December 11, 2015 at 17:52 #6364100ideasParticipant
I am building a 2-axis positioning system based on morgan. The steppers will be closer to the actual arms, similar to Daniel’s flipped variant.
As I’ve been researching the BoM and build instructions (thank you soooo much, RobertKuhlmann, esp the inventor assembly!), I’ve been trying to figure out:
1) how are the theta servo drive wheel and arm secured to the 22mm tube? Is it just a friction fit?
2) would it be reasonable to replace the threaded rod and associated nuts in the psi drive with a tube, either 8mm ID to work with the 608Z bearings, or a bit larger, for instance 16mm and stabilized with several sleeve bearings or needle bearings?
Since my z-distance is short, I might even try printing both drive tubes as extensions from the drivewheels.
If that’s unadvisable, I would appreciate suggestions about which of the following tubes would perform well as a replacement for the inner tube+threaded rod assembly: Teflon PTFE, delrin, fiberglass, aluminum (3.17 mm wall) , aluminum (rigid alloy, 1.5mm wall) or steel – all cost less that $15 for a 1ft length with relatively thick walls (1.5mm+).
Most of these tubes are also less than $30 for 3-6 ft lengths, fyi.
Thanks for your insight, everyone!
December 11, 2015 at 20:17 #6366100ideasParticipant
I studyied the theta arm drive tube assembly a bit more, and now I see how the threaded rod and 28mm washers clamp the tube to the theta a-arm and the 608 bearing inside it. As well as constraining the the rest of the drive assembly components vertically with all those nuts.
Cool! Well, I’m not sure that integrating these parts into the 3d-printed stepper wheels would lead to a less-complicated solution. Need to think about it some more.
Oh, and duh – those additions on the other side of the stepper wheels would make them much harder to print. hmmm.
December 11, 2015 at 21:01 #6368Quentin HarleyKeymaster
Jumping the gun a bit, but the Morgan Pro does have a solid bar as the Psi drive shaft.
I will be publishing Morgan Reprap 2 in a week or two. It is the lilian code on which Morgan Pro 2 is based.
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