# Go755... (x) Axis Lead Screw Nut??



## negatronix (Aug 15, 2016)

Hi Everyone,

I've got a question regarding my GO755.. This thing has been nothing but problems for me since I got it.. very frustrating to say the least.

Anyway, I went out to my shop to make a part, and my table wasn't moving in the (x) correctly. It would travel to the right, but not the left. I removed the table to find that the (X)axis lead screw nut was completely stripped out. The entire nut, which is held in place by 2 bolts was extremely loose as well. I can wiggle it and lift it by a 1/4". 

It seems odd to me that the nut is loose at all, but thought that I would ask the folks here on the forum what is correct. I've had a ton of slop in the table when machining, which seems like this could be where the problem was coming from. 

Let me know what you guys think, as I may remove the saddle and inspect the (y) lead screw to. 

Thanks!
-Kory



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## JimDawson (Aug 15, 2016)

Yeah, that's not good

The nut should be tight to the table.  Almost sounds like the nut has been loose for some time.  Take a hard look at the lead screw also, it may have a lot of wear.  I would be looking at all of the moving components, the support bearings and housings could also have issues.  Checking the Y lead screw is a great idea also.  Also check the lubrication system, it could be that the lead screws are not oiling.


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## negatronix (Aug 15, 2016)

Yup.. I think that it was loose when the machine arrived... my bad for not going through everything at that time.

It's funny, I've preferred milling using the (y) and locking the (x) since the beginning. I could literally lift the table a bit if it was unlocked. I kept thinking it was the gibs. I'd tighten the gib to the point of binding, then have crashes and broken tooling when the table would suddenly move. Not good, not safe!

BTW... there is a groove on the nut, and a bolt that looks like it pinches the lead screw.. any idea of how to adjust it, once I have things ready to reassemble?

I'll have to call Grizzly and see what they can do for me. Their site says there are no parts in stock. 

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## RJSakowski (Aug 15, 2016)

I have purchased a number of Grizzly machines over the past seven years and it is a good idea to check all fasteners for tightness on a new machine.  I don't think that I had received any machine that was properly assembled.

The 755 y axis leadscrew nut looks a lot like the x axis leadscrew nut on my G0602 lathe.  The bolt you mention provides a bias between the two sections of the split nut to take up any wear.  On the lathe, I adjusted the screw until I could just detect additional force  required to turn the crank and backed it off slightly from there.  To make the adjustment easier to detect, it will help to loosen the y axis gib. 

Another method would be to tighten the bolt so there is some binding.  Note the amount of backlash existing then by far you can reverse the reverse the crank before you detect movement of the table, again with loose y axis gib.  Slowly back off the bolt until you just see added backlash.  The added backlash is due to clearance in the lead screw nut.  Correct adjustment would be the point where you first see the increase.


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