Drill attachment for backlapping ?

Certainly clamping straight on to the spindle is a no,no; damage will almost certainly ensue. I don’t like the look of what appears to be a small quantity of ground up metal in your image. Also, most drills run far too fast for back lapping.  Being on the right hand side of the machine, I’m guessing that the sprocket or gear screws onto the shaft with a right hand thread so that it tightens in drive. Back lapping requires just a light touch* so if the sprocket is tight it should not undo during the process so perhaps a “ spider” with a handle  to engage the sprocket will do the job. Some years back I made a suitable one using a bit of 10mm plywood with three  bolts to engage the sprocket’s teeth and a handle from an old hand drill to crank it. That was, I remember, for a JP, but it was a while ago.

* That’s assuming that it’s for putting or maintaining the final finish on a properly sharpened cylinder - not attempting to recover a blunt cylinder. There’s been plenty of “conversation” about that on this forum in the past.

Yes, I  will pursue that.

Thankyou

Best wishes  to you

Hi,  I successfully used an 1/2" square drive socket in an impact gun to backlap my Shanks Golf Lynx blade.  I needed to fit onto a shaft with a key in it so I found a socket that fitted over the end of the shaft then cut a slot on one side of the socket to fit the key in and act as a drive.  It worked very well.  I have a Dewalt 1/2" impact wrench that has variable torque and speed.  I put it on the lowest torque setting and was able to use the variable speed to slowly turn the shaft.  The beauty is it has reversible direction and so you could use it on whichever shaft is most suitable and still be able to make it turn backwards.

To drive on your shaft in the photo how about finding two nuts of the correct thread (preferable half nuts i.e.narrow ones), screwing them both onto the shaft and then tightening them onto each other to lock them in place.  Then just use a correctly sized socked in an impact wrench to turn it.

As the shaft is free to spin the impact action never kicks in so it does not jolt however I guess you could also use a drill driver with the correct adaptors to do the same job.

Hope this helps?

Regards Rob

Yes indeed ! That worked.  Thankyou

As long as your driver will run slow enough, that’s fine, but true back lapping won’t need more than five minutes of hand cranking. Spin the cylinder too fast and it will fling off the grinding paste ( water based paste, not oil based valve lapping paste)  At the risk of going back over old ground , to prepare cylinders for true back lapping    they need to be relief ground. Two reasons for relief grinding: the first being to reduce the contact patch and friction and the second and less obvious one is that the relief creates a little “gully” on the back of the blade to hold the grinding paste and evenly distribute it during the lapping process.