[How-To] Gear diameter question

Change gears are usually made of cast iron so they wont be jingle jangling when running, for a low stress gear, I might choose Delrin, for one that is to run often, iron or steel, like HR or CRS.
 
I just used general purpose rods when welding the steel. Never had a problem turning the weld.
Made my change gear from cast ally blank with porosity oil holding holes, still going strong 10 years later.
 
Save the steel! Cut from ali, delrin or whatever. I've made loads from 12mm ali plate. It's not high speed or high stress, and change gears usually go on a hardened collar, so rolling contact on the teeth and more or less static loads against the collar and little need to worry about wear from friction. 3D printed plastics also work really well as mentioned.
 
DavidR8 said:
I need to cut a 16 DP, 14.5 PA, 40 tooth gear in the semi-near future.
My calculations indicate they gear will have an OD of 2.625".
I have a nice piece of 4140HT but it's only 2.5" and will be a tad smaller than that after the OD is cleaned up.
That's roughly 1/8" smaller that the calculated diameter.
Can I get away with this or should I spring for a length of 2.75" or 3"?
Click to expand...
Use a round of 3" Acetal, works well for gears and costs less.
 
I have nylon I can send you. Or steel. But the precut gear above for 60 USD looks attractive...
 
Dabbler said:
I have nylon I can send you. Or steel. But the precut gear above for 60 USD looks attractive...
Click to expand...
I have all the stuff to make them; cutters, arbor and dividing head. Building up the skills aresenal :)
 
Dabbler said:
Ah. Well worth the doing. offer stands.
Click to expand...
Thanks mate, I have some 4140HT of the necessary diameter for the smaller gear but not for the larger. I'll call Industrial Plastics and see what they have.
 
DavidR8 said:
I need to cut a 16 DP, 14.5 PA, 40 tooth gear in the semi-near future.
My calculations indicate they gear will have an OD of 2.625".
I have a nice piece of 4140HT but it's only 2.5" and will be a tad smaller than that after the OD is cleaned up.
That's roughly 1/8" smaller that the calculated diameter.
Can I get away with this or should I spring for a length of 2.75" or 3"?
Click to expand...
here ya go
2.5 is your pitch diameter.so that stock won;t work
Inputs
Number of Teeth: 40
Diametral Pitch: 16
Pressure Angle: 14.5 degrees
Gear Type: External

Outputs
OD Reference: 66.6750 mm 2.6250 in
Pitch Diameter: 63.5000 mm 2.5000 in
Root Diameter: 59.5313 mm 2.3438 in

Addendum: 1.5875 mm 0.0625 in
Dedendum: 1.9844 mm 0.0781 in
Working Depth: 3.1750 mm 0.1250 in
Whole Depth: 3.5719 mm 0.1406 in

Circular Pitch: 4.9873 mm 0.1963 in
Tooth Thickness: 2.4936 mm 0.0982 in
Base Circle: 61.4774 mm 2.4204 in
Undercut: No

for checking over pins
Inputs
Number of Teeth: 40
Gear Type: External
Diametral Pitch: 16
Pressure Angle: 14.5 degrees
Helix Angle: 0 degrees
Pin Diameter: 0.1300 in
Profile Shift Coefficient: 0 unitless

Outputs
Measurement over Pins: 69.5963 mm 2.7400 in
Minimum Pin Size: 2.5746 mm 0.1014 in
Pin Size on Pitch Line: 2.6035 mm 0.1025 in
Maximum Pin Size: 3.7648 mm 0.1482 in
Normal Pitch Diameter: 63.5000 mm 2.5000 in
Transverse Pitch Diameter: 63.5000 mm 2.5000 in
Profile Shift: 0.0000 mm 0.0000 in

enjoy,
Dan
 
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