I bought some 25mm IKO linear slides off of ebay. I unpackaged them today and tried to manually slide the carriages along the rail. They seemed quite stiff. Cleaned them up good, and it halped slightly, but I am still disappointed with them.

My question is, How freely should they slide? I was expecting to turn the rails at a slight angle (say 30 degrees) and watch the carriages slide down the rails on there own. These I can be turned vertically and they wont move.

This is my first go round with linear rails of this type. Am I expecting to much, or are these not quite up to par. I was seriously considering contacting the seller and voicing my lack of satisfaction, but I wanted to make sure I wasn't expecting to much in the first place. They were discribed in excelent condition.

Also, these bearings were greased, but the grease doesn't seem to be in the tracks of the ball bearings inside the carraiges. The inside of the ball bearings are completly dry and clean. Should the grease be completly through the entire raceway for the ball bearings? If so, what kind of grease should I use? These seemed to have a very thick type of grease on them, and I was thinking something with a little bit on the thin side viscosity.

Thanks all.

Dan

Hack,

I have had the same thoughts on linear rails before myself. To my suprise I discovered that by moving them in their free state they can seem a little stiff. Try placing the rail on a bench top and apply downward pressure on the bearing (thus emulating the weight of an axis) and try sliding it, you should notice it will slide freely. If it does not, then I would question the state of them.

My IKO linear ways will slide at a slight angle all on their own. It was NIB though...

I found that out by picking one up and just barely catching the block before it shot off of the rail!

Put some weight on the bearings and they slid much better. Good call Kook...I am gonna use these for a Z Axis. How will this effect things? The weight wont be directly applied. Might be a little stiff I'm thinking. I'll just have to try it and see.

Any help with the grease on these? Should all of the individual ball bearings be covered in grease? If so, what type?

Thanks all

The ones that I have felt feel a little stiff as well, a bit of sticktion before they start to move. If they have old thick dirty grease in them you sould completly clean them and relube with a bearing greese.

Should be OK as reverse canterlevered weight will have the same effect on them. Good luck with it all. Be carefull no to over grease them, just gloss the shaft with grease and run the bearings up and down a few times and repeat the process. If the bearings have greasing points don't go crazy with the grease gun, 1-2 squirts only. General bearing grease will safice, or if you have deep pockets use portzelacco (I think this is how it's spelt).

One other thing to point out:

Most linear rails have a certain amount of pre-load built in (ie. Heavy, light or no pre-load). This is due to how tightly the bearings hug the rail. Rails with a high pre-load will feel stiff, until, as others have noted, you apply weight to them. Generally rails with higher preloads give more accurate movement (THK explains this in some of their PDF literaure online).

Some truck designs even have an adjustable preload screw, though I have never seen these first hand...

Carlo

This is an old link but there used to be pictures of some THK linear guides with the adjustable preload screws in them.

http://www.cnczone.com/forums/showthread.php?t=7564

You got a good set of rails , if you hold the rail vertical and the truck does not slide off it is new or near new.