Gear DP

[Ghosty]

Hi All,
I have plans for a gear reduction unit, but they do not list the DP for the gear cutters. they list the number of teeth and the OD of the gears, but not the DP.
Question, How do you work out the DP. The small gear is 20 tooth, with a listed OD of 1", the large gear is 30 tooth and a listed OD of 1.3125"
Any help would be grateful.
Cheers
Andrew

 

[cathead]

Here is a page from Machinery's Handbook that may be helpful. Hopefully it is readable enough for you.

 

[RJSakowski]

D.P. = no. of teeth/pitch diameter, also (no. of teeth +2)/o.d.

There's a good discussion on Wikipedia.

Gear - Wikipedia

en.wikipedia.org

 

[Ghosty]

Hi All,
After doing some drawings(love autocad) with 1" centers, and a 1"OD small gear and a 1.454" larger gear with the offset of the adj cam setup on the driven gear at max offset, it leaves 70thou intermesh. the DP22 gear has a 98thou depth of gear, so it will be well within specs to cut the gears and build the reduction unit.
Thank all for the help.
Cheers
Andrew

 

[Ghosty]

Hi All,
Just done another drawing in autocad, using Mod 1 gears, with the 20 tooth at 0.868" dia OD and the 30 tooth at 1.260" dia OD, with 1" centers, the mesh is 0.064", the depth of cut for the Mod 1 is 0.085, I can cut the gears with Mod 1 cutters(that I have), and with the adj cam on the driven gear(30 tooth), I will get full mesh of the gears.
I will now go this way as I don't need to hunt down the 22 DP cutters.
Cheers
Andrew

 

[Ghosty]

Hi All,

Had a couple of days off, my back was tightening up on me, so had a brake from doing anything.
The gears that needed cutting, done in 4140, still need heat treatment.
Had a good day today got the shaft, nut, drive flange, prop washer and bolt machined.
All parts laid out and then assembled. The small nut that holds the gear on the shaft was 1/4"UNF in plans and pined to the shaft after assembly, I used M6 L/H thread, same as prop bolt, was listed as 1/4UNF, I used M6 R/H, had both taps and dies.
Now all I need to do is the two mount plates, will look at that tomorrow.
For all that want to see the McCoy 60 engine(glow version) that it is going on, have posted a pic, you can see an sparky of the same engine at

Cheers

Andrew