El Beast - Initial design phase, comments and critique welcomed!

[Zeeflyboy]

Decided to re-vist my original plans for a belt tensioning system.

I whipped up this design




And then set about making it. The idler I made from alu tubing which I turned down and bored out for the bearing pockets.






I also needed to make the upright piece which the whole assembly rolls around. Turned this from silver steel:




Final part that needed turning was the little rotating piece through which the threaded rod will go... Made a small jig to make sure I drilled it centrally, which could also then be flipped and guide the tap straight through.






I decided to try 3D printing the main parts in the CF composite material I use for functional parts and I must admit I was amazed at just how strong it's come out. I upped the infill percentage and used extra perimeters to beef up the part even more and the result feels like it could survive being run over by a truck... my backup plan was to make the frame parts from alu plate but it won't be needed.

Even more surprising is that I modelled the M6 thread in the bearing tube mating part and it printed fully functional... didn't even need to run a tap through it. That's the smallest thread I've tried printing so far and I'm suitably impressed :)


Final bunch of parts:






And test fitting

Untensioned:




Tensioned (can't fully tension for two reasons - screw thread isn't long enough, and the smaller pulley pulls in towards the bigger one without the top bearing counter plate.... but it gets the gist across):




Pretty chuffed with that little bit of design I have to say... worked out nicely. Still need to make a knurled knob and order some m6 threaded rod to make the proper tensioner adjustment, and I also need to make the little collar that goes on the m5 standoff to help capture the rod end.