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Involute cutter

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Peter Simpson 320/07/2023 17:39:44
122 forum posts
2 photos

I have been asked to produce some small gear wheels.

The dimension of the sample is as follows.

Diameter across the teeth.......0.467"

Approx PCD.......................0.400"

Number of teeth ...............14.

Using my limited knowledge of gear cutting. I work out the cutter would be

36 DP number 7 cutter to be the cutter required. Could anybody confirm my calculations ?

Pete Rimmer20/07/2023 18:03:55
1486 forum posts
105 photos

Hi Peter,

The figures could indeed indicate a 36DP gear. They do not align exactly with the traditional calculation of (n+2)/OD nor to the long-addendum adjustment factor od OD x 1.122 for hobbing a 14 tooth 36DP gear.

Do you have access to the same measurement figures for the mating gear?

EDIT: actually a 14 tooth gear of .400" PCD works out exactly 35DP.

 

Edited By Pete Rimmer on 20/07/2023 18:16:42

Peter Simpson 320/07/2023 18:29:07
122 forum posts
2 photos

I only have the single gear to work with. I cannot see any 35DP cutters so I will give the 36DP number 7 a try.

Pete Rimmer20/07/2023 18:34:09
1486 forum posts
105 photos

I have a 35DP hob in 20PA

OD for 35DP 14 tooth is 0.467" (non-modified addendum) only 10 thou smaller your measurement. 36DP is 0.444, 23 thou smaller.

JasonB20/07/2023 18:50:15
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25215 forum posts
3105 photos
1 articles

It's not far off 0.75MOD

DC31k20/07/2023 18:53:22
1186 forum posts
11 photos
Posted by Peter Simpson 3 on 20/07/2023 18:29:07:

I only have the single gear to work with.

Do you have any information on what the gear meshes with? Even if it is two identical ones meshing, the shaft centres will help confirm the PCD.

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