Sunday, September 07, 2008
Taking shape... of what, I don't know.
The pipe fittings aren't the most precisely machined things in the world. It takes some fiddling - over-tightening some joints, leaving some loose - to get things lined up right. Even so, one of the bearing assemblies needs some further adjustment, which I'll have to do by re-positioning the skate bearings on the bolts. Oh well... that's why they're there.
I'd edit your picture if I knew how to include a picture here.
I'd do away with two of the bearings and only use one on the top and one on the bottom and I was fiddling in the garage and think an end bearing could be made to hold it all together.
That's what's in the picture I posted. Really messed it all up but I think you'll be able to figure it out.
Even after I have it working, there will be plenty left to do deciding what can be modified, enhanced, and _especially_ removed from the design to decrease cost, complexity, and required tooling -- all three are already pretty low, but I think they can go lower.
I've also got a couple new ideas that might allow me to do away with the bearings entirely... saving those for a new post - after I give them a try.
Thanks for the ideas! I'll give them all a try eventually. They're all appreciated.
I would recommend spring loading the adjustable tightener bits, and using only one bearing on one of the pipe lengths. If both pipes are used to fix a linear dimension, the two pipes have to be perfectly aligned, or there will be backlash. If only one is used for the linear plane and the other sets the angular plane, no alignment is needed to produce a zero backlash system. The only effect of non alignment will be a slight angular variation that can be minimized by keeping the pipe pieces as far apart as possible. See this site ttp://www.opend.co.za/hardware/cnc1/p2.html
for more data.
Keep up the good work.
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