Drilling larger holes in aluminium with hole saws - advice please!

[Eusebius]

I want to make some DIY speakers cabinets out of aluminium, as used by hi-end makers like Piega and Magico though on a smaller scale. Aluminium is rarely used for DIY - it's all wood - and I can see why. I bought a 121mm hole saw to make a hole for the woofer, and my hand drill is inadequate for the task, overheats. I have a drill press I'll have to pull out and try - may be better. I was using paraffin as a lubricant.

If all fails, who can I get to drill larger holes like this? I'm in Hammersmith, London.

All suggestions here welcome - I have to find a solution. Maybe a metal department in a college or ????

[Tricky Dicky]

Use a bit brace and a tank cutter, old time plumbers used to use these for making holes in galvanised water tanks. You should be able to pick up the brace cheap on eBay, car boot sale or flea market as everyone has has gone over to battery drills. Tank cutters you may have to shop around for as again hole saws have replaced these. More detail about tank cutters can be found in the recent porthole thread.

Richard

[Tricky Dicky]

A bit more information here:

[Eusebius]

Ah! We're getting somewhere now. I saw this on ebay - looks like a version of a tank cutter - any use?

I saw this as well - doesn't look like it will do 121mm. Ideally I want to go up to 130mm. Would this work in a hand drill or should I use my drill press?

[Tricky Dicky]

The first one is calling itself a tank cutter but metals are not mentioned in the list of materials it will cut in the description.

The second one is a type I have seen used on metal but as you say you will need to check whether it has the capacity to do what you need.

As for using a drill press if you can get the rotational speed down to double figures and have some means of holding the metal other than by hand it should be possible if you take it easy.

Richard

[Eusebius]

Thanks Richard. I tried the hole saw in a hand brace, and while it did scratch away at a circle I wouldn't call it a success. Would take hours. The friction is just too great. May work in a drill press.

The tank cutter looks good. This is supposed to work in a hand brace. Much less friction. They do a 5" one which would just about be enough. Like the old Eclipse 280 model - plenty of those about.

You think this will work on aluminium in a hand brace?

[Harry Bloomfield Esq]

A tank-cutter would do that, with an old brace and bit. They used to be used to make holes for immersion heaters, in the water cylinders.

[Tricky Dicky]

I should think it should be no problem as I said in the first reply before the advent of portable tools for the masses, that is how old time plumbers used to make holes in galvanised steel tanks admittedly much smaller holes than you are planning but aluminium is far more softer than steel. It probably should suffer less from friction with only a single point cutter however I would be careful about how much pressure you apply as it might dig the cutter point into the metal. It is probably better to do the cut in several shallow cuts to get a smooth finish.

Richard

[Jim White]

Router with a milling bit and WD40

Cheers, Jim

[John Walliker]

Take it to a metal fabricator who has a laser cutter. I did this when I wanted a large hole and lots of smaller bolt holes cut in a sheet of 10mm thick steel. John

[Eusebius]

I don't have a router - just a small workroom with hand tools and a basic drill press.

Whenever I've contacted metal fabricators they've asked for stupid amounts of money. This is a simple job, done is a very short time with the right equipment. Someone who just wants a bit of money for a quick job would be great. But not a "custom job, arrange it with our receptionist....".

[Mike Clarke]

And clamp a sacrificial sheet of wood behind it to avoid a raggy break out at the end.

[Fredxx]

Plasma cutter. It cuts aluminium.

A noddy power drill won't have the stamina to deliver the required torque but a modest SDS drill would probably be ok.

With aluminium some cutting fluid is needed to stop balling. Oil or paraffin would be ok.

[Eusebius]

My REXON DP 200A drill press is 220W, but that's low speed.

My Bosch hand drill is 550W. The SDS drills seem to be 770W to 1500W. I can imagine a step up in power could have a good effect, but a 121mm hole saw has a lot of friction.

I've bought a tank cutter on ebay - waiting to see if that's any good.

There's always the long winded approach of multiple small holes and sawing out the hole then filing. The edges don't have to be perfect since the mid-bass unit covers them.

[Clive Arthur]

<snip>

In that case, get drilling. You know it will work, and the job would have been done by now.

If you have more than one, clamp them together first.

[Eusebius]

Yes, I have 2. Smart thinking.

[John Rumm]

How thick is the ali? The hole saw should work if you take it slow. WD40 is a good cutting lubricant for ali.

Fly / tank cutter as suggested, or just use a jigsaw. Router on a trammel would also do it.