Sprocket cutting success?

1

Hello,
Has anyone had success cutting out a functional sprocket?

Circumstance:
-using #40 chain
-generated drawing from sprocketeer
-rhino>sheetcam>mach3
-would like to use 70 teeth or around that amount.
-cut outs are looking good but chain is not falling into the whole circumference
-ive spent time tuning bearings and adjusting xy table to square. cut out a square and measures square
-do not have a THC
-using hypertherm 45xp
-have tried this using 1/8" and 16 gauge, 3 times each, all do not gear in properly

I would upload a picture but “new users cant upload”<?

Any insight would be awesome.
Thanks Forum!

2

If the sprockets are too tight, ie, the outside contour is a tad smaller than the design goal, I would increase your kerf setting in SheetCam (assuming you are doing outside offset cuts and your ‘reverse direction’ checkbox is checked.

Increasing the kerf will cause SheetCam to move the torch further from the ideal cut line by half the change.

On the other hand, if the outside dimension is larger than design goal and the teeth are too fat, then decrease the kerf.
Tom

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3

Wow thanks for the speedy reply TOM!

Going to go check this out now…

4

I use this program to create sprockets out of 3/16 for my son’s go kart and 4 wheeler. Like Tom said, the kerf has to be right on so the chain fits with out bunching up or riding up the teeth and being “out of phase”. I use a new section of chain and wrap it all the way around the sprockets I cut to make sure they’re right.

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5

Thanks for the encouragement.
I attached a snap shot and a dxf showing todays work.

I was able to get the contour outline where i wanted post cutting.

Spent time tweaking the CAD geometry and adjusting SheetCAM operations but its still no go.

I was advised to try using an old used chain because a new chain would be less forgiving.

Maybe its the chain itself?

SPROCKET_JAM.dxf (550.9 KB)

62329668686__8CDE8CDD-8B58-432E-8EA7-A9667759646F
62329668686__8CDE8CDD-8B58-432E-8EA7-A9667759646F3024×3024 2.63 MB

6

A used chain is wore out that’s why you need to use a new chain because the pitch is obviously correct, that way the new chain and new sprocket wear in together. If you use an old chain as the go gauge your literally cutting the sprocket to fit the pitch of the used chain. Which is an unknown pitch. The valley or roller pocket is more important than the outer diameter. You will have to lay your chain on it and run it all the way around to find out if the minimum diameter of the sprocket is too big or too small by the way the chain starts to mismatch on the teeth. If you can post a close up picture of how the chain is not fitting I could figure out which way you need to go on your kerf size. Oh and you need to make sure your machine actually cuts round circles. The sprocket generator I posted makes it super easy. Once you generate your sprocket only thing left is kerf adjustment.

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