saintjohnbarleycorn Posted January 9, 2008 Share Posted January 9, 2008 I converted an old table saw into a abrasive cut off, Well just added a metal cutting blade to it. I tried some different materials on it and was not that impressed with the cutting speed. I wonder if different blades are better or is it just the nature of the beast. thanks. Link to comment Share on other sites More sharing options...
Flop Posted January 9, 2008 Share Posted January 9, 2008 The rpm rate on a table saw is to high to cut most steel, most abrasive cutoff's run at a lower rpm rate. This could be why your disappointed with the results. Link to comment Share on other sites More sharing options...
saintjohnbarleycorn Posted January 9, 2008 Author Share Posted January 9, 2008 what rpm should I look for? I can change the pulley size to slow it down. thanks. Link to comment Share on other sites More sharing options...
Flop Posted January 9, 2008 Share Posted January 9, 2008 My milwaulkee cut off runs at 3900 rpms and it does a great job, you might try that or maybe around 4000-4500 rpms. Link to comment Share on other sites More sharing options...
skunkriv Posted January 9, 2008 Share Posted January 9, 2008 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. Link to comment Share on other sites More sharing options...
saintjohnbarleycorn Posted January 9, 2008 Author Share Posted January 9, 2008 ok this one is about 10" now and of course gets smaller, I will look at the shiv ratio and see what needs to be done, thanks. kevin Link to comment Share on other sites More sharing options...
Paragon Posted January 9, 2008 Share Posted January 9, 2008 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. Link to comment Share on other sites More sharing options...
FrogPondForge Posted January 9, 2008 Share Posted January 9, 2008 I have probably cut a mile of steel with the $50 Harbor Freight 14" chop saw. I bought 5 blades with it and am on #2 or #3. It is so cheap as to make converting hardly worthwile. I do use my 10" miter saw on aluminum (carbide tipped). Works super! Mike (FrogPondsDad) Link to comment Share on other sites More sharing options...
saintjohnbarleycorn Posted January 9, 2008 Author Share Posted January 9, 2008 mike what kind of widths and thickness's are you cutting? thanks. Link to comment Share on other sites More sharing options...
Glenn Posted January 9, 2008 Share Posted January 9, 2008 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. Link to comment Share on other sites More sharing options...
sstreckfuss Posted January 9, 2008 Share Posted January 9, 2008 Be careful with those RPMs on your setup, if that abrasive disk comes apart it could kill you, at least seriously maim you. I have a ridgid brand one at it works great but its more of a torque cutting tool than a speed cutting tool. Link to comment Share on other sites More sharing options...
FrogPondForge Posted January 10, 2008 Share Posted January 10, 2008 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. Link to comment Share on other sites More sharing options...
Ice Czar Posted January 10, 2008 Share Posted January 10, 2008 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... Link to comment Share on other sites More sharing options...
Paragon Posted January 10, 2008 Share Posted January 10, 2008 If I had the money, I would opt for a small horizontal band saw. It is nice to set it, walk away and come back to cut steel. Link to comment Share on other sites More sharing options...
saintjohnbarleycorn Posted January 10, 2008 Author Share Posted January 10, 2008 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. Link to comment Share on other sites More sharing options...
sdalcher Posted January 11, 2008 Share Posted January 11, 2008 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 Link to comment Share on other sites More sharing options...
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