Gear Hob cutter:

[ErichKeane]

Hi all-
I want to start out with a gear hob cutter for my hobber that will cut everything FOR the machine itself. The only gear I have right now is the worm gear: https://www.mcmaster.com/catalog/128/1255/

That lists a "Gear Pitch" of 12, PA of 14.5, Gear Pitch Diameter of 1", and OD of 1.17". I have no idea how to convert that to DP though!

Anyone have an idea? Also, perhaps an inexpensive one to get started? Figuring 2" MAX diameter is all this machine could handle. I saw another article for a similar device that claimed it was 20 DP, but I don't know if it used the same worm.

 

[benmychree]

It looks to me that the worm and worm gears listed are diametral pitch rather than circular pitch. Although CP worms and gears are also common, especially in the past.

 

[Chewy]

Go here first: https://issuu.com/deoc4114/docs/modern_methods_of_gear_manufacture_4th_edition

I have about 50 articles stored on the computer about making gears and measuring them. If this article doesn't have the answer you need. I will look at some others and post a link. If you Google gear cutting or gear making you will find so many answers your head will swim.

 

[ErichKeane]

Go here first: https://issuu.com/deoc4114/docs/modern_methods_of_gear_manufacture_4th_edition

I have about 50 articles stored on the computer about making gears and measuring them. If this article doesn't have the answer you need. I will look at some others and post a link. If you Google gear cutting or gear making you will find so many answers your head will swim.

The head swimming is part of the problem haha. I found all the calculations for normal gears, but can't seem to find anything for worm gears! Or even if my question makes sense (do worm gears have dp/module?).

I'll check out the link though, thanks!

 

[Chewy]

Go here, Way down at the bottom. This all math so I hope you can do it. Once you have figured out what you have, you can use the charts or contact a manufacturer to see what is matching.

https://khkgears.net/new/gear_knowledge/gear_technical_reference/calculation_gear_dimensions.html

 

[ErichKeane]

I still cat make heads or tails out of that math :/ BUT I Think I actually don't need to! There is only 1 gear that meshes with the worm-gear, and I have a McMaster part number for one... Otherwise I can just choose a common Hob cutter I think, probably something in about the 'normal' gear sizes, as long as they are consistent with eachother!

 

[Chewy]

Good Luck! Somewhere I read that a worm gear is figured out the way a rack is cut. Don't know. I would have gotten in contact with Boston Gear or one of the other company's and got a matching set.