I have been looking into using Chain as a backlash free Precision Rack and Pinion replacement.
The most practical size appears to be 6mm pitch drive chain.
The spec is well in excess of what we need.
I think that it can be used thus:-
Take a single length of chain for the Rack (Not a loop) secure at either end of the axis using a tensioner at one end.
On the carriage plate use 3 Sprockets (Need to print these) 2 idlers that ensure the chain raps 3 quarters of the way around the drive sprocket. The drive sprocket to be no less than 21 teeth. (smoothnes of motion avoiding the polygon effect)
If these are laid out correctly the chain should exit the assembly at exactly the same height it enters.
Idlers could be printed as a sprocket tyre to clip onto a 608 skate bearing.
Drive sprockets could be printed with an integral 8mm shaft to pass through the bore of a 608 bearing. A 2mm shoulder on the sprocket end of the drive shaft placed to give correct spacing from bearing.
The bearing to be mounted in a mounting bush, See Bearing accessories thread.
If the Drive Sprocket shaft were printed up with a 6mm + flat socket in the drive end mating a 6mm + flat output shaft from a gearhead and DC brushed motor should be dead easy.
Lack of tooling to make some of these things even if only in plug format to then mold some parts from is driving me up the wall.
If anyone wanted to have a crack at these and the Bearing Accessories I would gladly have your babies.
Less importantly so printing up a carriage end mounting plate that incorporated all of the above would be really clever.
Grin
aka47
Necessity hopefully becomes the absentee parent of successfully invented children.
mmmm, i'm thinking maybe normal bycicle chain. 