Re: [CAD_CAM_EDM_DRO] Buying or CNCing some odd angle bevel gears. I'm stuck !!

Hi Paul:
Are you talking about the "parallel tooth method" of creating a bevel
gear?
This was a common way of cheating in the war years in England because it
allowed war production from unsophisticated machine shops using dividing
heads and standard involute gear cutters.
It produces acceptable gears, but still cannot be produced by hobbing.
The hob cuts the spaces between the teeth, and these are still not parallel
when the teeth are of parallel form.
Cheating by changing the root angle is a fake that will result in rapid wear
of the tooth flanks because the rolling action of a true involute will be
lost.
Your suggestion to single tooth cut with an indexing setup is the most
likely to lead to success.
Cheers

Marcus

----- Original Message -----
From: "Paul" <Paul.Corner@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Saturday, January 12, 2002 10:38 AM
Subject: Re: [CAD_CAM_EDM_DRO] Buying or CNCing some odd angle bevel gears.
I'm stuck !!


>
> Hi Marcus
>
> p.100 Gears For Small Mechanisms by W. O. Davis
> ISBN 1-85761 015 6
>
> Whilst a bevel gear may not be perfect and true to form across the full
> width, this method would be acceptable for the model in question. The
gears
> could also be cut with a shaper or by conventional cutters - Neither would
> produce a high precision gear.
>
> I would agree with your statement and qualify it - An accurate and true
bevel
> gear can not be produced by hobbing.
>
> Regards, Paul.
>
>
> On Saturday 12 January 2002 5:52 pm, Marcus & Eva wrote:
> > Hi Paul:
> > You can't hob a bevel gear.
> > The tooth cross section changes across the width of the tooth.
> > Cheers
> >
> > Marcus
>