[Lathe] New to me Yangzhou TY-CO632 13x40 Gear Head Lathe.

So your problem is usually associated with wear on the dovetails. Scraping them is a pain, but it's hard to make things worse. Get some 1/2 inch dowel pins, and using a micrometer - not a vernier, check the distance. I'm sure at the ends, you are .001 or .002 more than the middle. That will give you a diagnostic, or not.
 
Dabbler,

The nut is tight on the screw. It screws freely until the last 1-2 inches. I've taken the screw and nut off the machine and it's still tight. The dovetails /ways are fine.

Chris
 
It sounds as if the screw is screwed up...lol
Do you have a caliper you measure the OD, ID and thickness of the treads.
I know the ID will be hard to measure as the treads are off set, but measure it on an angle where it is loose first and then down on the tight end.

Not knowing your machinist level or if you have a thread mic or thread wires, use a dial veneer. Can mic the OD.

You could probably order a new screw and nut, but first chuck the screw up in the lathe and slide the tail stock in to support the other end. Have the nut on the screw in the loose area. Oh and put the spindle in the slowest RPM. You should have measure it and know where it is big. Then you some die makers files and file the thick area's. Or if you know someone with a lathe have him chase the threads. If they know how to cut threads. If not file it. every now and then shut off the spindle and try to screw the nut up there. If the nut was tight the whole way I would suggest using some Timesavers Lapping Compound. It won't embed in the brass. But you can't lap it now, as it would lap the nut smaller.

If Im not clear on here call me. 651-338-8141. CST. Rich

PS a picture would sure help all of us
 
Hi Richard,

Thanks for the reply. I'm a hobby machinist with 20 years of experience. I have a dial caliper, 0-1 micrometer and thread wires. I can pull the screw back off and measure it.

I thought about chasing the thread on the lathe, but couldn't figure out how to do it without a cross slide screw. I don't know anyone in the area with a lathe. I wouldn't trust most people around here to use a screwdriver. ;^)

Thanks,


Chris
 
Thanks for the offer. I think Richard's plan to turn it on the lathe with files should work.

I just pulled this off this morning.

IMG_6075.jpg

IMG_6076.jpg
 
This morning I pulled the screw and nut off the cross slide and mounted them on the lathe as Richard suggested. I used a needle file to clean up that last couple inches of the threads until the nut would screw on and off smoothly. There were definitely some burrs on the screw.

Next, I put the cross slide back on the carriage and worked on the adjustment of the gib until it would slide freely over the entire throw.

Once I had the gib adjusted I loosely attached the nut to the cross slide. It was better than before but still a little tight at the near end. Once I tightened the nut to the CS the last 3/4" of throw was still a bit tight.

I think I need to clean up the screw a bit more and then make a .003"-.005" shim for the top of the nut.

That said, it's a lot better than it was before.
 
Run the nut as close to the front before tightening up anything. Be sure to stone everything sharp and the ways. Did you ever link to a print ? would help to look at a print.
 
If you have some Dykem paint on or spray on marking ink that dries, use it up on the tight threads before running up on the thread and see where it rubs off the most and then file that area. Sounds like it's coming your way.
 
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