I have a 70 year old Harrison Cub lathe with a badly worn bed. The bed is prismatic (I think that what its called), two flat shears like a Myford with a triangular rib along the front edge of both flats. This is so the saddle runs along the front angled section, the tailstock on the rear.

The main wear is under the rear shear, where the clamping strip which runs under the shear is steel and does not cover the whole width, so the rearmost half is badly worn ~ .01" for half its width which tapers out to about half way down the bed , because the saddle is not used much down this end.

The problem is two fold, in there is a lot of cast iron to be removed ( too much for grinding?) and the lack of a good reference surface, because the top of the shears near the chuck will be worn on the top. So the thickness of the rear shear near the chuck is .015 less then at the tailstock end.

To ameliorate the situation I have re-engineered the rear jib to make it out of brass and deep enough to bear on the original thick part of the shear.

There is a similar problem at the front, but it is made worse because there is no surface to measure from other then the top of the triangular rib. But in general there is the same wear, because if the gib is tightened under the front shear, then trying to move the saddle to the right causes it to bind.

Any one got any ideas, I suspect to have it machined true would cost hundreds of pounds (and a lot of aggravation!), so a total replacement would seem to be the most logical course of action?

Frank