Author Topic: Cutting Skew Bevel gears(again)  (Read 2561 times)

Offline PJPickard

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Cutting Skew Bevel gears(again)
« on: February 14, 2022, 11:09:34 AM »
I've read all I can here and of course Kozo's work. Nearly all start with making your own cutters, including Ivan Laws' book. I get that "do everything" approach...but say you just want to buy a cutter and get on with cutting.
THe general method is to take roughing cuts with a slitting saw then finish with two cuts with the homemade cutter.

If you used a purchased cutter can(should?) you just make the 2 finish passes and skip the roughing?

Thanks!

Offline Craig DeShong

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Re: Cutting Skew Bevel gears(again)
« Reply #1 on: February 14, 2022, 02:58:14 PM »
When I make my bevel gears I use an involute gear cutter and use three passes.  The first is down the center between the two teeth, the next slightly above as described in Ivan’s book, and the last slightly below.  The last two cuts create the parallel depth bevels he describes.  I don’t make these often enough and I usually pull out Ivan’s book and brush up a little first.
Craig
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Offline Don1966

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Re: Cutting Skew Bevel gears(again)
« Reply #2 on: February 14, 2022, 06:52:41 PM »
PJ if you have my gear sheet spreadsheet it explains it on the sheet. Craig is correct with the three passes but if it’s a small gear two passes will work. Just don’t cut the center pass only he offset passes. If you don’t have the gear spreadsheets PM me with your email address and I will send then to you. The sheets covers Kozo method and making the button tool to make cutters toncut your own gears, plus  making a gear hob.

Regards Don

Offline PJPickard

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Re: Cutting Skew Bevel gears(again)
« Reply #3 on: February 14, 2022, 07:49:11 PM »
Don,

I have the Skew Bevel Gear Calc Sheet Kozo Calculations Rev1. Are there others? Also maybe I missed the making a hob part, that sounds interesting for sure!
Nice work on that sheet, BTW!

Offline Don1966

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Re: Cutting Skew Bevel gears(again)
« Reply #4 on: February 15, 2022, 04:32:04 AM »
Don,

I have the Skew Bevel Gear Calc Sheet Kozo Calculations Rev1. Are there others? Also maybe I missed the making a hob part, that sounds interesting for sure!
Nice work on that sheet, BTW!
There are many sheets in the Gear calculation sheets. To big a file to upload to the forum. Send me your email by PM and it’s safe with me will not be shared.

Don

Offline gbritnell

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Re: Cutting Skew Bevel gears(again)
« Reply #5 on: February 15, 2022, 12:25:34 PM »
Skew bevel gears are a whole other exercise.  I made some when I built my replica Ford 9" differential.  With the help of Dave (Steamer) and Don I was able to make them. The don't just use one cutter per tooth but two, one for each side of the tooth. Kozo's article in Live Steam explains making skew bevel gears in depth.  I scanned the information but I can't post it because it belongs to Live Steam magazine.
gbritnell
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Offline Dan Rowe

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Re: Cutting Skew Bevel gears(again)
« Reply #6 on: February 15, 2022, 02:54:48 PM »
George,
 I have Kozo's book and saw that he designed the cutter with two different sides. Did you make a cutter or did you use two different off the shelf gear cutters to make your gears?

Cheers Dan
ShaylocoDan

Offline crueby

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Re: Cutting Skew Bevel gears(again)
« Reply #7 on: February 15, 2022, 03:58:21 PM »
Which one of Kozo's books has the skew bevel gear section?

Offline Dan Rowe

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Re: Cutting Skew Bevel gears(again)
« Reply #8 on: February 15, 2022, 04:44:15 PM »
Chris, Climax locomotives used skew bevel gears.

Cheers Dan
ShaylocoDan

Offline PJPickard

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Re: Cutting Skew Bevel gears(again)
« Reply #9 on: February 16, 2022, 11:13:20 AM »
Those books are now crazy expensive, I have all the Live Steam issues(from number 1 courtesy my dad who got it from the start( but another source is Ed Hume who built a class A Climax and used Kozo's methods. Ed is a funny and good writer, plus an excellent craftsman.
Here is a link to the book he did on the CLimax
https://www.amazon.com/Climax-Class-Steam-Locomotive-Model/dp/1545404895

And here is a link to Ed's photostream on the class A climax which has a lot of good pictures of the process

https://www.flickr.com/photos/edhume3/albums/72157649854075203

Offline gbritnell

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Re: Cutting Skew Bevel gears(again)
« Reply #10 on: February 16, 2022, 11:41:14 AM »
Hi Dan,
I made the cutters from drill rod and hardened them. I didn't make a first pass with a slitting saw bat took several steps with th finish cutter. When I get time today I will post a link to the video I posted on YouTube
gbritnell
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Offline crueby

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Re: Cutting Skew Bevel gears(again)
« Reply #11 on: February 16, 2022, 02:04:23 PM »
Those books are now crazy expensive, I have all the Live Steam issues(from number 1 courtesy my dad who got it from the start( but another source is Ed Hume who built a class A Climax and used Kozo's methods. Ed is a funny and good writer, plus an excellent craftsman.
Here is a link to the book he did on the CLimax
https://www.amazon.com/Climax-Class-Steam-Locomotive-Model/dp/1545404895

And here is a link to Ed's photostream on the class A climax which has a lot of good pictures of the process

https://www.flickr.com/photos/edhume3/albums/72157649854075203
I've seen used copies of Kozo's books going for well over $100 sometimes over $200, which makes no sense, since they are available new direct from the publisher for the same $50 they have been for years.

Offline gbritnell

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Re: Cutting Skew Bevel gears(again)
« Reply #12 on: February 16, 2022, 04:26:05 PM »
Here's some pictures of the cutters I made for the skew bevel gears and one of the finished ring gear
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Offline gbritnell

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Re: Cutting Skew Bevel gears(again)
« Reply #13 on: February 16, 2022, 04:27:48 PM »
Here's a video of the finished ring and pinion gears being test run together.
<a href="https://www.youtube.com/watch?v=fW5wzl9lGaM" target="_blank">http://www.youtube.com/watch?v=fW5wzl9lGaM</a>
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Online Alex

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Re: Cutting Skew Bevel gears(again)
« Reply #14 on: February 16, 2022, 09:51:31 PM »
Very well done!

Offline PJPickard

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Re: Cutting Skew Bevel gears(again)
« Reply #15 on: February 17, 2022, 01:30:31 AM »
Thanks guys, looks good. I think there will be some of these in my near future....along with some regular bevel gears too!

Offline PJPickard

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Re: Cutting Skew Bevel gears(again)
« Reply #16 on: February 26, 2022, 08:40:27 PM »
Reading more and more and also got the book several have recc., Gear Design Simplified.

Dan mentioned that Kozo used 2 different sides on the cutter, but a close reading of Kozo's text shows that his custom cutter was meant to be used to make one cut, then taken off and flipped to do the other cut. A lot of horsing around in my opinion, and in Ed Hume's as well since Ed made a 2 sided cutter and also made his cutters with 8 teeth, a much better cutter in my opinion.

I don't know if any of you follow Clickspring on youtube but he shows a way to get a form relieved cutter here:
<a href="https://www.youtube.com/watch?v=uKroZchwR04" target="_blank">http://www.youtube.com/watch?v=uKroZchwR04</a>
This idea is shown in Malcolm Wild's book on wheel and pinion cutting too. I'm sure it originated before that. Other ways to get the relief have been shown as well, one in the Levin book, where you drill holes, the saw cuts, then bend the teeth to achieve the relief. In fact this is how Kozo makes his cutter, but with less teeth.

And then there is the Eureka tool shown in Laws' book:

<a href="https://www.youtube.com/watch?v=F_w92CEMlT4" target="_blank">http://www.youtube.com/watch?v=F_w92CEMlT4</a>

So...back to my original question, which centered on NOT making your own cutter but selecting a commercial one for cutting Skew gears and the Law book has a special diagram(others have noted this) on how to calculate this for bevel gears. In general the chosen cutter used is one that would correspond to larger diameter regular spur gear.

Lastly...as Dan is doing, a 3D printed gear is an option. What this would allow is the "true" form of a bevel gear. This has some appeal...Build it in CAD, print it and make an investment casting.

Just wanted to post this in the interest of being "complete"!

Thanks all.

 

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