Sawing aluminium?

[ian maybury]

I have an aluminium router guide clamp (an extrusion) about 4ft long which i need to split lengthwise with a clean cut to make something. (it's about 3mm thick where it needs cutting)

I've made short cuts on the table saw before using an old blade and not seen much effect, but this time only have a new fine cross cut blade i've been keeping to make clean cuts cross grain in solid wood to fit the current saw.

Does anybody know from experience if it's likely to noticeably knock the real 'new blade sharpness' off it? I really don't want to do it if it's going to leave the blade noticeably dulled.

Aluminium will quickly knock the real sharpness off a fresh carbon steel band saw blade, but the effect isn't all that pronounced. I'm guessing (?) that a carbide blade should do better? Or not?

Thanks

ian

[David Hawxhurst]

it will remove the sharpness of the new blade. cut wood needs a sharper blade than cutting metal. save your old (dull) blades that don't satisfactory cut wood anymore are still fine for cutting metal. i don't recall the difference in the way they cut the blade (teeth) cut wood vs metal, just that they are different actions and wood requires a sharper blade then metal.

[Carl Babel]

A carbide blade should have no problem cutting 3mm aluminum. Unless you are cutting a lot of it, you will probably not be able to notice any dulling.

That is just under 1/8", so you might want to have a backer - maybe some plywood.
You should probably use wax/paraffin on the blade, set the blade height 1/4" (~ 6.35 mm) above the aluminum, and don't feed the aluminum too fast.

[Grant Wilkinson]

I use the inexpensive Freud 6.5" blades in my table saw for cutting aluminum strap and angle iron. The very thin kerf keeps waste and resistance to a minimum.

[Kevin Bourque]

I'm thinking a bandsaw with a metal cutting blade would do the trick.

[ian maybury]

Thank you very much guys - sounds like it's a bit of a toss up between trying it and getting an old blade bored to suit. I've just started using a Hammer K3 panel saw which has a 30mm bore with braking pins - which means that my old blades don't fit.

The bandsaw would do it, but I guess the attraction of doing it on the table saw is the clean and straight edge it'll produce...

ian

[Bart Garber]

As of the knowledge I have on blades, a bi-metal band saw blade will be enough to do the sawing. Carbide blades are just too expensive for sawing aluminum. But before cutting the material, I recommend you to break-in your new blades for it to last long and to maximize the blade’s life.

[John McClanahan]

I have a carbide tipped saw blade with a damaged tooth that I use for cutting aluminum on my table saw. The teeth have no visible dulling, but I have never cut wood with it.

Some aluminum alloys like to stick to the blade similar the pitch builds up on a blade. Giving the cut line a squirt of spray oil like WD-40 helps reduce the sticking quite a bit. If you don't have oil, I have read that water on the cut line works, too.

The cutting chips san be hot, so protect your face, neck and arms. Wear hearing protection too.

John

[Chris Parks]

I have cut a lot of aluminium on the bandsaw with no change of blade from cutting wood and using methylated spirits as a lubricant from a spray bottle. Just make sure the blade is not too aggressive as far as TPI goes.

[Leo Graywacz]

Won't take long to get rid of the new sharpness with aluminum. Same with MDF or melamine.

Aluminum is much softer than brass and on occasion I cut brass, but I use an older blade that will need sharpening soon.

[Ole Anderson]

Production cutting of aluminum is usually done with a carbide blade with a triple chip tooth with a negative hook. I wouldn't try cutting aluminum with a blade with a lot of positive hook. Wax the teeth and you should be OK. I have cut 3" round solid 6061-T6 bar stock with a 10" TC negative hook blade. But cutting heavy stock like that needs a good size gullet or else you will load up the gullet with solid aluminum. Been there. I have seen a supply house cut large 2" thick aluminum plates with a standard circular saw with a non-ferrous cutting blade. Stuff too large to get in their normal machines. You don't see too much production cutting of aluminum with a band saw.

I would hesitate to cut aluminum with a brand new blade that you want to keep super sharp, but it won't completely dull it either. As others have said, it will loose its crisp new edge, but then cutting anything will eventually dull the blade. I have used an 8" blade in my TS to rip aluminum before, worked quite well.

If you use a Freud blade, it will state right on the blade how appropriate it is to use that particular blade with non-ferrous metal.

[Kent E. Matthew]

We have a Dewalt chop saw at work that is dedicated to aluminum screen and glass channel. It has a carbide finish cut blade. 70 or 90 teeth I don't remember which just a lot of teeth. Similar blade in the table saw does just fine I have done it many times.

[Rich Engelhardt]

I've just started using a Hammer K3 panel saw which has a 30mm bore with braking pins - which means that my old blades don't fit.
That's one expensive piece of equipment to use in a manner it was never intended to be used for...I believe I'd find out from Felder what little chips of metal are going to do to the innards of the saw before I did anything else.
Losing that factory new sharp edge on a blade may not be the most expensive thing you can encounter.

[george wilson]

Aluminum may be soft,BUT,it ALWAYS has a clear coating of aluminum oxide on it which is a VERY HARD material,used in making abrasives. It forms instantly on aluminum,but is clear,giving the impression that aluminum is not affected by air. Chrome does exactly the same thing.

If you value your sharp,new blade,don't cut aluminum with it. I am the retired master tool maker from Colonial Williamsburg.

[ian maybury]

Good info again guys. It reinforces the thought that it's do-able, but not (unless you're a betting man) necessarily the sort of thing to use your brand new fine wood blade on.

Agree 100% on the issue of some grades of aluminium loading up, and about some lubrication being good - it's usually the soft non heat treated grades that are worst. Kerosene or diesel work well as a lube, but they stink. It helps to stop files loading up too.

I took a look today and as luck would have it (i never thought i'd find one locally) tripped over a reasonably priced (about the same price as a good sharpening job) thin kerf non-ferrous negative rake blade with a 30mm bore. It'll need the 8.5mm holes drilled for the Hammer braking pins, but i have a cobalt drill and with a bit of luck the plate won't be too hard.

It seems to be best bet - that way I get to keep my good fine cutting wood blade, and will have the non-ferrous blade for use on metals in future.

Thanks for the help!

ian

[johnny means]

Cutting that little bit of aluminum wil not have why real effect on your blade. Also, european sliders are designed for cutting of non ferrous metals, plastics, and all other manner of material. In fact Felder sliders can be bought with a lubricating option for shops that do a lot of metal cutting.

[Jerrimy Snook]

Important guidelines when cutting aluminum are clamping and lubrication. I assume you will clamp to the slider? Are saws metric or imperial in Ireland? Here it would be difficult to find a metric blade at the borgs.
The cobalt bit should do fine cutting saw plate. Again use some lube, drill at about 150-300 rpm, & use a slow steady feed rate. Forcing the bit through the plate may damage the bit or work harden the hole and then you will need a carbide bit to finish the job DAMHIKT.
Are the pin holes 6 mm on a 42 mm bolt circle or 8 mm on a 60 mm circle?

[Rich Engelhardt]

Also, european sliders are designed for cutting of non ferrous metals, plastics, and all other manner of material. In fact Felder sliders can be bought with a lubricating option for shops that do a lot of metal cutting.
There you go...you learn something new every day...I wasn't aware of that fact & the Felder website doesn't mention it - at least not that I could see when I went there before posting what I did.

[ian maybury]

You set me thinking Rich, so thanks for that. Just in case i've posted a question on FOG.

I suspect it will be OK too, but the Hammer might not be quite as bullet proof as the full bore Felder machines. The motor and belts should be OK (the motor is totally enclosed or TEFC), but aluminium flakes in the slider bearings mightn't be good - if that is they can get in. The dust system is a powerful (Pentz/Clear Vue), so it's not going to be floating about.

I made occasional aluminium cuts on my previous Robland with no problems, but it was different.

I'm set up with clamps for work holding Jerrimy, and thanks for the speed info. The 30mm bore non ferrous blade came from a small tool supplies place I drove by while picking up something else in Dublin, but I was a little surprised to find one in the 30mm bore. That said we've been Euro/metric here since the 80s with little imperial left over now. (it's just taken me two weeks to find an imperial set of hex keys in a local hardware)

The Hammer uses a 30mm bore with two 8.5mm braking pins on a 46.35mm diameter. I've a feeling it's non standard, as you see blades about with slots for the pins which suggests there are various spacings in use.

ian

[ian maybury]

PS The main men on FOG say there's no problem with cutting aluminium - that Felder sell non ferrous blades to suit, and that they have done it many times. Just to watch out for burning the dust hose on heavy cuts, and for the 'gummier' types which can build up on the blade.

Just for anybody else looking in - non ferrous blades and table saws are not suitable for cutting steel....

ian

[kenneth kayser]

On the table saw I always take very shallow cuts and go slowly. Have never noticed any dulling of the blade. The cut is way better than I can get with a band saw. When cutting any metal on my band saw, I use steel cutting blade speed, in the area of 200 ft/min.

[Jim Matthews]

Cutting something this long, and so narrow on a tablesaw sounds like a ballistics experiment in the making - sometimes slower is better.

May I suggest you score this by hand, with something like a marking gauge?

If the knife used is sufficiently hard, you'll get progressively deeper with each pass.
At a given depth (roughly 2/3) you'll be able to flex the piece and break it along the score line.

Filing by hand would be enough to get knock off the sharp edge.

Perhaps this could be done with a high speed rotary tool like the Dremel and a guide.


jim
wpt, ma

[ian maybury]

I think it'll be OK Jim. The extrusion is a about 4in wide in total, and i'm set up so I can clamp it on the slider. (at both ends) Appreciate what you are saying, but the problem is that I need a nice clean and straight cut, and for the piece to end up accurately parallel sided.

In the unlikely event that it might become a matter of ballistics i'll be well out of the line of fire :) - another advantage of a slider, especially when it's a 2.5m one.

I'd be much less enthusiastic about cutting it on the rip fence....

ian

[ian maybury]

Just to say that it all worked out fine with the non-ferrous blade on the saw. The blade drilled just fine - a little hard, but no problems at low speed as suggested. The sawing was a tiny bit noisy and the dust collection despite doing a great job on wood dust missed quite a bit - but no problem for the odd job.

ian

[Jerrimy Snook]

Glad it went well!

[George Gyulatyan]

The sawing was a tiny bit noisy and the dust collection despite doing a great job on wood dust missed quite a bit - but no problem for the odd job.

ian

It is recommended to not use the dust collector when cutting metals anyway due to the possibility of combustion due to heated metals.

[James Heisbert]

Just to say that it all worked out fine with the non-ferrous blade on the saw. The blade drilled just fine - a little hard, but no problems at low speed as suggested. The sawing was a tiny bit noisy and the dust collection despite doing a great job on wood dust missed quite a bit - but no problem for the odd job.

ian

It is amazing that all suggestions worked out for you! Good for you ian.

[ian maybury]

Ta James.

I actually took a look George on the fire risk topic, and could find no reference to any. Iron/ferrous materials are different because they can conceivably spark. Aluminium doesn't generate high temperatures while cutting, doesn't spark and what heat there is is quickly dissipated. (it's highly conductive) I mentioned earlier that it does seem to be able to get hot enough to melt a dust hose if the cut is heavy, but not as best i can tell hot enough to present a fire risk.

It is capable of supporting a dust explosion, but much like wood dust it needs to be very finely divided indeed (almost vapourised I think) for this to happen.

Is a fire possible? It'd be great to hear the details if this actually is the case...

ian

[James Heisbert]

George was right, it is not recommended to use dust collector when cutting metals. But with the fire risk concern, there is only a very slight chance(if any) for a possible fire or dust explosion to happen. Dust collectors are designed primarily for collecting dusts when you’re cutting wood. When you do metal cutting, using coolants is highly recommended. Except for cutting magnesium, you need to use a specifically designed coolant only for magnesium or you can stay with dry cutting. It is because of magnesium’s high combustibility and its reaction to water. As to aluminum, you can use general purpose coolants available in the market. They’re easy to find.

[Kevin Presutti]

Look on Amazon at the Freud Blades. Go to Freud website and look under the indutrial blades, get the appropriate non-ferrous blade with a triple chip grind with a negative hook angle as Ole has said. They make a blade lube for cutting aluminum but a good stick of bees waxs work as well. I have cut alot of Style Mark trim and had great success. The trick to good clen cuts is the TCG and many teeth with the lube.

[ian maybury]

My job is done Kevin using a negative rake non ferrous blade. It worked very well. I'd rather not do too much on my saw because there's a fair bit of cleaning up of the flakes afterwards.

The only question seems to be whether there's any fire risk when cutting aluminium. If there is it seems based on what I found to be at most minimal, but as before if anybody has hard evidence it'd be good to hear...

ian

[George Gyulatyan]

Ian, my comment on fire was based on an article I had read in one of the ww magazines, unfortunately can't remember which one. They had made a comment about completely disconnecting the DC hose from the saw before cutting aluminum.

But then again, that might've been to satisfy the legal department. Personally I've cut some 1/8" aluminum stock on my table saw using the Freud Glue Line Rip saw blade, because that's what I have and it is TCG, w/o any issues. And I've forgotten to disconnect the hose, although didn't run the DC itself.

[ian maybury]

Thanks George, appreciate that. I'm inclined to agree with the thought about the legal department - in that you can't absolutely guarantee a fire is always impossible.

It's a bit of an elusive topic though so far as I can tell. Aluminium is cut all over the place using bog ordinary woodworking tools and there's no sign in risk assessments or reports that it leads to fires - although it's fairly clear that a thick layer of hot dust could in certain circumstances get hot enough melt a plastic dust hose.

Fire is another matter though. It'd have to get hot enough to exceed the flash point of whatever it contacts, and even plastics require very high temperatures. Trawling the MSDS sheets and the like for aluminum shows that a dust explosion is possible (as in the case of wood or any other dust), as is a thermite reaction where an oxygen containing powder (e.g. iron oxide) is combined with an aluminium powder. Both require very high temperatures to kick off, and pretty precisely controlled conditions to get and keep them going....

ian