Motor screws require short right-angle allen-wrench to tighten.

[brandonheller]

I was able to get the motor screws started with a ball end hex driver, but then I had to finish with a regular right-angle allen wrench. This is even with button heads that give more space for the allen wrench. Making frame_motor a mm shorter on the top and bottom would reduce the angle and speed up assembly, as would tapering the inside edges of the enclosed trapezoid shape in frame_motor.

[brandonheller]

I recently got a bunch of M3x8 SHCS. The slightly larger (2.5mm IIRC) allen wrench, when used with the SHCSs, does NOT have this problem. So either all smaller 2.0mm ball-end allen wrenches have this problem, or it's just the one I bought (from Solarbotics). The workaround is to avoid BHCSs for the motor mounts, so I'm marking this as closed.

[brandonheller]

I'm reopening this issue. The SHCS does make the allen wrench a bit better at being able to actually turn, but under load, it still slips for me. I think the right solution is not to compress frame_motor, because it would remove the small air gap that helps with stepper heat dissipation, but instead, to just put holes through the whole part, next to the vertical openbeam, which would exit near the 2 holes for securing the vertical openbeam. The external curve won't be quite as nice, but it'll be much faster/easier to assemble this way. Will send a pull request once I've tried it out.

[jcdoll]

For what it's worth, I used a ballpoint hex key + SCHS without much trouble. Here are the keys I'm using: http://www.mcmaster.com/#catalog/119/2810/=n52w8l

Also if you build through holes into the frame it looks like you could only use them before installing the horizontal extrusions? That's just from eyeballing it. Not a major issue but would make them a bit less useful.

[brandonheller]

I implemented this yesterday and printed a few brackets with slots in the plane of the triangles:

The slots are definitely worthwhile! The allen wrench is guided right into the screw head, and the angle is smaller so the tightening force is way reduced. The holes clear all OpenBeam. Adding the motor is so fast now.

But, the problem is that the allen wrench would hit the screw heads for the triangular openbeam attachments in the center trapezoid if I assembled a triangle and then tried to attach a motor. This is OK - I put the motors in first - but I think just adding another angle to point the allen hole away from those conflicting screw heads would be the right way to go.

Also related: my previous attempts at frame_motor all had a significant YZ skew, so looking at the corner, the beam would tilt to one side. This mean my motor holes were not a square, but a parallelogram, which increases the force and might explain my difficulty.

[brandonheller]

Thanks!