Lubrication for the mini mills

[iron man]

I dont know if this is good advice or not I have had trouble with my GO727 knee mill. The problem is when you get the gibs tight to where the machine works well the knee or table will stick and shudder when you crank it up or down. I have tried everything short of a different gib like brass or even plastic. I was prepairing to make a different gib with some relief in it for less surface contact when I started checking into lubricants I tried everything I could think of way oil, Synthetic motor oil of different brands, slick 50 grease, Slick 50 oil, even Never Seize, nothing worked.


I dont know why but I picked up my bottle of straight STP it comes out just like honey I use it for open gears it really sticks well so I thought what have I got to lose? So I gave it a couple shots cranked it up and down and to my utter suprise it was smooth as silk. I had know idea something this simple would be the cure I was dreaming up all kinds of mechanical ways to cure the problem and ignored the simplest solution. It works great now,,, hope this will help someone.. Ray

 

[iron man]

This has stopped it for now but I discovered that when you crank the table real slow there is still some hesitation in the lift of the table so it will jump a couple thousands, You dont feel it but you can see it on an indicator. If you crank it up at a moderate speed the problem has quit. I may play with different gib material I will start with aluminum and brass and maybe cut some oil grooves to lesson contact area until I get the problem solved completely. But for now I was very impressed how far a simple application of this stuff made a dramatic improvement. Any suggestions will be appreciated.. Ray

 

[iron man]

It sounds like you are on you're way to solving it.

I looked up the friction of

cast iron to cast iron

Teflon to cast iron

Brass to cast iron

It seems brass to cast iron is only a point or so below teflon so brass it is. If the table lift screw was centered with the table this would not even be a problem and that would be possible but this would be easyier. I may cut oil grooves in the gib as well to reduce surface contact.

 

[iron man]

Started to make the new gib I cut off excess so I dont have to mill so much.



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Here is the cut after the bandsaw it come out nice enough you could probably use it the way it is but I will machine it. Ray

 

[iron man]

Well I finished the brass gib I cut some oil grooves in it and it works great brass seems to be the answer for a sticky table. Ray