Quote:
Originally Posted by Don Rotolo
...until the wheel slips, at least.
Because of the moment of inertia of a relatively heavy mass swinging around a central axis with little friction (those omnis) you will find such a design difficult to control - even with a wider wheelbase.
Commenting on the sheet metal: Cut the thickness by 30% and put a 1" flange (bent inwards for both) at the top & bottom. Saves weight, adds significant rigidity. Some of the flange can be lost or reduced by the omni wheels for clearance if necessary.
To keep the assembly from racking (parallelogram), consider very thin braces from outside corners, in an X pattern. Even 1/8" wire rope would be fine, since it is in tension.
Your hole pattern could be improved. The solid pieces should all meet at stress points, not tangentially to them. See the small round 'pin' in front, 1/4 way from the left side of the image.
Nice CAD work.
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I am expecting this to be hard to control, and thats why I pulled the wheels toward the center. I figured it'd be spinning out of control untill you got the hang of it, so I should just design it for experienced drivers (hence the fast turn speed).
As for the metal, putting such a large flange on both pieces will leave a 1/2 inch gap between the side plates (only 2.5 inch spacing). I thought about just downgauging and flanging one piece (outside), but wanted to leave it simple for the first prototype CAD.
Supports: We have always been fine without any angle braces since the tubes go through a square hole in the inside plate. Would just a simple angle bracket suffice?
Lightening
Does it really matter since the piece will never be under tension/compression in the direction that the lightening will help?
As far as the CAD goes, I enjoy it, so I've gotten really good with basically teaching myself.