Chained to a metric sprocket!

[JoeKahan]

Hello All,
So I'm just getting started in the live steam/ride-on hobby and I'm on a very limited budget. I'm building a battery powered Goose type thing for my first loco and I have a couple of questions regarding my drive system. I have the guts out of an electric wheelchair (2 24vdc motors with angle drives, control electronics, seat) that I think would work. I plan on using two deep cycle batteries. Here's the hitch. The angle drive outputs are 20mm shafts with 5mm square keyways. I'd like to use ANSI 35 or 40 chain for the drive but can't find a stock sprocket like that. Am I not looking in the right places or is this something that I will need to make? I could get a sprocket for a 1/2" or 3/4” shaft and machine it to match the shaft, but just wondering if some solution already exists. Also, since the two motors and drives are the same, is there anything "wrong" with having them both drive a common axle shaft? For certain reasons, I'm considering having just one drive axle.
Thanks for your thoughts or ideas,
Joe

[steamin10]

At some point you must cross over from the M&M's, and go with more readily available chains, sprockets and parts. So given the control for two drive motors, 24 volt, and the desire for heavy chains, ( #40 is my fave ), I would custom cut the drive for your shafts and go from there. It is easy to file a key to a size you need, without monkying with the shaft itself, and a step key if needed can be hacked out of larger key stock with a saw and file, so no sweat except for the arm motions.

Salvaging the core drive parts is half the battle, so now just work the details.

[JoeKahan]

Thanks for the ideas Big Dave. I guess that's what I'll have to do. Just seemed odd to me that nobody makes one.
Joe

[chooch]

Joe,
Smaller locos I have from 8-6- to 4 wheel use a common main (jackshaft) drive axle with # 35 chain and have no problems. Some other suppliers do the same, with chain from the main (jackshaft) to the other wheel axle(s) .
Number 35 chain as I understand is not actual Roller chain but quite suitable. # 40 IS Roller chain, and no doubt better for the Long run and heavier/larger locos.

As for Wheel chair motors, I know "Nothing" of How they work--same speed back / forward,
rpm`s, gearing etc., except they Are used for drive units. I expect though if wheel chairs go each way the same the motors and controls should be ok.

If I go back to check, I might lose this so--I think you said Two motors? Perhaps one might be good and you could use the other for a second power unit.

Also, overall, # 35 chain, sprockets etc. might save you a few bucks. (yes, I`m frugal. ok, Cheap)

chooch

[kvom]

McMaster has finished sprockets with Ansi key slots. You could get the desired tooth count with a .75" bore and drill it out to 20mm (.787"). Then file the key slot to match that on the shaft.

[JoeKahan]

Thanks for the info and ideas guys, I think I have it figured out. I found a solution to the metric shaft problem in a round-about inch size way. Martin Sprockets sells a taper lock sprocket bushing in inch size .787". Tada, 20mm without going metric. And Chooch, I'm frugal (broke in my case) too, and I may still go the #35 direction if it saves me enough. I need to power up the drive system and see what the final rpm is so I can calculate the sprocket ratios. If I need a sprocket with less than 14 teeth then it will have to be #35.
Joe