Does a thread on Diamond Cup Grinding Wheel need a locknut?

Question

I have a 4 1/2” diamond cup grinding wheel installed to my angle grinder.
I screwed it on all the way, but there is no room for the locking nut.
I called DeWalt and they said since it is a screw-on wheel, i do not need the locking device, but that kinda worries me.
Is this safe without a locking nut and how should I tighten it?

Alaska Man · Accepted Answer

The Dewalt person is correct.
Use the locking mechanism of the grinder to keep the shaft from turning while you  tighten it down by hand. (Always unplug the grinder when replacing discs.)
The rotation of the shaft is such that it will cause the wheel to tighten, not loosen. There are flat spots on back side of the wheel that you can get a wrench on, but there is no need to torque it down very tight.
The locking nut/washer is used for discs that are not threaded, such a cut off disc.

Harper - Reinstate Monica · Answer

Yeah, that's SOP for grinding wheels and wirebrush cups. The machine turns counterclockwise (from the business end), which will always tighten the screw thread. That's why the machine turns counterclockwise; if it turned the other way it would constantly be unscrewing the grinding wheels.

Answered by Harper - Reinstate Monica on April 15, 2021

Does a thread on Diamond Cup Grinding Wheel need a locknut?

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