Crawls Backward (When Alarmed)

IconProjects, musings about guitar builds, guitar repairs, vintage tube amplifiers, old radios, travel, home renovation, and other stuff.

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. 


Post a Comment 0 comments:

Post a Comment