In my case I am lucky, or unlucky enough to have access to a handy set of MT3 collets. These collets require a draw bar or bolt which has a 3/8-16 thread to fit the tapped hole in the end of the collets. The crank design which interests me uses a clamping method similar to the type used in clamping the handlebar assembly of a bike to the bore in the front fork for instance. This method blocks the passage of a draw bar fitting the MT3
collets through the spindle
bore.

I and probably many others have gotten around this by building a cranking system which uses the "bike" method and allows the passage of the MT3 collet draw bolt. This
one includes two concentric tubes (made from iron water pipe) each of which can be tightened individually. This is required to prevent over tightening or loosening the collet due to driving the spindle by cranking via the drawbolt, and it makes collet release a bit easier.

The brass nut in the photo, locks the crank to the spindle innards( bicycle type grabber). The jammed nuts on the left end of the threaded rod (drawbar) are the 'handle' to tighten or release the collet in the spindle. The jammed nuts on the inside of the handle assembly allow the leverage to effect the collet release, just pushes the collet out of the spindle bore, when turning the 'handle' backwards. Simple and easy thanks to Klaus's idea (See the 7x10 group, message 13489, Klaus shows a neat idea for a no-whack drawbar to use with MT collets).

An added feature, if one is using a 3 jaw or 4 jaw chuck, will allow long work up to 3/8 inch diameter to pass through the cranking assembly. This can be a desirable feature.

The top photo shows it in collet mode and this photo shows chuck mode with the completed assembly mounted on a 7x 10 lathe.

I have 2 minilathes whose spindle threads are different and would require 2 units as Klaus made it; this works on either one. The wooden handle for hand cranking is easy to slip off the end when one wants to drive via the motor.

Richard -- February 2004