) yellow when charging and green when fully charged. These operate from a single pin on the charger chip but that pin is not broken out and you can’t of course, see the LEDs when the box is closed. I added a wire (gray, leading off to the right in the photo) to the common side of the LED dropping resistors so I could have the Teensy display charging status on the LCD. Not difficult but would have been nice to have official access to that chip pin.
The keyer has four monitoring leads between the PowerBoost and the processor. Besides the status signal mentioned above, I wired up the LowBattery pin and USB (power). USB activates the Status signal which is only valid when USB is plugged in and receiving power from the host. LB goes low when the battery is REALLY flat (3.25 volts I think). I also wired the BAT pin to the Teensy A10 analog input through a 10k calibration pot so software can read and display the battery voltage. You can see the calibration pot at the bottom of the board in this photo.
The next photo shows how I insulated the External Speaker jack by opening up the mounting hole and screwing a small piece of Lexan to the box. The plastic had to be counterbored so the jack mounting nuts would fit.
Here is a close up of the box lid interior. You can see the LCD contrast pot which is glued to the LCD, perfboard for the LED, volume control, and Function button. Two screws and a couple of spacers mount the PAM8302 audio amp on top of the LED board.
Here is the completed keyer opened up. Clockwise from top left, I/O stereo jacks, 18650 batteries, memory button board, Teensy3.2 processor on top of 16×2 LCD display, LED board, speaker, on/off switch, PS2 keyboard jack, USB input jack, PowerBoost charger/boost converter, and the transmit interface board.
An Eagle schematic diagram of this project can be downloaded from:
February 25, 2016 MemoryKeyerTeensy3.2_V1.0 Initial sketch
March 9, 2016 MemoryKeyerTeensy3.2_V1.1.0 Rework battery alarm logic, bug fixes.
March 16, 2016 MemoryKeyerTeensy3.2 V1.1.1 Workaround fix LCD does not have backslash in its font.