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I Forge Iron

abrasive cut off saw


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The proper RPM depends on blade diameter. My 14" chop saw runs at 3900 RPM. Smaller blades will need to run faster. I have a 7" table saw I made with a ballbearing mandrel that runs at 8000 RPM. This one has no fence or guards and is used for free forming leaves and making tenons in flat bar etc. It has a 1-1/2 HP motor and I can lean on it pretty hard.

Buy good blades from a welding supply store or somewhere like northerntool. If you can buy it at Wally World and the label is yellow they work but don't last so long. The max RPM they should run at is right on the label.

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I tried this on a compound miter saw last year. I'm not sure what the RPM was but the stock wood was had 6k max so I got a metal chop saw wheel (Dewalt) 10" and it seemed OK for smaller stock.. but I think it would overheat too much on larger stock like 2" square tubing.. even 3/4 or 1" seemed to tax it too much. I wasn't impressed with it much. Also, be aware that the metal dust from cutting will get into every spot on the saw. I had to spend an hour trying to get the saw to rotate to do a miter. The clearances were not made to be caked with metal dust.
Also, the blade will get chips on the edge and will have a tendency to bounce off the steel. Constant pressure helps but I think it heats the steel on thicker walls. 3/8 solid square 1018 was hard to cut. 1/2" .065 wall was fine. 3/4 .065 was ok.. up from there was questionable.

After all that, I bought a Ryobi angle grinder and some cutoff blades. I needed a grinder. It is a nice kit.
It is the cheaper $40ish 4.5" You will need backing flange for use with cutoff wheels. It is similar to THIS They may have changed the design. They had it with the grinders at HD. Comes on a card. Mine looks like THIS

This works a ton better and cuts faster and cleaner than the makeshift chop saws. You figure a thinner blade spinning twice as fast. You just have to get used to it and to extra marking to get your cuts a square as possible. They are about on par with the cuts from the chop saw blade. I have not had to cut any of the 3/8" 1018 yet so I don't know how it is. I would expect it to be easier as well.

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The HF chop saw I purchased gave up before the abrasive wheel that came with the saw did. Milwaukee was 3 times the price but had a 5 (FIVE) year warranty. It has cut everything I have ask it to cut up to 2" solid round.

There has been a LOT of spring steel (leaf springs up to 1/2x4"), coil spring (1/4-3/4" diameter), and axles (1-1/4" diameter), as well as a bunch of mild steel (flatbar 1/4" and 3/8" some 1/2" up to 4" wide, angle iron, channel, pipe, tubing, etc etc), put through that saw. I would go Milwaukee again if this one ever had a problem.

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Glenn,
the HF chop saw is junk, but I knew that going in and probably coddle it a little. I have pretty much cut the same array of shapes from couple of inch bar to angles and tubes. We had a 3-phase 14" chop saw at the machine shop that made quick time through stuff that the HF struggles with. I take my time and apply most of the cutting pressure to the guard (in line with the wheel). The pivot is weak and, if you bear down on the handle, it bends and the cut goes crooked. It only cost as much as a couple of good wheels though. Everything I do with it ends up being a bonus. MIKE (DadofFrogPond)

PS, we also had a HF chop saw at the machine shop. Once we took the head off of the base and cut out a door hole in the side of a trailer. It survived it to cut again.

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Im very fond of building my own tools, so its nice to see all this rpm info for abrasives

but what Id really like is to make a cold saw. At work we have a Scotchman, but the rpm is considerably slower, somewhere around 50 rpm. If I can lay my hands on the right configuration of speed reducer...

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I had the saw already, so that is why I opted for it. I just did get the ( cheap yes) grizzly band saw with miter stand, $147. I used it last night its nosier than the milwalkee, but cuts about the same. The Millwalkee with stand is over $500. If I was using it all thet time I would go with the M, but I will only use it sporadically, I can use it for my business too cutting conduit.

Ice, I am working on the rpm thing for a very old horz. recip saw. I got hold of a roto tiller gear, I think that might work. i wonder if it would work for you, they are free, heavy duty,and reduce the gear pretty low.

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I have a small HF chop saw and the larger version. The small one was a complete waste of money. The larger one works well enough, it has its drawbacks, but I can work around them. It does tend to cut at an angle with excessive downward force applied. I was able to minimize this effect by simply moving the back stop so that the workpiece is quasi-centered under the disc. Once I did this I noticed a considerable increase in ease of cutting and angled cuts are now negligibile.

I also have a horizontal/vert bandsaw that I use for many things. The chop saw and band saw see about equal use. I couldn't imagine living without either one.

Steve

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