Smooth Idler Pulleys

Questions, Suggestions, Tips, Etc

Re: Smooth Idler Pulleys

Postby dirktheeng » Thu Jul 07, 2011 12:39 am

bdring wrote:Is the shim between the bearings?


Not on these ones... The idler pulleys don't actually need shims. The new v-groove bearigns do. The idler pulley bearings don't have any spacer on the outter race to cause a bind if you tighten down on the inner race, the inner race thickness matches teh outter race thickness very well (<0.0005" which is undetectable by my measurement ability). When I tignten down on them without a shim, I don't see a bit of difference in the friction of the bearings, unlike the v-groove bearings. Besides, even if I put one in, it wouldn't change the total distance from the sholder to the lip because it would just move the upper bearing up (and out of the assembly slightly) without shifting the pulley. The pulley is registered to the lower bearing in this configuration. It would make a big diference if the pulley were flipped on the screw/shaft.
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Re: Smooth Idler Pulleys

Postby bdring » Thu Jul 07, 2011 12:50 am

OK, I have mine flipped. I thought it would be better to put the ridge on the inside in case it even decided (unlikely) to come off. Probably OK either way, but my spacers for the other axis were calculated with ridge facing in.

Note: I have seen them bind bearing to bearing. That happened on the rotational engraver. It only takes a thou' or two to do it. It is not a robust design without the shim. You are right that it does not add length in your orientation though.
Bart
"If you didn't build it, you will never own it."
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Re: Smooth Idler Pulleys

Postby dirktheeng » Thu Jul 07, 2011 1:41 am

We can put a dab of superglue on the bearing/derlin sholder to keep it on. It held my shafts well.
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Re: Smooth Idler Pulleys

Postby dirktheeng » Thu Jul 07, 2011 2:20 am

bdring wrote:OK, I have mine flipped. I thought it would be better to put the ridge on the inside in case it even decided (unlikely) to come off. Probably OK either way, but my spacers for the other axis were calculated with ridge facing in.

Note: I have seen them bind bearing to bearing. That happened on the rotational engraver. It only takes a thou' or two to do it. It is not a robust design without the shim. You are right that it does not add length in your orientation though.


We can put a dab of superglue on the bearing/derlin sholder to keep it on if there is any concern. It held my shafts well.

I am curious as to if a piece of debris got stuck on the outer race when they were put together. I have used bearings side by side for rollers in many different applications and never had an issue as long as I put them in contact with very clean surfaces. Sometimes I even run a very fine bead of superglue in the valley between the two outer races to keep out desbris. The bearings are ground to incredibly tight tolerances (talking ten thousandths of an inch here). Unless there is a problem with a particular bearing (something not meeting spec), I can't see that being an issue. I can see a piece of plastic or something causing an issue if it gets in between the bearing surfaces, but I can't see face to face bearings causing an issue unless there is a quality or debris problem. There is more lateral slop in the bearing/race than the grind on the width.

At any rate, putting in a spacer will eliminate any concern. I put them in my pulleys just to be sure.
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Re: Smooth Idler Pulleys

Postby naPS » Mon Aug 15, 2011 6:57 am

Are these available as an upgrade yet? I'm running out of things to do to my laser. :)
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Re: Smooth Idler Pulleys

Postby bdring » Mon Aug 15, 2011 1:38 pm

The parts were swapped into the standard kits at no extra charge because they replaced existing parts at roughly the same cost. It takes quite a few parts to make a replacement kit, so the price is a little high. I can do a replacement kit for $25 with $3.50 shipping. It will consist of the following.

(4) smooth idlers pulleys
(8) bearings
(4) shims
(4) spacers (various lengths)
(4) plastic mounting brackets
(4) screws
(4) nuts
Bart
"If you didn't build it, you will never own it."
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