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Posted by on January 13, 2008, 5:38 am
Please log in for more thread options > Having turned, =A0milled, annealed and hardened and tempered, I now need t=
o
> add cutting some spur gears to my CV.
>
> I have a mill and decent rotary table, =A0so I'm assuming that I just need=
to
> buy the appropriate gear cutter and work out the "angle of dangle". =A0 =
=A0This,
> like most of the things I do, =A0will be fairly rare event. =A0 The design=
I'm
> currently working on suggests I need to make two 12 tooth and two 24 tooth=
> module 1 gears cut with a 20deg pressure angle (that is to say bog standar=
d
> stuff - but given my hobby is learning to make things, =A0buying them miss=
es
> point!).
>
> However, =A0one question I'd like some help with is the material to use - =
the
> gear chain of events is a 12 tooth spur cut in EN8 and hardened will drive=
a
> 24 tooth gear on a countershaft. =A0The countershaft also has a 12 tooth g=
ear
> which then drives the final 24 tooth gear, =A0to achieve a 4:1 reduction.
> This is being used to drive the valve timing cam in a =A015 cc model engin=
e
> (don't worry about 4:1 and four stroke -it's a trick I found on t'internet=
).
> Given I want minimum weight and to minimise gear noise what materials can =
I
> use in the gear chain after the driver spur =A0(typically running at 5000r=
pm)?
>
> Steve
Firstly, the tooth count will lead to the same teeth on the gears
engaging with eachother, this is not good practice and it would be
better to get away from 12/24 tothe ratio, secondly I agree that 12
teeth is a little low for a tooth count for a reliable set up, so look
at altering the module (or DP) to give a minimum of 14 teeth on the
pinion. As to material, I would go for hardened steel for the smaller
gears and possibly for the larger.
If I can help any more PM me
Peter
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> add cutting some spur gears to my CV.
>
> I have a mill and decent rotary table, so I'm assuming that I just need
> to buy the appropriate gear cutter and work out the "angle of dangle".
> This, like most of the things I do, will be fairly rare event. The
> design I'm currently working on suggests I need to make two 12 tooth and
> two 24 tooth module 1 gears cut with a 20deg pressure angle (that is to
> say bog standard stuff - but given my hobby is learning to make things,
> buying them misses point!).
>
> However, one question I'd like some help with is the material to use -
> the gear chain of events is a 12 tooth spur cut in EN8 and hardened will
> drive a 24 tooth gear on a countershaft. The countershaft also has a 12
> tooth gear which then drives the final 24 tooth gear, to achieve a 4:1
> reduction. This is being used to drive the valve timing cam in a 15 cc
> model engine (don't worry about 4:1 and four stroke -it's a trick I found
> on t'internet). Given I want minimum weight and to minimise gear noise
> what materials can I use in the gear chain after the driver spur
> (typically running at 5000rpm)?
>
> Steve