five gears instead of a belt?

I'm wondering if it wouldn't be better to use five gears instead of a belt to drive the Z stage? If the Z stage screws are N units of distance apart, then the diameter of the gears would be N * sqrt(2) / 2 units of distance. The motor drives the gear in the middle, which drives the four screws of the Z stage.

I'm suggesting this because the gears are RP-able whereas the belt isn't, and neither (really) are the gears the belt drives.

Assuming the Z post gears don't get much larger than the Z pulleys already in place (and in the current design they couldn't, they'd run into the support posts) the center gear would have to be very massive. You'd have to have an extremely accurate stepper motor driving that to maintain accuracy, and a powerful one to deal with the inherent gearing. Not to mention RP gears aren't that accurate yet.

But an interesting concept! You'd just have to give it a bit of thought to get around the challenges, I think.

Kyle

RussNelson Wrote:
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> I'm wondering if it wouldn't be better to use five
> gears instead of a belt to drive the Z stage?

Vik's Zaphod, which has been operational since last September, uses this concept. The only difference is that Vik uses four gears instead of five.

[www.reprap.org]

[reprap.org]

Well, my suggestion is that all five gears should be the same diameter. That way, in effect, the stepper is driving the screw directly. With those sizes, there's no overlap, so all the gears can be in the same plane. Or, if you need to change the ratios, the center gear could be thicker, and then the screw gears could overlap, top left and bottom right below, and top right and bottom left above.

I wonder if Zaphod is what Vik took to OSCON? I should have looked closer at it.

RussNelson Wrote:
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> I wonder if Zaphod is what Vik took to OSCON? I
> should have looked closer at it.

Yes, it definitely is.