What gear cutter set?

[maskell]

G Day everyone,
I have a project that needs a few gears cut and the information is a bit short on detail.
I have 12.5'' gears to cut with 74 teeth that mate with a pinion that is 2.5'' with 13 teeth and
A 5" gear that has 127 teeth to mesh with a pinion of 2.250'' with 13 teeth again.
I don't mind buying a set of involute cutters I was looking for one set that might do both sets and keep the ratio close to what they are now.
I'm a bit lost at present doesn't matter how many times I read the text it is not sinking in, metric modules seem to be 4.2 to 4.3 but I'm not sure of the dp or how to find it as I seem to come up with around 6 DP but the calculator tells me it should be between 12 and 120.
Any help would be appreciated.
Thanks Lance

 

[steamer]

It would appear from your description that you have gears of differant pitches..?

Got some pictures? Lets see what we're talking about.

Dave

 

[maskell]

Dave, I think you are right I will see if I can attach a pdf

Lance

View attachment scan0007.pdf

 

[tel]

I keep getting 6.667dp for the second ones - very odd.

 

[Maryak]

Tel,

I get between 5 & 6 DP and they don't match metric module either. Methinks some of the information is not correct. I can't find a 5" gear with 127 teeth the 5" on the drawing says 29 teeth

 

[Ken I]

A 13T x 6 D.P. is 2.166" pitch circle and 2.500" O.D.
A 74 x 6 D.P. is 12.333" pitch circle and 12.666" O.D.
Axle Centres are 7.250"


A 127T x 26 D.P. is 4.885" pitch circle and 4.961" O.D.
A 13 x 26 D.P. is 2.000" pitch circle and 2.077" O.D.
Axle Centres are 3.442"

Nothing really matches what you are giving dimensionally.

Are you stating pitch circle diameters or simply the O.D. of the gears ?

What are the axle centres ? Approx tooth depth ?

More info will help.

Then again you really might have a non-standard set of gears on your hands - then you're in trouble.

Regards,
Ken

 

[tel]

Just ran the 29/13 pair thru Marv's excellent program and the DP's don't even match! Curiouser and curiouser.



View attachment ScreenHunter_3.bmp

View attachment ScreenHunter_4.bmp

 

[Jasonb]

I can't make the numbers work buy this is what the gears are for - 1/3rd Case Baler, this was teh only one were you can see the bull gears that I could find

j

 

[maskell]

Thank you all for your interest.
I think I can change the shaft spacings to suit something more universal. As it is a 1/3 scale baler to run on a hit and miss engine as long as the lower bull gear stays around the same place the rest can be fiddled with. The pdf with the gear info is all I got with the plans the center to center on the pinion and bull gear is 7.250 and from the primary drive to the 5'' gear has the centers at 3.437'''but these can be changed to suit what ever is sensible to make.

Lance

 

[maskell]

Maryak,
You are right, i had taken the 127 from the mm od of the 5'' gear by mistake.

Lance.

 

[tel]

OK Lance, looks like your safest bet will be 6DP cutters and fiddle the od's and centres to match.

You won't need a full set tho, a No.2 for the 74, a No.4 for the 29 and No.8 for the 13t pinions.

 

[maskell]

Thanks Tel,
I will start snooping around and see if I can find some.

Lance