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felixe
2nd April 2006, 11:14 AM
Can anyone help with some advice.

I need to cut some aluminium lengths with a hollow section, walls are 5mm thick and the approximate width is 40mmx30mm, Length is between 900-1200mm (approx size only - I left them at work) they are non-anodized lengths from Capral that need to be docked to size.
I want a good clean straight cut and my options are by hand (not ideal due to the quantity), 10 inch table saw (10 amp) or 10 inch mitre saw (10 amp), I have searched the site and come up with no answers.
Does anyone have any experience with the non-ferrous metal blades from company's such as CMT and Freud. I am looking for any advice/feedback before I purchase a blade.
Any advice would be greatly appreciated

Thanks

Felixe

Groggy
2nd April 2006, 11:40 AM
Use the miter saw with a 100+ tooth blade. Be aware that the mess will cover your workshop and make it look like a silver wonderland. Most manufacturers of 100 tooth blades are OK. I use an Irwin for cutting aluminium.

Ashore
2nd April 2006, 12:19 PM
I use a SCMC with an Irwin Aluminium cutting blade, have cut a mass of aluminum mostly 25mm hollow box section, and get a clean cut each time
I would think that the mitre saw is the go , the 80 tooth version I got cost about $100 or so but I have been using it now for 3 years and its still ok.

The other thing is you would be advised to get an appropriate wax stick and use it when cutting , it helps lubricate the blade and thus give a longer life

Rgds

rodm
2nd April 2006, 01:44 PM
Good advice above but I would like to add cut with confidence. I don't mean to just plough through the cut as it should be a smooth downwards pressure but do not dab at cutting your ali as you increase the risk of something going wrong. Once you have cut through keep the blade down until it stops. This helps avoid the offcut from vibrating over to the blade and being picked up by a tooth and flung.

While the SCMS is fine for cutting ali I prefer the table saw as it is a more rigid machine and you have two hands free for holding your stock. It also offers more support for your stock than a standard SCMS and the offcut is free and cannot rebound off the rear fence like it does on a SCMS. The support comment is not applicable for long lengths of ali as ths is better handled on a SCMS. I have a sliding table on my table saw but a sled would do a good job on a project like this. A zero clearance plate for the blade is also a must but you would have this if you use a sled.

If you have carpet inside your house clean your hair if you still have any (LOL), shirt including pockets otherwise you will not be popular. A vacuum is the best way to clean up afterwards.

felixe
2nd April 2006, 04:05 PM
With the blade, are there any other special requirements other than 80-100 tooth?
Do I need specifics like grind of teeth, rake etc or is it better to buy a specific blade as recommended by the manufacturer (my choice I think for the 1st time experience).
Who sells Irwin blades in QLD.
Thanks for the responses so far, they have been very helpful.

Felixe

Barry_White
2nd April 2006, 04:21 PM
All good advise above. You will find Bunnings sell Irwin blades to cut aluminium. The best blades for aluminium are Triple tooth blades. They will give you the smoothest cut and wax cutting lube is advisable. A straight mitre drop saw is better than a SCMS but either will do it.

Auld Bassoon
2nd April 2006, 07:09 PM
I'd add that you might want to consider temporarily mounting the intake hose from a shop-vac (or similar), or better still a direct feed to the DC if you have one, close to the blade to pick up as much as possible of the "Ali glitter" that will pour off the cut - and wear safety glasses and a mask!

That last thing that you want is to get that debris in your eyes or lungs.

Ashore
2nd April 2006, 07:30 PM
With the blade, are there any other special requirements other than 80-100 tooth?
Do I need specifics like grind of teeth, rake etc or is it better to buy a specific blade as recommended by the manufacturer (my choice I think for the 1st time experience).
Who sells Irwin blades in QLD.
Thanks for the responses so far, they have been very helpful.

Felixe
The Irwin blades are marked "aluminium cutting" and have a negative rake on the second tooth from memory


Rgds

journeyman Mick
2nd April 2006, 10:46 PM
An aluminium blade will have negative rake on all its teeth. If you have positive rake the gullets will clog with swarf almost instantly.

Mick

felixe
3rd April 2006, 09:05 PM
Thank you everyone for all the help. I'll keep you posted.

Felixe

MrFixIt
15th May 2006, 04:18 PM
Hi

An aluminium blade will have negative rake on all its teeth. If you have positive rake the gullets will clog with swarf almost instantly.Mick
The negative rake is to help prevent the blade from "grabbing" not the prevention of clogging the gullet.

A sharp positive rake blade will slice into the soft aluminium and easily tend to dig in deeper hence the tendancy to "grab" a negative rake prevents this.

Just like when cutting wood, the number of teeth will affect the finished quaility of the cut. If you don't have to be concerned about the appearance of the cut ends then even a 60t blade will be ok. A finer tooth blade is (always) better especially if the material being cut is thin walled eg 1mm

journeyman Mick
15th May 2006, 11:05 PM
...............The negative rake is to help prevent the blade from "grabbing" not the prevention of clogging the gullet..........

Maybe so, but when the gullets clog up, as they will, you will run into some problems like teeth breaking off which is just as undesireable as "grabbing".

Mick

MrFixIt
16th May 2006, 12:12 PM
Hi

Maybe so, but when the gullets clog up, as they will, you will run into some problems like teeth breaking off which is just as undesireable as "grabbing".MickFor all those potetial aluminium "cutters" out there, generelly speaking, if the gullets become clogged (it hasn't happened to me) with aluminium swarf then the blade will not cut as well as it should and this will be immediately noticable in the saws performance. It is not too lilely that teeth will break off under these circumstances.

However it is very important to realise that a VERY FIRM grip or preferably a clamped hold on the aluminium being cut, is REQUIRED. This is very important when cutting hollow sections like tubes and extrusions, the most common use for cutting aluminium on drop saws.

If the piece of aluminium being cut moves even slightly when using a positive rake blade you can be almost certain that the next tooth entering the material will grab the aluminium and pull it into the blade. This is the most likely scenario that will break teeth on the blade (DAMHIKT :) )

Aluminium is easily cut with woodworking tools and blades. It is softer than many hardwoods. Aluminium can be routed quite well with normal router bits. However it is not as forgiving if you make a mistake. This can result in simply a broken blade or bit or it can be a disaster. You MUST be very careful when cutting aluminium and it must be firmly clamped when being machined.

What you WILL find is that after cutting some aluminium, virtually every tooth on the blade will have a little aluminium shaving stuck to it. The blade I use is an negative rake 80t Irwin brand blade. This blade is described on the box as an aluminium cutting blade. It works very well and gives a clean cut and finish. The same blade can be used on plastic manterial like reticulation pipe etc. The negative rake helps prevent grabbing of the plastic/pvc. This again is important as this is hollow section material.

FWIW I DON'T recommend that you cut SOLID aluminium on a drop saw eg bars or thick flats. This IS more likely to clog the teeth of a drop saw blade. You may be able to cut small section solids but again you must be VERY careful. The aluminium swarf in such a cut through solid sections tends to get warm and becomes "sticky" and sticks to the blade. This WILL clog the blade as Mick said. This can be a problem that does not occur with hollow section material.

The local steel/aluminium supplier that I use, cuts aluminium with a proper metal cutting (horizontal) bandsaw.

HTH :)

journeyman Mick
16th May 2006, 09:50 PM
Peter,
this will be my last post on this thread. The tooth breakage I described was in a largish workshop where there were 2 x 24 M boats (3 decks each) plus assorted smaller vessels being built, all in aluminium. There was a whole bunch of boilermakers working there (30 - 40) who were all experienced in aluminium fabrication. There were two 14" drop saws in use and the hold down vice was always used on any cut (workshop rule). Normally no problems. With positive rake blades: swarf clogging gullets, saws jumping up out of cuts, broken teeth. Perhaps I'm missing something, but my diagnosis was that the positive rake blades were the culprits. The positive rake would force the work back against the fence on the dropsaw, but this wouldn not cause the breakage as far as I can see. With the work held down securely there wouldn't have been any sideways pressure on the teeth. We're talking gullets that were packed so hard with swarf that it had overfilled the gullet to end up thicker than the saw itself and ended up smearing all over the rim of the blade. It was physically bonded with the steel of the blade from the pressures applied. Finally the teeth weren't broken off sideways like they usually are (you can usually see thet the tooth has been bent to one side). In some cases the teeth were still partially attached but bent back. Sorry, but these problems were caused by the gullets clogging.

Mick

soundman
29th May 2006, 12:30 AM
Ahh Another lasarus thread:D

I and a number of my mates work with aluminium extrusion quite a bit and there is some truth to all of this.

Clogging is a real problem and it will happen with almost any blade type or spacing as it is caused by the swarf getting hot and sticking to the face of the tooth. A lump forms and just gets bigger, this lump may not fill the entire gullet but the result is the same proor cutting and bad finish.

The cause is heat most usualy caused by failure to lubricate the blade sufficiently.
I very rarely will have a problem because I use a wax stick at least every second or third cut. more frequently on heavier stock or solids.
One mate who is not so prone to lubricate always seems to have clogs in his blade which have to be cleared with a screwdriver.
When a blade gets blunt it is much more likely to clog.

the lesson is lubricate, It seems to matter little what you use wax, deterget based, or even wd40. I prefer composite wax.

as far as tooth breakage.
Aluminium is a bastard if you arent carefull and catches can be particularly violent.
If the stock isnt firmly against the fence, isnt squarely held, bent misformed, or has stresses in it the catch that results can be very violent.
Light U shaped extrusions can be realu nasty.

I havn't had a bad catch myself but I have seen broken teeth, bent blades, bent fences and big chunks out of fences and guards.
In a big shop with gung ho fabricators...all the various problems would be a given. Totaly unnecessary but given all the same.

as for cutting solid, I have cut 25 x50 bar with a 80 tooth negative rake blade on a drop saw with no problem at all. Remember I lubricate regularly and keep my blade sharp.

I use both the drop saw and the able saw to cut aluminium extrusion and solid on the drop saw and also sheet material on the table saw.
With propper care and importantly lubrication there is no real problem.

As far as negative rake.... definitly give a better finish and is a a little less likely to grab.... but any carbide saw blade will cut aluminium.... but the care factor increases.

Most importantly with aluminium you must be cutting properly, with a sharp blade with suficient restraint and lubrication for trouble free resilts.

With aluminium, everything you should be doing right is 10 times more important and every consiquence is 10 times as bad.

With aluminium only the rightious will be blessed.

cheers