Eleven Grooved Box Step by Step – Part 8: Cutting the Box Open

Cutting the Box Open

View the original Woodwright’s Shop video here.

Getting the top edges flat and true is the next process.  The glue up is never perfectly even.  I use a number five plane for this as it has a bed long enough to use the opposite side of the box as a reference surface.  I set the plane on the box at about a 45 degree angle and start the blade exactly in line and over one of the miter joints. The direction to move is determined by the grain of the side pieces. Then push the plane down the side and when the blade nears the next corner, slowly rotate 90 degrees and continue down the next side.  Continue this rotary sequence until a shaving is coming off evenly from all four sides.

level the bottom surface as well.

Leveling the box top

Leveling the box top

Set a marking gauge to a distance from the top edge to just above the center of the (now hidden) lip groove.  Mark the box carefully and heavily on all four sides.

Marking for saw cut

Marking for saw cut

I have a nice old dovetail saw for cutting the box open. Dovetail saws are rip filed and make a very thin kerf, but any rip filed fine toothed saw would do.  Begin at the corners, cutting in at a shallow angle, gradually working back along the line.  Rotate the box and start the next corner.  Remember the saw is guided by the kerf itself so you have to watch both sides the saw is working. Work carefully and watch the line.

Saw the Box Open

Saw the box open

Once you get two or more sides cut completly through, the vise wants to pinch the saw blade. Insert a steel ruler in the cut side kerf to minimize that problem.

Ruler Trick

Ruler trick

Continue rotating the box, sawing a bit and rotating again until all four sides are separated.  It’s always a good feeling to see the inside for the first time (unless you find a lot of glue squeeze out to clean up).

Finally open

It is open

Use the circular planing technique as described above to level both freshly sawn surfaces.  Remove all saw marks with the plane.

Leveling the sawn surface

Leveling the sawn surface

I do a final flattening of both sawn surfaces using a sheet of sandpaper on the (flat) table saw top.  First 150 grit then 280.

Final flattening of sawn surface

Final flattening of sawn surface

Hold the box top and bottom together to check how good you have trued them up.  Can you see the cut line? It doesn’t have to be absolutely perfect as later we will ease both edges slightly with a block plane which will cover up small gaps.

Checking for true edges

Checking for true edges

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Eleven Grooved Box Step by Step – Part 9: Applying the Lip Strips

Applying the Lip Strips

View the original Woodwright’s Shop video here.

When the sawn box edges are as good as they are going to get, it’s time to install those lip strips.  The glue up is not as intense as when the box itself was assembled but it’s still a good idea to dry fit and lay things out before hand. Remember these strips were carefully marked to match the grooves they were created in. If the strips appear to fit too tightly, trim them on the shooting board.

Glue protocol is similar to the first glue up. Brush glue evenly on the rabbit on the inside of the box all around, then brush glue on the bottom and lower half of the back of each strip, and carefully on the mitered ends. Insert the strips as they are buttered up. Don’t use so much glue that you get squeeze out. If you do, wipe it off immediately with a damp rag. Sometimes you have to bow the strips to force them into place. When they are all in place, tap all around with a soft mallet to make sure they are seated in their groove.

Preparing to glue the lip strips

Preparing to glue the lip strips

I use a tight string to make sure the miters on the strips are pulled together well.

String clamp on lip strips

String clamp on lip strips

As I said before, it never hurts to add another clamp.  These make sure the bottom edge of the strips get pressed home.

Spring Clamps on lip strip

Spring clamps

Since we removed one saw kerf plus planing both sides of the opening, the lip strips are now too tall.  I mark an estimated amount to remove around the lip then plane to the line. The planing will be more even that way.

Marking lip for removal

Marking lip for removal

Using the circular planing technique, remove material from the lip strips down to the line.  I’m rotating the plane counter clockwise here because that’s the way the grain lines up. Be careful as the strips are thin and chip easily.

Planing to the line

Planing to the line

The lid may go on at this point but usually not until a small amount of wood is removed from the periphery of the lip. A rabbit plane is a good tool for this job, but sand the corners round a bit first and watch the grain direction to reduce the chance of tear out at the end. Check the corners of the lid’s inside rabbit for glue squeeze out which can prevent the lid from seating.

Test fit the lid after each pass. For extra credit, also test fit the lid rotated 180 degrees from it’s original box position. Angle the plane slightly so the lip is tapered and the lid will go on easier. You may find that a bit more has to be circular planed off the top edge of the lip for the lid to fully seat.

Thinning lip for better fit

Thinning lip for better fit

Once the lid fits satisfactorily, go around the lip and all the other box edges with the block plane and chamfer the edges one or two passes. Ease the inside edges where the plane can’t reach to match with fine sandpaper.

Breaking the edges

Breaking the edges

With the lid sliding on easily and a nice even line all around the cut, the box construction is done.  Final sanding the outside and applying an oil finish is next.

Checking the lid for final fit

Checking the lid for final fit

Eleven Grooved Box Step by Step – Part 10: Apply Danish Oil Finish

Apply a Danish Oil Finish

View the original Woodwright’s Shop video here.

Roy leaves his Oak box unfinished, or suggests it be covered with veneer. That would be interesting, but I like a classic rubbed Danish oil finish. This always starts with a very heavy first coat. Completely flood the piece, let it sit for 1-3 hours then wipe off any excess. Let it cure for a day, or two days in cool weather, before applying another coat.

liquid oil enters and caps pores in the wood, trapping air below, so it’s best to apply at the warmest time of day, usually 3:00-4:00 PM. Then when the piece cools down, oil will be drawn farther into the wood by the trapped air contracting (good).  If instead you apply oil early in the day and let the piece warm up, the trapped air will expand, the oil “bleeds” out the pores (bad), and you have to wipe it down several times.

It’s always satisfying to watch the grain come out when applying the first coat of oil.

Apply first coat of oil

Apply first coat of oil

After a couple of hours the oil saturated wood is wiped down with paper shop towels. Any wet areas must be removed.  I wrap a paper towel around the end of a plastic putty knife to get into corners.

Wiping the first wet coat

Wiping the first wet coat

I once asked my Danish brother in law how to apply Danish Oil. He replied “Once a day for a week, once a week for a month, once a month for a year, once a year forever.” A mantra good for Scandinavians, but I use an ancient secret technique (that I got off the internet) to shortcut the process.  I apply the oil with wet or dry sandpaper, starting with 320 grit on the second coat, 400 grit for the third, and 600 grit for the fourth coat.  That’s usually enough for a finish so smooth that it begs to be touched. I cut a  full sheet of sandpaper into 16 pieces and use a small wood block to do the application. It is critical to keep the work area clean. One particle of sawdust on the applicator will destroy the hard won finish.

Apply coats of oil with sandpaper

Apply coats of oil with sandpaper

Below I’m finishing up the second coat application.  I wet the surface with Watco, then sand lightly a few minutes until it begins to set up. You can tell by the sandpaper starting to drag noticeably. At that point I ease off pressure on the sanding block and lightly go over the surface while holding the piece up to the light so I can see how even it is.  The slurry of oil and sawdust will be pushed into and fill the wood pores.  The process is not unlike spit shining your shoes.

I’ll only apply two coats to the interior of the box and don’t bother sanding in there too much.

Second coat application

Second coat application

In 1-3 hours, the sanded surface will have dried to a dull haze. I  wipe the piece down to remove any excess oil, and all dried haze from the surface.  At this stage, wipe the surface cross grain to avoid pulling the drying slurry from the wood pores. Rub until all the hazy coating is removed. I check carefully in strong reflected light as the haze is very difficult to remove after it has completely dried.  12-24 hours later wipe the piece again, using more pressure.  The oil will still be a little plastic and the surface smooths out even more.

Rubbing the surface out smoothly is critical to the success of the finish. The piece will fingerprint easily at this point, so I always hold it with a paper towel.

Wiping second and subsequent coats

Wiping second and subsequent coats

I wait at least a day between coats, repeating the sand and wipe procedure with successively finer wet/dry sandpaper.  Finally, allow two days for complete drying, then apply two coats of paste wax.

I’ve used the same sandpaper procedure with Boiled Linseed Oil, thinning the first flood coat a bit with turpentine.  It comes out just as smooth but the Watco cures faster.

These four boxes were made between late July and late October 2013. There were several other distracting projects in August and September that lengthened the build.  I can make a box in two days if I have the jigs set up, but my goal is to get practiced enough to make one in a single day.

Family Portrait - Four boxes

Family Portrait – Four boxes

Four finished boxes

Four finished boxes

Spline detail

Spline detail

Single box for 3x5 cards

Single box for 3×5 cards

Finally, the results of a couple months work, ready for Christmas wrapping.

Family Portrait

2014 Family Portrait

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Update July 2014:

Somebody at the local woodworkers club left two slabs of Butternut on the free table. I turned them into pencil boxes. Attempted to stain one with Minwax Chestnut, it did not come out so good. The other box I left alone and finished with the usual Watco natural. My spit shine technique takes longer but I can get a really amazing surface in four coats.

 

eleven grooved box

Two pencil boxes in Butternut.

Splines and lip strip fit very well. Reflected light on the box side shows how well the oil has filled in wood pores. Compare the inside of the box which did not get the super smooth treatment.

Eleven grooved box

Spline detail on box

Clothes pins in series

I have a drill battery that for some reason will not work in the factory charger. (possibly because I rebuilt it myself) So I need a way to kludge on a laptop power supply to do a trickle charge. Not having a socket for the business end of the battery, I have to attach wires somehow. I tried a standard clothes pin, will stretch to the one inch spacing if you bend the spring. It is not satisfactory. So I made a wider clothes pin by gluing two together in series. The glued blades are sawn off and the tips shaped a bit. Works great.

Clothes pins

Clothes Pins in Series 1

 

I can make a triple too.  A standard clothes pin will open less than a half inch. A double will open an inch, a triple an inch and a half.  Those are the spade tips I used to make the actual contact with the battery terminals.

 

Clothes Pins in Series 2

Clothes Pins in Series 2

 

SPI Backpack PCB for Liquid Crystal Displays: Part 4 LCD library

Adafruit’s LiquidCrystal backpack library doesn’t use the Arduino SPI library to send data to the 74HC595 chip. They just shiftOut bits directly, which works fine if the only device is the backpack.  However, the fazjaxton CAN library does call the SPI library.  This caused major problems when switching back and forth between CAN and LCD because the clock rates were way different.

I decided to investigate the LCD 74HC595 SPI implementation by Juan Hernandez from the Arduino playground which uses the Arduino SPI.  It took quite a bit of time to get that library working because Hernandez uses a different pinout connection from the ‘595 chip, and did not have the LCD backlight control.  Since I already have the PC board cut for the Adafruit pinout, I had to figure out how to rearrange the Hernandez code.  Once I finally got his HelloWorld-SPI demo working though, it was simple to add the backlight bit, and I could modify the head end sketch to match. I changed the LCD code to use the same SPI clock rate as the CAN and they play together very well now.

This is the backpacked head end with new code displaying light level and temperature from remote station 31.

LCD display at head end node

LCD display at head end node

SPI Backpack PCB for Liquid Crystal Displays: Part 3 Assemble and Test

The completed printed circuit board needs to be stuffed with components.

Populating a PC board is best done by placing the shortest components first and the tallest components last.

So first to go on are the Z wires. These connect traces on the bottom to traces on the top.  They are necessary because this homemade board does not have plated through holes.

Z wires

Z wires

The next higher parts are the resistors.

Adding resistors

Adding resistors

Next capacitors, chips, and the crystal.  Some of the leads have to be soldered on the top and on the bottom of the board.  Again, this is because I do not have plated through holes.

Add capacitors and chips

Add capacitors and chips

Now I attach the CAN connector, the contrast pot, and the header that mates with the LCD. These are the tallest parts

Add connectors, headers, and the contrast pot.

Add connectors, headers, and the contrast pot.

Finally, some rainbow wire to connect the backpack to the Arduino.  Also the backlight switch transistor at this time because it took a while to find one in my junk box.

Add wiring and the backlight switch transistor

Add wiring and the backlight switch transistor

Finally solder it onto an LCD display and see if it works.

It does!

Remote light level and temperature on the display

Head end prototype showing light level and temperature from the remote

Head end prototype showing light level and temperature from the remote

The project needs quite a bit of work on the software to be effective. The two SPI functions seem to interfere with each other.  Suspect a library conflic.

SPI Backpack PCB for Liquid Crystal Displays: Part 2 Print to Finished PCB

In this part I’m showing a method for transferring the laser printouts to double sided PC board material.

Double sided printed circuits must have the top and bottom masks perfectly aligned.  I begin by using a sharp scribe to pierce the exact center of each corner hole on both the bottom and top layer printouts.

Starting holes for alignment

Starting holes for alignment

Next I insert one of these tiny nails (3/4″ #18 gauge) into each corner of the bottom mask.  I could use sewing pins but nails have flat heads which keeps them standing up during the next steps.

Alignment nails

Alignment nails

The next photo shows the bottom layer printout with alignment nails inserted into the mask’s corner holes. If I was making a board without convenient holes, I would add holes to the Eagle drawing outside of the board area and just trim them off after completing alignment.

Bottom mask with alignment pins

Bottom mask with alignment pins

Now I take the top layer mask and carefully slip it face down onto the alignment nails, smooth it out and tape the top edge. The tape maintains the mask alignment from here on.

Top mask aligned with bottom mask

Top mask aligned with bottom mask

Next I removed the four nails.  In this photo you can see how the two masks align face to face. Holding the aligned sheets up to a strong light should show any problems.

Top and bottom masks aligned

Top and bottom masks aligned

I’ve scrubbed the blank PC board material with fine steel wool and wiped it down with lacquer thinner. It cannot have dirt or fingerprints.  Now that my masks are aligned I can position the blank over the bottom printout. I use bits of Kapton tape, though the board should stay put without tape if the paper is not moved before applying the Iron. I cut the blank about a quarter inch oversize on all sides to make this step easier, the excess will be trimmed off after etching.

Blank PC board on mask

Blank PC board on mask

It’s time to heat up the Iron. I use the highest setting, which I think is still a little cool.  I let it sit on the mask/board/mask sandwich for two minutes to make sure the copper is hot enough to melt the toner. There’s a slab of MDF underneath the paper so my workbench doesn’t get cooked.

Ironing the toner onto the board

Ironing the toner onto the board

I remove the Iron and immediately use a small rubber roller (brayer) to press the mask firmly onto the copper.  Not sure this step is necessary but I think it helps even out the transfer when the Iron face is not perfectly flat, or the Iron temperature may not be even across the face.  When the board has cooled a bit, turn it over, repeat the heating and rolling process on the other side.

Rolling out the toner

Rolling out the toner

When the board has cooled enough that you can handle it, trim away most of the paper but leave a little bit around each edge. Be careful at this stage, pulling the paper off will ruin the toner transfer.

Finished mask transfer

Finished mask transfer

Next the paper has to be carefully removed from the board in such a way that all the toner is left on the copper.  I put the sandwich into a tub of warm water with a small amount of dish soap. In a half hour or so, the paper will begin to disintegrate.  Just rub the paper gently with fingers, center towards the outside, and it sloughs off easily.  If a bit is stubborn, give it more soak time. You must remove all the paper from the areas that will be etched.  Paper left on the masked areas is OK.

Removing the paper from the toner

Removing the paper from the toner

This is the transferred board dried and ready for inspection.  The toner is somewhat delicate so you can’t touch it.  I use a visor magnifier and check all traces for complete coverage.  Repairs can be made with a fine point Sharpie pen though I believe a typewriter correction pen would work better.  Sharpie ink is too thin.

I painted the quarter inch of excess copper around the board edges with typewriter correction fluid and it stood up well to the etch bath.  Also have to watch for smudges in the mask.  My old laser printer has a tendency to drop toner in random places, I have to scrape these off with the scribe.

Toner transfer finished

Toner transfer finished

Finally into the etch bath.  I’m using the aerated cupric chloride method as learned from Jim Williams. I have a good size aquarium pump feeding four air stones at the bottom of a 4 inch square etch tank.  There’s about a pint and a half of Muriatic acid in there. I pull the board out every minute to check progress. In this photo it’s about 2/3 done on one side. At that point I turned the board over so the other face got the bubbles.  Took about 15 minutes to do both sides.

Into the etch bath

Into the etch bath

It can be difficult to see when all the copper is removed.  You have to inspect both sides carefully.  Here I placed the board fresh from etching onto a florescent light so I can see through it.  The alignment is looking pretty good as evidenced by light through the pad holes, and I’m not seeing any shadows where the copper was removed.

The etched board

The etched board

All that is left now is to clean off the toner with Lacquer thinner, trim it to final size with my big garage sale tin snips, and drill  holes with a #64 bit in a Dremel tool.  This composite photo shows the top and bottom after drilling.  You can see the pad alignment around the drilled holes is very good.

Completed board ready for components

Completed board ready for components

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