# Half nut problem



## RickMc (Oct 14, 2019)

Need to remove and clean the apron but while I have it off I need to figure out what's wrong with my half nuts. The carriage moves with the lead screw and the lockout works so I can't engage the half nut. When I move the half nut lever down it engages but the carriage won't move. I adjusted the half nut down as for as I can but no movement. Is there something in the apron I should be looking at besides the half nut. Seems like something is not moving to engage the lead screw after I move the lever down.


----------



## kb58 (Oct 14, 2019)

Posting the Grizzly lathe model number would help. Also, consider calling Grizzly directly, they're usually really helpful about that sort of stuff.


----------



## Technical Ted (Oct 14, 2019)

Does the lead screw stop turning when you engage the half nuts? If so, maybe you sheared off a pin or something is loose in your QCGB???

Ted


----------



## RickMc (Oct 14, 2019)

Technical Ted said:


> Does the lead screw stop turning when you engage the half nuts? If so, maybe you sheared off a pin or something is loose in your QCGB???
> 
> Ted


The lead screw keeps turning and qcgb is all good as far I can tell. Can change speeds no problem.


----------



## RickMc (Oct 14, 2019)

kb58 said:


> Posting the Grizzly lathe model number would help. Also, consider calling Grizzly directly, they're usually really helpful about that sort of stuff.


I think it might be an early version or a clone of a G4000. It's Grizzly green. May have been bought at Princess Auto inCanada. years ago.
Plate has Mod. #5167
Ser # 205056 and date 199112 on it.


----------



## Alexander McGilton (Oct 14, 2019)

Does it have longitudinal feed other than the half nut? I had a similar problem on my lathe where the feed interlock came loose and was always engaged.  So as not to allow you to engage the slow power feed and fast half nut at the same time there is an inter lock in the apron assembly that prevents you from engaging them simultaneously. That may have gotten loose and is prevent ting the half nut from moving fully.


----------



## RickMc (Oct 14, 2019)

Yes its got longitudinal feed and the lockout seems work but I'll have a closer look before I pull everything apart. Lots of swarf in the apron and maybe not letting something to move all the way.


----------



## Chuck K (Oct 14, 2019)

If the leadscrew is turning and the half nuts are engaged but your carriage doesn't move, you don't have any threads left in you're half nuts. Did you buy the machine used?


----------



## RickMc (Oct 14, 2019)

Hi Chuck.  I bought it used.Your right on. I just back from the shop and came to same conclusion. Everything works as they should but the half  nuts are probably stripped. I'll know more after I pull things apart. Being trying to analyze without taking to much apart but I'll have to jump in and take the apron off.
Thanks everyone with the suggestions. Ill post the results after I do some C.S.I. on it.


----------



## Chuck K (Oct 14, 2019)

There's not much that would surprise me on a used machine anymore.


----------



## Ulma Doctor (Oct 14, 2019)

Hi Rick,
at a guess, you may have a gear that has stripped inside the apron and/or the half nuts are d.o.a.

here is a lathe manual that will have parts very similar to yours.
if you look on manual page 49, you'll see the breakdown of the apron.


----------



## RickMc (Oct 15, 2019)

Thanks for the manual. The half nuts are stripped out. I'll order new ones along other parts after I finish my cleaning.


----------



## RickMc (Oct 15, 2019)

Chuck K said:


> There's not much that would surprise me on a used machine anymore.


A lot of wear hidden by all the dirt and swarf. I jump on this lathe too quickly but they don't come up for sale in my area too often. A lot of elbow grease and small parts should yield me a decent lathe. I'm learning a lot from this one.


----------



## Chuck K (Oct 15, 2019)

RickMc said:


> A lot of wear hidden by all the dirt and swarf. I jump on this lathe too quickly but they don't come up for sale in my area too often. A lot of elbow grease and small parts should yield me a decent lathe. I'm learning a lot from this one.


Been there done that.  You'll know better next time. I don't know what those half nuts look like,  but you might be able to make them. I made a set for a Logan. They were pretty basic though. Sort of square...no brackets on them or anything.


----------

