machining a synchronous belt sprocket

ewaring · Oct 17, 2011

Hi Everybody
I need to make a synchronous belt sprocket 14mm pitch . A formed cutter would be nice and I can get one ground but the cost to use ratio is hard to justify.
Can the operation be done using a fly cutter with a square HSS toolbit ground to profile and get a good job. This question does not include ability or equipment. The job needs to be spot on so I don't damage the belt.
I am making a drive reduction for a bush buggy that will be used in the middle of nowhere (HEARST , ONTARIO) where a guy doen't need to get stranded and leave his machine.
Thanks ED
PS I'm cheap because it is amazing how these projects add up quickly to the point where a used machine would be cheaper.

bcstractor · Oct 17, 2011

Some of the profiles are proprietary and vary with PCD. If you don't get them right the belt, particularly with high loadings, will climb and may cause damage if there are any weak links. Can you not just buy a "rim" and then modify the hub?

What's the profile and number of teeth?

Chris P

Mud · Oct 17, 2011

Can the operation be done using a fly cutter with a square HSS toolbit ground to profile and get a good job. This question does not include ability or equipment.

Yes. But... You need to get the geometry of the cutter perfect.

Armenius · Oct 17, 2011

Yes it can be done.

Your success will depend on how accurately you can grind the form tool to replicate the required tooth space. To do this successfully you need a drawing of the tooth profile of the belt.

My son did exactly this. He used a timing belt from a Tercel to run a supercharger in his car. He hand-ground a fly-cutter tool from 1/4" HSS blank and machined the toothed pulley in a horizontal mill using a dividing head.

The estimated transmitted power was about 20 HP at 8000 RPM or so. And the belt survived! No shredding or tearing at all.

BTW if you are going into the back woods of northern Ontario using this drive it would be worthwhile to carry a spare belt or two!

Arminius

ewaring · Oct 17, 2011

synchronous belt question

thanks for the responses. I think I'll get a cutter ground .On a second thought it would probably be the least expensive way to go now I looked at the cost of the belts. Thanks ED

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