Cross slide nut jammed

[chris.epp]

I picked up a used King Industrial 10x22 lathe (same as Grizzly G0602 I believe). The cross slide was stuck. I took it apart, and the nut is actually stuck on the lead screw. I managed, with great effort to get it off, but it was almost impossible to remove. Any idea what would cause this or the fix? The lead screw looks ok to me, each end of the nut threads on easily, but once you get about 3/4 of the way it get's tight and then eventually so tight you can't turn it at all any more. Can that be fixed or do I need to order parts?

Thanks!

 

[piper184]

What is the nut made out of?
Some nuts have a backlash adjustment so there may be some sort of set screw in middle of the nut?
If you can, post a picture of it.
Guessing it is bronze or brass so that it is softer than the screw one would think that there was a "Crash" that caused the screw to deform the threads. If that is the case, you can probably chase the threads with the appropriate tap. Is it an Acme left hand thread?

Buying a tap may cost more than just buying a new nut

 

[chris.epp]

So it appears to be a cast iron nut. The adjustment on these is a grub screw that pushes up against the beveled edge where the slot is.
It measures as 10mm 1.5 pitch left hand thread. I'm honestly too new to identify past that. I have a 10x1.5 left tap I could run through the nut to see but I don't want to mess it up if it needs to be a specific tap. The nut was near the end of the rod where it was seized. I BARELY managed to get it off. It threads pretty much OK for the first inch, and then get's bad, so it may be the lead screw that is messed up. (or is as well) ? However, to me it looks like a standard metric thread, doesn't appear to be acme, but I need more education in that area so I would not presume to be correct.

Strange thing, when putting the nut on backwards, it is not quite the same. It get's stiff sooner backwards then it does the way it normally does (adjustment is facing inwards normally)

 

[matthewsx]

If it works on part of the screw but not the whole way it's probably the screw. It may have been twisted, or damaged at the point where it jams. Probably just need to replace the screw but it might not be a bad idea to replace the nut as well.

John

 

[rabler]

You have a slit in the nut that is often associated with backlash adjustment. Is that the point where it is jamming?

Inspect that area inside the nut as closely as possible. It may be deformed or it may even just have a chip or bur hung up there.

 

[piper184]

It appears to me that the threads on the screw are rolled over and deformed in the center portion pictured above. To my eye, either there is a lot of wear in that area as in the lathe saw most of it's use in that area or there was something that got bound up in that area and caused the damage.

If a standard metric thread check gauge fits the undamaged area of the screw you can be fairly confident that it is just a standard thread, although left hand.

Two things I would consider if it were mine.
Order a bolt that size and left hand thread. If possible. That can be used as a thread check against the nut.
Use the tap you have to make a nut out of some piece of stock. Brass or aluminum or even mild steel or plastic. Heck even wood would work. Use that to thread check the screw.

Another alternative is to buy a left hand die in the appropriate size and use that to chase the threads on the screw. Just remember that you might wind up replacing the screw if you mess it up.

Have you checked with Grizzly to see if parts are available and at what cost? It might be more cost efficient to just get a new screw and nut at the same time.

 

[aliva]

I have a King 12x36 and had to replace the cross slide screw and nut not overly expensive, I paid under $100.00. contact the nearest dealer parts for king are stocked in Montreal. Mine was and acme thread. I kept the old screw and made a tap from it ,incase I ever need to made a new nut.

 

[chris.epp]

If it works on part of the screw but not the whole way it's probably the screw. It may have been twisted, or damaged at the point where it jams. Probably just need to replace the screw but it might not be a bad idea to replace the nut as well.

John

Ya, I agree, it appears to be the screw.

It appears to me that the threads on the screw are rolled over and deformed in the center portion pictured above. To my eye, either there is a lot of wear in that area as in the lathe saw most of it's use in that area or there was something that got bound up in that area and caused the damage.

If a standard metric thread check gauge fits the undamaged area of the screw you can be fairly confident that it is just a standard thread, although left hand.

Two things I would consider if it were mine.
Order a bolt that size and left hand thread. If possible. That can be used as a thread check against the nut.
Use the tap you have to make a nut out of some piece of stock. Brass or aluminum or even mild steel or plastic. Heck even wood would work. Use that to thread check the screw.

Another alternative is to buy a left hand die in the appropriate size and use that to chase the threads on the screw. Just remember that you might wind up replacing the screw if you mess it up.

Have you checked with Grizzly to see if parts are available and at what cost? It might be more cost efficient to just get a new screw and nut at the same time.

I am not 100% certain that they use the same thread/nut from grizzly. I am finding it very difficult to make traction on parts from King Canada, they only sell through distributors, and none of them carry parts, all special order. Really annoying that I can't just order parts direct. Waiting on pricing, but eta for parts is 1-2 months. Grizzly has stock, and they are a little cheaper. Cross slide leadscrew is 64.40 and nut is 37.70. Once changed to Canadian pretty much the same price, but they are in stock and ready to ship. Look identical. I ran my tap through the nut, and I could feel a touch of resistance in a spot but it cleaned right up. So I think it is a standard screw thread. I have an appropriate die coming tomorrow morning, I can see if it cleans up or not. May as well try since I'll be ordering a new screw and nut afterwards regardless if it doesn't. If it's right on the end where it would never be used for machining then it might be ok... worth a shot since the die is cheap I guess.

 

[chris.epp]

I have a King 12x36 and had to replace the cross slide screw and nut not overly expensive, I paid under $100.00. contact the nearest dealer parts for king are stocked in Montreal. Mine was and acme thread. I kept the old screw and made a tap from it ,incase I ever need to made a new nut.

KMS Tools is the only dealer near me, and they don't seem to comfortable with ordering parts, I guess they don't do it much, even though they sell their machines. I'm still waiting to get a price and availability. (since yesterday).

You have a slit in the nut that is often associated with backlash adjustment. Is that the point where it is jamming?

Inspect that area inside the nut as closely as possible. It may be deformed or it may even just have a chip or bur hung up there.

Unfortunately no, that is not the issue. It threads fine past that and well into the nut before there are issues. After cleaning up the nut, I have a tap that fit, just a touch of cleanup in there, it still has the issue, so the threads on the leadscrew must be damaged. I assume that would have happened in a crash from someone previously? (I have yet to use it, as it came that way).

I just got a quote back for a new leadscrew and nut while typing this, and only 139 all in, so probably worth just replacing. But if a crash caused this, I probably need to inspect everything else carefully...

 

[Ulma Doctor]

Maybe this is something to consider….

Zero Backlash LH Trapezoidal Thread Cross Slide Nut, From Delrin

My good ol' Shenwai SW900B is showing signs of excessive slop at the dial. excessive slop for me is right around .050" after pondering materials to construct a new nut from, delrin was immediately apparent. its tough and structurally sound, it's easy to get and cheaper than other materials...

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