Where to buy gears

[newshound]

I think you will find that they do, except that it is a separating force. There is also a large tangential force, which also has to be supported by the bearings.

[newshound]

In the very old days you would have been able to pick up a mangle which had a suitable train of cast iron gears (plus the bearings and shafts in a suitable frame). These days they would be silly money as a garden ornament.

[James Harris]

Maybe. My fear there is that I gather a universal motor (as found in an electric drill) would not be up to continuous motion, being designed for lots of start-stop use.

[tabbypurr]

So having chosen a mechanism that will result in slower throughput, you now realise that it's rather harder to implement too - but still persist. Genius.

NT

[Andy Burns]

Talking of lethal looking chains/belts

The rotor head looks rather less home-made than the rest, so I'm guessing it was salvaged?

[James Harris]

"slower throughput"?

I've no idea what you are talking about.

[tabbypurr]

I'm comparing this plan of yours to the standard industrial approach of using vibration. Good luck with it.

NT

[newshound]

IS could find it useful.....

[harry]

Use Vee belts or a bicycle chain instead.

[Chris Holford]

In article , James Harris writes

Snip I wonder if you could cannibalise an old manual sewing machine?

[Fredxxx]

20 to 30 : 1 reduction is some reduction.

Even an automotive flywheel to starter pinion ratio might be only 10-15 : 1

I would suggest a rethink.

Have you considered a chain and sprockets?

[T i m]

I might not, I might design the ratio I want using a toothed belt drive and print the pulleys on a 3D printer. ;-)

If the big gear ended up bigger than 200mm diameter (as big as I can print on my printer) than I might print it in 4 quadrants and mount them on a common hub?

FWIW, a guy called Cedric Lynch used to hand make smaller rear sprockets for the local lads mopeds from a sheet of nylon and apparently they used to outlast the steel ones?

Along similar lines, I build a fairly large reduction stage on my electric racing bike (moped size). I used a (small) camchain sprocket off a Honda 90 welded to an adaptor I turned on my lathe on the motor to a hand made 1/8" thick dural sprocket. I drilled the holes for the teeth and cut the teeth from a sheet, mounted in place of the bottom gear on a 5 speed cycle sprocket, running on a lay shaft. From there the std cycle chain when back to a 5 speed derailer system. This meant I could manually choose one of the remaining gears on the front block for the particular track and the rear changer for dealing with the course bends / hills etc.

24V PM Motor, small sprocket > big home made gear on layshaft > manual pre-set cycle sprocket block on layshaft > derailer cycle sprocket on rear wheel. Six one hour races, one (lucky) win and not one transmission failure. ;-)

Cheers, T i m

[The Other Mike]

HPC are indeed expensive but for low quantities, off the shelf and delivered in a day or so you won't find it new much cheaper anywhere. Proper engineering costs money. You also know that your choice will probably work if you have sufficient basic data to make an engineering decision.

Of course if you are making it up from something on the junk pile then other than your time the cost is zero.

Without any idea of the torque requirement, speed and lubrication any gearing choice is simply a wild stab in the dark.

[Alan Braggins]

[...]

Or worm gear? These are the right sort of ratio, but I don't know where you would find a more substantial but not too expensive equivalent:

[Steve Walker]

If you go for pulleys, you could get the small one turned up cheaply at a local engineering workshop and get the large one from a scrap washing machine. Good reduction ration, strong bearing, etc. sorted. Usually the pulleys have more grooves than the belts, so you can often fit a slightly wider belt too, being stronger and capable of transmitting the same power with a little less tension.

SteveW