Stickiness an oiling the rod and bearings

[Slider388]

Hey, I'm using 3/4 steel rod and oilite bearings.
Two questions. One, my tables don't move very smoothly once they are installed. This is cause I missed the tolerances on the rod holders, but they still move pretty freely once oiled, they just have a bit of a "stick" to them. Will this interfere? I have 300oz/in unipolar steppers, and I hope it won't affect my accuracy or speed, but is it a problem if my tables don't slide perfectly? Also, what kind of oil should I use to oil the rods and bearings to lubricate them and keep the rod from rusting?
Thanks a ton, Alex

[Boort]

Slider,

I have used WD40 to clean my axis guide rods, but nothing to really oil them. My thinking there is that the sintered bronze bushings are self lubricating and that adding oil to the rods will attract dust which might cause problems if it wedges between the bushings and the rods.
When you say you "missed the tolerances on the rod holders" what do you mean? Are the rods for each axis out of parallel with each other?

BoorT

[Slider388]

Ah, I used a bit of after run motor oil for hobby motors to clean the rods and for them to slide better, it helped a ton with the friction and hasn't had any negative effects(yet). I figured a bit of oil would help the pre-oiled bushings, and I hope it won't have any negative effects.
And yeah, I mean that the rods for each axis are not perfectly parallel. They slide fine by themselves, but if I mount that axis assembly and put the rods in place the table sticks a lot more, so they must be a bit un-parallel.
Is a bit of stickiness enough of a problem to have to redo some parts, or should I be ok for now?

[Boort]

Slider,

If you have rails that are out of parallel then you will probably be fighting problems where for no apparent reason the cutting gets to a spot and then sticks for a bit before moving on. I don't know if this will bother you or not. It depends on what you are planning to make with you router. If it only sticks at 1 end and you lose an inch or two of travel from that axis are you willing to avoid that area to have parts come out the same each time?
If the area where the axis is sticking can't be avoided or you are unwilling to lose the amount of travel that you lose then you should repair or remake the part.
When I first built my router I was getting sticking in about 3-4 inches at one end of my Y-axis due to a mis-alignment between the rails and drive screw. (See my photo album if you want to see pics of what happened.) In the end I was able to rework the motor mount so that I only lost about 1/2-3/4 of an inch of travel on my Y-axis. I'm willing to accept this rather than rebuild the whole Base and Y-Axis assembly.

Regards,
BoorT

[Slider388]

Yeah, I see what you mean.
I got the motor for the X axis mounted and it works perfectly, I probably lost an inch or two of travel, but for now I'm just happy that I got my first axis working!
Expect a big build log in one of the main forums soon. Thanks for the help Boort! :P

[Boort]

Slider,

Good To hear that you have it moving. Glad I could help. I look forward to seeing your build log.

BoorT