Reverse Engineering Gears 1

[mfg11eng11guy]

I have a gear that I want to figure out the information on. I do not have a cmm with reverse engineering capabilities.

Can I use traditional gear inspection methods (dimension over pins, span, #teeth, etc...) to figure out the gear data of this particular gear?
Is there a sequence of steps that I need to take in order to achieve such a thing? Maybe there is a simple calculator out there for standard gear sets?

please advise.

 

[gearcutter]

Can I use traditional gear inspection methods

Yes you can.
The only thing that'll throw you is working out the helix angle.
The only way that this can be done *properly* is by setting up the sample (or the mating part) on either a hobber or CMM.

Use Google to help you find the math you'll need to learn.

 

[mfg11eng11guy]

Helix angle is 0 degrees

 

[gearcutter]

Then your job is going to be relatively easy.
The hardest part will be trying to work out if and how much addendum correction has been used.
Once again, Google can be your friend.

When you're done, come back with the data and we'll help you confirm your results.

 

[mfg11eng11guy]

http://www.geartechnology.com/issues/0100x/regalado.pdf

This is the procedure I will follow.

 

[gearcutter]

Look up 'base pitch' along with 'base pitch charts'.
This will help you work out what the pitch & pressure angle is.

 

[mfgenggear]

good info from gearcutter, plus there is more to do. It is a must to get an Involute check to verify the the gear data is correct. also what about the material it is made from? and the type of heat treat that was used. so a meturgical eval is in order. reverse engineering can be very tricky. is this a critical application? or something else.

 

[mfg11eng11guy]

it is critical from a geometrical point of view. The machine this particular gear goes on uses the gear as a timing device. It doesnt actually spin a full 360 degrees, but rather back and forth. Low speeds and low directional change. I would say it is more important that we limit our backlash with the mating gear. Material I am not really concerned with from that point of view.

 

[mfgenggear]

great then accurate MOW or Span Measurements, the Involute check with confirm the Module or DP & PA is correct. once the data is calculated the and Involute check will verify it. roll it with an existing part to make sure it rolls smoothly.