Grinder Jump

[a_67vdub]

OK, when I'm using a 4 1/2" angle grinder to cut sheet metal, I always have this problem of the grinder "jumping" out of the cut. Is this common?

This never happens to the guys on Monster Garage, American Chopper, or Junkyard Wars.

What's the deal?

Thanks,
Steve

[Kubel Nick]

Are you using the right attachment, the thin ones? It takes some practice on how to cut the best. You can't just be experts on any tools you just picked up right away. Are you using both handles or both hands just on the main grip handle? When you cut, is the disc fully into the metal being cut or just barely touching? I find it easier MOST of the time to cut the metal when the disc is barely touching the metal, especially on curve cuts.
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[a_67vdub]

Well, the grinder I have has a sort of "dish" in the middle, so the thinnest blades I have seen are about 1/8" thick. A little thicker than I would like. I have used a thin (1/16") blade, but it is flat and I can't tighten it very much without distorting it, because of the dish. Is there an attachment I can buy that will remove the dish?

I understand that practice is required, but I've actually used this for quite a while and thought I was pretty good at it. I just thought that jumping out of the cut was part of life and I had to get used to it. Then I see these guys on TV holding on to the grinder with one hand not even paying attention to what they are doing with the blade burried deep in the cut and no jumping. I always hold on with two hands and try to keep it as straight as possible.

Now that I think about it, I could probably stack some 5/8" washers in the dish to bolt on the thin blades. Hmmm, I'll have to try that.

Thanks for your reply,

Steve

[Kubel Nick]

I had the same problem about the dish on the hold-down screw. Flip the hold-down screw around (upside down) and it should hold down the discs tight now.
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[Major Woody]

Steve, I don't think you're really using the best tool for cutting. A smaller cut-off grinder, die grinder with wheel, nibbler or body saw would do a much better job, depending on what you are trying to accomplish. Those angle grinders are good for cutting bolts and removing material from welds but they don't do a very good job cutting sheet metal.

Chris

[Kubel Nick]

I have to beg to differ. I prefer using an angle grinder with a thin cutoff disc to cut most of my parts unless I need a perfectly straight line (I use an air nibbler for that) or super thick metal (sawzall, but still use angle grinder at times too).

I agree that an angle grinder with a grinding attachment is not best to cut metal, but with a cutoff disc made for cutting metal is pretty much like an die grinder with wheel (only bigger).
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[Air-Cooled Head]

I'm w/ Nick on this. I use a 4-1/2" grinder w/ flat cutting wheel for almost all non-curve cutting.
I've found that jumping occurs when you move too fast. When you let the blade do it's job, all you have to do is guide it. You can also cut perfectly straight lines by watching what the rear side of the blade is doing. If sparks start flying in the opposite direction, you've tilted the blade, and the back end is trying to cut too. You'll also notice that the blade slows and more effort is required for guiding.

I have a fresh 3 inch cut on my inner forearm from holding the tool too loosely. Must have angled the blade and it dug in. Snatched the grinder from my hand as it jumped out of the groove. Because of the way I was holding the metal, the blade skipped across my inner forearm, barely breaking the skin. Gotta remember to hold tight, regardless of how little effort is required!
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[Major Woody]

Good points guys. I was assuming he could not get the cutoff discs for his grinder. I have a hard time finding them locally as well and ended up ordering them online.

It sounds like he's only got this one tool. It is fair to say that you need more than a 4" grinder to do clean work, which was what I was getting at.

Chris

[a_67vdub]

That's true. I don't have a lot of tools. I have enough to get me by, though.

Thanks for all the replies. I'm going to try and turn that hold down screw around and see if that works.

Steve