Mating Gears 1

[Brianpore]

Hi, I am having a problem mating gears. I am trying to figure out how to do this with only mating and expressiosn if at all possible.

Right now I have my 2 gears assembled and rotating around there center axis. I am using an expression to link the to and have them rotating in the same direction. I am trying to get them to rotate in opposite directions at the same time.

I do not need them to actually be mated, as long as it looks as they are mated and are moving in the correct manner.

Thanks!

 

[JohnRBaker]

What version of NX are you running?


John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

 

[Brianpore]

I am running NX4

 

[JohnRBaker]

OK, about the best that you're going to be abale to with Mating Conditions is create an angle constraint that will control the rotation of the shafts and create relationships between the expressions that account for their gear ratios. For example, if the 2 gears are say 50 tooth and 25 tooth, that's a gear ratio of 2:1, that means that if the 25 tooth gear is the so-called driver and the expression associated with the Angular Mate for the shaft was ANG50, the angle of the 50 tooth gear was ANG25 the you should define the folliwng expression:

ANG50=ANG25*2

Now change the value of ANG25 and the gears should move as required. Now you will have to make sure that they are rotating in the proper direction and so you may need change the sign of the above expression to accomplish that:

ANG50=-ANG25*2

Now to actually animate the assembly you'll need some what to quickly edit the expression value for ANG25. Below is a link to a GRIP program to do that. I'll reference the Source Code in this note and the Executable in the next.


John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

 

[JohnRBaker]

Here is the Executable.


John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

 

[Brianpore]

John, thanks for the input. My gears are actually 3 to 1 ratio, and I can get them to rotate in that manner, but only in the same direction. I can't get them to rotate in opposite directions as a real gear would. Any suggestions?

Thanks!

 

[JohnRBaker]

Change the sign of the expression that is being driven by the input expression.


John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

 

[Brianpore]

Hi, I still can't get this to work out.

Right now, I have both gears as parts in a final assembly. There center lines are aligned to a common datum plane and there faces are aligned. The distance between there center lines is also constrained.

I can not seem to figure out how to get them to rotate in opposite directions. Should I be using the expressions to mate them to eachother, or a common part inside the final assembly? When I am mating do I reference a datum axis or what were you using as your reference for the angle?

Thanks!

 

[JohnRBaker]

You don't have to mate the gear with each other, other than perhaps to align the front faces, but you don't have to worry about any actual gear to gear type mating. However you will need an angle constraint controlling the rotation of BOTH gears and as I said you use a ratio to get them to rotate the correct amount. Now when changing you input angle if the other one rotates backward, just change the sign.


John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

 

[Brianpore]

Got it, thanks!!

 

[Brianpore]

Hi John, one more quick question on the GRIP program.

This is my first time using this GRIP program. I have gone NX open grip, but am not sure how I am supose to get the program to actually run in NX4.

Any help would be great. Thanks again!

 

[JohnRBaker]

Do a File -> Execute -> GRIP... and select my GRIP program.


John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

 

[Brianpore]

Amazing, thanks!