Tech tip for the do it yourself built chassis

[Buffaloamps]

For those of you who make your own chassis by drilling and punching out your own holes you may wonder how in the world can one drill a 1/8" or 3/8" (or other size) hole without it blowing out the backside and making a burr?

Well, here's what you do...

Go to Home Depot or Lowe's or some other hardware store and buy a BRADPOINT drill bit in the size that you need. Make sure that you use cutting oil when you drill...NOT 3 in 1 oil...CUTTING OIL. You can find cutting oil in the plumbing dept where metal piping is kept at Home Depot.

The Bradpoint drill bit is intended to be used on a drill press. So don't think it will work in a hand held!...It may if you're steady enough, but I wouldn't want to do it!

The Bradpoint drill bit will make a nice clean cut hole if you set your drill press belts to about a medium speed. Check the RPM's for the hole being drilled in the belt adjusting area.

I hope this will help any of you who scratch your head on drilling holes.

If anyone has any other or better solutions, by all means please share!

Rob

[kiteflyer]

Thanks! useful info....

[Wakarusa]

So how many holes, on average, do you get before your wood bit dies from drilling steel?

As an alternative you can use the tried and true method of going back over all of your holes with a chamfer bit or you can try one of the various nifty deburring tools (see pg 2293 of the McMaster-Carr online catalog for some examples).

The other "tricks" to good holes in steel are:
- use the right speed for the bit/material
- clamp your work
- use shorter bits
- no really, CLAMP your work

These last two can help you avoid the "triangular hole" problem caused by a wobbling bit/workpiece.

[Popoon]

Reamers are great,how else would one make the hexagonal hole.

[Buffaloamps]

Surprisingly, the wood bits have held up on at least 5 chassis so far and still going strong. And using the cutting oil helps keeping from burning them up too.

I'm just going to keep using it until it breaks...


Oh, please don't forget to use safety glasses! I forgot to mention that on my original post. Safety's important!

[Wakarusa]

Reamers are great,how else would one make the hexagonal hole.

The answer to that one is a straight fluted bit -- but be prepared to pay dearly for them :)

[donnyjaguar]

Just use an aluminum chassis. The metal is a lot softer. There may be a benefit to a steel one, but I've not seen it. Its pretty hard to get a tranny to vibrate a non-ferrous chassis. Aluminum dissipates heat better anyway. Just this hobbyists 2 cents.

[Buffaloamps]

Aluminum IS a better conductor than sheet metal yes, but it costs a whole lot more. If I were to have my local sheet metal shop make me a batch of aluminum chassis, then I'd be paying out the grand wazoo for them.

If only I had access to a hydraulic press!

[Wakarusa]

If only I had access to a hydraulic press!

Heh.. a shear, a press break, and a turret punch would all be nice. That and 480VAC 3 phase to run 'em ;)

Aluminum is dandy for a hobby build because it's just a lot easier to work with -- particularly if you don't happen to have a drill press handy. Don't know about vibrating transformers (and, in fact, Al is a bit better because it doesn't react in the transformer's magnetic field the way steel does), but the huge drawback is that, in the same thickness, the ruggedness of steel kick's aluminum's tail. Dropping an amp with an aluminum chassis off the loading dock can tear the transformers right out of the chassis.

[Buffaloamps]

Ya darn tootin' the trannies will rip off! Good point!

And besides, if you align the power and output transformers perpendicular to each other, they'll both phase cancel each other and you won't have to worry about transformer noise and hum...