darmach's blog

tech junkie

Not so ‘smooth rod’ ?

I received yesterday smooth rod sample from one of the local suppliers.  I’m pretty sure something is wrong, but I have no idea if with the rod, or the bearings. Take a look how it behaves:

I must admit I expected it to slide smoothly along the rod, and even when I tilt it vertically – the bearing just sits there, on the top, until I pat it! This doesn’t seem all right… Also a certain stuttering can be felt when you try to slide it.

Funny thing – I cooled the rod to below 0 degrees centigrade (just put it in the freezer actually), and suddenly it slides perfectly! The question stands: is the rod too wide, or the bearing too tight…….?

2 Responses to Not so ‘smooth rod’ ?

  1. Nutz95 says:

    what kind of smooth rod is it? Steel? inox? aluminum?
    I know that aluminum rods are crappy.
    On my side even with building construction steel rods i had correct result.
    Somehow i’d say the smooth rod is the issue.
    Did you try to lubricate the rod?

  2. darmach darmach says:

    That’s what is weird – This is supposed to be smooth rod dedicated for CNC machines, and linear bearings!

    Seller claims it’s cf55/cf53 steel, inductive hardened surface (0,5mm deep), smoothness 0,2um, dimension tolerance h6. Here is the link to the offer: http://goo.gl/28yOiN
    The worst thing is both of my calipers are analog ones, so I can’t even measure it precisely enough – according to my calipers it’s somewhere between 7,95 and 8,5 mm .P

    As for lubrication, I’ve lubricated bearing, with ŁT-43 grease, it wasn’t better. The bearing definitely sits too tight.

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