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ZS6HDV — That is my concern as well. Please note that the one issue I saw when I posted the image with a section cut is that the internal fillet is on the wrong side. My thought is to put a radius (fillet) on inside to support the bridge in the layers leading up to the top most layers. The radius of this feature may need adjustment to work; larger radius = better support for bridging. As a fall back the external overhangs could be omitted, or also use a fillet/radius.
At some point It would help to see this come out of a printer to see how the sagging looks.
A note about the external flange: It could be used to attach or ‘clip’ things onto the arms. Say, a wire holder/router, light, fan, etc. I’m thinking of a gun rail mount system, for example. See this image:
http://www.thefirearmblog.com/blog/wp-content/uploads/2012/04/glock_go_pro_small-tm-tfb.pngStill some work to be had to crank out this idea. I see one issue right off the bat that I didn’t catch earlier. (I put an internal radius in the tube on the wrong side. Should be on the sloped side. This facilitates closing in the square cross section for the printer as the layers build up. My plan here is to print with the flat side down and the tapered side up)
The wall thickness and overall part heights are complete guesses right now. At some point I’ll prototype these…
Future plans:
* add wire routing holes/paths.
* decide on an extruder or make it a separate part/adapter you bolt on to the arm structure depending on which extruder you want.
* multiple extruders??? 😀
* B3 Innovations Pico Extruder shown in image. I like it because it is light weight and well designed. Also, the mounting threads will be cool (not hot).
* Continue design down to the motors. i.e. figure out what nuts and bolts are supposed to be there that didn’t come with the model I mention above. Figure out how said nuts and bolts make it work properly and copy/paste into my drawing or see what modification ideas I come up with.Basically my idea is to create x-y DoF arms that are a cross between I beams and square tube. Both of which are more structurally stiff. I add the taper because the internal bending moment of the cantilevered beam decreases as you get closer to the tip, thus the required stiffness is less so one could save some weight. Lower inertia (mass) means the motors can have better control authority, or operate at faster speeds.
See the top two diagrams here as a reference.
Awesome. I’m looking forward to that. 🙂
In the mean time I’ve been plugging along and having at my idea. See pictures:
Thanks for the prompt reply.
My link didn’t come through before…
http://reprap.org/wiki/RepRap_Morgan_extended_BOM
is this who you’re working with?
