[jcclark]

I just got a National Detroit DA, it's a great tool that uses a lot less
air than my cheap one, but, I thought I would be able to lock the shaft and
use it as a rotary, but no, the lock is only for pad removal.
The tool says there's a loss of power if the shaft lock is on and you
really can't use it that way. I'm really disappointed.
I thought I read on here about using DA's in the rotary position, is this a
feature only found on those super pricey units?

[jcclark]

Update.
Well I couldn't find a DA that was capable of rotary only mode
so I exchanged mine for a National Detroit rotary sander.
It's just like a DA except it spins only, without the dual action.
This thing strips paint unbelievably fast. I love it.

[powerrodsmike]

Most of the time when I use my DA in the rotary mode (which isn't often) it just abrades on one side of the disc anyway.
Or the disc adhesive lets go and the paper becomes a frisbee.
I usually only locked the disc when I used a DA for grinding tool marks off of an aluminum part so I can polish it. I have since adapted a PSA style backing pad to my 5" air disc grinder. That way I can use the finer grit PSA type discs in a rotary fashion. I just made an adapter with the 1/2-20 threads on one side and the 5/16 24 threads on the other.

Later, mikey