Custom Bearing - Calculate # of Ball Bearings 4

[BrittToolEngineer]

Greetings:

We are designing an inspection fixture where a round part will sit on a plate and rotate about its center. The size is fairly large, so we are looking at designing custom thrust type bearings. General information: Ball bearing diameter is .250". We are cutting (2) grooves where these balls will ride, one radius is 34.500 and one is 36.500. I know how to determine the circumference and then divide by .250, and this gives me a perfect fit number of ball bearings; however, is there a rule of thumb to reduce that number so that the ball bearings have sufficient space to perform their job?

Thanks in advance for your assistance,

Brent

 

[dhengr]

BrittToolEngineer:
For all the screwin around... A difficult design problem, difficult machining problems, heat treating problems, one of a kind special, very thin, thrust bearings, significant costs, etc.; you have told us very little about what the test piece weights, its size, how it’s tested, how it is fixed to the turn table, etc.; how the turn table is driven, speed/rpm, cycles per day, etc. Would something a little cleaner and simpler work as well as the ball bearing thrust bearing arrangement? A fairly heavy turn table plate, with a centering bearing over a vert. axis on a heavy base plate, for centering the turning table. The underside of the turn table plate has a 34.5" i.d. and 36.5" o.d., flat bottomed, washer shaped, shallow groove machined up into it. This groove takes a Teflon/fiberglass (Fiberglide?) flat thrust washer or a metal backed flat plastic bearing thrust washer (GGBearings.com). The base plate gets a similar shallow groove for a chrome plated steel, flat washer shaped, thrust washer. I don’t know exactly what vertical, thickness and flatness tolerance this system can achieve.