Cutting thick stainless (5mm) ?

[chris2012]

I'm wondering what the best was is, to cut 5mm thick stainless.

I'm currently looking at:

https://www.starrett.co.uk/shop/power_t ... id=BF56132

Which looks like it should do the job?

I was originally thinking of using a punch I've got but it looks like the qmax can do up to 1.62mm, so even if I flipped it round during cutting, it wouldn't work afaik?

Cheers

[PeeBee]

I've got to cut a very large diameter hole (100mm) through 8mm stainless steel plate and tracked down an excellent solution! Find someone who can do it for you! They have laser cutters and they weld in the tri-clover flange too. Expensive, but the tools to do it yourself are flippin' expensive too and you don't have to worry about breaking the expensive tool, or it munching through things you hadn't predicted (like yourself). And the time you save and anxiety you avoid. Do-it-yourself is great as long as you are careful enough to keep contact with reality.

[Kev888]

The Q-max punch (and similar) certainly won't do anything near that thickness, and you can't punch half the thickness at once either, so you're right to dismiss it as an option.

For DIYing a one-off hole of around 30mm or so, personally I would just drill a circle of smaller holes and then use half-round and round files to smooth the resulting jagged edge - cheap and no waiting. Though if there might be many more holes of the same size in future, I'd order the TCT holesaw, they're good things and less tedious. (Don't attempt either unless you have a drill that will turn quite slowly).

[LeeH]

You can cut that thickness with a standard bi metal hole saw.

1. Speed 1 on your drill.
2. Firm pressure
3. Lots of cutting fluid to keep it cool. WD40 will do


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[chris2012]

Thanks a lot everyone!

PeeBee - I'll bear that in mind for more complex jobs, but I should be able to do this one.

Kev888 - "Don't attempt either unless you have a drill that will turn quite slowly" That's good advice, I hadn't thought of that. I'm pretty sure it's high time I got a decent drill, we've just got an ancient corded drill that doesn't really have a speed control. So I'm just looking at DeWalt or Makita ones at the moment.

LeeH - thanks for the procedure, didn't realise a std. one would work, well that makes things a lot cheaper!

[Kev888]

..we've just got an ancient corded drill that doesn't really have a speed control. So I'm just looking at DeWalt or Makita ones at the moment.

Yes, i'd suggest getting/borrowing something that'll go slower - in an ideal world with a two (or three) speed gearbox rather than relying entirely on the speed control.

Stainless needn't be bad at all really, unless it is pre-hardened. But if the cutter rubs more than cuts (either through being blunt, going too fast or insufficient pressure) then you'll 'very' quickly harden the material; quite shortly after that the cutter will get blunt even if it wasn't before, so a downward spiral begins and you'll be trying to almost burn through. So the name of the game is avoidance through good technique - mainly lots of pressure and slow speed, ideally with some cutting fluid.

Buying a drill specially might not be cost effective compared to PeeBee's suggestion. But if you want to get one in any case then FWIW I've had both DeWalt and Makita drills, both corded and 18v Li-ion cordless; they've both been fine. IMO Makita do more of a range of qualities and tools, which can be useful with lots of tools based around the same batteries, so personally i rationalised on that. But if that is a factor, make sure you buy into a standard battery range; some manufacturers do cheaper/special tools that are the same voltage but a different battery fitting.

[chris2012]

Yeah I need a decent drill anyway. That's interesting to know with respect to Makita. I was looking at their 18V ones too, there's quite a number to choose from.

"Stainless needn't be bad at all really, unless it is pre-hardened." - What's that mean out of interest, is that independent of the grade of stainless? I _think_ this is probably 304.

[Kev888]

Stainless can be hardened during manufacture or fabrication - through heat treatment or cold working. The method and amount may differ with the grade but I think it can apply to any of them, certainly it can be done to 304.

An example from homebrewing might be some of the thin-walled pots we use, which are slightly hardened - I assume the stainless is cold rolled and that it helps to stiffen the pot. But I've never had any that can't be drilled, it just requires more attention to good technique to stop things going pear-shaped in shorter order.

Re Makita 18v tools, the most flexible would be to go for the LXT range. Preferably with decent capacity batteries since some of the more power-hungry tools intentionally won't work with the smaller capacities (the threshold is 3.0Ah, but I can't remember if that is below 3Ah or including 3Ah). I haven't bought from ITS but they have a useful overview of the drills here

[chris2012]

Thanks Kev, the comparison on that website is very helpful!

[jamieN]

Also you should clean out the hole whilst drilling with an air line if you've got one or use a paint brush to sweep the chips out as they are another factor in trashing your cutters.
Another good pointer is take the holesaw off when drilling the pilot as when you break through that's when you generally break the drill bit.