lmf8uu for z axis?

The price of this kind of flanged linear bearings seems to be decreasing, as compared to the plain lm8uu. It seems to me that they could simplify the design and improve reliability for the z axis, especially for those more inclined to keep a horizontal x axis. Do you see any inconvenients for an x-ends design using those? thoughts, comments?

Edited 1 time(s). Last edit at 01/06/2012 09:58PM by Lanthan.

Looks nice for cnc projects. Reprap z axis sees little action though. A tight bushing would give the same results.

Perhaps if we used a lmf8Luu (a long one), we could get away with bolting only one of them to the x ends. Pointing it downwards might even give some extra z height, depending on the extruder.

But to use two lmf8uu with four bolts each instead of a simple snap in lm8uu and a zip tie? Nah..

Other that than, I think it could be worth looking into scs8uu for the y axis, as several people already have.

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-Nudel
Blog with RepRap Comic

Thank you guys for the feedback!

@jcomp316: lightly touch the vertical smooth rods and the y-ends while printing a fill at high speed: they do vibrate a lot. Parts of it are related to: 1) flexion of the whole structure for the lack of cross-bracing along the x direction 2) flexion of the smooth vertical rod , 3) the springy way to mount the lm8uu. The flanged bearings with printed plastic sandwiched in between would help reduce that last component.

@Nudel: with scs8uu you still have to solve the right angle between the bearing and the (horizontal) carriage. The flanged ones instead provide for that --> flatter, simpler x-ends, easier, quicker to print, increased rigidity.

+Simplicity: You just attach a flanged bearing on each side of a horizontal plate. eight bolts, eight nuts, the same using a single long bearing or two shorter. BTW the long versions still fetch higher prices, not very interesting for now.

Other than that, I have been looking at 12mm diam. hardware, especially for Z where increased weight of the x-ends doesn't really matter. But: 1) it wouldn't provide for an incremental upgrade path (you'd have to change both the x-ends and the z ends) 2) spacing between the smooth rod and the lead nuts might need to be increased from 30 to 40 mm to be at ease.

of course you also don't need to use 8 screws. two or three would probably be enough, since the flange is so rigid.

i think it's a fine idea, but just like lm8uu, somebody has to create a design that uses them before people will realize the benefits,

I'll give a shot at it. after I finish the crossbraces.