Hacksaw blades for aluminium

[TerraHertz]

(However, be very careful grinding alu, because it's so soft it tends to clog up grinding disks/wheels and throw them out of balance. Wheels have been known to shatter when grinding alu with very dangerous results)

If you look through the range of cutting and grinding disks at the hardware store, you should find that there are some specifically for cutting aluminium. They work very well, somehow the metal does not stick to the wheel, so there's no clogging. Cuts the metal like butter. For roughly cutting large bits of alu to shape, or hacking alu things apart, they are great.

[TerraHertz]

Here we call it chop saw I think. I have one, but I would need a special blade, the one on it now is only for wood with perpendicularly placed teeth.  And even then, the heatsinks are too small to be secured properly into such a large tool. I fear on first contact the heatsink is going to fly off.

It won't go flying anywhere if you hold it (if it's big enough to do that safely!). A normal fine wood blade won't have a problem with alu.

Bad advice there about the holding. NEVER hold small objects by hand close to the blade on a dropsaw. If the object twists it can jam on the blade, after which very loud and fast things happen. Even if it happens to not pull your fingers into the blade, or hit you in the face/eye, just the very fast rotation of an object in your fingers can cause injury. The first (and last, hopefully) time I made the mistake of hand-holding a small bit of wood in a dropsaw, it impacted against the tip of my finger, pulped the flesh down the tip of the bone, and bruised all the joints of that finger. High velocity accidents - it's like being shot.

One thing to do to make cutting small objects feasible on a dropsaw, is to make a no-gap cutting base and backstop. For the base just put a sheet of old MDF or plywood across the saw stage, so there's no slot. Set the drop saw vertical stop so the blade just cuts into the MDF.
Also get a bit of scrap trued-up wood, and put it right across the back of the stage against the back stops. Clamp the new backstop and base sheets in place on both sides. Make a cut - now you have a backstop with just a thin slot the same width as the blade. You can put stuff there and either hold it with a scrap wooden push-stick, or clamp in place with other scraps of wood and G clamps. It won't move.

Apart from that, yes, fine toothed wood cutting blades work perfectly well on aluminium. Even with zero or very little set on the teeth.

[Monkeh]

Here we call it chop saw I think. I have one, but I would need a special blade, the one on it now is only for wood with perpendicularly placed teeth.  And even then, the heatsinks are too small to be secured properly into such a large tool. I fear on first contact the heatsink is going to fly off.

It won't go flying anywhere if you hold it (if it's big enough to do that safely!). A normal fine wood blade won't have a problem with alu.

Bad advice there about the holding. NEVER hold small objects by hand close to the blade on a dropsaw. If the object twists it can jam on the blade, after which very loud and fast things happen. Even if it happens to not pull your fingers into the blade, or hit you in the face/eye, just the very fast rotation of an object in your fingers can cause injury. The first (and last, hopefully) time I made the mistake of hand-holding a small bit of wood in a dropsaw, it impacted against the tip of my finger, pulped the flesh down the tip of the bone, and bruised all the joints of that finger. High velocity accidents - it's like being shot.

One thing to do to make cutting small objects feasible on a dropsaw, is to make a no-gap cutting base and backstop. For the base just put a sheet of old MDF or plywood across the saw stage, so there's no slot. Set the drop saw vertical stop so the blade just cuts into the MDF.
Also get a bit of scrap trued-up wood, and put it right across the back of the stage against the back stops. Clamp the new backstop and base sheets in place on both sides. Make a cut - now you have a backstop with just a thin slot the same width as the blade. You can put stuff there and either hold it with a scrap wooden push-stick, or clamp in place with other scraps of wood and G clamps. It won't move.

Apart from that, yes, fine toothed wood cutting blades work perfectly well on aluminium. Even with zero or very little set on the teeth.

I explicitly said if it's big enough to hold safely, did I not? Thank you for the lecture on tools I use almost daily, though..

[akis]

Due to the way the drop saws work, wouldn't a band saw be better to achieve a perpendicular cut? What I mean is that with the circular and very large blade, you need a lot of gap depth and a lot of contact with the flat part of the blade when its teeth are cutting the last bits of the object, this is the same with table saws too. With the chop saw sometimes I had to turn the object over to be able to cut it through.

But I think a band saw would cut squarely and there would be much less contact and need for clearance.

I have gone on Amazon and the band saw ratings are not that good even for the Sealey. Would you know of a cheap and good make?

[Monkeh]

What I mean is that with the circular and very large blade, you need a lot of gap depth and a lot of contact with the flat part of the blade when its teeth are cutting the last bits of the object, this is the same with table saws too. With the chop saw sometimes I had to turn the object over to be able to cut it through.

This is called using too small a saw. They make those blades the size of tractor wheels, you know.

[mzzj]

Use an axe, just swipe through it with one big swipe. If if won't go through in one swipe, use a bigger axe.

Swedish axe vs. aluminium heat sink:
https://dl.dropboxusercontent.com/u/93888484/WP_20140529_001.jpg

[akis]

That is not an axe, that is a little hatchet. Did you really whack the heatsink with it?

[Paul Moir]

Due to the way the drop saws work, wouldn't a band saw be better to achieve a perpendicular cut?

A bandsaw, whether it be vertical wood type or horizontal metal type, will leave a finish like a hacksaw or a little rougher if using a blade designed for cutting wood.  (No real surprise there - it's basically the same thing).   The circular saw leaves almost a milled finish.
Does anyone really use friction saws anymore, especially for aluminium?  Maybe real thin stuff?

[KJDS]

Use an axe, just swipe through it with one big swipe. If if won't go through in one swipe, use a bigger axe.

Swedish axe vs. aluminium heat sink:
https://dl.dropboxusercontent.com/u/93888484/WP_20140529_001.jpg

That's brilliant

[mzzj]

That is not an axe, that is a little hatchet. Did you really whack the heatsink with it?

Yes i used that hatchet to "cut" the heatsink in half. That type of heatsink is made of tightly pressed aluminum strips and it will split with gentle persuasion 

[G7PSK]

Cutting aluminium with a friction saw or cutting disc will cause the disc to pin (clog up) to stop this rub some candle wax onto the disc this also works when cutting with a hacksaw, for small quantity of cuts a good hacksaw with 14tpi blade all hard blade is best flexible blades wander all over the shop making it very hard to get a straight cut.