CNC Plasma Cutting Sprockets.

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Ryley

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I have a CNC plasma cutter and I want to try to cut my own assortment of sprockets for testing. The motorcycle engine that Im using has a 530H sprocket from a motorcycle. I need help collecting dimensional and metallurgic information. Or can someone tell me where to buy a #530 compatible sprocket with around 25T?:huh:

i have found a online program to make sprockets. use it here.

A little more digging and i came to a conclusion. Plasma is not accurate enough to do something like this. I will need to get it laser cut and then taper, harden and temper the teeth. This is going to take a while.

maybe i can figure out another route
 

itsid

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dimensional is easy since the program you linked exports a dxf where you can read the dimensional infos from with about any CAD program there is..
(since you have a CNC cutter, some sort of CAD / CAM should be familiar to you)

And while you can read the info from GCode as well, dxf is the easier one IMHO ;)

Now metallurgical is a different question, since there is no strict rule to what a sprocket should be made of
common motorcycle sprockets (JTsprockets) can be
7075-T6 aluminium
SCM420 chromoly steel
and C49 steel
as well as about everything in between
depending on what task is at hand

Material thickness is fixed however (9.5mm or so to fit the 530 chain nicely.. 3/8" minus some clearance)

'sid
 

itsid

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Shouldn't the sprockets be hardened??? They might not last long.....

not necessarily... many prefere "soft" sprockets
so the sprocket wears before the chain does too much
you rather hava a chain jumping than whipping you ;)
front sprocket is hardest then depending on preference either the chain then rear sprocket or the other way around)
in an ideal world all three wear at the same rate (not possible)

also hardened sounds untempered..
wedged in debris could crack the brittle sprocket open quite easily then..
heat treated to proper hardness yes..
what's proper is up to decide upon the task and personal preference.

'sid
 

Ryley

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Thank you all for your replies. So I have a family friend that is letting me use their laser cutter so that solves my accuracy and cleanup problem. It also turns out that Solidworks has an accurate sprocket generator so I can export a dxf of it to the laser cutter.

Sid, you said that I should use 9.5mm to allow for clearance. This seems reasonable but I will need to taper the teeth anyways with a grinder on the lathe so I believe I can use whatever 3/8" steel I have laying around.

As far as hardening goes, the "H" in 530H, stands for hard but I'm not sure if its referring to the chain or the sprocket or both. So what I will do is make 4 sprockets, one with 22T and 2 with 25T and one with 27T. I will test the gokart with one of the 25T sprocket and check how it wears then I will harden if it's necessary.
 

itsid

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As far as hardening goes, the "H" in 530H, stands for hard
NO, no it does NOT!!!

it stands for "heavy duty"
(and has about 5-7% higher average tensile strength)
usually because of the sideplates being 1/32" thicker [1/64" each]
(some mfgs use different pin material as well.. a thicker pin would be "F")

noone uses different heat treatment making the same material "harder" as far as I know.

And chain nomenclature ONLY tells you about the chain.
(no matter if 530, 530H, 530SO, 530HO 530FHO, 530FSX, 530FHX or some fancy 530ZVM-X [D.I.D. rules ;)])

never about the sprocket (well apart from what size chain it should fit of course ;))

sure, 3/8" and sanding it down afterwards to clear the chain inner dimension is fine.
keep in mind that we do not talk about chamfering though.. all teeth and a bit of the meat below has to clear the chain plates.

I read on another page that ideal sprocket thickness for a 530 chain would be 8.7 mm or 0.343"
*shrugs*
IDK will go and measure my rar sprocket later and see what it says ;)

[EDIT]
oops sorry.. just checked I run 525 chain that's narrower than 530 anyways, no point in measuring my sprocket I'm afraid

'sid
 
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Bansil

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I'm not a huge fan of plasma tablets for cutting metal. The molten steel left behind on the finished product is pretty hard and clean up of it sucks. 26 tooth is the smallest that I can find quickly that's not for the engine side. http://www.rebelgears.com/sprockets/chainsizes.html

If your machine is setup correctly, cut HT, air pressure, feed and amps, up to 1/4 should cleanup easy with minimal dross with a wire wheel or da sander.
 

anickode

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No reason it shouldn't work with a decent machine.

Sprockets are generally slightly bevelled on the sides of the teeth, so some delicate grinding or chucking it in a lathe would probably be a good idea.
 
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