Chassis

Chassis is a wooden box I made.

Note the original plan was going to be a 2 piece amp with a separate Power Supply unit.  I built the power supply chassis first.  But then I set the project aside for a few years, and when I restarted, I decided to simplify it, and build it all in one box.  So I took the box I had already built, and figured out how to fit the amp into it.  Luckily, the fiberglass top plate fit in the chassis, and I was able to figure the rest out.

Top Plate

I bought pieces of g10 fiberglass from these guys

http://www.alphaknifesupply.com/zdata-ordering.htm

They had  earth/coyote/tan at 0.128 thick on sale at the time.

I also ordered these

http://www.amazon.com/gp/product/B000HE86L4/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

I used them to make the holes for the tube sockets in the g10 sheet.

They have better sets available now, or you can use hole saws made for wood, I did that for the bigger holes.

Heatsinks: I have to make some adjustments for the heatsinking because I am bottom mounting all of the heatsinked parts, and I want to use larger heatsinks

I have a bunch of metal bars (PN 401-67502) from surplussalses.com a while back. 

Heatsink. Spacing - Tapped holes for four TO-247. Tapped mounting holes on edge. Dimensions: 3-13/16" x 1-1/2" x 1/4"H. 

Basically just a flat, thick bar.  1/4" thick was thick enough so I could drill a hole in them, and tap a 4-40 hole, which I used to hold them to the TSE board.  I have a drill press, makes it a lot easier to drill a hole like this that needs to be kind of deep into a fairly thin piece of metal.

I drilled new mounting holes in the PWB, and then drilled and tapped holes in the bars guys to hold them to the board.

I drilled/tapped a few more holes to add a PN 401-27211 to one of my bars.  Added some thermal compound between the metal pieces for heat transfer.  Maybe overkill, but my heatsink is quite a bit heavier with more surface area than the ones called for.  Also a lot more work to make with all the drilling and tapping I did.

Wooden Chassis

I made the chassis a few years ago, so now trying to remember what I did lol.

The main box is made from curly maple wood I bought online from here

I did some research on popping the grain in curly maple.

My technique was to use mix 2 oz water with about 5 drops of TransTint Dyes, Dark Vintage Maple.

Sanded down the wood to 320 grit or so.  Apply the dye, when resand so dye only remains in the grain.  

Apply shellac over that, I used Zinsser Clear Shellac Traditional Finish and Sealer because you can buy it locally, but would no longer recommend because Shellac lasts about a year after it is mixed, and Zinsser stopped putting dates on their Shellac.  

I put a 1 pound coat to start, then one or two 2 pound coats.  

Finally, I used Deft spray lacquer.  The blue can is real lacquer.  Spray cans are more expensive, but work fine for a small project like this.  

Lacquer is very flammable, and dangerous to breath, so you need a good mask and I did it outside.  Few coats of lacquer, and I called it finished.

I made 45 degree cuts on my Dewalt table saw for the corners of the box.  I also made grooves in each side, and the same place.  The grooves were to hold a piece of thin plywood, which would serve as the floor of the box.  The grooves were about 1/2" from bottom, to allow airflow under the floor.  

Note that I made holes in the floor and the top plate to allow air flow.

I also made two cutouts at the bottom of both sides, for airflow and to make it easy to pick up the chassis.

Corners

For additional strength, and also because they look cool, I added dovetail keys as described here

www.woodmagazine.com/woodworking-tips/techniques/joinery/dovetail-keys

Pretty sure I used Bubinga for the keys because I had some, and it has a nice color after finishing..

I practiced on a test piece first, then did them to my box.  I remember making the keys as the hardest part, but I also made test pieces to get the fit right before making the real ones.

Front

From the old 2 chassis design, I had drilled two holes in the front of the chassis which were going to be the PS outputs.  I decided to use one hole for the headphone jack, and 2nd hole for volume pot, problem solved.

While I was enlarging one of the front holes, I tried to use a step bit and messed up the hole.  Well that sucks.  So I'll need to cover my mistake, will add another piece of some different wood, add a design element to the box.

I bought some burl walnut veneer, was going to veneer a couple small pieces to go over the front holes, and a larger piece to hold the output transformers behind the fiberglass top plate.  But I messed up trying to hammer glue the veneer to the transformer piece, so needed an alternate plan.

Went to my local Rockler, and bought a 1/4" thick piece of Leopardwood.  It was very cool looking, distinctive pattern.  Did some test finishing on a scrap piece with dye, Watco oil and pore filler.

My final formula was sand to 600 grit, dye with a mix of 1 oz water, 1 oz denatured alcohol and 5 drops of TransTint Dyes, Dark Vintage Maple.

Sand after dye tried, few coats of Watco natural danish oil then a few coats of shellac.