Gear Hobbing Differential Math with Proof of Concept Test

[@sky173]

'The Rabbit Hole' would be a perfect name for the channel. I'm learning about gear cutting myself and feel the same way. Thanks for sharing your content. Great stuff..

[@thomasstover6272]

Gear making is a kind of gateway drug! Have fun!

[@peternedsmith]

Thomas, I always knew there should be more uses for a differential than in the rear of a car, love it.

[@johnhowell2339]

Hi Tom, thanks for the heads up. I seen your video the day you posted it, but I wanted to go over the math and make sure I understood it, which I did. I also wanted to look at the Lego video. I did a search on the internet today looking for any new information on cutting prime gears and only found a discussion on a magazine web site which talked about a home hobbing machine which could use a differential to cut prime number gears. There was not much information on its use. If you could, in your next video would you show your spindle input and your output to the gear blank. I am a little unclear about this part of your design. Thank you for going into this subject with so much good detail.

[@lawmate]

Thanks for the explanation. I haven't ever seen a differential being used like this

[@kennyrmurray]

The math was my hard part to learn. I had my daughter help me and I think at the time she was 14 or 15 lol. I haven’t actually made a gear in a while so it would be like starting over but I love using my dividing head. Right now as I watch your videos I am running my tool post grinder on my shars live center attachments. It’s a 5 piece set and not one of them run true. They’re from .002” - .003” out which is a lot in my book!

[@thomasstover6272]

I have a shars set….i think I’ll check them out!

[@kennyrmurray]

@@thomasstover6272 I’d like to know if it’s only me. Let me know what you find out. My set is MT3 202-3543

[@greglaroche1753]

Thanks.

[@DudleyToolwright]

Ah, you're a lefty. I like you already.

[@thomasstover6272]

👍We’re going to rule the world someday!

[@timogross8191]

0:45 yes! Channels I have found so far LSCAD, Evolvent Design, Andy Pugh and Andy Machines, Tom*s Rabbit hole ......

[@alishihade4751]

Thanks for this good tutorial ,but I dont understand Km=90 is for what can you show us it between what and what, its so confusing without knowing Km is for what

[@thomasstover6272]

The ratio between the hob and the gear blank (overall) is 1/Z, where Z is the number of teeth you are trying to cut…so the hob must rotate Z times for every revolution of the blank. In every machine there is a fixed ratio of input revolutions that is required to produce 1 revolution of the gear blank; this is the machine constant, which I have called Km. In my case, I’m using a standard rotary table, which has a 90:1 ratio…it takes 90 revolutions of the input to produce 1 rev of the blank. In general, no matter the machine constant, you have to produce Km revolutions at the output of the index train to get 1 rev of the blank. Therefore, the index train ratio is Km/Z…in my case that’s 90/Z. I appreciate the question, and I hope this helps!

[@aldoblasigh7533]

Could you use a land rover differential from the transfer case it looks smaller than your one

[@thomasstover6272]

Maybe. It would depend on how complicated the adaptation would be…but clever designers usually find a way!

[@premprakasam911]

What is the purpose of this differential unit

[@thomasstover6272]

It allows me to take advantage of the mathematics of differentials to make prime number gears, which can’t be made under normal gearing rules unless you already have that gear number or a multiple. I go through the math in another video. Thanks for watching!

[@jimsvideos7201]

🤯