Does a VSlot z-axis still need smooth rods?

I'm about to start a rebuild of an i3 derivative using Misumi 2020 extrusions and VSlot extrusions for the moving carriages. I'll be using the mini v wheels from Openbuilds. My question is if the z axis is built using this and still using M5 or M8 threaded rod for the drive, do I still need smooth rods to constrain any wobble in the threaded rod, or is the vslot setup rigid enough to handle it? The x and y axes will be belt driven as they are now so I guess those are less of an issue, but I want to make sure I'm not introducing any z-wobble with the new setup.

Im planning a wolfstock based on the V slots so from what I gather it is made for linear motion. The whole system would make sense if the slots and wheels weren't precise enough for it.

On the openparts site they have a whole section with many different printer and CNC designs all based on V slot and there are no smooths rods involved.

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sungod3k
Im planning a wolfstock based on the V slots so from what I gather it is made for linear motion. The whole system would make sense if the slots and wheels weren't precise enough for it.

On the openparts site they have a whole section with many different printer and CNC designs all based on V slot and there are no smooths rods involved.

Yeah, that's the feeling I'm getting is that there won't be a need for smooth rods which would be great. My parts are on the way, so I guess I'll find out soon.

Bruce

Ali Extrusions are stiffer than rods, base on typical sizes. I have some V-Slot and I can say it's fairly stiff, especially the wider sizes. Full 1500mm length only bends a tad with fair pressure. I can't imagine even a full speed typically sized printer putting out bending forces that would effect prints on this. But I don't have wheels yet, so I can't say anything there.

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brucehvn
My question is if the z axis is built using this and still using M5 or M8 threaded rod for the drive, do I still need smooth rods to constrain any wobble in the threaded rod, or is the vslot setup rigid enough to handle it?

It's best to not try and constrain the wobble! Trying to hold slightly bent threaded rods rigid is what leads to z wobble. Use flexible couplings (rubber fuel hose works well) and leave the free end (non motor end) free. The solutions that support the threaded rod at both ends are a poor design, there is no good reason to do so.

Edited 1 time(s). Last edit at 06/23/2014 04:35AM by konwiddak.