Old Sears electric die grinder - can I use a metal cutting wheel with it?

[gdguarino]

I've got an older Sears electric die grinder, Model #315.27440. I don't remember how I came by it. I didn't buy it. Quite a few years ago I tried using it with a dremel-style tiny cutting-wheel and mandrel. That was the day I learned about the concept of a "Maximum RPM" rating. :(

It was also the first and last time I ever turned it on. Luckily the the shard that broke off the wheel only gave my calf a shallow wound.

I've been using a Roto-Zip with the wheel attachment to cut EMT tubing. It cuts the tubing very nicely, but can't cut deep enough to make the whole cut in one pass. I'm wondering if the die-grinder with a metal cutting wheel would work. I see guys on TV with air die grinders cut sheet metal, but I have a few worries.

1. The manual says the tool operates at 26,500 RPM. I guess that's unloaded, but a lot of the wheels I see say they are rated at 25,000. I'd hate to get a slice of a 3" wheel in my neck.

1. The tool doesn't have a speed control, and wouldn't have a guard on it.

2. The manual, all eight pages of it, doesn't mention anything like a large cutting wheel. It shows many kinds of burrs.

I'm a frugal sort of guy. It really appeals to my sense of efficiency to finally make use of this tool, and to have a dedicated tool for this task hanging on a nice convenient hook. But I'm not sure if it's possible to do safely. Any thoughts?

Alternatively, do you think it would be a good idea to use the Roto- Zip (which DOES have a speed control), with a die-grinder style cutting wheel and mandrel, but mounted in the regular chuck rather than using the Roto-Zip wheel attachment?

[Bob Villa]

You really need to buy a pipe-cutter for EMT. Safety, ease, straight- cuts...you'll kick yourself for using anything else after you try it. Yes, you can buy cut-off wheels that can handle the speed. The wheels I remember using in a Sears die grinder were about 1.5".

[gdguarino]

I believe someone gave it to me, many years ago. Someone who knew I liked tools and didn't know what this one was for. I didn't know either.

[willshak]

[e-mail] wrote the following:

Doesn't anyone know how to use a hack saw anymore???

[gdguarino]

By "pipe-cutter", do you mean something similar to the tubing cutters that plumbers use on copper pipe? I've been curious to know if the ones they sell for electrical work are any different from the plumbing style. I'm curious for two reasons:

1. I have a Ridgid tubing cutter, and wouldn't want to buy a separate tool just because it's painted green. :).

but more importantly...

1. An electrician friend of mine doesn't think that's a safe way to cut EMT; it leaves a very sharp edge inside which is harder to file down than the usual flash from a hacksaw cut. He thinks it will tend to nick the insulation as you pull wire through it.

Having said that, I did use the tubing cutter for a couple of jobs before I got his advice. I switched to the RotoZip both because of that advice and because (at least according to my friend) I'm not enough of a real man to use a hacksaw. :)

The RotoZip is much, MUCH faster than the tubing cutter. Easier too. In addition, I live in a house in which some of the walls are plaster over cinder block, so I sometimes need to cut metal Wiremold (surface mount) conduit, which isn't round. The only drawback of the Rotozip is that the wheel clearance is not enough to go through the whole tube in one shot. Hence the question about the die grinder. I'm not sure 1.5" would comfortably do it. Do you suppose anyone makes larger diameter wheels that can safely handle the speed?

Greg Guarino

[Joe]

[Bob Villa]

I don't think you have to be that particular about deburring because the fitting has a counterbore that the EMT lays in.

[gdguarino]

I have prefaced some of my other questions here with a description of my skill level. While many of my friends are quite impressed with my home handyman prowess, and my electrical acumen in particular, I don't kid myself. That said, my friend's 40 years of experience are no match, speed-wise, for my modest skills - if I get to use power tools against his hacksaw. I'm sure he does a nice job, but for me, it would take longer and yield a poorer result.

On a construction site, cheap, effective tools that don't break, aren't theft-bait and work without an outlet nearby are probably a good idea. In my own house, with me as the entire "crew", anything that makes for a quicker, neater job is a good thing.

Greg Guarino

[gdguarino]

I took a look at that very thing once. While I don't think it would happen all the time, I think my friend was right. The tubing cutter seems to actually bend some of the material inwards before it finally cuts through the last little bit. That leaves an edge of a slightly smaller diameter than the original tubing, which might not be covered by the "flange" of the fitting.

[Bob Villa]

Most tubing cutters have a beburring tool built-in. (flips-out)

[gdguarino]

As does mine. I'm certainly no expert, but the deburring tool didn't seem to do enough to reduce the sharpness of the edge on EMT. It might work better on copper, and I suppose it wouldn't matter as much for plumbing.

Greg Guarino

[bud--]

I agree that you can't easily remove the sharp ridge on EMT that is cut with a tubing/pipe cutter. You will probably never see an electrician using one. The deburring tool is kind of a joke. For smaller EMT sizes a hacksaw is likely used.

Greenlee makes an EMT cutter that looks like a pipe cutter. The cutter wheel has a limited depth of cut - you never cut all the way through the EMT. (I have never used one.)

When cutting and threading rigid pipe, an electrician may use a threading machine. It includes a pipe cutter that leaves a serious ridge. It also has serious torque and a serious real reamer to remove the ridge.