Compound gib issue

[DiscoDan]

Here is a shot of the end of the compound. The compound doesn't slide smoothly and it appears that it is because the set screws force the gib to ride all the way up in the slot and the edge of the dovetail digs into the gib, as seen in the other pic. Should it ride that high up? The problem is that the set screw dimples are already at the top edge of the gib and keep it held at the top of the slot. Do I just need a new gib? Is the roughly 1/16" space between the two pieces of the compound normal?

Thanks.

 

[T Bredehoft]

The "slots" for the set screws should allow the gib to be central in its' slot, neither top or bottom. Possilby yours has worn to the point it is not longer functional. They were made to be replaceable.

 

[DiscoDan]

Looking some more, it looks like part of the issue is that the set screws are so high in the slot that when you start tightening them they skew the gib to a more vertical position making it rub on the edge or corner of the dovetail. It seems that it should ride lower so that it can't skew in the slot and the flat faces ride against each other. I have new ones on order but the one for the coumpound and the one for the slide are the same in the Sears system, even though they aren't but I may be able to make them work.

 

[wa5cab]

Yes, the roughly 1/16" vertical clearance is normal. The compound slide is supported vertically by the bottom of the slide resting on the two lower flats of the dovetail. And the gib should not touch the right lower flat.

My guess would be that either there is a "dinged" spot on the top right nearly sharp edge of the male dovetail on the swivel, or one of the gib screws is catching on the edge of its flat bottomed hole/slot instead of seating in the hole against the flat bottom.

The proper/safe way to install the gib is with the compound swivel and compound slide removed from the pintle on the cross slide and inverted on your work bench. In that position, the gib's beveled top surface rests on the slide, instead of the bottom bevel wanting to rest against the swivel, which will try to happen if you try to install the gib with the swivel sitting on the pintle as in your photo.

I have some new steel (Clausing went to plastic in the mid 1970's) gibs. However, aside from the line of wear (that won't much matter after you find and fix the problem), there probably isn't any reason to replace the one that you have.

 

[markba633csi]

Hi Dan I have the same lathe, mine is a little stiff too, but usable. Check the gib strip for bends and rough spots, maybe polishing with some garnet paper and re-greasing (or oiling)would help. I'm planning to replace mine with either bronze or brass eventually. I put a brass one in my 6" and it's considerably smoother. It will wear faster I'm sure, but to me it's an equitable trade.
mark

 

[wa5cab]

I was writing my last while you were writing. You did not show what the back side of you existing gib looks like. But your use of the term "dimple" makes me wonder whether your gib is original or not. The steel gibs should have what amounts to a flat bottomed slot that starts shallow and finishes deeper, or a flat bottom hole cut at a 30 degree angle with the deeper side nearest the top of the gib. Only the carriage gib has countersunk "dimples".

The reason that the current compound and cross slide gibs are the same part number is that you install them and then cut off the part that sticks out. I don't think that anyone here who has made the change back to steel gibs would recommend that you try to use the plastic ones.

Show us a photo of the other side of your existing gib.

 

[DiscoDan]

Here is a pic with the gib installed. You can see how it gets skewed to a more vertical position and rubs on the corner.

 

[DiscoDan]

 

[DiscoDan]

I was writing my last while you were writing. You did not show what the back side of you existing gib looks like. But your use of the term "dimple" makes me wonder whether your gib is original or not. The steel gibs should have what amounts to a flat bottomed slot that starts shallow and finishes deeper, or a flat bottom hole cut at a 30 degree angle with the deeper side nearest the top of the gib. Only the carriage gib has countersunk "dimples".

The reason that the current compound and cross slide gibs are the same part number is that you install them and then cut off the part that sticks out. I don't think that anyone here who has made the change back to steel gibs would recommend that you try to use the plastic ones.

Show us a photo of the other side of your existing gib.

Here is a pic.

 

[wa5cab]

Yes, I see the gap. Are the bottoms of the three holes still flat and at a 30 degree angle to the surface that they are cut in?

Pull the three gib screws and confirm that the ends are flat, not rounded. If they are rounded, use the side of a grinder wheel to flat them. You might want to make a quicky holder by taking a piece of aluminum round stock and drilling and tapping a hole in the end. You can do that without the compound being assembled. Just don't make it too deep or you might screw the screw into it and not be able to get it out. Run the screw in no more than about five turns and tighten the nut to hold it.