DIY Audio Projects Forum

Nice tip, Matt. That never occured to me.

_________________
The key to a successful build is to keep the smoke IN the circuit.
-Les

We cannot solve our problems with the same thinking we used when we created them. - Albert Einstien
_________________________________
LM380 Bridged Guitar Amp, Oatley K301 Phono Pre-amp, Oatley K272 Headphone Amp, Tube proto-board

I use aluminum plate from the junkyard aka recycling center, and there are big differences between types of aluminum.
Some are very 'sticky' to machine, others machine beautifully. Unfortunately, I haven't learned to recognize the good kind by sight alone.

I use a carbide non-ferrous metal circular saw blade to cut (with a sliding table and clamp-downs) and a stepped drill bit (unibit) for all but the smallest holes. I have an expensive name-brand Unibit and it doesn't cut any better than the gold colour cheap ones I have. BTW, they also make non-stepped tapered bits - like a reamer on steroids - which are handy for 'adjusting' the size of holes.
My holesaws are not accurate enough (wobble, cut oversize) for chassis work. Larger twist drills try to cut triangular holes in thin stock, with my drill press and workpiece clamped.

I have a punch but never use it. By the time I've drilled a 3/8 hole with the stepped drill, I just press on with enlarging the hole, rather than switch to the punch.

Tip: Rub your file with blackboard chalk before filing aluminum (or brass/copper). It makes it easier to clean the file.
I seldom work with steel chassis.

Do a search for Q-Max punches.
http://www.google.com/search?q=Q-Max+punches

One method that I didn't see discussed is using a flycutter.

Upside: Very adjustable, cheap as dirt and cuts a beautifully machined hole.
Downside: requires a drill press capable of very slow speeds (or mill), grinding a toolbit to suit, and a very rigid setup. Insufficient clamping of the piece being cut will cause some catastrophic results!

Here's one example (sans toolbit) for under $5:

http://www.wttool.com/index/page/produc ... s+%28WT%29

It has a 1/2" shank, which might not work for everyone's drill chuck. 3/8" shank models are out there too.

_________________
-Jimbo

"That which is overdesigned, too highly specific, anticipates outcome; the anticipation of outcome guarantees, if not failure, the absence of grace."
–William Gibson

well, when we learned to process the aluminum into the box in school, for large hole drilling we first used small drill (cca 6mm), then we used a hole cutter to size the hole up to the final diameter. and at the end, some edge refinement with countersink tool just to make fine edges
http://www.ultimatehandyman.co.uk/Metal ... rsink6.JPG

results are pretty nice.

I use these as well. As long as you are using a drill press with them they work great. Slow speed works better than fast. I have used them on steel, and as long as the blade is lubricated it will work fine with that as well.

If you try to use a hand drill with these it will look like a blind guy with an axe tried to make your holes, at least when I did it that way it did.

If you look around on fleabay, you can find them pretty cheaply out of HK. Those are what I have and had no issues with them. I think the most I paid was about $8USD or so each.

These are not meant for hole cutting. They are meant to be used in a milling machine for thickness machining.
Dangerous advice. Not recommended.
Step drills or hole saws are by far the easiest and safest. Hole punches (Greenlee) work well, as long as the panels not too thick.

_________________
Dan Santoni
DTS Audio Electronics
www.dtsaudioelectronics.com

Speaking of safety, chassis punches are made to be used with a hand wrench. The knockout punches can be used with a hydraulic wrench, air wrench or hand wrench, but NEVER use a power tool on a regular chassis punch - like a regular socket on an air tool, it could shatter and spray shrapnel everywhere!

_________________
-= Gregg =-
* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
Work: Classic Valve Design

Here is something i have not seen mentioned as yet.
"Forstner Bits".
They are used mostly for wood but work very well for aluminum as well. They are reasonably priced and are available in regular and hardened carbide steel. Used only with drill presses and on slow speed but they work very well.

Any particular brand?

I tried a $30 titanium Forstner and a $8 cheapie (the cheapie did better) on 3mm 5052-H32 and got nothing but frustration

_________________
-= Gregg =-
* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
Work: Classic Valve Design