# Cutting Roller Chain Sprocket teeth



## Kamloopsendo (Sep 5, 2019)

Not sure this is the correct forum but if not maybe someone could direct me?  I'm trying to make a sprocket for a late 60's Yamaha 350 and need to cut the teeth.  Does someone know if there are cutters readily available to do this?  I have considered getting a new sprocket with the correct number of teeth and chain size and cutting the tooth ring off and welding it onto the hub of the old sprocket (after turning off the teeth) but would like to try making a new one from scratch.
Any thoughts are appreciated.
Thanks gang.
Alex


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## Latinrascalrg1 (Sep 5, 2019)

Im sure you could probably find a premade cutting tool for your needs but im thinking it depends on how you intend to do the cutting based on what your toolbox arsenal looks like I.E. lathe, mill, drillpress, rotary table etc.

I think maybe the easiest way would be to temporarily bolt or tack weld the old sprocket to the new blank and using a rotary table on a mill side cut each tooth using the worn part as the guide. Finding a side cutting endmill the same size as the sproket rollers should be much easier to find and cheaper to buy!


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## Ulma Doctor (Sep 5, 2019)

you will need to determine whether the sprocket is a metric pitch or an imperial pitch.
my guess is metric
yes, there are metric endmills that can give you the necessary pitch provided the d.o.c. is to the correct dimension
metric 08B chain sprockets may be very close


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## cathead (Sep 5, 2019)

Alex,

I would use a rotary table on a vertical mill using an end mill for cutting the teeth.  Getting the chain to fit the sprocket
may require a bit of fine tuning and fitment.  One would need to calculate the angular movement needed to produce the
desired number of teeth.  If I remember correctly, the tips of motorcycle sprockets are narrowed for smoother operation
(at least on the driven sprocket).


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## C-Bag (Sep 5, 2019)

cathead said:


> Alex,
> 
> I would use a rotary table on a vertical mill using an end mill for cutting the teeth.  Getting the chain to fit the sprocket
> may require a bit of fine tuning and fitment.  One would need to calculate the angular movement needed to produce the
> ...


There used to be a great blog where a guy made his own crank sets for his recumbent trikes and he went through in detail about how he did it. He was very into huge chain rings that nobody made. The blog dissapeared a couple of years ago unfortunately and I mostly just looked at the pictures of the setups not how he got his dimensions because is was more interested in other things. But he did it mostly on a vert mill with a rotary table. It is very precise work and like has mentioned you could possibly get your spacing from a used sprocket but you have to be careful to use the backside or non drive side of the sprocket because the drive direction is going to be worn. 

He just used an end mill of the proper size and did holes first then the lead and trailing tooth angles and did the tooth side angles last. And if I was going to get a new sprocket I'd not want to weld it on for fear it would mess up the case hardening as that's very crucial to the longevity of the sprocket. I'm sure I'm leaving a lot out because that was not my focus at the time.


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## Eddyde (Sep 5, 2019)

Here is a Youtube video showing a primitive but apparently functional method of making sprockets.


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## royesses (Sep 5, 2019)

Interested in this so I did a search on eBay and came up with is:








						INVOLUTE ROLLER CHAIN SPROCKET GEAR CUTTER UNION TWIST DRILL   USA NEW  | eBay
					

Marked 1/2 Pitch. 313 Roll 12-17 tooth 1.0 Bore cutter. Looks new and sharp.



					www.ebay.com
				




I only checked on that one but there were others available. Looks like it works with a standard gear cutter arbor. Thanx for bringing this up. I need to pick up one or two of these for a project.

Roy


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## Kamloopsendo (Sep 5, 2019)

Thanks for the responses guys, I have sourced a cutter to fabricate this sprocket.  Couple of sources, one is on E-Bay and out of China so quality is just a bit suspect, the other is north american high end from Ash Gear and Supply.  
Both will cut an accurate sprocket with correct involute tooth shape. 
Roy, that's a great cutter deal but I need 5/8" pitch not 1/2",  I'm in no rush so may just keep looking.
Alex


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## Bob Korves (Sep 5, 2019)

It appears that making sprockets is a lot like making gears.  Another option is to buy a sprocket blank with the correct pitch and tooth count, and then make it fit your project or make your project fit it.  A sprocket blank is probably less expensive than a sprocket tooth cutter, and there would be much less chance for messing up the job.  On the other hand, if you may end up playing with different gear ratios, then buying the cutter might make more (monetary) sense.


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## Kamloopsendo (Sep 5, 2019)

Bob, I went thru the same mental gymnastics as I would like to make a couple of different size sprockets for the rear wheel.  No question turning a blank and cutting it to fit would be simpler and cheaper than buying a cutter and milling it myself.  Not sure which way I'll go as if the correct sprocket turned up on E-Bay or elsewhere I think I'd be lazy and cheap and simply buy it!  (sloth will win out sometimes)


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## benmychree (Sep 5, 2019)

Sprocket cutters are the same situation as gear cutters, so far as numbers of teeth are concerned; there is  whole set of them for various numbers of teeth.


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## Kamloopsendo (Sep 5, 2019)

Yes, I'm aware of that but since I'm looking for 35 to 45 tooth sprockets in a 5/8" pitch I only need the one cutter.


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## MontanaLon (Sep 5, 2019)

You should be able to find a sprocket meant for a weld on hub. Just find one and weld or bolt it to the existing hub.


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## John O (Sep 7, 2019)

I just made a blank and got someone with a cnc mill to do the cogs(teeth)


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## savarin (Sep 8, 2019)

heres a simple program I've used in the past for sprockets, tedious but works well.




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						MozBike.com: Giles' programs
					





					moz.geek.nz
				



The tube mitre program ia also a goodie

This may be of assistance as well




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						ChainringGen / making a chainring with open source software | Nothing Labs
					





					www.nothinglabs.com


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## Kamloopsendo (Sep 12, 2019)

I'm still trying to locate the correct sprocket online, E-Bay etc but if push comes to shove I think I'll buy a tooth cutter for the size of sprockets I need and mill it out of 7075 aluminum (530 chain on this motorcycle) and my mill is a manual Bridgeport clone and that is basically what will be used (although might use the Lathe for some parts of it).  
7075 comes in a couple of forms and I'm wondering if there is much difference in machinability between T6 and T651, both of which seem to offer the best properties for what I want in a bike sprocket and are (I hope) faster and easier to machine that steel.  Any thoughts or experience out there with these alloys.


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## Denisj (Dec 31, 2019)

I regularly have to source rare sprockets. PBI and Rebel Gears have never let me down. 
They had the spec for a first year Kawasaki that only a dozen were made. I love making parts, but sometimes its really just for the exercise.


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## Kamloopsendo (Jan 1, 2020)

Well, we found a sprocket, turns out the later series of 350 Yamaha street bikes used the identical mounting and bolt pattern just a different pattern in the lightening holes so I left it.   I'll check out those guys if I'm stuck in the future, cheaper and simpler than producing my own.  Piece of T6 aluminum was going to cost me $65 (Canadian) just to make one sprocket.


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## markba633csi (Jan 5, 2020)

Having owned a couple bikes I know that they are hard on chains and sprockets-  probably best to stay with steel anyhow


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