Reconditioning a Relmac lathe

[irving2008]

At the risk of resurrecting this thread, I have been asked if its possible to redo the bearings on another similar lathe. Those who followed the original story will know that this was no mean task and not one I really want to revisit. However I was thinking about how to make it easier. I now know that the original lathes were line bored on a huge jig (see pic) but replicating that isnt going to be easy. I was thinking, maybe it would be possible to make a jig to line-bore the bearing insitu once they had been part filled with white metal around a mandrel smaller than the required bore.

The mandrel would be a piece of steel sheet with a tubular steel core (so as not to require too much heating) approx 1" dia. - this would be clamped to one side of the bearing. The lathe would then be clamped to the end of the workbench with the bed vertical and the bearing recess filled with molten metal. Both bearings would be done at the same time (two mandrels needed).

The question then is how to bore them accurately parallel with the bed? I have a round head mill so swinging the head over is an option, but I'm not sure how I would align everything. Some form of powered spindle (poss the original lathe spindle since it has a MT3 taper and pulleys) clamped to the ways is another and more easy to align but I can't see an easy way to move it through the bore unless I use the existng saddle and I am not sure how rigid that would be... or maybe I'd have to create a new saddle... or a base plate that clamped to the bed with linear bearings? Or that overkill?

Any ideas?