Looking for parts for Boyer Schultz 612 grinder

Hi
I have gone through the old threads looking for someone or place that might have some parts for my old BS 612 manual machine. I have a dead spot in the z axis lead screw. I put an indicator on it to check and it moves good until it hits the dead spot and I can crank it 020-025" before it moves again. I also need new spindle bearings. It's a nice little machine and I can make do with the noise but not the lost motion in the spindle movement.

Anyone have any resources? While a 714 would be nice I don't have a lot of floor space so I would like to get this 612 in better shape.

Thanks in advance.
Gary

No one with info?

I suspect you will need to fabricate a new feedscew and nut as it's unlikely that you will find a NOS one. Any used one in good condition is likely to be attached to a good machine.

You may do better posting in the machine reconditioning & scraping forum fo help on how to do this.

Ther are lost of threads (sorry) on making new screws & nuts for various machines, I'm doing the same for my grinder. Here is where I would start.

Pull the feedscew and examine it you will most likely ses that the lands on the threads where there is wear are visibly thinner. Measure the dia. and pitch and see if anyone make that thread as a stock item Roton do a good range. It's most likely to be ACME but if you are repacing it, pitch is the most important thing to match. Just beware that the std accuracy fit i think 2g, is a bit sloppy but better fits may be available in the US. If you can't do better you could custom make the nut to fit, thats what I'm going to do. You may be able to make the new screw direct from the stock screw or have to graft the new onto the old, again lot s of video content out there. It's not a big job for a competent machinist if your'e not one yourself.

Is motion lost while raising as well as lowering? If not, loss is more likely a sticky spot on the vertical slide ways, in which case a new screw would not be a solution.

Just look in the back to inspect the Z screw. Do you see a difference in the width of the crests? Mine is ancient and beat to crap, but the Z screw is near to perfect. You need to disassemble, clean everything and check clearances. As said above, it's probably the vertical slide ways. There should be a drip feed oiler on top. It drips on the gears, runs through a hole and down the screw. It also drips to a round milled out spot and distributes to the ways via some slots. If the pipe cleaner in the oiler is good it will drip quite a lot, maybe the whole reservoir in a day or two. If it stays full for days on end, it's not working right.

My cross feed screw is shot and I need to make another. The original arrangement had the screw protected with a bellows, but that's long gone. I've got about 0.050" of backlash. Still works OK, but annoying. I don't know if the machines originally had some sort of rear cover to protect the Z screw and ways.

The machine has - or should have - a sliding sheet metal covers front and back on the Z drive as well as rubber bellows (two, one on each end) on the cross screw. The Z drive dead spot can be caused by other parts (top gears, nut, nut mount, slide...) than the lead screw itself. If indeed it is a damaged screw it should not be difficult to replace it with a ball screw and ball nut. There is a huge selection of those both new and used and for very reassemble prices. After all replacing the ball screws is a common conversion of mills and lathes to CNC. Not long ago I bought a similar size ground ball screw and nut assembly to the one you need (on eBay, used, for about $150.00 from Korea). Rolled screws are less expensive. There is no advantage in ball screw in this application as the Z movement is heavily per-loaded by the wight of the spindle assembly, but ball screws are so common. Regular lead-screw and nut of similar size can be sometimes located as well, though those are not as popular.

Thanks guys for the info. I didn't get a chance to come back here till now. I will look again at it and see if it's hanging up and if it's always in the same place. That would be great if that was the issue and it could be since this came out of an old factory. I was looking to get another grinder but I think the one I wanted is spoken for so I am back to getting this one in better shape.