[Psychotechnoid]

Agreed on the bolt holes - mounting the arm directly to the holes in the sprocket seems to be a much better idea that attempting to mount the arm directly to the shaft itself.

I'm sorry if my explanation of the reduction was poorly done: what I meant was this: Taigene coupled to 22-tooth, linked to 48-tooth, coupled to 9-tooth, linked to 60-tooth - total reduction: ~14.5:1, and according to JVN's design calculator (my gracious thanks go to him), perfectly ok (close to the peak of the power curve). Stalled motor = hot motor = dead motor = bad situation.

Also, yes it is 190 ft-lbs. in a worst-case scenario (ball in claw, arm completely extended) - the arm, when fully extended with the claw, measures 108" long. While we cannot fully extend it and stay within the 80" bounding cylinder (the robot will have to do a "dunking" motion), it is important that the physical mechanisms be able to handle the arm being in this position for testing purposes and in case of programming glitches (we might get a penalty, but at least the arm won't break off).

I will definitely check the loading specs on the bearings as well - another point of good advice for which I am very grateful.

P.S. Are master links available for double-strand chain? Would we need a different kind of chain breaker for it? Or should I just use two loops of single-strand (on two 9-tooth sprockets on a keyed 3/8" shaft) and couple the double 60-tooth sprockets really tightly together to ensure even loading? Also, is 28.5 ft-lbs. an acceptable torque on a short 3/8" steel shaft, or will I need to find some sort of exotic material or larger-bored sprockets? Current opinions on the 3/8" shaft appear somewhat discouraging, and I'm wondering if there is any way to obtain perhaps 3/8" keyed titanium or something uber-strong. That shaft, of course, will also have to be supported against the large load from the 60-tooth sprocket linkage, although it will be pulled downward by the linkage to the van door motor as well (that will have to be supported really well, too).