Teeth in a spur gear rack

[rarefruit]

How is the number of teeth counted in a mod 1 spur gear rack?

 

[???]

By the number of teeth

 

[Superbowl]

By the number of teeth

Use fingers until you get to 10 then start on the toes.

 

[rarefruit]

That does not help with the spur gear I need. Sure, I can count the number of teeth. How does that help in getting the correct spur gear? In 30 mm there are 10 teeth. Pitch is 2.27 mm.
I need to know the number teeth per inch or mm to get the correct spur gear.

 

[???]

Google it and then when you have a clue on how to phrase your question correctly come back and ask the question. Last time I checked my crystal ball didn't work over the net.

 

[Overland]

Use fingers until you get to 10 then start on the toes.

Can I help:
One, two, three .......

 

[sfriedberg]

I need to know the number teeth per inch or mm to get the correct spur gear.

You have a module 1 rack? Then every module 1 gear (with the same pressure angle) will mesh properly with your rack.
Do you know the center distance between your spur gear axis and the rack pitch line? If so, you can compute the appropriate number of teeth for the spur gear. If you don't know the center distance, you are S.O.L. unless you can measure it.

 

[EPAIII]

If it is a mod 1 rack, then a mod 1 spur gear should fit. And it can be any number of teeth. The number of teeth will determine the spacing between the rack and the axis of the spur gear's shaft, but that is all.

But more below.

How is the number of teeth counted in a mod 1 spur gear rack?

 

[EPAIII]

Here you are confusing. You say there are 10 teeth in the rack in 30 mm. That means each tooth is 3 mm wide. And 3 mm / pi is the module. So 10 teeth in 30 mm means you have a module 0.9549 gear, not a module 1 gear as you stated in the first post. Unless your measurement is not accurate.

So, just what are you saying? If there really are 10 teeth in 30 mm, then where did you get the 2.27 mm or "mod 1" numbers?

Generally speaking, gears measured with English units (inches) are normally defined in units of diameteral pitch. Diameteral pitch is the number of teeth divided by the pitch diameter. And it is NOT called mod or module. Metric gears are usually defined in units called module. The module of a gear is the reciprocal of the diameteral pitch or the pitch diameter divided by the number of teeth. Thus the module is just a linear distance and it is the distance between teeth divided by pi (to convert from the circumference to the diameter).

That does not help with the spur gear I need. Sure, I can count the number of teeth. How does that help in getting the correct spur gear? In 30 mm there are 10 teeth. Pitch is 2.27 mm.
I need to know the number teeth per inch or mm to get the correct spur gear.

 

[Erich]

When you measure a rack, you are measuring Circular Pitch. Google how to convert CP to Diametral Pitch or Module.
Done.