What's new
What's new

Are shims in a gib common?

marka12161

Stainless
Joined
Dec 23, 2016
Location
Oswego, NY USA
Just brought home a 1941 Monarch 16 CY. As part of the taper attachment removal (to lighten the load before i lift if off of my trailer) I removed the compound and the cross slide. I found what looks to be a couple of pieces of shim stock in the cross slide leadscrew "trough" which i'm guessing was shimming the cross slide tapered gib. The compound tapered gib had a shim running its' full length. Is this common practice? Is this a sign of extreme wear?

I've seen & read some of the material on scraping and i'm thinking scraping in the cross slide, the compound or both would be nice scraping projects if i can find the time to attend one of the classes.

Mark
 
Mark,

I added a shim to the tapered gib of my Studer cylindrical grinder, because I did not want to go to the trouble to make a new gib. Details are in this post. The experts don't do this, they just buy or make a new gib.

This is for the "manual cross slide" which normally is moved only during setup for a job, then locked in place for the grinding itself. So it's not critical for the accuracy of the machine. The gib shim is made of steel shim stock 0.005" = 0.125mm = 125 microns thick.

The most difficult part of making a shim is to avoid burrs or kinks which prevent the shim from having constant thickness. You should cut the shim from smooth high quality stock with very sharp scissors, then stone the edges. If you have to make holes in the shim for clamping screws or oil passages, this is difficult because it tends to raise burrs. If you clamp the shim between thick supporting material before drilling, this helps. Then file/stone afterwards.

An alternative which I meant to try but did not yet, is to "burn" the holes using muratic or sulphuric acid or ferric chloride. The way to do this is to make a "mask" out of paint or etchant-resistant tape, and reveal the metal only in the areas you want to remove. Then drip acid or etchant onto it, repeating as needed until you get the desired hole.

Good luck!

Bruce
 
Last edited:
A sign of wear for sure but I would not automatically say extreme wear. Depends on how much tapered the gib is, a steep taper and shimming would likely indicate more wear than a gib with little taper to it as you sooner run out of adjustment on the later.
Properly done shimming can be an ok fix, but in my opinion it should be squeezed in on the stationary side of the gib-piece so the shim never see any sliding movement apart from adjusting the gib.
For it to be an ok fix one still has to fit the whole assembly properly so it is really like Ballen says, merely removes the labor of making and fitting a new gib. I think one needs to start with assessing the old gib. If it is in reasonable condition it can make sense, if the gib is toast a new gib may be the best way to go as you´ll likely need to do some work on the old gib anyway, maybe straightening (Rich has a good method for gib straightening described here and shown somwhere on YT) and likely some scraping work.
As RK says, be a detective. When you get it home, take it apart, clean it up, inspect and asses it. Maybe you find some more clues.

Don´t worry, be happy - you found yourself a nice lathe :)
 
Thanks you for all the input. Last may i had considered taking Richard's scraping class in Vermont as it's an easy drive from upstate NY but timing didn't line up for me. This may be just the project to push into one of the classes as fixing the cross-slide and/or compound might be a nice scraping project.
 
You have a chance to attend then definitely do so.
The compound is a nice starter as it can be treated as a separate assembly with a clear interface against the crosslide.
 








 
Back
Top