Quote:
Originally Posted by Cothron Theiss
This all looks great! A few quick things before I dive back into your CAD:
You're missing a few parts in your GrabCad folder for this assembly, like the small bearings around the first wobble gear, or the countersunk screws bolting the two wobble gears, and just a few small parts here and there.
Also, where did you get the 50mm ID 65mm OD bearings? Just wondering what supplier sells those.
And how did you determine the dimensions for the lightening pocket on the camshaft?
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As usual, I forgot to do a Pack and Go. Try downloading the STEP file (GrabCAD has an option for that). Alternateively if you download the massive Parts folder it's all in there.
Recently I discovered the 6700 series bearings, and less recently the 6800 series bearings. These are very thin-section bearings, with the 6700 series being a mere 4mm wide and usually having a difference in OD between 6-7mm, so you can get a 30x37mm bearing. These are crazy useful for a lot of designs, and cost just a few dollars on Ebay or Aliexpress, as they are standard sizes. I believe I am using 6810 bearings in this design. There's an amazon supplier for 6800 series bearings that offers Prime, but they are vastly overpriced and usually cost $10-50 each compared to $1-5 for Aliexpress.
To get the lightening pocket just right, I first drew the maximum size pocket on the camshaft, in this case somewhere around a 0.09" outer wall and 0.125" thick material between the front and back pockets. I then made an assembly consisting only of the cam and the off-center rotating components including all the the gears, screws, and bearings. I mated the center of the cam to the origin and took Mass Properties readings to determine the center of mass, and trial-and-error adjusted the depth/wall thickness of the pocket accordingly. In this case, I ended up with a 0.09" wall and a 0.187" wall between the two pockets, and under 0.0001" of theoretical concentricity.