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By frodeheg
#771
Thanks, you're always so fast replying :-D

I'm a bit uncertain what route to go, eliminating the bottom bars was in my option a, but I was just worried about the length of the bar and wanted to add extra support for the weight. Open Rail will probably work pretty nice.

However, that's more work than just keeping the 4 bars and add more sliders.

...unless I just offset the bottom slider 10 cm. or so in relation to the topmost slider.... maybe that could work?
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By AJ Quick
#772
You certainly could use 3 sliders, but I would try to use 2 sliders and 1 shaft per side.

When engineering things like a sliding / rotation shaft, I have always been taught that any more than 2 support points on a shaft and you are going to have alignment problems. Almost every major power tool or application with shafts will only have 2 bearings... 3 will require more precision, and 4 even more. When they have more than 2, there will be 2 shafts connected through flexible couplers to avoid alignment issues.

I also see that you don't have anything rigid supporting the gantry. I think that might be the cause of some of the rotational problems. Make sure your stage with the Z-axis is firm, and the Z-axis can move freely from side to side... then tackle the remaining axis. I'd be very worried about flexing from all of the shafts hanging pretty much freely.

Your design is still very awesome and I hope you can make it work before the Maker Faire!
By frodeheg
#773
I have now removed the bottom sliders and replaced them with OpenRail sliders, just a few more holes and screws to get it attached, so I think I have it ready tomorrow. The support for the OpenRail sliders are 4 cm. high stainless steel tubes, so you can stand on them and they wont move at all. So, I think this will work better, but I'll see tomorrow when everything is attached :-)

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