how to cut aluminium cleanly??

[wozzzzza]

security door aluminium extrusions im trying to cut using my mitre saw with 80 tooth carbide blade that is used for aluminium so it says. running at 5000rpm, it appears to be melting the damn aluminium and leaving far from clean cut and burrs everywhere.
what is the best way to cut this stuff cleanly??

[aldav]

Are you cutting too slowly and letting the heat build up? The optimum feed rate is maybe faster than you think. I've cut a lot of solid and extruded aluminium on the table saw and can't recall having a problem with melting.
Is the blade sharp?

[wozzzzza]

Are you cutting too slowly and letting the heat build up? The optimum feed rate is maybe faster than you think. I've cut a lot of solid and extruded aluminium on the table saw and can't recall having a problem with melting.
Is the blade sharp?

ok i will try faster, im not going too fast, and its a brand new blade. haven't had much to do with aluminium

[wozzzzza]

going faster made it worse.

[rambunctious]

Too fast and you will jam it or it will grab and cause damage to the saw, or what you are cutting, or you ???.
You must use either a wax block or WD 40/RP7/Silicone spray or similar to lubricate the blade.
The more lube the better.
Slow and steady wins the race.
I use a 100 tooth blade.

[Simplicity]

Try a cutting disk in a grinder or go old school an use a Hacksaw.

Cheers Matt.

[rambunctious]

Try a cutting disk in a grinder or go old school an use a Hacksaw.

Cheers Matt.

Useless on extrusion if you want a good mitre cut.

[aldav]

What blade are you using?

[jack620]

A brand new blade that's suitable for cutting aluminium won't need lubricating. It should cut ally window extrusions like butter. It will leave a small burr on the exit side.

Is it a dedicated metal cutting blade, or some sort of multi-purpose blade?

[AJ.]

You shouldn’t need to, but you could add a squirt of WD-40.

Cheers Andrew

[wozzzzza]

this is the blade im using at 5000rpm
TradeTools

[BobL]

You need a blade with NEGATIVELY raked teeth. Regular wood blades have positively raked teeth to bite into the wood and self feed ie drag the material into the cut. Using this on Al will end up cutting too fast and that's why you're get melting (technically called galling). This can also result in teeth tip loss that end up flying all around your shed like bullets - I have had this happen and is scary as %#$^. Negatively raked teeth push the material away slightly so the teeth scrape the material away rather than puncture the material. This results in a slower, MUCH smoother cut.

Sometimes these blades are called multi material blades. I have a negatively raked blade for my TS and one for my SCMS. Both of mine are Bosch branded - I've had the TS one for 15 years and it still works a treat.

If you don't want to go to the expense of buying a dedicated blade you can try using a much slower feed rate but the cut won't be as smooth.

[wozzzzza]

You need a blade with NEGATIVELY raked teeth.

can you recommend one? got a link?

[BobL]

can you recommend one? got a link?

This is the same blade I have for both my TS and SCMS.
https://www.totaltools.com.au/135963...ial-2608644607

I see the prices have gone up horrendously.
I bough the one for the TS 15 years ago and I think it cost me $90. The blade for my SCMS cost $120 about 3 years ago.
It does a great job on Al and plastics. It will even cut wood - slowly and very smoothly.

[jack620]

Looking at the blade in wozzza’s link, it does appear to have negative rake on the teeth.

I think the issue might just be the quality of the blade. $30 doesn’t get you much in a 10” aluminium blade.