# GO727 gib modification



## iron man (Jun 29, 2014)

My little GO727 mill has suffered a problem from day one and after reading about some other Sieg mills the problem is not just isolated to this Knee type mill but to other mill/drill machines as pictured below the stock castiron gib is on the right a brass one on the left. Both work well but as soon as you tighten either one to where the machine is usable the table gets jumpy I also noticed that the 55 degree dovetail when locked down was a degree off so I have to fit that into the equation. So I scrapped both and started over.




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So I started with a piece of 5/8 T6 Aluminum I was going to use this as an experiment I can make a new one out of cast iron later this is easy and quick to machine. I also wanted a table lock so I made the gib longer and I have a brass plunger that pushes out into the dovetail. This Gib unlike others once it is locked down does not move so I had to do it this way I also made it stick out the top a little as well I changed the angle 56 degrees instead of 55 when it bolts solid to its mount the angle is corrected. 





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Much to my surprise the aluminum Gib worked flawlessly and at this time I am not going to do anything with it, I run the table up and down a couple dozen times with no jump or hang up any where. I took out the aluminum gib to check how much wear and the surface looked like it did when I installed it not a scratch so for now I am going to leave it along. This longer gib provides more support as well and this maybe part of its success rather than the type of material I will not know till I make a cast one in the future this may be cure for other mills as well. Thanks Ray


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## benmychree (Jun 29, 2014)

Oftentimes, gibs need only to pe properly scraped to fit the opposing member; this is generally not to difficult of a task, and fairly easily learned by the beginner, which I have personally witnessed at Richard King's scraping classes, which are geared to the beginner, and are even of good value to those with previous experience in machinery rebuilding.
I recently made two tapered gibs for two customers, one about 20" long for a lathe cross slide, and the other for a vertical slide of a knee type vertical mill; this was my first attempt at making gibs in my 50 years as a machinist; it was a learning experience, and went very well, two happy customers and money in my (retired) pocket.   I used cast iron for both, actually ductile iron from McMaster Carr, it proved to be quite stress free and easy to work with, with no straightening required, only some minor shimming between cuts to keep it straight.


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## iron man (Jun 29, 2014)

Making a gib fit is easy this was a design flaw from the beginning if all mating surfaces are machined properly scrapping it really not needed. I have scraped a few machines with good results but I have also machined two pieces that fit so nice it was not needed. Ray


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