Sherline Lathe Problem (GiB)

[ZenModeling]

Hello,
I’ve owned my Sherline 4000 Lathe for about 3 years. Never had any issues with the GiB adjustments till I installed the DRO kit. Since you need to disassemble the Lathe in several areas, I decided to do a good clean of everything & lubricate. I immediately noticed that my “Z” Axis dial was EXTREMELY HARD to turn. It will turn & the screw is moving it’s just Ridiculously hard.
So naturally I checked the GiB’s. [nothing had moved everything looked exactly the same] so I inspected everything closely & didn’t see any issues that would cause this?
I removed the GiB for that area & wiped it clean & did an inspection of the composite material GiB (looks new still not nicks or anything that would cause it to bind…- I probably only have 150 total hours on machine)
(BTW:the rails were sufficiently oiled )
With that GiB removed the Z-axis screw movement is Totally free & smooth.
I inspected the rails the GiB is pressed against & then made sure it was totally smooth & Oiled.
I reinstalled the GiB leaving the “Locking” Screw out, still with the GiB lock “L” wire in. Placed it in as many different positions I deemed possible. I could get a tiny amount of relief in a turn, but still about 90% too tight compared to how it’s operated past 3 years….
‍I couldn’t find any more info for this issue & im completely stumped…?
I’ve attached some photos I took of the area I’m referring too.
I’m hoping that someone with experience on a Sherline Lathe might have some troubleshooting options for me…
…PLEASE…
Many thanks!
Lee
SUMMARY: My Z-Axis wheel is wayyy to hard to turn, making GiB adjustments don’t seem to help?

 

[markba633csi]

Could it have anything to do with the DRO install?

 

[Ulma Doctor]

If the gib has moved, the clearance has been altered.
The gib doesn’t appear to be fully seated in the dovetail in picture #3.
If the gib is extended further from casting, the dovetail to gib clearance increases, the converse is true.
disassembly may be required as a small piece of swarf could be detrimental to the longevity of the machine and cause a condition to which you have described.
Only one way to find out, unfortunately. Since the machine is small, the task is simple .
There are many methods to verify the integrity of the dovetail surfaces,
The simplest is a flashlight and a straightedge- the light shown on the rear of the straightedge, will show the clearance.
The surfaces can be swept with an indicator
The cross slide can be blued up and the transferred blue would indicate high spots, the rubbed off blue also indicates high spots.
Scraping can be performed to make the assembly fit and function better

 

[ZenModeling]

If the gib has moved, the clearance has been altered.
The gib doesn’t appear to be fully seated in the dovetail in picture #3.
If the gib is extended further from casting, the dovetail to gib clearance increases, the converse is true.
disassembly may be required as a small piece of swarf could be detrimental to the longevity of the machine and cause a condition to which you have described.
Only one way to find out, unfortunately. Since the machine is small, the task is simple .
There are many methods to verify the integrity of the dovetail surfaces,
The simplest is a flashlight and a straightedge- the light shown on the rear of the straightedge, will show the clearance.
The surfaces can be swept with an indicator
The cross slide can be blued up and the transferred blue would indicate high spots, the rubbed off blue also indicates high spots.
Scraping can be performed to make the assembly fit and function better

Now this is why I Luv platforms/Websites like this! I appreciate your incredible response to my dilemma. The explanation of cause & mechanical theory totally makes sense & you’re solution suggestions had the lightbulb come on inside my ADHD BRAIN… BRAVO Mate! I’m very appreciative! Tomorrow early I’m going back in to see if I can get her sorted out.
Thanks Again!
Lee

 

[ZenModeling]

Could it have anything to do with the DRO install?

Hi, thanks for your response. Answer is most likely yes, as I never had the issue with it sense purchased. I’m thinking it must of gotten bumped or tapped while I was like a Monkey humping a football during the disassemble & cleaning.
I think that Sir Ulma MD’s post explains everything.
Thanks again,
Lee

 

[Ulma Doctor]

Now this is why I Luv platforms/Websites like this! I appreciate your incredible response to my dilemma. The explanation of cause & mechanical theory totally makes sense & you’re solution suggestions had the lightbulb come on inside my ADHD BRAIN… BRAVO Mate! I’m very appreciative! Tomorrow early I’m going back in to see if I can get her sorted out.
Thanks Again!
Lee

I’m happy to be of service, lmk how it goes

 

[rwm]

Since you are operating it without the locking set screw on the L wire, is it possible the gib is moving tighter as you attempt to advance the carriage?
Also, your Z axis gib looks to be longer than mine. In your pics, it sticks out on both ends of the dovetail. Mine does not. Is it possible you mixed up the X and Z axis gibs?
@Ulma Doctor - The gibs on Sherline are plastic (delrin?) and typically stick out about an inch. The L wire keeps them in place longitudinally.

 

[Ulma Doctor]

Since you are operating it without the locking set screw on the L wire, is it possible the gib is moving tighter as you attempt to advance the carriage?
Also, your Z axis gib looks to be longer than mine. In your pics, it sticks out on both ends of the dovetail. Mine does not. Is it possible you mixed up the X and Z axis gibs?
@Ulma Doctor - The gibs on Sherline are plastic (delrin?) and typically stick out about an inch. The L wire keeps them in place longitudinally.

Yes sir, I understand the operation.
The L wire is adjustable, setting the protrusion of the gib.
His set screw appears to be present, although I can’t say if it’s locked or not from the pictures

 

[rwm]

No set screw on the Z axis gib in this pic?

 

[Ulma Doctor]

No set screw on the Z axis gib in this pic?
View attachment 509000

Good eye, I missed that