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Center of Gravity in Drawings

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Center of Gravity in Drawings

Considering that the position of the CoG can be calculated using the mass properties function, is there a way that the CoG can be shown in a 2D drawing and be dynamically updated as changes are made to the part/assembly?

I know I could display the CoG csys and then manually lay a symbol over the top but I'd like this to be automatic.

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18 REPLIES 18

Re: Center of Gravity in Drawings

Analysis --> mass properties

Click on the Preview button.

Ensure that the Feature Option is selected at the bottom.

The following pictures should explain.

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Having done this, you may choose to have a POINT at this COG which would update dynamically at every REGEN.

Re: Center of Gravity in Drawings

How do you turn on the CSYS_COG or PNT_COG as they are greyed out?

I can create the feature as you state above but the resultant feature has no tangible properties to which I can attach a drawing symbol. In fact I can't find where the feature sits within the model as it does not create any visible reference when it is highlighted in the model tree.

Same question as asked here: http://communities.ptc.com/message/174277#174277

Re: Center of Gravity in Drawings

Hi

Those greyed icons (CSYS_COG or PNT_COG) can be activated if you have Behavioral Modeling Extension (BMX)

Check your license

Regards

K.Mahanta

Re: Center of Gravity in Drawings

Hi

I have tried to create a part as suggested by Srinivasan Sir

I have created the feature and tried to use this in creating a csys

Note-These parameters are feature parameters

Check the following

I have created a csys with some random x,y,z offset value

Then i tried to control these offset values with relation

I have also attached the sample part for your reference

I hope this will help you

Regards

K.Mahanta

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Re: Center of Gravity in Drawings

Thanks for clearing that up.

BMX is not listed in my licence file as an optional module. I'll be going through a licence file review with PTC soon when I go from WF3 + IntraLINK3.4 to Creo/Parametric + PDMLink.

Re: Center of Gravity in Drawings

Great bit of out-of-the-box thinking there and another few points I have learnt from this:

1) When creating the mass-properties feature ensure that you select the CSYS that you are to later going to reference your COG indicating CSYS from, as leaving default box ticked does not mean that the COG is calculated from the default CSYS in the orientation you may expect!

2) The COG indicating CSYS can be positioned in the model tree before any features and before the mass_properties to which it is referenced.

3) Although the COG indicating CSYS can be placed anywhere in the model tree, the mass_properties feature will base its results only on preceding features. I have not yet determined what effect assembly driven cuts have on parts as these always appear after the last part feature.

4) In order to position the COG symbol on a drawing you need to use a datum point instead of a csys. However when placing the symbol on the datum point it is not snapping to the COG point centrally, but is offset slightly to the left, which to say the least is a bit annoying after going to all this trouble to determine where the COG is!

Re: Center of Gravity in Drawings

Cannot see the picture posted.

However, one can do it this way by creating PART relations as given in the picture...cog.JPG

NOTE:

XCOG is defined at the "Part Level"

xCOG:FID_MASS_PROP_1 is at the Feature Mass_prop_1 level. The feature parameter is called in to define the position of a point which is offset to the FRONT, RIGHT and TOP planes.

Re: Center of Gravity in Drawings

Thankyou, much easier to use the name rather than the dimension number.

Now I have just got to find out why the COG in my complex assembly is being calculated in the wrong direction.

Re: Center of Gravity in Drawings

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