Trainwreck - Cheezey Chassis - Test sample

[RJ Guitars]

Hi folks. I have one old 17 x 8 x 2 Bud box chassis here that I bought used from the local electronics salvage place before they went out of business. It had been part of some mad scientists experiment and had been punched full of holes to the point it looked like swiss cheese. However, it was adequate to use as a template for an authentic Wreck chassis.

I took it to the local shop that makes most of my chassis and asked them to duplicate it. They didn't say no but they did ask why numerous times. They put it off and dragged their feet and whined about how Cheezey it was made... but finally they came through with a prototype. It looks quite good although we still haven't sorted out how to have the corners spot welded.

Take a look and see if this and see if you agree it looks like the real deal. This will be slow to develop into something I have on the shelf but I think for the purist it will give us one more authentic item.

[RockinRocket]

That certainly fools me from the outside. The only thing that probably wont make any mojo difference is the 90 degree corners on the inside lip.

Now why wont Bud make us these chassis under the custom chassis option?

[geetarpicker]

Good question. The originals are a little nicer quality then you would think, though they are thin. This pic isn't the best of angles but you get the idea. The Francesca pics show the welds inside somewhat. The early ones had small triangular corner cut outs and double spot welds, though the later ones had perhaps only single welds and square cut outs I'll have to check as I have both kinds around here. I think all the Ken F. built amps had the triangular cutout chassis though perhaps the last wrecks built may have the square cut ones. They aren't that easy to make, and I tried to get a local shop to make me a pair but they turned out so bad I tossed them in recycling. I ran across some originals later on instead. I built my two personal clones on a pair of BUDS, and saved two more for the day I get brave enough to build me a Rocket and Liverpool....someday when I can find the time.

[galtjunk]

There are aluminum brazing rods available to weld your chassis.
You can get them at harbor freight.
You can use a propane torch with it and it flows like solder.
It doesn't discolor the chassis and it is really strong.

[RJ Guitars]

Here is the link from back in the day when Selloutrr was trying to get all the original spec parts and tried to set something up with BUD... https://tubeamparchive.com/viewtopic.ph ... 99da0f90a5 -- Somehow this looked real promising then fell apart because of the cost and the minimum order required... I expect that is still the case today.... BTW I think Selloutrr works directly with Trainwreck now.

I'll add the photos of my original box that I had the shop copy. It is slightly different than Geetarpickers... mine doesn't have a label and it's entirely possible it is from a different vendor but at the very least a different age. Because it was so cut up I put a plate over the top and ends before I decided to stop working with it.

This box is well made from the fabrication technique standpoint. The downside is that it's only .032 inches thick and they use the lower grade soft aluminum rather than the stiffer 5052 which also bends nice but machines about 10X easier. In my prototype I had them use the soft aluminum.

Thanks for the tip on the Harbor Freight aluminum brazing stuff. The local welder tried a couple different TIG efforts and none of them looked good. He didn't want to mess up the prototype with a melt thru so maybe this is a good solution. I'm going to the big city (Albuquerque) tomorrow and I'll get a sample to try.

You can see in these picture they don't use the 45 cuts at the corner and also get a nice look at the double welds. Did Hammond or anybody else make this chassis size - does anybody know?

[RockinRocket]

Thanks for the link RJ. After reading I cant understand why there wasnt enough interest. Even if they weren't punched, a wreck chassis is on the easy side. I would be willing to pay more for a resisue Bud chassis

[geetarpicker]

That swiss cheese chassis sure looks like some other brand or something. The BUD AC-425 is correct and with a digital caliper the one in my pic above measures .050" thick.

When I built my two clones I used a hole puncher for the tube sockets, and a step bit worked well for the rest.

[RJ Guitars]

Thanks Glen, That might help explain things... now you can see where the "cheesey" part of my description comes from. What a crazy deal that there was another manufacturer out there making that same size and I am the only one that has found one so far... That thing could have been 40 years old for all I know.

I's all good news to me, I'll go back to the shop and tell them we can work with .050 aluminum and I think they will get extremely more pleased with the project. Do you think that the 5052 alloy aluminum would be acceptable as well? It's a little more expensive and doesn't polish up the same as the soft aluminum but it's much more rigid and machines much nicer.

[martin manning]

FWIW, the rigidity is all about the thickness of the material since the elastic modulus doesn't change much with different alloys of the same basic material. I hate working with soft gummy aluminum chassis, though!

Does the flimsy chassis have something to do with the tone? Would KF have used a better box if he could get it? Surely he could have had some fab'ed if he had wanted to.

[Paultergeist]

RJ,

I am not following that HUGE hole in the chassis......3 pre-amp tube holes, yes.......4 power tube holes, yes.......but then the rectifier hole looks like you could put your fist through it?

I am missing something?

Paul

[cbass]

RJ,

I am not following that HUGE hole in the chassis......3 pre-amp tube holes, yes.......4 power tube holes, yes.......but then the rectifier hole looks like you could put your fist through it?

I am missing something?

Paul

That's the beer holder

[RJ Guitars]

RJ,

I am not following that HUGE hole in the chassis......3 pre-amp tube holes, yes.......4 power tube holes, yes.......but then the rectifier hole looks like you could put your fist through it?

I am missing something?

Paul

Yeah that's odd and I hate to kill all the fun speculation... but I'm not one to promote warm beer (my apologies to those in the old world).

Early in the thread I mentioned that this was a recycled chassis from a science lab. There was a big analog meter mounted there at one time that had nothing to do with guitar amplifiers. I think I also took out two 1000 wattish 10K Ohm resistors that I occasionally use to load power transformers.

[Zippy]

FWIW, the rigidity is all about the thickness of the material since the elastic modulus doesn't change much with different alloys of the same basic material.

Not entirely so - you are referring to the elastic modulus. The rigidity, in this case, is also due to the strength of the metal - dead soft vs hardened, either via cold working, dispersion strengthening, or precipitation hardening.

[martin manning]

FWIW, the rigidity is all about the thickness of the material since the elastic modulus doesn't change much with different alloys of the same basic material.

Not entirely so - you are referring to the elastic modulus. The rigidity, in this case, is also due to the strength of the metal - dead soft vs hardened, either via cold working, dispersion strengthening, or precipitation hardening.

For a given structural shape, rigidity (deflection under a given load) depends only upon the elastic modulus. Strength (yield stress) determines the load required for permanent deformation. To increase rigidity without going to a different material (steel e.g.) the only option is to use thicker stock (change the structural shape). I would prefer a chassis that is both rigid and resistant to permanent deformation, and thin low-strength material is not going to do it.

[Zippy]

For a given structural shape, rigidity (deflection under a given load) depends only upon the elastic modulus.

True - as long as the applied stresses remain below yield.

I would prefer a chassis that is both rigid and resistant to permanent deformation, and thin low-strength material is not going to do it.

Agree.