Author Topic: involute cutters  (Read 7628 times)

Offline grayone

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involute cutters
« on: November 30, 2011, 10:43:52 AM »
Can some one explain what the different module number mean  :smart:
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Offline Lew_Merrick_PE

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Re: involute cutters
« Reply #1 on: November 30, 2011, 11:54:29 AM »
Grayone,

Module is the metric equivalent of Diametral Pitch that establishes most aspects of a gear's tooth form.  Diametral Pitch (P(d)) is the number of teeth on a gear divided by the diameter of the gear (P(d) = N/D) with the diameter measured in inches.  The Module (M) is the inverse of the Diametral Pitch, only the diameter is measured in mm -- M = D/N.  A gear of a given Module or Diamteral Pitch having the same Pressure Angle and application form (straight tooth, angled tooth, herringbone tooth, etc.) will mate together and drive properly (assuming the rest of the design is properly matched).

Industry has standardized on specific Modules and Diametral Pitches -- though it is possible to create just about any value of Module or Diametral Pitch which is done in special applications.  If you go to http://www.sdp-si.com/catalogs.htm you will find handbooks that can be downloaded giving you more useful information than is contained in many expensive reference books.

Offline raynerd

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Re: involute cutters
« Reply #2 on: November 30, 2011, 12:48:01 PM »
 A 1 mod gear has 1 tooth for every mm of pitch circle diameter. So a gear of 60mm PCD of mod 1, would have 1 tooth for each mm, i.e 60 teeth. A 0.5 mod gear with 50 teeth, would have a 25mm PCD. (Where PCD is the distance between the gear center and the point of contact with a meshing gear). Hope that also helps.

You will find that things get a little more confusing as depending on the number of teeth on the gear, you need a slightly different cutter profile to mesh correctly. This is why for each module, there is a "set" of 8 cutters to deal with all the wheel counts. So to aquire a complete set of cutters, you not only need the module, but a set of 1-8 cutters for that module!   
Here is an example of a range of Cutters for Involute gear form pinched off the net:

Cutter Number     - Teeth to cut
1              135 teeth to rack
2              55-134
3              35-54
4              26-34
5              21-25
6              17-20
7              14-16
8              12-13

If your interested in cutting clock pinions (which your not as you are specifically mentioning involute and clock cutters take on a cyloidal form) your talking £70-100 per cutter!! So near 600-800 for a complete set .... then the options of all the different modules available...!!!!

Ivan Laws Workshop practice book - Gear and Gear Cutting #17 is amazing when it comes to gearcutting.

Offline Davo J

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Re: involute cutters
« Reply #3 on: December 01, 2011, 03:51:53 AM »
I was browsing ebay the other day and one guy had a lot of clock building type gear and was from China (If I remember right). When I was looking through his shop I noticed a clock gear set for $230, so if your interested I could chase it back up for you.

Dave

Offline raynerd

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Re: involute cutters
« Reply #4 on: December 01, 2011, 05:10:10 AM »
Hi Davo
There are quite a few gear cutters coming from china but no-one  has made any comments on them on the clock making websites/forums. They are also making quite a lot of watch and clockmaking machinary and attachments, some get good reviews and some no so good.

The problem as always, is even if it was a beautiful PP thronton set, if they are pinion cutters then you`d be getting a cracking deal but with the likelyhood that I`d not use some of them in my entire life for a still massive outlay!  If they were the price of involute cutters for a set, I`d perhaps take a punt and slowly build up your collection over the years, but anything cycloidal just seems crazy!! I`d certainly be interested in the link if you have one..?   

Offline Davo J

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Re: involute cutters
« Reply #5 on: December 01, 2011, 10:10:27 AM »
I just went and chased them up and they are watch makers gear sets, not clock. :Doh:
http://www.ebay.com.au/itm/Set-8-Gear-Cutters-SCHAUBLIN-BERGEON-Watch-Lathe-/110770612964?pt=LH_DefaultDomain_0&var=&hash=item5f7877d5b4

Sorry about that

Dave

Offline raynerd

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Re: involute cutters
« Reply #6 on: December 01, 2011, 10:17:01 AM »
Hi Dave
Thanks I have seen those before. They are listed as watchmakers but some of the modules available are quite large for watches so they are really selling a generic clock/watchmaker selection. I`d be interested to see if they would sell a set of wheel cutter in a selection of modules instead of a full set of cutters (inc pinions) in one module.

Chris

Offline Davo J

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Re: involute cutters
« Reply #7 on: December 01, 2011, 01:03:24 PM »
The Chinese seem eager to sell so they might, worth a try anyway. Just send him a list of what cutters you want, as asking him about it might get lost in translation.

Dave

Offline wildman692

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Re: involute cutters
« Reply #8 on: December 19, 2011, 03:46:40 PM »
there are sets of mod cutters from hong kong on ebay for around £90, RDG also sells individual involute cutters from around £21 each (also on ebay.)
I have a box full of hobs, one day I'll get around to building a hobbing machine.