Gib material question

tweinke

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So the Question is, I want to make a gib for a project that is still in the dreaming stages of design. What is a good material to use? It is a straight gib with set screws to adjust and will be running against cast iron. Steel, bronze, brass, all come to mind but I think I sure would like some advice before I dive in to this. If the project becomes feasible in respect to the skills I have or have access to I will start a new thread.
 
Greetings tweinke, if it helps, the gibs on my Atlas lathe are cold rolled steel.
 
I've seen cast iron, CRS, Delrin, and glass filled teflon. Ideally you want something stiff and with a low coefficient of friction. If loads are high, cast iron is a good coice, if loads are low I would stick with a stable low-frication plastic.
 
Ideally, the part that is easiest to replace would be the wear part. It is generally easier to replace a gib than refurbish the ways so I would make the gib the wear part. I would probably choose brass.
 
Is the aspect ratio of the gib long and skinny or short and stout? Steel, and other cold worked metals love to spring and move around when machined and fitted. Cast metals are more dimensionally stable, but also usually more fragile.
 
Generally, dissimilar materials make for longer wearing gibs. As RJ said, make the gib the wearing part. Easy machining ability and easy to scrap are good qualities for gib materials. Most common are cast iron and brass. Cast iron Durabar is more dimensionally stable.
 
I've made brass replacement gibs for my mini mill. They were the "long and skinny" variety. The brass I used displayed a tendency to warp, unless I machined off about the same amount of material on both sides of the work. Based on info I found on the web, I also tried annealing it @500F in our kitchen oven but I'm not sure it did much.

Gibs for the mini mill class of machine are not tapered, which simplified the machining job. The downside is that the gibs on mini mills are notorious for poor fit.
 
Is the aspect ratio of the gib long and skinny or short and stout? Steel, and other cold worked metals love to spring and move around when machined and fitted. Cast metals are more dimensionally stable, but also usually more fragile.

Long and skinny and I would say a pretty fair load, also repeated travel. I think I should have also included dove tail and cast iron in my initial post also
 
I've made brass replacement gibs for my mini mill. They were the "long and skinny" variety. The brass I used displayed a tendency to warp, unless I machined off about the same amount of material on both sides of the work. Based on info I found on the web, I also tried annealing it @500F in our kitchen oven but I'm not sure it did much.

Gibs for the mini mill class of machine are not tapered, which simplified the machining job. The downside is that the gibs on mini mills are notorious for poor fit.
500ºF is where brass just begins to anneal. 600º to 800ºF is a better choice. Annealing time shortens with an increase in temperature.
 
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