shaft drive

[Joseph F]

Were planning on doubling up our wheels on the drive axle. Last year with a single wheel we had a fixed axle and attached the sprocket directly to the wheel. Whats a good way of connecting the wheels and sprocket to the shaft without using a keyed shaft. Should we drill clean through the shaft and wheel hub and put a screw through it? drill a hole in the hub only and find a way to set screw it? or is there a better way? btw we are using 1/2" diamater shafts if that makes a difference.

[CharlieWilken]

We did the same last year and will do the same as you this year. We are using 1/8 inch diameter spring pins. We do this by drilling the hub of the gear right on center with a 1/8 drill. We place the gear back on the shaft and then use a hand drill to mark where the hole will go on the shaft. We then take off the shaft and drill through. Spring pins expand a little in diameter to hold themselves in.

[Ken Leung]

A little warning: There is a LOT more pushing force this year than last year, so be careful about the pins breaking or the wheel home breaking. You got away last year because you are only pushing goals over a slope... This year will be a lot of robots puching your drive train.

Imagine all those force pushing on the robot, and that in turn push the wheels around the shaft, and the powered shaft being pushed the other way by the motor.

It sounds like you guys are using the wheel hub small parts made for the skyway wheelchair wheels. Those are not the best material to pin through on the wheel.

And then, if you guys are putting BOTH sprocket and wheels on the shaft, why have the sprocket there if you are powering the shaft? Or the other way around, why power the shaft when you have are sprocket next to the wheel?

It would be much easier and stronger if you use the sprocket connect to the motor with chains. Let the wheels spin freely on the shaft, and sandwich the sprocket between two wheels. Just have enough spacers to clear the chain from the wheels.

If you can successfully attach a sprocket on the shaft of the wheel, you can easily attach a sprocket to the motor powered shaft, and use that to drive chain to your wheels.

[jonnywalk]

Consider using a taper and press fitting them together

[Joseph F]

we are planning to run a chain from a sprocket on the motor shaft to a sprocket on the shaft with the wheels. Our wheels will be to far apart to drill clear through and attatch the sprocket to both wheels so that they turn together. We need some way of attaching the wheels to the shaft without using a keyway. Were looking for the best way to do this... Oh and we are not using the hubs from small parts. We are using much larger hubs from skyway and of course the wheels that go with them.

[jonnywalk]

Well I still say you can taper and press fit. OR you can turn the shaft a make it smaller on the ends then use a tap and die to put threads on the shaft then inside the sprocket. Also if you use the same material for the shaft and sprocket, i.e. alum on alum or steel on steel. then you can just weld them together. We are using a press and taper but I have access to a nice machine shop with a precision CNC mill and lathe so that might not be easy for you. Also you could taper and use a shrink fit press for an even stronger fit. But welding will be the easiest if you have compatible materials. I hope this helps and I hope I understand the system right, if not e-mail me at jonnywalk@hotmail.com and describe it better or scan a drawing and send that and i will try to help you the best I can.