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Old 9th Nov 2014, 7:44 pm   #1
Steve_Bell
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Default Cutting aluminium chassis with a Dremel

I quite often need to cut rectangular holes in aluminium chassis and front panels. Up to now, I've never owned a Dremel tool and note you can get various types of cut off disc: the brown ones (supplied with the Dremel kit I bought), circular steel blades with teeth and diamond discs. The latter two would need to be bought separately.

The brown discs look like they will do the job, albeit with quite a thick cut and taking a long time, from initial tests. What would you recommend for a quick, neat job?
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Old 9th Nov 2014, 8:12 pm   #2
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Default Re: Cutting aluminium chassis with a Dremel

The boss uses the Dremel cutoff discs sometimes. I stand off at a good distance

It's a bit dodgy doing this freehand, the discs tend to get trapped and come to pieces. He gets a rather rough and jagged edge. You'd need to cut carefully undersize and finish off to final shape with a big file. Bigger files are easier to get lines straight than smaller ones. You'll need a lot of discs!

Circular saw type toothed discs may grab, diamond wheels may clog with aluminium, it's difficult stuff to grind, it has a tendency to turn to thick toffee and build up on wheels.

I use an Advel nibbler, but they're hard to find nowadays, a hacksaw blade.... and a big file

A firm I worked for had a rotex punch and some of the punches in the turret were square. These could be repeated to build up a final cutout shape. A punch in a flypress if available would be ideal.

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Old 9th Nov 2014, 8:53 pm   #3
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Default Re: Cutting aluminium chassis with a Dremel

I find the diamond discs work quite well in my Dremel clone - I use cheap Chinese ones. The brown discs are hopeless and break at the slightest provocation.

I wouldn't want to cut big chunks out of an aluminium chassis with any of them though.
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Old 9th Nov 2014, 9:09 pm   #4
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Default Re: Cutting aluminium chassis with a Dremel

Hi

Depending on the thickness of the Aluminium you can cut a it using a sharp chisel, a decent wood chisel will do it fine. Cut from the front face onto a block of Aluminium or Copper to protect the chisel.

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Old 9th Nov 2014, 11:01 pm   #5
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Default Re: Cutting aluminium chassis with a Dremel

It's 1.2mm aluminium in general. I must admit, I'd never thought of using a chisel - I think I'll give that a go.
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Old 9th Nov 2014, 11:22 pm   #6
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Default Re: Cutting aluminium chassis with a Dremel

Quote:
Originally Posted by Steve_Bell View Post
It's 1.2mm aluminium in general. I must admit, I'd never thought of using a chisel - I think I'll give that a go.
1.2mm will cut fine with a chisel, assuming its normal ali and not anything special / hard etc

The easiest way is to cut most of the centre out first, either using a drill or Qmax punch or chisel it, whatever, its not critical but try to leave 3mm or so to your finished edge. That way it gives the remaining metal somewhere to go as you cut with the chisel. A wood chisel works best so you can have the flat edge facing the outside of your hole.

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Old 9th Nov 2014, 11:40 pm   #7
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Default Re: Cutting aluminium chassis with a Dremel

I use a jigsaw with a coarse blade, something that will survive melamine-faced MDF will also survive aluminium. I would never attempt to cut with a Dremel or a cutting disk of any size, aluminium is a complete b*st*rd to cut with a grinder, you need to get the chips away as fast and as clear as possible, hence the jigsaw and a coarse blade (I'm talking 6 or 8 tpi). If you try and cut with a cutting disk, the aluminium will almost certainly grab and either wrap itself around your hand or the blade will disintegrate and insert bits of shrapnel into bits of your body.
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Old 10th Nov 2014, 1:19 am   #8
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Default Re: Cutting aluminium chassis with a Dremel

I have some hand nibblers and they work ok

I did have one of these but I think someone borrowed it!

Hand nibblers work well though there is a definite knack, the drill powered one works well on larger pieces but you need to work with a definite amount of steady confidence or it's very easy to go off course and ruin your work. Cutting undersize and finishing with a file is to be recommended!
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Old 10th Nov 2014, 1:27 am   #9
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Default Re: Cutting aluminium chassis with a Dremel

I'm a big fan of mini-drills and have used the discs to to do extremely useful jobs that would have been damn hard by other means, though eye-protection is an absolute must. However, the discs are most suitable for hard materials and are not at their best with aluminium. If the Al is thin, a router/arbor tool on the drill may work (certainly useful on plastics), but otherwise I'd be calling on my piercing saw - though not sure if that qualifies as quick. A milling machine would be nice!

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Old 10th Nov 2014, 9:02 am   #10
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Default Re: Cutting aluminium chassis with a Dremel

Indeed! Oh for a nice little Bridgeport and a garage tall enough to clear the motor.

But mills don't cut square holes, you still are reduced to filing to un-round the corners.

Anything short of a proper punch and die for the exact size comes down to filing. Maybe all those hours as an apprentice communing with a file, a vice and a lump of metal weren't wasted after all.

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Old 10th Nov 2014, 11:12 am   #11
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Default Re: Cutting aluminium chassis with a Dremel

I can still hear my mechanical apprenticeship workshop instructor's voice echoing round my head, "plus or minus a sixty-fawth", every time I pick up a file.

I too find that a file is the most useful tool for getting aluminium the right shape, though I did find recently that a Dremel cut-off wheel was actually easier when tickling out the hole for the mains connector on the back of my HP 5245L counter so I could fit an IEC socket to it. The Dremel, though generally very poor on aluminium, was good because I could use it gently and, being small, it ran no little or no risk of damaging the electronics crowded around the hole.

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Old 10th Nov 2014, 5:23 pm   #12
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Default Re: Cutting aluminium chassis with a Dremel

I often use a Monodex cutter - they're about £25 now. Available from many places plus they often appear on eBay.

I also have a similar Eclipse tool but they're no longer available now.
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Old 10th Nov 2014, 7:36 pm   #13
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Default Re: Cutting aluminium chassis with a Dremel

A dremel is tediously slow in anything but the thinnest metal. I use punches and hole saws for round holes and a drill and jigsaw for square holes.
You can get square or oblong q-max punches but they are mega bucks.

I notice dremel do a nifty mini jigsaw head attachment for craft work but I havent tried one. Third party manufacturers do them to fit dremel as well.
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Old 10th Nov 2014, 8:41 pm   #14
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Default Re: Cutting aluminium chassis with a Dremel

I have an air nibbler (air powered, not for nibbing air) works a treat but does use a lot of compressed air. And leaves thousands of very sharp crescent shaped bits all over the workshop. I like the wood chisel method.
 
Old 10th Nov 2014, 9:18 pm   #15
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Default Re: Cutting aluminium chassis with a Dremel

Four (actually two will do) holes in the corners, a coping saw and a quick tidy up with a file works for me for rectangular holes (and D-Type connector ones too).
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Old 10th Nov 2014, 10:30 pm   #16
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Default Re: Cutting aluminium chassis with a Dremel

I still like the idea of 4 holes in the corners and coping saw, and then a file - it's worked well up to now. The chisel idea is something to try, as is the Dremel cutting wheel. Hole punches are ideal but costly, if they can be found in the correct size.

I'll have a play at the weekend.
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Old 10th Nov 2014, 10:38 pm   #17
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Default Re: Cutting aluminium chassis with a Dremel

Reading this with great interest.
On the shelf to do, I have a pair of chassis in what looks like 1/16" steel to build 2 monobloc EL34 amps (5-20 style, although I am going to use an adaptation of a Leak circuit). There's only one rectangular hole been cut which is for the mains Transformer and I need another one, the same dimensions for the Danbury DB910 output trannie at 90 degrees to the mains one. I am waiting for an answer as to whether I can buy end caps to mount this transformer above the chassis, I am not sure if its possible as its not got wire ends but tags and I am afraid of shorts to an endcap. That would solve the square hole issue as I could just drill a hole and feed the wires into the chassis with a grommet to prevent chafing. The only solution I could see would be to drill the 4 holes at the corners and use a steel cutting blade in the Black & decker. then clean it up with a file.

Bit scary for me.

Andy.

Last edited by bikerhifinut; 10th Nov 2014 at 10:39 pm. Reason: size wrong
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Old 10th Nov 2014, 11:35 pm   #18
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Default Re: Cutting aluminium chassis with a Dremel

Hi Andy

Steel will cut very nicely with a 1mm disk in the 4 1/2" grinder, and finish the corners with a file. If its a fairly small hole a nearly worn out disk is easier to control. Slow and steady, with the chassis firmly clamped down.

As said above a grinder will do ali, but it tends to grab.

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Old 10th Nov 2014, 11:37 pm   #19
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Default Re: Cutting aluminium chassis with a Dremel

The Dremel cut off disks (the thin brown ones) do work well with steel. Wear rate is a bit quick so buy a bunch.
 
Old 16th Nov 2014, 3:51 pm   #20
Sean Williams
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Default Re: Cutting aluminium chassis with a Dremel

Stick with a jigsaw, disc cutting can be very dangerous.

Aluminium requires different discs to steel, and they overheat when clogged with aluminium powder, you don't need too many disc explosions to make you think of better options.

We use a jigsaw for all panel work where I am employed, lots of masking tape, and a slow and steady approach results in holes that need little or no finishing at all.

Regardless of what method you try, remember you only have one set of eyes, and body parts do not respond well to high speed shrapnel - grinding sparks are a superb way to start quite impressive fires as well!
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