Adjustable Diamond Dresser

The photo above shows a couple of diamond dressing tools for truing a grinding wheel.

I've had the one on the left since shortly after getting my first bench grinder. The sleeve is held against the front edge of the tool support and the dresser is then "swiped" across the front of the wheel. It's quite hard to adjust the sleeve to take a very fine cut from the wheel: it's a case of loosening the cap screw, shuffling the sleeve very slightly and then tightening the cap screw.

I recently inherited a second diamond dresser. Since I now had a spare, I decided to experiment. After centre-drilling the flat end (at the bottom of the picture), I held it in the lathe and turned the body down to 12 mm (from 12.7 mm). I then cut a 1 mm pitch thread along most of the length. The brass piece you can see in the picture is about 30 mm diameter. It has an internal M12×1 thread to match that cut into the dresser and is knurled on the OD. This allows easy fine adjustment of the position of the tip of the dresser relative to the edge of the tool support.

Manufacture of this part was all fairly simple. The only complication was cutting the internal thread in the brass adjuster. I don't have (and haven't made) an internal threading tool small enough to enter into an 11 mm bore. As an alternative, I mounted an M6 tap in a tool holder and set up the lathe for "single point" threading. This worked very well (taking fairly gentle cuts on each pass), I just had to be careful to quickly wind the cross-slide handwheel in before disengaging the half-nuts. It also meant I had to cut this thread with the lathe running forward; I usually prefer to have the lathe running in reverse and with an upside-down tool as it gives a lot more time to disengage the half-nuts as the tool exits the part.