RTM7 Mounting Mandrel Holder - Essential for Die Grinder Accessories & Cut-Off Wheels, 3/8" Arbor Hole & 1/4" Stem, Ideal for Holding Die Grinder Bits - Rotary Tool Accessories - 2PC

Just what I ordered.

I used this in a right angle die grinder into a cutoff tool. I needed to cut off a truck sway bar link bolt.Do not recommend doing this, because the grinder isn't designed to have much of a side load (compare bearing size around the spindle on a right angle die grinder to bearing size of a dedicated cutoff wheel, and you'll see a noticeable size difference). Plus there is no guard if the wheel blows up. Use a face shield with safety glasses just in case.It does get in tight spots better than a dedicated cutoff wheel with guard. Unfortunately too much safety makes work very difficult or impossible.

I'm ignorant of what A3 carbon steel is exactly, but going by appearance and heft it seems hard and strong while being relatively lightweight. How that translates into longevity, only time will tell. It is a well machined mandrel, no problem there. It accepts a variety of discs and attachments, so I'm quite hopeful about its versatility.I hope in fact to keep it with my electric drill stuff rather than with my pneumatic grinder, because the idea of a variable speed cut off tool intrigues me. Of course angle grinders normally are one speed and it's a very high speed, so not exactly great when finesse is needed. This mandrel in conjunction with a small cut off wheel on a 3/8 drill should be handy for certain things that an angle grinder is overkill.Note that fully tightened there is a sizable gap where the disc goes. They included a brass washer to fill some but not all of the gap. It's thus possible with a super thin cutting disc that you'd need an additional washer to get it tightened or else the disc would just flop around and not spin. Not sure why they designed it so the screw piece does not tighten completely - maybe they are saying to not bear down too tightly so the the disc can slip if need be, like a clutch? The instructions are not good; very sparse.This is listed at $8 currently. Not sure how that price compares with the typical home center pricing. I see no reason to believe A3 carbon steel is anything special, though I could be wrong, so I rate this 4 stars. The mandrel seems quite versatile as far as you can put various attachments on it, and chuck it into anything from a little 1/4 drill to a pneumatic grinder to a big 1/2 inch drill.

Needed another arbor for cut off disk this works great

Calidad

Great craftsmanship, works perfect with die grinder. Gives me the ability to mount a common 3 " 3/8 hole cut off wheel without buying a separate cutoff tool.

Simple to use, very convenient.

The Rotary Thread RTM7 Mandrel for die grinder is a very strong and useful accessory for attaching die grinding tools to grinder. Its design allows quick and sturdy attachment of tools without excess size to get in the way of performing tasks. You simply lock it into the die grinder collet, unscrew the retaining screw and attach and tighten your die grinding accessory using a large flat blade screwdriver. It doesn't get more simple than that. It has a respectable amount of stand-off length to help maneuver grinding accessories where you need them. I'm very pleased with the design and performance of the Rotary Thread RTM7 Mandrel and consider it a very good value in power tool accessories!