Questions on mini kossel belt system

Hi everyone, I am building a mini kossel. I'm generally following the instructions here:

[www.think3dprint3d.com]

I see that they are using two flanged bearings pressed together for the belt idler. Is this really a good idea? It seems to me that I should use another GT2 20 tooth pulley on the idler. My solidoodle uses pulleys on the idlers and it works fine. It seems like having a smooth idler would lead to slipping.

The GT2 20 tooth pulley is the best choice, right?

Also, is there anyone out there who has built a mini kossel with spectra line? I was looking on thingiverse and I didn't see any carriages that had been modded to use spectra line. I like the idea of zero backlash and I think I'm more likely to get that with a spectra line system, so if there is a design out there already, I would like to use it unless someone can convince me why I am better off with belts.

Thanks.

Why is it a problem if the idler slips? It does not turn the belt, and less friction is desirable. There are thousands of MK's in the wild that use the flanged bearings as idler pulleys, because they work and are cheaper than putting a wheel over the bearings to accomplish the same exact thing.....

Hmm, I guess it indeed does not matter. I was mainly thinking it needed a gear on the idler because that's what my solidoodle has. I guess its okay if it slips because it is still moving the same amount. I'm going to go ahead with belts now instead of spectra line. I will try to find some prime line rollers that other people have had success with instead of dropping ~$130 on the nice track systems

Hi RDM6

We have found there are no issues with using an untoothed idler, rather than an pulley, however i have seen a design using a pulley as well.

Cheers

Tony

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