Large diameter holes!!!

[theskytoucher]

I need to cut a 2" hole and a 3 3/8" hole into a sheet of aluminum that is about and 1/8" thick, What would your guys' sugestions be to do this? They need to be clean holes top the cane be oblong or nasty cuts!!! Any ideas? Thanks

[averagef250]

Holesaw the hole slightly undersize and use a boring head in a mill or drill press.

If the sheet is too big to fit in a mill you can use a mag drill by clamping a thick steel plate under the aluminum or setting the al on a steel table. My mag drill gets used maybe a few times a year, but when it does it's a life saver.

I have a bunch of big knockout electricians punches. They're expensive buggers, but if you have any electrician friends they might be able to help. I think a greenlee punch will handle 10 gauge al depending on it's heat treat/alloy.

[theskytoucher]

My dad is an electrician but all the knock outs he has are under sized or over sized and we were thinking a hole saw wouldn't leave a clean cut! If i had a mill It would be easy but alli have is a bench top drill press!
Wat this is for is a gauge cluster for after market gauges and i don't know how precise the hole for the gauges has to be, i want to get the panel done so my Cousin can powder coat it before he leaves his job! So i guess another question is how close to the exact size do i need for gauges?
Thanks

[spartman]

I second the hole saw idea.

Just put it into the drill press.

Worked like a charm for me.

[390Nut]

So i guess another question is how close to the exact size do i need for gauges?
Thanks

That will depend on your gauges, how they mount, and how much overlap the trim ring has to cover any "oops" that happens when trying to finish the opening.

Haven't had a chance to use it yet, but my Dremel kit has the router base and circle guide for just that purpose. With the right bit, it would cut through aluminum relatively easily (if not slowly to keep it from binding) and another bit to deburr the edges. $67.00 at Wal-Mart.

Would only work on a flat piece of metal, wood, plastic, etc, however.

Barring that, I'ld use a hole saw and finish it off with sandpaper to make clean edges.

[71Ford100]

Why not just drill a hole large enough for a sawzall and cut it out with one of those following the inside of your mark for the circle.

[Leadfoot]

a hole saw or fly cutter works best, even with a hand held drill, remember any thing that works on wood works on alm..

[theskytoucher]

a hole saw or fly cutter works best, even with a hand held drill, remember any thing that works on wood works on alm..

Really! i didnt figure a wood hole saw would work on alu> well i guess ill have the try it

[foghorn]

We used to use wood hole saws in my dads shop they work just fine at slow speeds so as not to burn up the tool. Also this was in body sheet metal. I have a friend of mine that does semi trailer repair and he uses a skil saw to cut heavy round alum stock for the ramps of a bull wagon.




Foggy

[Tim P.]

It should be a bimetal hole saw home depot has them Ace hardware has them. A standard wood hole saw will heat up,,, even in aluminum and the teeth will go away fast.

[basketcase0302]

Also recommend getting a good brand.
Lennox is one and Milwalkee makes a real good one too.
Like foghorn said: slow is the key. And don't be afraid to spray the drilling surface with some oil while drilling to prevent heating up, (and possibly destroying) the bit.

Basketcase

[hardtailjohn]

I get to do this alot, building aircraft instrument panels..... use a fly cutter, or make one if you have to... hole saws walk and make a mess... but can be used. In aluminum, you don't need a bi-metal as long as you take your time and use some cutting fluid. Fly cutters are by far more accurate and leave a nicer hole. If you want to get really cool..you can have it water jet cut...but that's some $$... Like I said, I use a fly cutter. Grizzley or HF usually have a decent one.
JH