Aluminium cutting with circular saw

[Dave SParticipant @daves59043]

Evening all,

I find myself with the need to cut a chunk off an aluminium extrusion. The extrusion is 75mm x 360mm box, 3mm wall with diagonal internal ribbing.

Too big for hand hacksaw, so I’m looking for other methods.

I have a 185 mm carbide tipped circular saw that I could use. It is a normal wood blade, 24 teeth.

It feels like a possibility, but any other ideas would be welcomed. (The circular saw feels like the most dangerous tool in the world…)

Dave

[Mark EasingwoodParticipant @markeasingwood33578]

The carbide tipped blade will certainly cut it, but if it is a hand held saw then it may not be a pleasant exercise!!

I think the proper blades for cutting Aluminium in a chop saw, have negative rake teeth.

Mark.

Edit; The Aluminium will probably stick to the teeth, wax may help pevent this.

[John PurdyParticipant @johnpurdy78347]

I have cut 1/8″, 3/16″ and 1/4″ aluminum sheet with a normal carbide blade (80 teeth) on my 10″ table saw with no problems. A full face shield is highly recommended as chips fly everywhere! I am not sure if I would want to do it with a hand held 7 1/4″  skill  saw as even on the table saw the material tends to jump around and has to be held very securely and fed slowly. I think for the size you are talking about the safest way would be a chop saw as Mark suggests, where the material can be securely clamped down.

John

[noel shelleyParticipant @noelshelley55608]

A hard point wood saw would do it, just take it steady. Noel.

[JasonBModerator @jasonb]

As Mark says the non ferrous circ saw blades are negative rake both for table, chop and handheld which stops them grabbing the thin sections and being drawn in. usually around -6deg. Also have a lot more teeth which will also reduce the risk of grabbing

 

[Mark EasingwoodParticipant @markeasingwood33578]

Just a thought, if you have a Router, then a Carbide cutter, say 1/4 dia. will probably cut through 3mm in say 4 passes per side, nice and neat held against a straight edge. Certainly less fraught!

Might need the handsaw for the ribbing.

Mark.

[MacolmParticipant @macolm]

I cut aluminium sheet up to 3mm on my radial arm saw. Almost always, I use clamps to the table so that both hands can be used to smoothly control the saw against self feeding. The finish using a sharp carbide wood blade is excellent, helped by a smear of wax along the saw path. Radial arm saw blades nearly always have negative rake. Can confirm that chips fly everywhere. Cutting forces are certainly higher than for softwoods, more like cutting thick hardwoods.

I would be very wary of trying to use a hand held circular saw, but if needs must, a fine tooth metal blade would be a bit safer than a wood blade, and if possible of as small a diameter as will make the cut, for example-

https://www.screwfix.com/p/titan-wood-metal-circular-saw-blade-85mm-x-15mm-60t/809pt

[HuubParticipant @huub]

I have cut 8 mm aluminum with a very old circular hand saw using the blade for wood. That worked surprisingly well. Then I bought a cheap blade (15 U$) for my table saw that was sold as “suitable for aluminum”. I have cut 30 mm thick aluminum on my table saw using a bit cutting oil at the top of the aluminum. It worked but the cutting edge wasn’t nice and needed cleanup using the milling machine. Also the dimension was 0.5 mm off.

Doing this is dangerous. So I stood beside the table saw, wore gloves, eye protection and ear protection. I positioned the saw table so that in case of a disaster, the blade or aluminum would do minimal damage.

For the saw blade, it was abuse because the RPM was way to high. Never the less, I got the job done and I think I can still use this blade to cut some aluminum.

[Mark RandParticipant @markrand96270]

I’ve cut a few metres of 15mm aluminium plate with a Skill saw. Overalls and safety glasses are recommended!

[Speedy Builder5Participant @speedybuilder5]

I wear safety glasses and a visor plus ear defenders with a chop saw.  I don’t like the idea of free hand though.

[Dave SParticipant @daves59043]

Well, after a dose of looking at it I’ve managed to cut it.

I clamped the extrusion to an immovable object (my mill), clamped on a fence and set the saw to the smallest depth it would go.

This was after 2 passes

Wasnt that bad as it happens. Noisy as hell (had ear defenders and full face visor on).
The stagger on the teeth appears to have pushed the blade left and right hugely, the kerf was 1/4” wide!

Did the cut in about 5 or 6 small doc passes.

The blade wasn’t big enough to go right through, so flipped and chain drilled the other side. Probably should have thought of that earlier, but I think the saw was faster.

Now I “just” need to cleanup the ends and bring to size, but at least it’s now within the size I can clamp to the mill and machine.

Dave

 

[Dave SParticipant @daves59043]

Just to finish this off I’ve squared up and sized the extrusion.

Now waiting for some sikaflex to glue it in place before mounting my CNC mill to it.

 

 

[Neil LickfoldParticipant @neillickfold44316]

The specific Aluminium cutting blades are different to a wood blade. If cutting a box section, place timber or other similar material inside to support the section being cut. Typically it is a fine blade, with about 10 to 12 mm distance between the teeth. Saw diameter will dictate the teeth number.

They typically use an oil mist onto the blade, the oil being a vegetable oil, like canola oil. A squirt of oil along the line of cut is usually sufficient.

I have not used a circular saw to cut Aluminium sections, only a drop saw and a radial arm saw, with Aluminium cutting blades. Also, both sides are clamped in position so they can not move.

The secret is a slow controlled feed, and a vacuum system to draw away the swarf as it is formed .

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