Crawls Backward (When Alarmed)

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The '42 Tube amp, Cont'd

Looking around the internet doing research for the '42 Amp, I saw a lot of different approaches to finishing the chassis, or building a cabinet of sorts.  One that was particularly appealing was to create a 'frame' of sorts around the bare chassis, so that it has a nice finished look, but still shows the tubes and some of the hardware.

I got a 1x2x7 piece of maple from the Despot and cut it into appropriate lengths.  You may wonder about the 7 foot length - my piece probably started life as an 8 foot section, but someone cut a bit off.  Not a problem as 7 feet was more than what I needed.

An aside: my piece of maple actually started life as a tree...but then became a board.  It actually has some nice flame to it - I went through about a dozen pieces and found a good one. 

Hopefully this picture better illustrates what I'm aiming for.  I measured and cut one piece, and mitred those ends so the 'short' side (e.g. the inner side) would line up with the long side of the chassis.  Then I measured and did that for the other 3 sides.

I discovered something during this exercise: I found out that my $99 mitre saw isn't the world's most accurate.  For some reason, the mitre angles wouldn't line up when I cut them at an indicated 45 degrees on the saw!  With some trial and error, I did wind up with 4 pieces that worked.  I wound up with just enough wood out of my 7 foot section to get 4 sides.

I then glued the sides together to form a 'box' around the chassis.  Since I have only one long clamp, I used rubber bands and the power transformer as makeshift clamps.  Note to self:  get more clamps.

I also realized I'd need some sort of feet on the bottom of the amp so it wouldn't just lay flat.  I originally just envisioned rubber feet, but then I had an actual flash of inspiration: round feet cut from the maple scrap!

I used a 3/4 hole saw in the drill press to cut the feet.  Now, if you don't know this already, maple is a hardwood.  This means you must go slowly when you cut it.  I found if I rushed the cut, the wood (and the drill bit) would get so hot the wood would (ha ha wood would!) start to burn! 

So working very slowly, I cut the feet - it took over 10 minutes to drill each one.  But it was worth it I think.

After the frame was glued up, I drilled holes from the inside for attaching the chassis.  I previously drilled holes in the sides of the chassis as a mount.

I lined the chassis back up in the frame and marked the holes.  Since I couldn't get it under the drill press or use a hand drill, I used my Dremel right-angle adaptor to drill pilot holes.  I've had the adaptor for a while (it came as a freebie with my Dremel), but I've never used it.  It worked a charm on this job.

Again, the maple is hard and there's no way you can run screws into it without a pilot hole.  This is one place where I planned ahead and it paid off later.

With the holes drilled, I then glued the legs to the bottom of the frame.

One thing I would do a bit differently is the actual fit of the chassis into the wood frame.  I had to take the chassis in and out several times, and it was a very tight fit.  So tight, in fact, that I dropped the frame and the corner joints came apart!  I had to reglue it.

I think in my really serious amp build (with the 2A3s), I'll shave some wood off the inside of the frame somehow so the chassis will slide in a bit easier.  This I shall ponder. 

 
 
 
 

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