# Making a spur gear for the Webster



## deere_x475guy (Feb 11, 2008)

Hi everyone...it's me again.

No heart feelings to the purists in the group but I once again used Marv's programs to help me figure the OD of the gear I needed and dividing plate I needed. I don't use this math enough to remember it, plain and simple. And the way my memory is anymore even if I used it once a week I would probably forget it. So the fastest way for me to solve this math is to open the folder I have on my desk top, select the program I want to run and punch in the numbers. If you don't have Marv's programs the calculation for the gear OD can be found with a search on the net as can the math for the dividing plate to use. I am using an involute gear cutter with a dividing head. As others have posted here you can make your own cutter and I think you can probably use a rotary table in place of the dividing head. If you know of other ways to do this please feel free to post to this thread if you want to. This is a place for all of us to share our knowledge and our projects. Please keep these two quotes in mind when your posting..



> _When someone throws an idea in the fire and it flairs into something more
> that can teach an old dog like me a new trick, I see it as a positive event._


Borrowed from a post Rick placed
And:



> _Each of us has a favorite method but that is not license to denigrate other ways to do the job._


Borrowed from a post Marv placed

Now..on with the pics.. ;D
First is a screen shot of the gear diameter results from Marv's "GearSpur" program.
I entered zero for the diameter (cause that was the unknown) ;D, 13 for the number of teeth and 20 for the DP because that is the DP of the cutter I have. As you can see the OD is .75, also the whole depth is .110. This means I will cut .110 deep for each tooth. There is also a lot of other info in there but I want to get this posted sometime this evening ;D so if you want to know what the other numbers mean just ask me... ;D ;D







Next I wanted to find out what plate to use in the dividing head. Mine came with 3 different plates.
I told the program I wanted 13 divisions. The results showed to use a 39 hole plate and doing 3 full cranks plus 3 holes. I have added a video that will show using the dividing head. Hopefully you will be able to see the sector arms being used to help me keep track of the 3 holes I need to go after the 3 full turns.







[youtube=425,350]http://www.youtube.com/v/2SCHS-sUA24&rel=1http://www.youtube.com/v/2SCHS-sUA24&rel=1[/youtube]

Here is a shot of the gear blank mounted in the arbor. I was conservative with the depth of each cut and only took around .025 per pass.






Here is the finished gear. It is going to run with one I made about 2 years ago when I was learning how to do this.






All normal disclaimers apply


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## Bernd (Feb 12, 2008)

Nice job on those gears Bob. I remember back in High school shop class we learned to make gears. I was fasicnated by the process. I just which those darn cutters were'nt so expensive. Kozo has a great write up on how to make your own in one of his engine books. I may try that. But I also need an indexing head.

Keep up the great work.

Bernd


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## deere_x475guy (Feb 13, 2008)

Bernd, thanks for the kind words. I really enjoy sharing my progress on my projects. The cutters are expensive but you can make your own single point cutter that actually work pretty well. If you have a rotary table you can sometimes pick up dividing plates and avoid the expense of the dividing head. Marv's program allows for changing the parameters of the numbers on your dividing plates available and change what the worm gear ratio. I think most rotary tables are 90:1. I know mine is and my dividing head is 40:1.

This is where I got my dividing head:
http://cgi.ebay.com/BS-0-DIVIDING-H...41943QQcmdZViewItemQQ_trksidZp1742.m153.l1262

He also has rotary tables and dividing plates. I have bought some stuff from him and have been happy with everything.

Here is a link to a site I used when I was trying to find out about dividing head and how to use them.

http://www.atmsite.org/contrib/JSAPP/divide/divhead.html
He does a pretty good job of explaining the math also.

If you would like to browse though a manual for a dividing head here is a link to Steve Bedair's page:
http://www.bedair.org/Divide/Divide.html


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## Bernd (Feb 13, 2008)

Thanks for the links Bob. I think for the occaional gear that I'd cut the single point cutter would do nicely. I'm going to have get Kozo's book out and look at how he did it.

Bernd


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