Help ! Fixing 8mm dia pully over 8 mm rod and so on..

I am finding it difficult to put in 8 mm bore dia pully over 8 mm rod. Also some F688ZZ bearing are also not accomodating 8 mm rod. Seem 8mm rod is not actually 8mm rod but slightly more. I am tight on budget.

Any innovative ideas ?

sand paper much?

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

try heating/cooling the mating parts, you'll get a pressfit but wont really be able to tweak it.

Quote
Trakyan
try heating/cooling the mating parts, you'll get a pressfit but wont really be able to tweak it.

...Now, that would be an issue.. Any one please !

There are only so many ways to make parts that don't fit together fit. You either remove material from the outside of the part that's too big, or remove material from the inside of the part that's too small, or you try a thermal trick (but in this case it would probably destroy the seals on the bearing). Do you have a caliper with which to measure the parts? Do you have any tools? Put the rod in a drill, get a piece of sand paper. Spin the rod and grip it with the sand paper. Stop frequently to see if it will fit inside the bearing.

Cheap parts are made with poor tolerances. That's why they are cheap. Now you know what can happen when you buy cheap stuff. Think about it the next time you're shopping for parts. There's a reason for the expression "buy cheap, buy twice"...

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Thanks digital dentist !

"buy cheap, buy twice"... True but sometimes the costs are astonishingly high such that you may like to purchase two cheap parts (95% times work) rather than one costly and may or may not work...

Anyhow, I like your suggestion of grinding while spinning with drill....Many thanks...

Ouch ! while using drill and sand paper. I think I bent the a rod somehow. Is that possible ?

How much tolerance is accepatable for straightness of 8mm dia 350mm long rod.? How to measure this tolerance.

Please help !

It takes a lot of force to bend an 8mm steel rod.

Acceptable is whatever you define it to be. A bent guide rail will create a distortion in the print, assuming it isn't so bent that it keeps the axis from moving or causes the motor to skip steps. But you're going to be spinning this rail, so it's being used for power transmission and a little bend may not matter at all.

Edited 1 time(s). Last edit at 01/05/2018 02:29PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

If you can see it is bent, then it is too much bent.

If you managed to bend it; it is crappy recycled steel from Lychee cans or your name is Bender

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