Every so often I come across references to this tool. For the sort of work I do it would make a lot of sense. However the chances of me running across such a thing in the UK are miniscule so given the simple nature of the thing I've decided to have a bash at making my own. I think I've gathered most of the information I need from looking at photos but I'd like to sense check a few things with those who may have used the real thing.

What I'd like to know:-

How long is the hollow bolt that the drill spindle runs thru?

Is there a thrust bearing used? And if so where is it, top or bottom of
the hollow bolt?

So far I am planning to use a M16x1.5mm bolt drilled to take the spindle and an off the shelf thrust bearing at the bottom of the bolt running against a flange on the drill spindle.

For the ratchet drive best I can come up with at the moment is to use a 1/2" drive ratchet from a socket set which kind of leads to the logic of turning the drill spindle from an extension bar from a 1/2" set.

If I can find some cast iron chunks I could use this for the body of the drill head and base but failing that there should be no problem using cut offs of mild steel, say 3"X2" ?

Once again all information, ideas and suggestions gratefully received. If I get started with this I promise to take photos!