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Involute, Circular Gear-Cutter on Eccentric Arbor...

Gear Cutting

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Andre ROUSSEAU16/01/2019 03:20:04
15 forum posts

I am trying to find a comprehensive online web resource giving a full technical description of an (effectively) single-tooth, circular fly-cutter for cutting involute gears using an eccentric arbor. This seems to be a little-known method and is most intriguing. An excellent demonstration of this approach is shown on "myfordboy" YouTube video:- https://www.youtube.com/watch?v=7zMgJXMHcNs

The obvious advatages are the superior strength of the resulting cutter compared with a conventional straight shank HSS cutter and the avoidance of back clearance facets through the cunning eccentric mounting...

.... neat idea!

 

Edited By JasonB on 16/01/2019 07:28:55

Mike Crossfield16/01/2019 09:13:45
190 forum posts
17 photos

Andre

The method you describe is actually well established. I have used it a few times with good results. I use a similar method to make clock wheel and pinion cutters, though instead of using an offset arbor I turn the profile on the end of a bar of silver steel, then offset in the 4 jaw chuck before drilling the centre hole and parting off. Incidentally, it isn’t essential to make the two button tool. You can make a tool with a single button and cut the sides of the profile one at a time. You can also use an end mill of the right diameter to cut the profile - Graham Meek uses this method with excellent results.

I would recommend buying Ivan Law’s excellent little book on Gears and Gear Cutting, which describes the method for involute cutters. It’s in the Workshop Practice series, and inexpensive.

John Haine16/01/2019 09:27:19
2577 forum posts
133 photos

There's a refinement of the technique, which may be covered in Law's book, that can generate multi tooth cutters. My album **LINK** shows the manufacture of a cutter, using CNC to shape the profile but could also use buttons. An easily made machining fixture is needed. Also worth looking at Mike's Workshop site for info on designing and making cutters. **LINK**

John Haine16/01/2019 09:27:20
2577 forum posts
133 photos

There's a refinement of the technique, which may be covered in Law's book, that can generate multi tooth cutters. My album **LINK** shows the manufacture of a cutter, using CNC to shape the profile but could also use buttons. An easily made machining fixture is needed. Also worth looking at Mike's Workshop site for info on designing and making cutters. **LINK**

Russell Eberhardt16/01/2019 10:09:05
avatar
2465 forum posts
83 photos

Some time ago the late John Stevenson described an easy method of making single point gear cutters using a tapered cutter to give the required clearance. I can't find the thread at present but it is somewhere on the forum.

Russell

not done it yet16/01/2019 10:17:59
3165 forum posts
11 photos

This link might help.

**LINK**

Roderick Jenkins16/01/2019 10:23:03
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1758 forum posts
445 photos

John suggested using a Conecut **LINK** It's a neat solution to making a single point cutter but more difficult for a circular cutter.

Rod

John Haine16/01/2019 10:28:36
2577 forum posts
133 photos

The Mike's Workshop link above describes using cone cutters too.

Neil Wyatt16/01/2019 13:09:18
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Moderator
16277 forum posts
679 photos
74 articles

I make symmetrical cutters from silver steel disks, then cut out a T-shape piece. Mounted eccentrically on an arbor they work as single point cutters and can be reversed to use the second edge. A stop on the arbor makes sure they can't shift.

Neil

Andre ROUSSEAU23/01/2019 04:08:24
15 forum posts

Thanks everyone for the great spread of replies, liked Neil's interesting variation on the theme.

Yes, John Stevenson was a very prolific contributor to engineering topics but particularly because he seldom re-gurgitated old ideas, nearly new and original every time. I was well aware of his contribution to the topic before I placed my post but for all who are interested you can peruse these links:-

http://bbs.homeshopmachinist.net/threads/42051-A-form-tool-for-gearcutting

....and-

https://metalwebnews.com/howto/gear/gear1.html

Thanks again.

By the way, I suspect that most of you posters are in the UK (I'm in New Zealand). I can't resist relating an amusing anecdote to you. Some of you may well know that New Zealand has a mini cottage industry re-building de Havilland Mosquitoes (the production form-tooling/jigs are amazing, by the way). Having witnessed the first public display flight of the first-build I was mightily impressed.....

..... so there I was just about to walk into the local supermarket in Papakura last Wednesday when, what should I hear, but the familiar sound of two roaring R-R Merlins overhead? Yes, it was the latest new-build dH-M doing test-flights. A great sight and as I craned my head skyward I muttered to the guy standing next to me, words to the effect "I bet that'll frighten a few Germans!"

He said something like "Hmmm, Interesting" - but in a thick, German accent and "No", he wasn't having a joke with me!

"Ooops!"

Brian G23/01/2019 07:01:37
513 forum posts
11 photos

Circular cutters on an offset arbor are featured in Ivan Law's book (which has free shipping worldwide here **LINK** ). Incidentally the technique doesn't just work for gears, Colin Binnie wrote of using the same method of obtaining clearance with "roller" form tools for the lathe **LINK** .

Brian

Michael Gilligan23/01/2019 07:08:54
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13573 forum posts
586 photos
Posted by Brian G on 23/01/2019 07:01:37:

Colin Binnie wrote of using the same method of obtaining clearance with "roller" form tools for the lathe **LINK** .

Brian

.

That's a great reference page, Brian ... Thanks for the link yes

... I also like the 'Privacy & GDPR' statement.

MichaelG.

Edited By Michael Gilligan on 23/01/2019 07:16:20

Michael Gilligan23/01/2019 07:13:57
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13573 forum posts
586 photos
< double posting deleted >

 

Edited By Michael Gilligan on 23/01/2019 07:15:38

ega23/01/2019 11:05:56
1216 forum posts
101 photos
Posted by Brian G on 23/01/2019 07:01:37:

Colin Binnie wrote of using the same method of obtaining clearance with "roller" form tools for the lathe **LINK** .

Thanks for the link: excellent illustrations and it made sense once I realized that you have to read across the columns of text.

Has anyone here used the static form? A photo would be welcome.

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