Making some multi-tooth wheel cutters

Hi,

I'm trying to make some multi-tooth clock wheel cutters and I was wondering if I should provide some " relief " , I guess you would call it , on the front face of each tooth? I've provided some pictures to help explain what I mean.

Thanks,

Mark

Edited By JasonB on 11/07/2016 18:33:14

Hi,

Sorry about the appearance of the post.

Mark

For brass it is not necessary. Purists would argue that it alters the profile.

Hi Mark,

Here is Dean's writeup of how he makes multi-point gear cutters. Cut away what you have marked red to make the cutting edges.

Thor

Hi Thor,

Dean's are the instructions I'm using to make my cutters I just couldn't figure out if he put any relief on his or not.

Thanks,

Mark

Looks more like Dean's cutters have some rake to them

Commercial involute cutters do not have any rake. That way, when the cutter is sharpened on a radial, the form of the cutter is not altered. The commercial cutters work fine on cast iron and low and medium carbon steel. I suppose it depends upon how concerned one is about the profile being wrong.

Andrew

Normal practice on gear cutters is for the cutting face to pass through the centre line, then when re-sharpening them the profile remains the same. This applies to hobs as well as single tooth cutters.

I grind the trailing face of the tooth first to give a datum to work from, then use the cutter grinder detent finger on that face to index for grinding the actual cutting face.

Phil

.

Mark,

I think you have a slight problem with the terminology ... The 'relief' is the increasing clearance behind the cutting-edge, and this is provided by what you have already done.

As Jason has shown; the teeth on Dean's cutter also have 'rake', which may be useful [*] on ferrous materials, but should certainly not be necessary on the hard Brass used for Clock Wheels.

MichaelG.

.

[*] Edit: Andrew's comment is noted, and is self-evidently correct.

Edited By Michael Gilligan on 11/07/2016 19:26:34

You don't have to remove that much metal, you only need to mill away down past the 'shoulder' of the form, taking such big chunks just increases the chance of distortion when hardening.

Neil

To be honest I can't see why they can't be gashed radially. The clearance angle is the important aspect but it is possible to make do without that with risk of rubbing which is likely to wear them out more quickly and possibly spoil the cutting action a bit.

The link posted seems to show radial gashing on some.

John

-

Hi,

Thanks to everyone for the replies. I could not remember the proper term for the rake angle. I think I'll cut them radially ; I can always grind in some rake later on.

Thanks,

Mark

Hi,

Me again. The reason he cuts so much off of the cutter is that the partial hole that's left acts as an indexing point on the jig that holds the cutter blank while you cut away the waste. But as I was typing this I got to thinking that maybe you don't need the hole to index from you could just use the perpendicular line from the radial cut and just butt that up against the indexing pin? If you click on Thor's link you will see a picture of the jig.

Mark

You could still use the whole hole to index the cutter while you work on the smaller cutouts and shape the cutter

Edited By JasonB on 15/07/2016 07:27:23

For info.

David Creed's article [as credited by Dean] is available at various locations, including 'docfoc'

**LINK**

MichaelG.