# G0602 Compound Gib Adjustment Trick



## 54100 (May 1, 2016)

The gib adjustment of my G0602 compound has never been satisfactory, countless adjustments left it tight and still allowed too much vertical movement.  I noticed the the gib itself would rock on the upper casting due to a hump in the middle of the upper section, I was attempting to hold the gib "up" on both ends during my adjustments to eliminate the movement.  After some careful grinding the gib would now lay in the upper casting with no movement, I re-installed the unit, lightly shimming the gib upward at each end during adjustment.  The compound is now rock solid, with almost no movement vertically.  Movement effort is reasonable, and parting is now easy, even with a large tool overhang for a large diameter solid.  

I had already performed the addition of bolts as recommended on the Projects in Metal site, which had helped, but not nearly as much as this.  Good luck.


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## Bob Korves (May 2, 2016)

54100 said:


> The gib adjustment of my G0602 compound has never been satisfactory, countless adjustments left it tight and still allowed too much vertical movement.  I noticed the the gib itself would rock on the upper casting due to a hump in the middle of the upper section, I was attempting to hold the gib "up" on both ends during my adjustments to eliminate the movement.  After some careful grinding the gib would now lay in the upper casting with no movement, I re-installed the unit, lightly shimming the gib upward at each end during adjustment.  The compound is now rock solid, with almost no movement vertically.  Movement effort is reasonable, and parting is now easy, even with a large tool overhang for a large diameter solid.
> 
> I had already performed the addition of bolts as recommended on the Projects in Metal site, which had helped, but not nearly as much as this.  Good luck.


Welcome to the forum!

Congratulations on figuring out how to improve the fit.  You should now be getting more accurate cuts with more rigidity and less flex.

Asian import lathes commonly have had less than careful attention paid to gib (and other) fits.  That is a major reason they are cheaper to buy.  Not trying to be elite here, I also have a Chinese lathe which had the same issue.  Gibs, and all the mating surfaces, should be scraped in to fit.  That takes a fair amount of time, some learned skills, and careful thought.  That greatly adds of cost to the lathe.  So we are really buying projects that look like lathes, not the real finished product.  Grinding them, even carefully and correctly, and even using a surface grinder, gets you going, and improves the fit, but does not really achieve a good, long lasting, smooth sliding, and fully rigid fit.

If you want to know how to do the job right, here is the bible:
http://www.hobby-machinist.com/threads/connelly-on-machine-tool-reconditioning.41802/

Often a new gib must be fabricated to be able to get it right.  The first spotting of gib to ways tells the tale...


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## HBilly1022 (May 2, 2016)

54100 said:


> The gib adjustment of my G0602 compound has never been satisfactory, countless adjustments left it tight and still allowed too much vertical movement.  I noticed the the gib itself would rock on the upper casting due to a hump in the middle of the upper section, I was attempting to hold the gib "up" on both ends during my adjustments to eliminate the movement.  After some careful grinding the gib would now lay in the upper casting with no movement, I re-installed the unit, lightly shimming the gib upward at each end during adjustment.  The compound is now rock solid, with almost no movement vertically.  Movement effort is reasonable, and parting is now easy, even with a large tool overhang for a large diameter solid.
> 
> I had already performed the addition of bolts as recommended on the Projects in Metal site, which had helped, but not nearly as much as this.  Good luck.



I've had a similar problem with mine but can't visualize your fix. Do you have any pics? 

I've replaced numerous parts on my _new_ lathe, including the saddle, cross slide and compound. I discovered on one of the compounds that the gibs would not sit flush against the dovetail and was only riding on the top edge of the dovetail. The bottom of the gib was not touching the dovetail, at all. This would cause binding and made it impossible to get the compound to slide and be snug / solid at the same time. The new compound is better but still not 100%. I think the issue is 2 fold. 1) the gib adjusting screws are too high, which causes the gib to rotate upward when tightened. If the screws were lower they would put even pressure against the gibs, allowing the full face of the gib to ride on the dovetail. 2) in addition, the gibs on the first compound were not tall enough, which allowed them to rise up and roll over over when tightened. This aggravated the issue. The gibs in the new compound are taller and fit a little better. At some point I may make some gibs that are tapered, from top to bottom and are a little taller, in an attempt to reduce the tendency for the gib to roll when tightened. A better fix would be to lower the adjusting screws but I'm not comfortable doing that to a machine that is still under warranty.


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## RegisG (May 14, 2016)

I really like the video that Bob posted.  My question would be ..... if I get the scraping done well and the gib adjusted correctly on my G0602 cross and compound slides, will they indeed be very smooth moving and accurate.  Or, because it is relatively small/light lathe would it just be a slight improvement?   I see some of these lathes on youtube and they just seem to glide so smoothly. 

Also, what is the really FLAT surface that he was using to mark the base for scraping?

Thanks,
Regis


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## fitterman1 (Feb 5, 2017)

Yes it will be very smooth and accurate if you follow Nicks procedure as shown in the video. You will notice a huge improvement. In the video Nick uses a granite surface plate I believe good to better than 50 millionths of an inch.


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## Mark Stonich (Feb 8, 2017)

HBilly1022 said:


> I think the issue is 2 fold. 1) the gib adjusting screws are too high, which causes the gib to rotate upward when tightened. If the screws were lower they would put even pressure against the gibs, allowing the full face of the gib to ride on the dovetail. 2) in addition, the gibs on the first compound were not tall enough, which allowed them to rise up and roll over over when tightened. This aggravated the issue. The gibs in the new compound are taller and fit a little better. At some point I may make some gibs that are tapered, from top to bottom and are a little taller, in an attempt to reduce the tendency for the gib to roll when tightened. A better fix would be to lower the adjusting screws but I'm not comfortable doing that to a machine that is still under warranty.



I'm planning to add 2 more adjusting screws to both the compound and the cross slide. Seems like it would make sense to add them lower than the others so you're defining a plane instead of a line.


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## Bob Korves (Feb 8, 2017)

I think you want them in a line so the gib can adjust itself to fit the dovetails.


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## HBilly1022 (Feb 8, 2017)

Bob Korves said:


> I think you want them in a line so the gib can adjust itself to fit the dovetails.



Bob, If you see the pic I took of the way the gibs ride on the dovetail I think you would understand what he is saying. I could find the pic if you're interested. The center line of factory adjusting screws on my lathe are above the top of the dovetail and this causes the gib to roll over and only ride along the top _edge_ of the dovetail. If I was adding gib adjusting screws to my G0602 I would put them lower than the factory ones and probably only use the new lower ones. Would have to be a trial and error process to see if it was better with just the lower ones or both sets. Mine is working OK after getting some new parts. I now use a new bigger lathe which doesn't have this issue. 

Try to line the center of the adjusting screws up with the center of the dovetail face. That should make the 2 surfaces ride more evenly.


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## Bob Korves (Feb 8, 2017)

HBilly1022 said:


> Bob, If you see the pic I took of the way the gibs ride on the dovetail I think you would understand what he is saying. I could find the pic if you're interested. The center line of factory adjusting screws on my lathe are above the top of the dovetail and this causes the gib to roll over and only ride along the top _edge_ of the dovetail. If I was adding gib adjusting screws to my G0602 I would put them lower than the factory ones and probably only use the new lower ones. Would have to be a trial and error process to see if it was better with just the lower ones or both sets. Mine is working OK after getting some new parts. I now use a new bigger lathe which doesn't have this issue.
> 
> Try to line the center of the adjusting screws up with the center of the dovetail face. That should make the 2 surfaces ride more evenly.


OK, I did not understand that there was a problem with the original screw locations.  What we are after is even bearing over the entire gib so the gib can properly fit to the dovetails (or box ways.)  If the screws need to be relocated, put them where the force will be equal on all the gib and so the gib can move to conform to the dovetails.


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