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 (https://www.tradetools.com/renegade-industrial-250mm-x-80t-tct-ri25080alu)

[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-bosch-305mm-100t-tct-circular-saw-blade-multi-purpose-multimaterial-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.

[wozzzzza]

This is the same blade I have for both my TS and SCMS.
BOSCH 305mm 100T TCT Circular Saw Blade for Multi-Purpose Cutting - MULTIMATERIAL | Total Tools (https://www.totaltools.com.au/135963-bosch-305mm-100t-tct-circular-saw-blade-multi-purpose-multimaterial-2608644607)

this is my size, will give it a try, but whats the difference between mine i have now and this?

https://www.totaltools.com.au/135960-bosch-254mm-100t-tct-circular-saw-blade-multi-purpose-cutting-multimaterial-2608644604


This is the same blade I have for both my TS and SCMS.
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.

what hasnt gone up?? being 15 years ago at $90 i was expecting $180 when i clicked that link.

[EagerBeaver71]

I'm not convinced its the blade that's causing the problem. What TS are you using?, fence setup etc?.

[aldav]

My current aluminium cutting blade is a CMT, 235mm, triple chip grind, 6 degree neg. rake, 48 teeth. I agree with Jack that the blade you've linked to appears to be negative rake. I can't understand why you're not getting a relatively clean cut from it regardless of what you paid for it. Makes me wonder whether there is something else going on. :whatonearth: Have you tried cutting a piece of timber with it?

[jack620]

I'm not convinced its the blade that's causing the problem. What TS are you using?, fence setup etc?.

He’s using a mitre saw.

Other possible problems? Blade on backwards. Incorrect or no arbor bushing used (assuming the arbor isn’t 30mm).

[EagerBeaver71]

He’s using a mitre saw.

Other possible problems? Blade on backwards. Incorrect or no arbor bushing used (assuming the arbor isn’t 30mm).

Blade on backwards would give similar results to what he's reporting.

[wozzzzza]

I'm not convinced its the blade that's causing the problem. What TS are you using?, fence setup etc?.

your are correct. i just went to the shed to have a look, guess what, blade is on damn backwards.:no::no::no::no::doh::doh::doh:

IM A BIG BLOODY

536636

[EagerBeaver71]

your are correct. i just went to the shed to have a look, guess what, blade is on damn backwards.:no::no::no::no::doh::doh::doh:

IM A BIG BLOODY

536636

We've all done it lol.

[EagerBeaver71]

When you have eliminated the impossible, whatever remains, however improbable, must be the truth, also eliminating the most obvious first is always a good place to start.

Elementary my dear Beaver.

[wozzzzza]

We've all done it lol.
i saw old blade writing pointing out, so i just threw the new one on writing pointing out without thinking.

[yvan]

This is the same blade I have for both my TS and SCMS.
BOSCH 305mm 100T TCT Circular Saw Blade for Multi-Purpose Cutting - MULTIMATERIAL | Total Tools (https://www.totaltools.com.au/135963-bosch-305mm-100t-tct-circular-saw-blade-multi-purpose-multimaterial-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.

BobL,

What sort of materials will it cut?

[BobL]

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.

Thanks Jack, that blade should work OK. Maybe try slowing down the feed rate?

[jack620]

Maybe try slowing down the feed rate?

All sorted Bob. He had the blade on backwards. So does a negative rake blade installed backwards have a positive rake? :D

[BobL]

Blade on backwards :oo: - its not the first time this has happened - It even happened to an experienced woodie on this site who seems to have evaporated.

Negative rake applies to the forward facing face of the tooth - when on backwards in practice it becomes a hyper negative rake which will still cut but will get super hot hence the excess galling.

[wozzzzza]

this is all i can say.
learn from my stuff up
536749536750