Chassis Manufacturing

[lowell]

Hey all,
I'm doing some research for building some amps. I have settled on a design that I'm real happy with and people have shown some interest in them. I initially made 5 identical amps, well somewhat identical as I made some changes throughout building the 5 amps. In any cases I've made my revisions and think I'm ready for a larger run. My chassis guy is only going to give me a decent deal if I do a run of 25 or more. I'd like to know if anyone can help me with a few things.

Has anyone been inside a Dr. Z amp? The chassis are simple and very solid designs made from I believe 1/16"-3/32" aluminum or thereabouts... which is exactly how I want to go about this. More specifically the Dr. Z chassis have internally mounted cylindrical nuts inside, so if you screw a machine screw into the chassis you don't need to use a nut on the other side... it's already built into the chassis itself. Does anyone know what this is called in technical terms if I want to relay this to my chassis manufacturer? This simple addition to the chassis design will save much time in the assembly process.

My only other question I have at this time is does anyone have any referrals they can send me for chassis manufacturers? I may go with my guy, but not if I can get a better price so I'd like to call/email around and have some options.

Thanks in advance!

[guitarmike2107]

You can use nutserts
nutsert - Google Search

or you can use cage nuts
cage nuts - Google Search

I always buy my chassis in batches of 25, so can't be much help there.

[lowell]

Nutserts! Ha what a funny term. Who makes your chassis? Do you have any pictures?

[Sock Puppet]

FWIW, clinch nut is another term:

clinch nut - Google Search

[Steve Conner]

I think they are also called Hank bushes or riv-nuts in the US.

I've used the self-clinching type quite a lot in my own builds.

[lowell]

From what I see there is some of the rivnut/nutsert that protrudes from the flat side too after it's inserted into the chassis. That is to say that you can't get something flush anymore when it's screwed in. Is that correct? Or am I seeing it wrong? Or maybe there's a specific tool/rivnut that can get around this issue? On the Dr. Z chassis there is no part of the rivnut protruding from the outside, it's flush.

[J M Fahey]

I use the "Rap" rivets Fijaciones Rap - Tuercas - Remache , which are huge Pop type rivets , applied with a similar tool, which are internally threaded either in 1/4" Imperial or 6mm Metric.
It pays to very lightly grease the thread, for an easier tool extraction.
The page is in Spanish, but click around, they show products and installation very clearly.
*Or* in relatively "thin" chassis, say less than 3", (Twin Reverb) you can avoid the problem by using long bolts, which go all the way through the cabinet wood and the full chassis, with a regular nut on the far exposed side.
Quick and easy, although usually one of the free nuts is hard to handhold (until the bolt screws a couple threads into it) because some transformer or filter cap gets in the way.
As of the chassis , I make them my self in 2mm aluminum (have shears, folding brake and punch presses with an assortment of dies) *but* for one-offs (or, say, up to 5) you may work on a flat aluminum sheet, making all holes with regular drills and a couple Greenlee punches or stepped drills or cup saws, easily deburr everything (the big problem of handmade metalworking) and only after that have it bent 90º twice, making a C shaped one.
Saved my bacon more than once when I was a rank beginner, and asking somebody to make just a couple simple bends in a simple sheetmetal shop (the kind that makes air conditioning ducts and such) is much easier than finding a dedicated chassis maker, with all those dies (or CNC machines) who will ask for a relatively important amount, simply because of the time wasted in setup.
Guys usually didn't even charge me for a couple bends, but a "long neck" bottle of wine or two (maybe a sixpack in US) was always appreciated.
It made sure I was welcome next time.
EDIT: with the Rap type ones, you always have the shoulder thickness , although the typical 1mm doesn't hurt; the ones you saw in Dr Z's chassis use another system, they are internally applied to the chassis thanks to a short neck which is exactly the sheet metal thickness.
They (high) pressure fit into a very tight hole; I don't think they will give good results if home-applied , if they can be applied at all.
Chassis makers, of course, have all those hydraulic presses.

[pdf64]

PEM nuts are another type
PEM nut - Wikipedia, the free encyclopedia

[guitarmike2107]

Have a look at this page for a range of options , self clinch nuts looks like what you are after, or rivet bushes

Threaded Inserts and fasteners for Plastic, Wood and Metal - Buy online at low cost!

I use a sheet metal fabricator in Scotland, there are plenty about here thanks to the oil industry.

[lowell]

all good info... thanks guys!

[defaced]

In Chicago I'd be surprised if there weren't several small sheet metal shops locally. Take your prints and send them to every place that'll do small run/one off parts and get a quote. Usually when I get quotes for small quantity parts I ask for pricing for say 1, 5, 10 and 20, so I can see where the price break might be. To a sheet metal guy, an amp chassis is just bent metal like every other part he makes.

[tubeswell]

Speed Nuts
Blind rivet nut - All companies
Springfast Limited – +44(0)1452 416688 – spring steel clips, fixings and fasteners
Cage Nuts and Steel Clip Nuts, and Multiple Thread Engaging Nut and Bolt Retainers by H.W. Eckhardt Corporation
Locking Fasteners