Cutting Aluminum

[VRaptor SpeedWorks, LLC]

Well, after 20 years, I learned something new today. I normally buy all of my 4.5" cut-off wheels from Harbor Freight....the "Warrior" brand 40 Grit Metal wheels. Years ago, I picked up a 10 pack of the 40 Grit Masonry wheels by mistake as they look identical to the cut off wheels for Metal. I've done a ton of metal cutting in the past few days fitting doors on a GTM and used up all of my Metal wheels....so I threw on one of the Masonry wheels. One of the aluminum tank covers (1/8" thick) needed to be trimmed to fit, so I proceeded to cut on it with one of these Masonry wheels.....AND IT CUTS THRU LIKE BUTTER! The metal wheels, you grind and grind and grind and it seems to just smear the aluminum around and takes FOREVER to cut thru aluminum. This Masonry wheel cut thru 1/8" aluminum like a metal blade cutting thru 20ga steel. Just thought I'd throw that out there in case it helps someone else. Sure wish I knew this 20 years ago!

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[VRaptor SpeedWorks, LLC]

Just now trimmed the tank cover on the other side of the car and same thing. What would have taken probably 5 minutes of cutting....with considerable effort....with one of the "Metal" cut-off wheels took all of about 20 seconds with very little effort or pressure required with the Masonry wheel. Almost too good to believe!

[PNWTim]

It kind of makes sense. Metal cutoff wheels are typically aluminum oxide and concrete wheels are silicon carbide or similar. I am not sure how they are both bonded together - that may be a limiting factor.

[crash]

Look at the thickness of the wheels. My experience, and guess in your situation, is that the masonry wheels you have are much thinner than the metal wheels. This is great for getting through metal material fast, but can be dangerous.

The issue is that with aluminum the cutting process can heat up the metal so much that it melts and then sticks to the cut off wheel. With the metal wheels being much thicker, they can handle the build up and have a much lower chance of catastrophically having a rapid unexpected deconstruction.

There is typically no build up with masonry cutting so the thinner wheels are fine. On a side note I only use solid diamond blades for masonry work.

I rarely, if ever, cut aluminum sheet with a cut off wheel these days. Plasma for the thicker stuff and shear or snips for the thinner stuff. I would highly recommend you not using an abrasive cut off wheel on aluminum for the very reason described above.

Yes I have seen cut off wheels come apart, and I have seen people physically injured from cutting aluminum with cut off tools. Thankfully nothing debilitating, but blood and stitches were involved.

I also occasionally used a cut off tool without a blade guard. Not anymore after what I saw happen.

[VRaptor SpeedWorks, LLC]

The cutoff wheels are all the exact same thickness....1/16th". Other than the label, you can't look at them and easily tell the difference. I bought them by mistake because even WITH the label, they're easy to get mixed up! :D

Yes, when cutting the .040 stuff, I use a tin snips or air shears. But a ton of the stuff I cut is either .080 or 1/8" like the tank covers....too thick to use shears, but not thick enough to warrant taking all the time to drag out the plasma torch and try to set up a fixture to cut a straight cut when all I'm doing (as with the tank covers) is trimming maybe 1/8th or 3/16" off of an edge in one location. The tank covers I trimmed were already covered in dynamat crap....so using Plasma wasn't really an option.

Yes, when using the Metal wheels, that's what's happening...as you describe. Instead of cutting, the alum melts and sticks to the cutoff wheel and from there it just feels like you're smearing it around instead of cutting....and yes, it takes forever. It's a totally different experience with the masonry wheel. No melting, no smearing.....just cutting. The cut I made yesterday on the 1/8" tank covers was probably about 10" long.....and I kid you not, I doubt that it took a full 20 seconds to make that cut, with virtually no pressure required....the blade just "slides thru" the material almost like it's not even there. I'm guessing that same cut with the Metal wheel would have probably taken me 3 or 4 minutes with considerable effort used.

I dug around in my drawer and found a new Metal wheel to compare.....

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[crash]

Surprised that they are the same thickness, but looking at those pictures there is a significant difference in the reinforcing structure between the two different wheels. I can understand why you would use what cuts fastest, and I would likely do the same, just be aware that these wheels, even when doing everything as prescribed, can come apart. Be prepared for it and assume it WILL happen.

[ggunter]

If you have issues with the wheels getting clogged with aluminum spin them into a bar of soap at low speed before you start, this keeps them from clogging.

[ggunter]

They don't call them the wheel of death for nothing.

[VRaptor SpeedWorks, LLC]

Surprised that they are the same thickness, but looking at those pictures there is a significant difference in the reinforcing structure between the two different wheels. I can understand why you would use what cuts fastest, and I would likely do the same, just be aware that these wheels, even when doing everything as prescribed, can come apart. Be prepared for it and assume it WILL happen.

Yes, I do always use a guard on my grinder and try to keep my head out of the "cut path". These are the only cutting wheels I've used in 20 years....the cheapest you can buy at HF, and I have yet to have one come apart.....with the exception of using the outer edge of one as a grinding wheel instead of a cut-off wheel until the outer edge thinned out to the point where small chucks started flying off. (incorrect use...yes....)

[crash]

If you have issues with the wheels getting clogged with aluminum spin them into a bar of soap at low speed before you start, this keeps them from clogging.

Yes, on the off times that I end up having to cut aluminum with my abrasive chop saw, I use cutting wax to keep the wheel from getting clogged.

I recently bought a carbide bladed chop saw, which is AMAZING, but the cutting wax is also needed with the carbide blade when cutting aluminum.

I've been looking for a good used automatic band saw for doing machining blanks, but have not found one yet. Until then the carbide chop saw will have to do...with the wax.

[cob427sc]

I agree with Crash. I bought a carbide wheel for my steel chop saw a couple of years ago and it just lasts and lasts. No more continually replacing cut off wheels and no problem with aluminum plugging the wheel.