Thread: Cutting Aluminium Extrusions

Dear Paul,

I would be much more inclined to use the new metal-cutting blade in your Compound-Mitre Saw, than in the 14" Cut-Off Machine. For one thing, the bore through the blade might only be 16mm, which would be okay with the Mitre Saw, but would probably require an "Arbor Bush" in order to get a snug fit onto the Cut-Off Machine. Secondly - depending on the Depth-Stop arrangement on the Cut-Off Machine - the new 10" blade might not even make it down to the surface of the Machine's base, given that the machine was originally intended for a 14" disc. The Cut-Off Machine's RPM will be a bit slower than the Mitre Saw's, but not by any critical amount. In terms of accuracy - it's hard to say; some of those Cut-Off Machines are really solid, whereas others can move around a bit during a cut. Same thing applies for Mitre Saw's, though...

Regarding Lubricant - don't get too hung up on using it in this case. You could experiment with something along the lines of RP7, but high-speed cutting through a square section just doesn't really lend itself to using lube - it just doesn't have anywhere to sit or pool, and you wont be able to dispense it in a practical manner onto either the side of the blade or the aluminium tube during the cut. You'll be okay without it, though. The really slow proper Cold-Cutting machines (as in something like only about 60rpm) have their own little lubricant feeds onto the side of their blades, but you definitely wont need it through small aluminium sections. That new blade of yours will have been designed to work without lube anyway...

So in summary: Put it in the Mitre Saw, and don't worry about the Lube .

Good Luck,
Batpig.

Thanks for your advice Batpig.

If it's OK, I'l just just pick your brain a little more

The bore on the blade is actually 1" and I think that 14" cut off wheels have the same bore.

My compound saw does only have a 16mm boss but I do have a set of bushes so that the blade should be adaptable either way.

Both of the saws are cheapie GMC units so they may both be a inclined to wobble a bit.

If I find that the 10" blade does travel all of the way to the base on the cut off saw, do you think that it may be preferable (considering it has a vice and the slower speed) or should I just go along with your first suggestion with the compound saw ?

Thanks again for your time and advice

Cheers

Paul

Paul I have used a lot of qubelok and use to cut it all on a compound mitre saw ( until I managed to get one of those discounted triton steel cutters )
Go with the compound saw the blade is designed to cut within a speed range and I think you will find the compound saw will fit into that speed range
I started using a wipe on lube when cutting, but then found no diffrence without it
I clean up the cut ends on the disk of a belt disk grinder, dont worry with cleaning up the inner part as the plastic corner pieces stick better with a bit of swerf
The compound saw should have a fence and just hold the aluminium by hand the 80 tooth blade does a nice quick cut ( of course small pieces should be clamped )
I also found that I could cut 4 lengths at once easily with the saw which improves accurately cutting to length
If you are using the qubelok with the lip I made a 45deg block to fit on the saw table so that I could run all the lipped pieces in one at a time and cut just the lip off at 45 deg so they fit into the corners better, a lot easier than grinding , hand filing or hand cutting it off

most of my work involves cutting a lot of aluminium,
I use Inox brand oil that I dab on with a brush onto the blade, not the piece, because that wastes oil and you have more work cleaning it.
oil helps in that it stops the aluminium from sticking to the blade
and aluminium is very "gummy", that's the reason aluminium blades have negative rakes,
it also helps it cool, and it extends the life of the blade anywhere between 3-10 times.
The best part though I find is that it produces much cleaner/accurate cuts.
Any of those penetrating oils work okay but I prefer Inox because it smells the least offensive,can't stand WD40.

keep the blade in your mitresaw, but line the fence and bottom with plywood,
having a solid backing to the piece to be cut, again increases accuracy and makes it much much safer, well this is in my experience over the last 20 years anyway.

Dear Paul,

Originally Posted by Paws 'n' Hooves

The bore on the blade is actually 1" and I think that 14" cut off wheels have the same bore.
My compound saw does only have a 16mm boss but I do have a set of bushes so that the blade should be adaptable either way.

Oi oi oi! I had it the wrong way around, didn't I?... But I'm glad one of us is thinking straight

Originally Posted by Paws 'n' Hooves

Both of the saws are cheapie GMC units so they may both be a inclined to wobble a bit.
If I find that the 10" blade does travel all of the way to the base on the cut off saw, do you think that it may be preferable (considering it has a vice and the slower speed) or should I just go along with your first suggestion with the compound saw ?

If it's that $99 Cut-Off Machine that they did a couple of years back, I'd definitely say to go with the Mitre Saw. Less Hernia problems compared to the Cut-Off Machine, if nothing else. Regarding the lack of an on-board vice, Ashore is quite On-The-Money when he says to clamp the piece with your hand, because the negative rake on the Blade's teeth will decrease any tendency for the piece to jump off the table and pull your hand over into the Blade. If you are really worried, grab yourself a Quick-Clamp or two from the BigB, and you'll be in business. I've seen them for about 10 or 12 dollars a pair. What Phantomas says about the ply-backing would definitely be better again...

Best Wishes,
Batpig.