I bought V slot POM wheel bearings (11mm x 24mm x 5mm I.D. ) that look exactly like the Creality V-Slot POM
Wheels. However, when mounting them on a 88 mm x 88mm gantry plate and sliding it on a V slot extrusion, the drag coefficient on theses bearing is not what I expected. The gantry plate can hardly slide off when I place the extrusion in a vertical position. Surely, there has to be V slot wheels with internal bearings that are far more free to roll. I’m assuming that the polycarbonate transparent V slot wheel with 625ZZ bearing have less drag. Would that be true? If not, which V bearings have as less drag as all the others? I’d appreciate the help. Thanks, George
@VerticalMan56 Welcome to the RobotShop Community.
Do you mean coefficient of friction? Not sure we can get many details about that. How well the bearings roll is a different issue, which would involve bearings, grease etc. Can you provide links to the products in question?
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[quote=“cbenson, post:2, topic:111597”]
Do you mean coefficient of friction?
[/quote] Yes…
Hi cbenson,
Thanks for replying. I got my V slot bearings at Amazon https://www.amazon.com/dp/B0B99WTBSY?ref=fed_asin_title and they look exactly like the Creality V-Slot POM wheels. I’ve been a machinist for decades and I’ve never seen bearings like these that have considerable drag. I think you are right in saying it’s because the bearings in theses wheels are packed with grease- either that or they are defective. Anyway, I bought another set of wheels with the 625 2RS bearings in them [Amazon.com: uxcell 10pcs 3D Printer POM Rollers, Solid High-Speed Gantry Wheels V Slot POM Pulley Wheel with 625-2RS Double Shield Bearing for 3D Printer, CNC Machine (Black) : Industrial & Scientific] (I have yet to get them) because they do not look the same as the first ones I bought. The 625 2RS are double shielded but with plastic so if these bearings drag on me as well, I’ll take off one side of the shield to get the grease out. I hope this will solve my problem.
Aside from the above, if these V wheels are designed this way, it would be very helpful for buyers to know it and offer wheels that are not packed with so much grease.
Thanks, George
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Good question, George — yes, what you’re seeing makes sense: drag on V‑slot wheels depends a lot on the bearing inside plus how the wheel is preloaded, shimmed, and how well the bearing seats in the wheel. The transparent polycarbonate (“PC”) V‑slot wheels with 625ZZ bearings are often noticeably smoother than cheap POM wheels with poorly matched bearings or sloppy mounts, because 625 bearings (5×16×5 mm) tend to roll very freely and you can tune the preload better. In short: yes, PC wheels with 625ZZ are very likely to feel freer than what you’ve got now — but equally important is the quality of the bearing + how it’s installed and preloaded — simply swapping to better bearings + proper setup should give you a big drag reduction.
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