Currently, I have 2 options of GT2 idler for my Hbot. 1.

3D Printing
,
1

Currently, I have 2 options of GT2 idler for my Hbot.

  1. (left) GT2 idler with bearing(I.D=5mm) and thrust washer (O.D=8mm), and M5 bolt

  2. (right) GT2 pulley(I.D=8mm) with 2 flanged 693zz bearing(3X8X4), and M3 bolt

But the problem of these 2 options is when I try to fasten it tight to frame, bearings won’t rotate by force of bolt
Now, I have to use right option with loosen it a bit and securing with nylon nut.

I’m thinking about using ‘shoulder bolt’ with 8mm bore gt2 pulley.

How do you implement GT2 idlers of yours?
I’d like to hear your opinions.
Thank you.

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2

The shoulder bearings are a good solution, but you need to place a tube of the right length between the two bearings so you don´t press them together when tighten the screw.

3

Your version 1 is probably easyer to use. You just need to have a thick washer that supports the inner part but doesn´t touch the outer part of the bearing.

4

@cprezzi Yeh, I thought it also, but I can not source rigid spacer(or tube?) for it.

5

@cprezzi About version1(left), bearing is so small, I can not find right washer not to touch outer shell of the bearing.

6

@DongWon_Han_DWONH You could print something!

7

Version 1: Take all your washers put them on a M5 bolt with an unthreaded upper shank. Lube between washer ID and bolt. Use grinder to reduce OD.
Version 2: Buy long tube with 3mm ID and cut to length. I think stainless automotive brake line will work.

8

@DongWon_Han_DWONH use a short bit of brass tubing that has same ID as the bearing. It’s a.common part at r/c hobby stores.

9

What do you think of using shoulder bolt (8mm OD) with 8mm bore pulley?

10

Depends on the pulley bore material and lubrication. It will always have more drag, and may suffer from wear.