Making Gear Cutters

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Making Gear Cutters

This topic has 11 replies, 8 voices, and was last updated 25 September 2014 at 16:44 by Neil Wyatt.

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23 September 2014 at 17:55 #164417
Engine Builder
Participant
@enginebuilder
I have made gear cutters in the past using the information from Ivan Laws book with great success but remember reading somewhere here a different way of calculating the cutter dimensions. I think it may have been from John Stevenson, a link to a web site somewhere.

I am referring to the method of making 2 buttons and spacing them apart to form the cutting tool.

Can anyone lead me to it ?
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23 September 2014 at 17:55 #17510
Engine Builder
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@enginebuilder
23 September 2014 at 18:07 #164422
Thor 🇳🇴
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@thor
When I tried the http://www.metalwebnews.com/ (where John's article was published) it seems to be down (temporarily), you can get much of the same information from the website run by M. Cox.

Thor
23 September 2014 at 18:10 #164425
Michael Cox 1
Participant
@michaelcox1
You may be interested to read these pages on my website:

http://mikesworkshop.weebly.com/making-gear-cutters.html

http://mikesworkshop.weebly.com/improved-gear-cutters.html

http://mikesworkshop.weebly.com/update-on-gear-cutters.html

http://mikesworkshop.weebly.com/designing-gear-cutters.html

This method is based on John Stevenson's method. The last page shows the maths involved in calculating the button diameter, spacings and infeed.

Mike
23 September 2014 at 19:58 #164445
Engine Builder
Participant
@enginebuilder
Thank you for your replies and links to the same site. Mike shows an interesting method of using cone drills to make the cutters. I will give it a try.

David
23 September 2014 at 21:35 #164460
John Haine
Participant
@johnhaine32865
Hi David, if you look at the what did you do today 2014 thread a while back I posted some photos of making a cutter by cnc turning. The method was based on Michael Cox' formulae, has the advantage that you can do things like make cutters for high tooth counts where the buttons would be impossibly big or strange pressure angles that allow small pinions to be made without undercuts. I'd post the pictures again here but life is too short to grapple with this site's c**p software at this time of night. They are in an album anyway… I will write this up when I get a chance.

john.
24 September 2014 at 02:41 #164470
John Ockleshaw 1
Participant
@johnockleshaw1
Hello Engine Builder,

The article you remember was by D.J.Urwin starting in the Model Engineer of the 1st October 1971.

If you cannot lay your hands on it let me know your email address and I will send you a copy.

Regards, John
24 September 2014 at 20:10 #164556
Engine Builder
Participant
@enginebuilder
John H, This site has the worst search feature of any forum. searching for "what did you do today 2014" shows no results. I had to include brackets and question mark before the thread showed anything (what did you do today? (2014))

Not much use if you don't know the full title.

Anyway, thank you for your link but I'm a manual machinist

John O, I should have that magazine, I'll check my collection.
24 September 2014 at 20:25 #164559
Michael Gilligan
Participant
@michaelgilligan61133
Engine Builder,

Strangely … I've just put the two words "what did" [without the quotes] into the search box, and it returned just two threads [one for 2013 and one for 2014].

That said; the alternative "google" search on the home-page is often more useful.

MichaelG.
24 September 2014 at 20:27 #164560
Engine Builder
Participant
@enginebuilder
Just tried it again and working fine now Michael G. Very strange.
24 September 2014 at 20:52 #164564
Roderick Jenkins
Participant
@roderickjenkins93242
David,

Ivan Law published a new set of Tables in ME 15 June 1990. In the preamble he says that Professor Chaddock showed that "considerable variations to the button diameter could be tolerated without any appreciable error in gear tooth shape, provided that the distance between button centres varied with the change in diameter". It seems that there are many ways to skin this particular cat.

Norman Hurst wrote an article in MEW December 1999 demonstrating his methods.

For what it's worth, like you, I've used Ivan's tables to produce gear cutters that have made satisfactory gears. It is quite a faff though. I like the idea of the cone drill method.

Cheers,

Rod
25 September 2014 at 16:44 #164634
Neil Wyatt
Moderator
@neilwyatt
> In the preamble he says that Professor Chaddock showed that "considerable variations to the button diameter could be tolerated without any appreciable error in gear tooth shape, provided that the distance between button centres varied with the change in diameter".

The fact the buttons are mounted at an indeterminate angle and then the cutters ground at a similarly vague angle both act to change the tooth shape.

I think the truth is:
- The errors in with the button approach are broadly similar to those for 'everyday' off the shelf gears.
- Involute gears are very tolerant of anything except 'too fat' teeth.
- Most errors in mesh can be dealt with by slightly varying the spacing.
- Involute gears tend to wear towards an ideal shape (some people even 'run them in' with fine valve paste, not something I would do).
Neil
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