Making a Gear cutter

[BH_Nomad]

Hi, I have Ivan Law's book, Gears and Gear Cutting and have a question on what material to use for the cutter. Can I use HSS? I was thinking hard + hard = crash.
The buttons are hardened tool steel so will that cut and form HSS?
Thanks

Tim

 

[arnoldb]

Hi Tim and welcome to HMEM

HSS will not work if you use the button method. As far as I'm aware, both the buttons and the cutter is made from unhardened silver steel (drill rod).
You have to make the buttons first, then harden and temper them, after that the un-hardened cutter itself is made using the hardened buttons to shape it, and once complete, the cutter is then also hardened and tempered.

Regards, Arnold

 

[hammers-n-nails]

i dont have an opinion on this but i have the same book and would like to cut some gears sometime, please keep us informed of your progress

 

[BH_Nomad]

I will let you know how it goes, may take a couple of days because of my work schedule

 

[steamer]

What arnold said... 8)

The heat treat of HSS is WAY beyond the HSM shop equipment.....

Production records are not needed either, just slow the cutter way down. ;D

Dave

 

[Majorstrain]

Hi Tim,
When I made some change gears for my lathe I whipped up an excel spread sheet that takes Marv's gear calculator data (pitch diameter etc.) and calculates the button diameter, button spacing, and in feed depth needed for any individual DP and tooth number combo.

I'll post it when I get home tonight.

Cheers
Phil

 

[modeng2000]

Hi Tim,
When I made some change gears for my lathe I whipped up an excel spread sheet that takes Marv's gear calculator data (pitch diameter etc.) and calculates the button diameter, button spacing, and in feed depth needed for any individual DP and tooth number combo.

I'll post it when I get home tonight.

Cheers
Phil

That would be most helpful Phil. I have used the button method and the resultant gears worked fine.

John

 

[Majorstrain]

Your wish is my command. :big:
But not wanting to do any high jacking of this thread, the info is here.
http://www.homemodelenginemachinist.com/index.php?topic=6536.msg69822#msg69822
Cheers,
Phil

 

[Cliff]

Can somebody explan what the button method is in relation to cutting gears some years ago I worked in a job shop machine shop and had to make gears and splines with a single point cutter and I never heard of the button method. Thanks Cliff.

 

[gbritnell]

Cliff, the shape of a gear tooth is called an involute curve. For simplification lets just say it's a given size radius for a given tooth shape. When making a cutter with 'buttons' you are coming close to that desired radius and spacing. You first cut the piece of stock with the 'button' cutter' and this forms the tool to make the gear. It's a 3 step process, make the cutter to make the cutter to make the gear. For a desired diametral pitch and a specific range of teeth you make specific sized buttons and mount them at a specified center distance. It takes a little more work than making a single point tool but it's much more accurate.
gbritnell

 

[applescotty]

Here's an article by John Stevenson about the method:
http://www.metalwebnews.com/howto/gear/gear1.html

Scott

 

[Cliff]

Thanks for explaining that is the first time I heard of that way of doing it. Cliff

 

[shred]

Is anybody CNC-ing single-point gear cutters? Seems like you could get the 'proper' curve that way and it shouldn't be all that difficult to program. Presumably with a 4th axis or lathe you could make the round cutters as well.