Imported Involute Gear Cutter Sets

So if I were to ignore the cutter's series #, and just abide by the diametric pitch range they should cut, I'd be safe? Or did they screw up that tooth count too?
 
Why would you want to ignore the series numbers? They are correct as I posted them. If you pick up a #3 and it says 35 to 54 teeth you have a pressure angle, usually 14.5,* (English) cutter. If you pick up a #3 cutter and it says 17 to 20 teeth you have a module (metric) cutter. They numbered them that way so you would not make the mistake.

Diametral pitch, is the number of teeth divided by the pitch diameter. It changes from gear size to gear size. A guess on my part would say yes you can, but I would rather use the numbering system. Just my opinion.

There are only two commonly used pressure angles, one is 14.5* the other is 20* with 14.5* being the most common.

"Billy G"
 
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Thanks gents, interesting thread because... I'm looking for inexpensive 16 dp 20* pa gear cutters, here in the UK I can find 20* module and 16 dp 14.5*, but not what I'm looking for... I'd be delighted if anyone can point me in the right direction!

Dave H. (the other one)
 
English is Pitch Angle. Metric is Module. They are two completely different animals.

Not really completely different - just different units measuring the same basic quantity, like feet vs metres.

Module = 24.5/DP

so as I understand it a 20 DP gear cutter would be identical to a Module 1.225 cutter of the same pressure angle (if you could get one).

Now by convention there are certain DPs and Module (and pressure angles) that are in common use, and in that regard the normally available imperial/DP cutters and the metric/Module cutters are different.
 
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The bottom line -- we were trying to find out why the cutters are numbered backwards, we succeeded. By renumbering the cutters the way they did, they have differentiated between Metric and English.

"Billy G"
 
Sorry. Re-reading your previous post cleared up my question. So, they were NOT numbered incorrectly, but still, the method of differentiating Metric from English was still nebulous enough to bite a few people. Thanks for bringing that to our attention.
 
Thanks Bill. I almost screwed up and order a metric set. You saved me some grief.
 
I am just a newbe at this so I could be way off base here. Involute gear cutters interest me because I need to make some gears for my projects. I plan on buying a set of involute gear cutters.
After reading all the posts and then researching the difference between DP (imperial) and MODULE (metric) I don't think that you can be as simplistic as just looking at the numbering sequence. In the perfect world DP No.1 is 135 and MODULE No.1 is 12-13. Based on my research not everybody follows this convention. I found a company in Australia that numbers both DP and MODULE with No. 1 being 135. http://www.millerstooling.com.au/Cutting-Tools-Gearcutters-and-Hobs.asp. And after reviewing a dozen or so EBay listing it appears that all involute gear cutters from China and some Eastern European countries, whether DP or MODULE, No.1 is always 12-13. Based on this I think that you really need to go by what is marked on the actual cutter and not whether it is a No. 1 or No. 5 or whatever cutter. That is what I intend to do.
 
Your thinking is no different than any here. All we are saying is do not cut one gear DP and the meshing gear Module. This will cause problems. It's that simple.
The numbering system of that Australian Company is awesome. They mark them either DP or M and use the same order. They are the first I have seen do this. Kudos to them.

"Billy G"
 
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Hi Billy,
All of the gears that I saw were marked with No., DP, pressure angle and tooth range or No., Module, pressure angle and tooth range. I didn't see anything with just the number and tooth range. When I get around to buying I will go by DP and pressure angle.
Chuck
 
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