Required Prusa i3 Idler Bearings?

Ok so I have been looking all over trying to find out two things.

1) What bearings are used for the x and y belt idlers?
2) Is there any printed part that goes on them or does the belt just sit right on the bearing?

Edited 1 time(s). Last edit at 08/14/2013 12:31PM by hcker2000.

1) the bearings are parametric, meaning who prints the parts decides what bearing dimensions to use. I believe the default is 624 bearings (two of them for each idler)

2) It depends on which bearings your parts were designed for. The default uses no bearing guides, the belt just rides on the bearings.

Thanks for the info that helps a lot. I'm planing to use the default parts from the prusa i3 github repo.

There are now two repos for Prusa's i3. The original which has source for the single plate, box frame and mini that requires the user to generate their own .STL files. There is a newer "vanilla" repo that is a generic build that has .STL files already generated. The default belt idler bearing for the "vanilla" Prusa i3 version is 624zz. The original box and plate versions were configured when the STLs were generated and used either 623ZZ or 624ZZ depending on how whomever generated the parts configured the build.

There is a printed bearing guide in each repo that replaces what used to be fender washers in the earlier i2 builds. Either bearing will work, you just need to make sure you have the right size bearing guides for the bearing used.

Any chance you can link me over to the vanilla repo? The one I have did include some stl files in an sample_stls folder.

vegasloki, it sounds like you are saying that bearing guides are used for the default bearings, but my understanding is that they are only used if you print the idlers for 608 bearings.

mjrice Wrote:
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> vegasloki, it sounds like you are saying that
> bearing guides are used for the default bearings,
> but my understanding is that they are only used if
> you print the idlers for 608 bearings.


The vanilla default is a 624 as is the recently reconfigured original single plate. In the box version line 68 of configuration.scad.dist using "idler_bearing=" sets the belt idler size in inc/bearing-guide.scad.

hcker2000 Wrote:
-------------------------------------------------------
> Any chance you can link me over to the vanilla
> repo? The one I have did include some stl files in
> an sample_stls folder.

github.com/josefprusa/Prusa3-vanilla

The .stl files are in /distribution .

thanks for the link over to vanilla repo. Its interesting to see the difference between this repo

[github.com]

I wonder if one is better than the other?

I just checked the y-idler.stl in the vanilla repo and it looks to be sized for a 623 bearing. But the belt-guide.stl is wrong for the 623 bearing so I'm not actually sure what its supposed to use. The hole in the belt-guide is 8mm and what ever bearing is supposed to snap in should be 8 x 10 x 6.

The good news is it looks like a 623 bearing would work just fine if you dont want to use the printed guide.

I haven't printed anything from vanilla yet but a couple of people that have kits from me have and they've requested 624s to replace the 623s included in the kit. One person indicated it was too big for a 623 and needed trimming for a 624. The file header indicates a 624 but that's no guarantee. I'll print one out and see but if you need one you can config one from the box version or IIRC there are some alternatives at Thingiverse.

Idlers in vanilla repo expect an M3 screw and nut, so you need to go to 623 bearings for that.

I have done a quite a few prints of vanilla repo and it will fit a 623 though the comment says 624. If you look at the radius of the internal hole is 5.1 (which will fit a 623 nicely and tight).

I printed one earlier and while it requires a bit of trimming, at least from my prints, it's indeed a 623ZZ.

Great info as thats exactly what I ordered!