Gearing Crash Course 3

[AuWing]

The person who did our gearing quit. Now I have to solve what should be a simple problem, but I am stuck.

First I am working off a drawing from 1956.

What I know.
Gear: 3DP, 107 Teeth, 35.66" P.D., L.H. Helical, 20deg Involute- Full Depth
Pinion: 3DP, 19 Teeth, 6.33"P.D., R.H. Helical, 20deg Involute-Full Depth

This is all the info on the drawing. Seems there is missing info, job security.

Question I was asked, Are these Transverse or Normal?
I was told there is a difference in the cutters.
Can anyone help?

 

[gearcutter]

"a normal diametral pitch gear hobber can cut eighter in transverse or normal, if the engineer or the hobbing setup guy knows how to
adjust the the machine to cut the correct geometry. it does not have to be a transverse hob."

I'm sorry mfgenggear but I feel that I need to correct you.
You CANNOT use a normal pitch cutter to cut a transverse pitch profile (or the other way around), it doesn't matter what hobber, shaper or setup you are using. The pitch is simply not the same.
In other words; normal pitch is slightly smaller than transverse pitch eg. 3DP normal = 3.1058 transverse.

Ron Volmershausen
Brunkerville Engineering
Newcastle Australia

http://www.aussieweb.com.au/email.aspx?id=1194181

 

[mfgenggear]

Gear cutter

Not a problem I am glad you pointed that out. Thats because most engineering drawings I deal with on daily basis are standard normal DP callouts.
The normal DP of the hob would be 3.1058 normal DP as noted above if that is the case then I would order a special hob for that part. then my statement is true. see my point. I cut helical gears all the time so I was getting tunnel vision. OK
Most Engineers are smart enough to start with a standard normal DP. just saying of course. but such in this case it's not. so I would stand corrected.
my statement would be true if the transverse DP & PA calculate back to a standard DP & PA. which I missed on the above post. I apologize to the poster.

In the states (from Ash Gear) a transverse 3 DP cutter is available. with 20 Deg helical but without the gear & hob data together. unknown if it will cut the correct gear attributes.
if the gear data is sent to their gear tool engineer over there they can verify if it will cut correctly




Mfgenggear
if it can be built it can be calculated.
if it can be calculated it can be built.

 

[gearcutter]

I made a little mistake in my last post:

"3DP normal = 3.1058 transverse" should have read 3DP transverse = 3.1058 normal.

Ron Volmershausen
Brunkerville Engineering
Newcastle Australia

http://www.aussieweb.com.au/email.aspx?id=1194181