Having finshed the post mortem of ARNIE 1 I conclude:
"The design for ARNIE Mk 1 was flawed using a tension transmission for its z-axis movement: uneven tension behaviour caused jamming at the z-bed/vertical bearing surface which prevented the z-bed from working properly. This was exacerbated by an unstable structure, under-engineered and poorly build-orientated components, a critical modelling mistake which caused damage to critical corner supports and over-constraint of the z-bed’s movement."
I'm off to get drunk, and possibly wipe my face with my degree certificate.
I think that the concept for the Arnie Z-axis stage is sound. Certainly, very similar approaches are used to keep the cross bars on drafting tables very stable indeed.
ReplyDeletePerhaps the design error was a result of trying to apply the power to move Arnie to the cable. I also wonder if you removed the power feed to the cable, tightened it up a bit and then used a scissors jack arrangement to raise and lower Arnie...;
http://www.domarproducts.com/images/product_hdsj1.jpg
...if it wouldn't work very nicely.
I reckon combining screw threads with ARNIE's frame might be a worthwhile exercise.
ReplyDeleteVik :v)
The scissors jack approach is a screw thread approach. It has the advantage of not requiring extra space vertically or penetrating the existing Arnie working surface. :-)
ReplyDelete