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Old 11th Jun 2020, 12:40 am   #1
Sparky67
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Default Cutting hole in 1/8" ali panel

Hi all,

I need to cut an oblong hole in the painted front panel of a power supply to fit a switch. The hole will be about 1" x 1.5" and the panel is a pretty solid 1/8" thick ali.

Is a Dremel-type tool suitable for this, and if so, what sort of fitting would be best? Or is there a better method?

Thanks,

Martin
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Old 11th Jun 2020, 12:57 am   #2
frankmcvey
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Default Re: Cutting hole in 1/8" ali panel

A rectangular hole punch is what you need, but they're way too expensive for a one-off, and 1/8" is pretty thick. The best thing would be to chat up a carpenter/kitchen fitter or plumber friend with a multi-tool with a bimetal blade, which would make a neat job and pretty short work of it.

Failing that you could always go back to the time-honoured method of marking the hole out, then chain-drilling around inside the marked lines, then join the dots with a hacksaw, then use a file to clean up. Sounds harder work than it really is - aluminium's pretty soft.
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Old 11th Jun 2020, 2:10 am   #3
Bazz4CQJ
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Default Re: Cutting hole in 1/8" ali panel

I don't have a Dremel but I have a Minicraft drill (perhaps a bit small than the Dremel) which is in constant use.

You might try using the drill with a burr, however, it will not be very fast with 1/8". A slitting disc on the drill might work, those such disc are not at their best with Al.

A friend with a small router would be the best solution!

B
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Old 11th Jun 2020, 5:16 am   #4
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Default Re: Cutting hole in 1/8" ali panel

I routinely drill and file such things. File from the painted side only, release pressure for the return stroke otherwise it will pull paint flakes off. The forward stroke will cut the paint cleanly along with the ali panel.

Dremels are difficult to cut into corners with. They're a bit too fast for best control, and cutting freehand with a burr tends to lock in places and dig in, so straight lines are hard to do. With a router you need to make a template to guide it, and you still need to get the files out to do the corners.

If you have a reasonable collection of files, you'll find that they are quite powerful tools.

On an engineering course (disguised apprenticeship?) we each got given a task. Given a couple of lumps of mild steel a radial arm drill, hacksaw, a tap with wrench and a set of files but no milling machine!.... to make a vice to a drawing. The screw had already been turned. So yup, I've filed a vice out of solid. Fortunately it was fairly small. It was a bit tedious at the time, but what I learned has come in useful many times. The more precise your hacksawing, the less filing you had to do!

David
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Old 11th Jun 2020, 7:31 am   #5
Sean Williams
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Default Re: Cutting hole in 1/8" ali panel

Certainly chain drill and file - a really nasty side effect of abrasive disc cutting with aluminium is that the disc tends to clog quickly, then overheat and explode.

Not so serious when the disc is 1/16" thick and only 1" diameter, but the 15-18000 RPM bit sends shards of cutting disc all over the place.

I can normally cut out a hole for an IEC socket with a cordless drill and couple of files in about 10 minutes.
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Old 11th Jun 2020, 8:35 am   #6
M0FYA Andy
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Default Re: Cutting hole in 1/8" ali panel

I think I'd be tempted to find an alternative switch which just needs a circular hole...…….

Andy
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Old 11th Jun 2020, 8:46 am   #7
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Default Re: Cutting hole in 1/8" ali panel

Metal cutting blades are available to enable a jig saw to be used.
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Old 11th Jun 2020, 9:53 am   #8
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Default Re: Cutting hole in 1/8" ali panel

You need to drill a hole close to the size of the aperture then file , I bought a drill hole cutter to cut the same thickness , they come in all different sizes , pm me if you want info ,I can recommend them. I did post them on here but they seem to have removed Mick.
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Old 11th Jun 2020, 10:25 am   #9
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Default Re: Cutting hole in 1/8" ali panel

I have used a fret saw for things like that. Only a small hole is required, one at each corner for easy direction change.
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Old 11th Jun 2020, 11:15 am   #10
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Default Re: Cutting hole in 1/8" ali panel

To reduce the tedency of the teeth to clog, apply parafin or turps to the fiie before you start, and use a wire brush to clean the teeth.
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Old 11th Jun 2020, 11:19 am   #11
chriswood1900
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Default Re: Cutting hole in 1/8" ali panel

My usual technique is mark up the area with some masking tape, to drill out the corners, if you need rounded corners use an appropriate size drill, drill a short slot with a few adjacent holes and then a metal blade in a jigsaw finishing off with a file with care only takes 10-15 mins, the longest part is finding where I put the tools!!
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Old 11th Jun 2020, 12:41 pm   #12
Sparky67
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Default Re: Cutting hole in 1/8" ali panel

Thanks all.

It's an illuminated rocker switch going in the panel. I did consider a toggle switch but decided on the former for aesthetic reasons. Hmmm....

I don't have any real metal-bashing facilities here, not even a vice, so was looking for a reasonably quick method I could use with the multi-tool without damaging it, the panel or myself, too much. I did try an abrasive wheel before posting but it wasn't easy to use and must have clogged as it disintegrated after a short time.

Plan B is now to sharpen a few drill bits of various sizes, drill out as much as possible using a light oil and maybe a tapered hole cutter, then saw and file the rest. Not a quick job I'm sure. Thanks for the anti-clog file tips.

Martin
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Old 11th Jun 2020, 12:56 pm   #13
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Default Re: Cutting hole in 1/8" ali panel

I have a nibbler which I bought at a car boot sale. I was told that it needed a very powerful drill to drive it. I took it apart with difficulty and found the shaft was half a thou over half inch. I sent an e-mail to the makers to find out the correct size and was told the firm had moved to Australia. The director sent me a new shaft and a spare anvil by airmail, free of charge. That was sevice. She was pleased that I would use it to make equipment for disabled people. It works well.

I also have a double tin snips which cuts a slot without distorting the remaining sheet. Bought by my neice from Cheap Charle
ys. I think it would need a stong grip to use on 3mm aliminium.
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Old 11th Jun 2020, 3:11 pm   #14
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Arrow Re: Cutting hole in 1/8" ali panel

Quote:
Originally Posted by Radio Wrangler View Post
File from the painted side only, release pressure for the return stroke otherwise it will pull paint flakes off.
"Release pressure (on the file) for the return stroke". Exactly: most metal cutting flies have teeth that are non-symmetrical - like a saw blade - so the cutting takes place of the forward stroke. If the pressure is maintained on the reverse stroke, no cutting will result and doing that will also blunt the teeth. It seems that that correct use of a file is not often realised.

Al.
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Old 11th Jun 2020, 3:27 pm   #15
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Default Re: Cutting hole in 1/8" ali panel

Keeping pressure on for the reverse stroke also means it takes about as much energy to move the file as it does in the forwards direction, and you don't even cut anything! Why do unproductive work?

Oh, you also make sound effects that broadcast over a five mile radius "Over Here! Guy that doesn't even know how to use a file! Step tight this way!"

Nibblers have the disadvantage that their anvil leaves marks in aluminium. Put some masking tape on and you have the added entertainment of it quickly bashing through the tape, and then it leaves marks in the aluminium.

My fall-back for any shape of hole is to make an over-sized hole in mdf of something amenable, and use that as a template for the torch of my plasma cutter. But the nuisance with aluminium is that I'd have to change over to a feed from my spare argon bottle. You can cut steel with compressed air, but you do need argon for aluminium. Paintwork will be discombobularised.

David
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Old 11th Jun 2020, 3:40 pm   #16
vinrads
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Default Re: Cutting hole in 1/8" ali panel

Hmm ! all this just to cut a hole . Time for a Mick.
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Old 11th Jun 2020, 4:44 pm   #17
M0FYA Andy
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Default Re: Cutting hole in 1/8" ali panel

My late father, who had served his apprenticeship as a metal-fitter back in the 1930's, always used to very critical of anyone who kept pressure on the return-stroke of a file, woe-betide me if he caught me doing it! Similarly he had no time for the use of an adjustable spanner rather than find the correct one to fit a nut - a bodger's tool in his book!

Andy
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Old 11th Jun 2020, 5:03 pm   #18
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Default Re: Cutting hole in 1/8" ali panel

For this sort of job, I have always favoured Abrafile tension files that fit into a hacksaw frame. Just one hole to feed the file through fit into the frame and file in any direction within the scribed marks, clean up with standard files afterwards.
The downside is that Abrafile blades have not been made for twenty years or more but modern tile cutting blades are very similar and fit into junior hacksaw frames.
Neil
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Old 11th Jun 2020, 5:54 pm   #19
turretslug
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Default Re: Cutting hole in 1/8" ali panel

Chain-drilling a rectangle and dressing the hole to size with a file will likely take less time than reading and digesting this thread! I've really lost count of the number of IEC C14 apertures etc. that I've cut in panels, thick or thin, aluminium or steel to replace funny/dodgy old connectors, I don't even hesitate. Just beware that if it's one of those switches with compressible retaining wings that the hole needs to be very precisely sized for effective grip- with aluminium in particular, filing may be more effective than you realised! I'm reminded of an old airframe fitter's comment that the difference between plain aluminium and aluminium alloy is that you can bite through the former.
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Old 11th Jun 2020, 6:13 pm   #20
David G4EBT
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Default Re: Cutting hole in 1/8" ali panel

Quote:
Originally Posted by turretslug View Post
Chain-drilling a rectangle and dressing the hole to size with a file will likely take less time than reading and digesting this thread!
True.

It took me no more than 15 minutes to cut a 1" x 1.5" slot in a piece of 1/8" scrap aluminium.

Drilled the holes with a 5mm drill in a pillar drill - no need to be too neat so long as the holes are within the lines.
Removed the waste.
Neatened up the hole with 20cm long coarse and fine files, each with one 'safe' edge.
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