Gib adjustment question

[RSG]

I was adjusting my gibs on the mill when I encountered a situation were the front screw on the table ways couldn't be adjusted cause it was so tight. So I watched a youtube video on the topic. My gibs are the type that have a screw in the front and one in the back. The guy mentioned having to undo the rear one to tighten the front. I didn't think that was correct but I thought I would try it so I unscrewed the rear one and tightened the front. It didn't seem to do anything. I think the fellow was incorrect, that or my system is different.

Anyone care to provide a tutorial on the proper method to adjust this type of gibs?

Thanks in advance

[GlennW]

If it has a screw in front, and another in the rear, the gib gets locked between the two screws.

Perhaps the adjustment you made pushed the gib out, rather than in farther.

Try loosening the front, and tightening the rear.

[mcostello]

The possibility also exists that Your gib is worn out and the front screw is bottomed out as far as it goes.

[warmstrong1955]

What was the question again?????
I got sidetracked watchin' Glenn's new avatar.....
Goodun Glenn!!


I found it doesn't take much to go from snug to too tight. I had the same problem quite some time ago.
Let things go a spell, and sections of the ways get grunged up, mostly in the areas you don't travel things so often. My lathe was due for a good cleaning anyway....and that cured the problem.

Just a thought.

Bill

[spro]

A wedge thing, where the surface untraveled finally makes contact.

[Glenn Brooks]

What Bill said. I've had two different situations with gibs in dovetails, that got a lot better when I pulled the gibs and cleaned the old dried gunk off.

Gpb

[RSG]

Thanks for the replies guys.

mcostello, the machine is only a few years old so the gibbs aren't worn much (I wouldn't think).

The screw on the front protruded quite a distance and when I loosened the rear one I was able to turn the front one in allot. I'm guessing I should have perhaps only loosened the rear one a touch then tighten it back up after moving the front screw a bit. I'll mess around with it a bit more tonight. Either way it's not bad but I just want to understand how they work exactly so I can make the machine perform to it's highest capability.

[larry_g]

I'm being dense here this morning. You have two screws to adjust the gib. Do these screws run parallel to the gib or perpendicular to the gib? Are they arranged in a push/pull arrangement or a push/push arrangement? When you say front and back are we to assume this is on the Y axis? Can you give us a link to the vid you watched and confirm that it is what your machine looks like?

lg
no neat sig line

[RSG]

Larry,

Here's the video. It's one of Tubelcaines videos on gibbs for his lathe but the principal is the same in the fact that there are two screws (one at each end of the gibb) that turn.

https://www.youtube.com/watch?v=5OcQddOEMnM

Your question "are both push/push or push/pull" has me wondering. Once unscrewed the screw on the back was loose as was the one on the front, so perhaps they are both meant to be tightened the same amount to put pressure on each end. Further to that when I loosened the rear one it allowed the front screw to move in a large amount.

[John Evans]

The gib is tapered . The screw at the big end pushes the gib in tighter,the screw at the small end locks the adjustment. To me a much better arrangement than one screw with a notched at one end gib ,as Bridgeport does it.

[larry_g]

I agree with John. You have a tapered gib. If you cannot lock up the carriage by tightening the front screw then something is wrong. The gib is being prevented from traveling far enough. The gib could have debris behind it, or it could be to long, or the casting could have a stop in it. You may have to disassemble things to figure it out.

lg
no neat sig line

[Harold_V]

If you cannot lock up the carriage by tightening the front screw then something is wrong.

Not necessarily true. With double screws, as have been described, the gib is locked in place by the opposing screw. In order for the gib to advance enough to lock the given slide, the opposing screw must be backed off to allow the screw on the large end of the gib to advance.

This system is somewhat superior to the single screw system, which can allow some movement of the gib when a slide reverses direction of travel. Unless the slot in the gib is a snug fit with the head of the single adjusting screw, that's often the case.

Harold