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Samuel
05-11-2004, 04:39 AM
due to the high cost of new and my inability to scrounge what I need, I was sitting there thinking( dangerous... I know) and I thought, what the heck, why cant I just turn a blank on the lathe, then torch cut and grind the tooth profile, using some sort of jig, and a die grinder? on larger chain it cant be that hard, can it? this is for some # 60 roller chain and the rpm is no greater than 100. what do you think? is there some sort of obvious source for sprockets that I never thought of?

thanks

Samuel

winchman
05-11-2004, 05:55 AM
Hubless Plain Bore Steel Sprockets for #60 chain listed on page 922 of the McMaster-Carr catalog don't look all that expensive. They average a little on either side of a dollar per tooth. http://www.mcmaster.com/

The other vendors probably have similar items.

Roger

SGW
05-11-2004, 06:08 AM
Machinery's Handbook has the specs for the tooth profile, I think. I'd probably do the machining on a rotary table. As long as the application isn't life-threatening if the thing fails, I suppose you wouldn't lose anything if it didn't work, except some time.

I question the durability though, unless you plan to have it hardened after you make it, and if you have that done (I question the success of trying to harden something like that at home), you're not going to save much money.

metal mite
05-11-2004, 07:10 AM
I have cut some sprockets on the cnc.
The profiles have to be pretty accurate for the chain to run smoothly over them.
Drawing with Mastercam, or cad will show the relationship of the tooth profile and root of the tooth, and the chain as it moves around.
I had to use the root of a tooth two teeth away to form the tooth profile radius.
The gully on the other side of the tooth does not give chain clearance and left much fileing and grinding.
Good luck.

mite

Some steel warehouses may be able to torch cut these on cnc for you.
I have heard of real traction engine gears replaced with torch cut and ground gears.

John Stevenson
05-11-2004, 07:31 AM
Rough and ready way for sprockets is to work the pitch diameter out from the tables in machinery handbook, P 2427 in the last edition.
Draw a circle this diameter on an oversize blank with calipers, mark off the number of teeth and centre pop. For a #60 chain which is 3/4" pitch the roller diameter is 0.469" so on every pop mark drill a 15/32" hole. Turn on the lathe to the OD, also in the same table and then hacksaw, file, grind or mill the surplus from the widest part of the hole to the tip.

Hardening is up to you but all blank sprockets like from McMasterCar come in the soft form.
Most also run in the soft form and last well in a lubricated condition.
Racing sprockets on motorcycles are often in aluminium and last a reasonable while so hardening isn't always nessesary.

Update, just read Mites post.
Have a look at a program called Machinists Mate from http://www.wadeproco.com
This can write the code for one tooth form direct to your CAD system.

As well as this it will give you the pitch and outside diameters for you to set out to without having to revert to the very complex drawings in Machinery Handbook.
It's $15 to register this and well worth it for what it contains, Usual 30 day free download, no association but when I saw what it did for sprockets I paid up in a heartbeat

John S.

[This message has been edited by John Stevenson (edited 05-11-2004).]

torker
05-11-2004, 07:54 AM
I just bought two 14T #60 from Kaman bearing up here for $20 Cnd. About $15US. Turned a hub for them and made up a twin row sprocket. Saved about $85 over the cost of a pre made one. Doesn't seem worth making my own plates for that.

dsergison
05-11-2004, 08:36 AM
A farm supply store typically has a lot of sprockets in stock.

maybe one you can use?

YoheShop
05-11-2004, 09:45 AM
Try the < http://www.surpluscenter.com >.

Herb

wierdscience
05-11-2004, 10:26 PM
Sprockets especially the type "a" sprockets are dirt cheap,I order them in every size from 25-#200 they can be cut,machined,welded you name it and can even be ordered with induction hardened teeth.Martin Sprocket is my favorite source,you can get then throuh Kamaan and Applied Industrial Tech. I bought some 15 tooth #80's the otherday for $11.00 each,could have had then hardened for $8.00 extra,hardly worth the effort,unless you are bored.

Samuel
05-11-2004, 10:50 PM
thanks guys, apon closer inspection I guess my logic has flaws. thanks, I was just looking for some larger sprockets, like say an 11 tooth that went to a 50 tooth or something, some great Ideas on how to approach the process. I guess I am not that broke so I will just keep collecting cans untill I get enough for some "real" sprockets.

Samuel