How to loosen gib?

[mcman56]

I adjusted the gibs on my Chinese copy of a Bridgeport vertical mill but have made the vertical one a bit tight. I loosened the adjusting screw and tried moving the table up and down to get the gib to slide up and get the assembly looser but it is not moving. The table remains kind of tight. Is there a trick to this?

[mcman56]

I found the screw at the bottom and loosened up but operation is still stiff. The screw feels sort of sticky like dried up oil. Can you clean without disassembly? Would spraying with wd40 be a bad idea?

[Harold_V]

In order for you to achieve a loose sliding fit you may have to drive the gib by turning the screw on the small end of the gib by several turns. Simply backing off most likely won't work. Once you have it free you can then adjust to your liking.

It would be in the best interest of the machine if you could remove the slide and clean it well, but that would be a daunting task. Alternately, if you can remove the gib, do so. If not, oil well and hope the excess oil flushes contamination. WD40 would do no harm, nor would any oil or solvent. Just make sure that when you're finished that the slide has been properly lubricated.

H

[Steggy]

I found the screw at the bottom and loosened up but operation is still stiff. The screw feels sort of sticky like dried up oil. Can you clean without disassembly? Would spraying with wd40 be a bad idea?

What Harold said.

Bear in mind that WD-40 is a solvent more than it is a lubricant. While it is good for initially freeing a sticky machine part, it’s not a long-term substitute for a proper lubricant. There are lubricants made specifically for machine ways that combine lubricity with a controlled amount of adhesion. Adhesion is important, as it keeps the lube where it was applied, especially on machines with vertical movement, e.g., knee-type mills. However, the wrong lubricant can have too much adhesion, leading to the problem of “sticktion.” Sticktion can produce jerky motion when the slide is slowly moved, making it difficult to do very precise work.

[mcman56]

I looked on line for vertical gib adjustment procedures. Everything I see shows one adjustment screw at the top. This mill has an adjustment screw at the top and another at the bottom so I am confused. Does this suggest two gibs? See pictures.



https://ibb.co/qsFY3hN



https://ibb.co/HtH9Q4L

[Bill Shields]

One screw pushes the gib tighter

The other prevents it from moving further and getting too tight

Back the screw on the large en of the fib out and push on it with the screw on the small end.

Think of it as a tapered wedge...

In the case of your machine, the gib has a groove in one end, and an internal shoulder on the screw.

Turn the screw out a bit and try to move the way in the opposite direction....the idea is the screw PULLS the gib out with it.

Might take some wiggling of all components to get there.

Eventually, if you back the screw out the gib will come with it.

Don't be magilla gorilla...you to not want to break anything.

[John Evans]

The upper screw controls the adjustment ,the bottom one locks the adujstment. Having 2 screws is something Bridgeport should have done !Turnthe upper screw CCW to loosen the gib.