showing shrinkage (temp) on a drawing

[vonhofs]

I posted this in the Analysis section and then noticed it is an area that doesn't get much traffic, so figured posting here as well would be a good idea.


We have parts that are made at room temp, but are used at cryogenic temps. Because of this, the engineers would like to add another sheet to the drawings, showing the "USE"or cryo dimensions of the parts. These would all be reference dimensions and the sheet would have big notes saying not to use the dimensions for manufacturing.


We are trying to figure out how to do this and don't have any good answers. We would like the models to be dependent on the original models as any changes need to show up on the "Use" models as well.


One suggestion was to do an inheritance model and then warp it in three directions, but that didn't work as it ended up making the holes into strange looking shapes.


Another option would be the simple "scale" command, but we want to leave the original model alone, but have the "use" model connected to it and we cannot figure out a way to do this. I was thinking of making a family table with just different names and then opening the instance and scaling it, but the command is not available in instances.


I had noticed the "shrinkage" command in the set-up menu, but since we don't have Moldesign, that is not available to us.


Anyone have any ideas? If we can't get anything, the easy way to do this is to simply make a copy of the original and then scale it and if the changes to the original are significant, to re-copy it and scale it again (loosing all the dimensions on the views).


Thanks for you help!

 

[jason_]

Use the Warp command, Transform. This will add a feature to your model tree that scales the entire model. This way you can create a family table with two instances, one with (the original) and one without the warp feature. Then add both models to your drawing and create views with each. Dim them up and they should both update whenever you make changes to the original.

 

[vonhofs]

Jason,


O.K., I am trying this out and since it's the first time I am doing it, I am not getting anything like what I want. I mean, I was able to get it to shrink the model, but it's random... Is there a way to specify how much it will transform the model in each direction (should be the same).

 

[vonhofs]

Oh, wait, I may have found it.


Under "options" there is a "scale" section where it looks like it scales the model in all directions. Does that sound right?


It looks right and seems to work. I made a drawing and the dimensions seemed to work just fine.

 

[vonhofs]

So, in trying this, everything works except when you try to put a radiior diameter dimension on the part in the drawing, it doesn't recognize the surfaces as circles or arcs.


This is something we can work around for now as it seems this solution is the best so far.

 

[dr_gallup]

Here is a workaround for you, Create a new low temperature model and create an inheritance feature of your room temp model. In the new model create a new unit "shrunk". I made 1 shrunk=1.05 mm. Then make a new system of units, I also named it "shrunk". Now change your low temperature part to unit system "shrunk" & have the part convert the dimensions. In your drawing both parts will be exactly the same size but created dimensions on the low temperature part will be smaller than on the room temperature part. You could always change the view scale on the low temperature part to make it look smaller too.

 

[vonhofs]

Here is a workaround for you, Create a new low temperature model and create an inheritance feature of your room temp model. In the new model create a new unit "shrunk". I made 1 shrunk=1.05 mm. Then make a new system of units, I also named it "shrunk". Now change your low temperature part to unit system "shrunk" & have the part convert the dimensions. In your drawing both parts will be exactly the same size but created dimensions on the low temperature part will be smaller than on the room temperature part. You could always change the view scale on the low temperature part to make it look smaller too.

Hmm. Not sure that would work in our situation, since one of the things they want to see is how the assembly of parts works together at cryo temps. And since the materials are all different (alum, gold, berilium...) the models need to be accurate.

 

[jason_]

So, in trying this, everything works except when you try to put a radiior diameter dimension on the part in the drawing, it doesn't recognize the surfaces as circles or arcs.


This is something we can work around for now as it seems this solution is the best so far.

Yeah, the dimensioningIS a little wacky on the drawing side. I called PTC and they didn't have a great answer. The warp feature is more or less a free form surfacing tool where you can morph the part in a multitude ofshapes, apparently it doesn't create new dims to define those surfaces either. This may not be the best method for you, I'd hate for you to go down that road and have problems later.


Also, are you saying that you'll be using these warped models in assemblies? I'm not really sure how that will work. If you replace by instance in the assemblies it may not see the same surface ID's in the warp as in the original. You should definitely test around with that before commiting to this technique. It makes me a bit nervous that I can't select on any of the radial geometry, I question it's integrity.


I'm looking at a possible sharaed data technique. This may also be a good candidate for behavior modeling but I wasn't sure if you had that so I was sticking to the standard modeling tools. This is something ourcompany may need to do so it's worth my time investment.By the way, PTC's solution it create two seperate parts. I don't give up so easily though.
Edited by: jason_

 

[vonhofs]

Jason, as far as the assembly goes, it is a smaller version of a larger assembly and is jut for reference and to see the actual sizes of the parts at cryo temps. It will be used on the assembly drawing with ref dimensions only. I am not worried about it as long as we can assemble parts to each other (insert, mate, align). That is all we will use the shrunken models for (besides showing ref dimensions on the part drawings) as well.


According to the PTC reps, we have almost every module available. But the one time I wanted another module (Moldesign), we didn't have it. Or maybe we do have it, but it has never been installed? That actually could be the case as it has been known to happen. If you come up with anything else, let me know. According to the PTC Guru assigned to us, he said that "Shrinkage" may get us exactly where we want to be and I should check and see if we can get an evaluation license.

 

[jason_]

According to the PTC reps, we have almost every module available. But the one time I wanted another module (Moldesign), we didn't have it. Or maybe we do have it, but it has never been installed? That actually could be the case as it has been known to happen. If you come up with anything else, let me know. According to the PTC Guru assigned to us, he said that "Shrinkage" may get us exactly where we want to be and I should check and see if we can get an evaluation license.

Yeah, I was able to get into the shrinkage command and that's definitely what you need if you can figure out what the deal is with the license.


I got a license error initially when I tried to use it as well. Here's what I did to get it working. Go to Tools>Floating Modules and then check off "Tool_Design_SET". Go back to Edit>Setup and try selcting your "Shrinkage" pick again.


You can also go to Help>Technical Support Info and scroll down to the options (should be near the top) and you should see Tool_Design_SET in the that list (at the end in my list of options). If you don't it's possible that your company has more advanced licenses that aren't getting used, talk to your admin.


If you can get it working, great, try using the same family table technique along with it.
Edited by: jason_

 

[vonhofs]

I am trying to get the info for our PTC rep so I can see about an eval license, but nobody seems to be in the office today to get me her info!


Jason, have you tried the shrinkage command to see what it does to the part (is it a feature that can be put into a family table like warp) or can you do it to an inheritance feature from the original part?

 

[jason_]

Iam trying to get the info for our PTC rep so I can see about an eval license, but nobody seems to be in the office today to get me her info!

Did you try setting the Floating Module option? This will enable the command.

Jason, have you tried the shrinkage command to see what it does to the part (is it a feature that can be put into a family table like warp) or can you do it to an inheritance feature from the original part?

Yes, this is exactly what you need, this command was created for your specific application in mind. It places a feature in the model tree that can be used in a family table and it dimensions in a drawing nicely. No need for an inheritance feature.

 

[vonhofs]

Oh, BTW, I figured out that the warp/transform command won't work for us properlybecause since the part no longer cosiders the circles as circles, that means we cannot assemble the parts via "insert".


So, I will continue to look into the shrinkage feature and see where I get with that.

 

[vonhofs]

Oh, I tried the floating module and we don't have anything available that will give us that option.


All we have are:


1)Advanced_Render


2)Comp-Aided_verif_set


3)Diagram


4)NC-Complete_set

 

[charlesrichard]

W

 

[vonhofs]

Had another member help get me on the right track in the "Analysis" section and decided to host the files needed to get it to work.


The Pro-e file is here: www.vonhofs.com/files/cast_scaled.prt.1


and I did a write-up on how to use it (we are using Intralink) here: www.vonhofs.com/files/Showing_shrinkage_on_a_part.doc


Remember that you need to decide if you are allowing the part to shrink or grow and you need to choose the proper formula. I needed the parts to shrink so that 1 would be .99851, so I used the 1/1-S formula and used the shrinkage scale of -0.004208 to get it to work properly. Here is the spreadsheet I used to get the number: www.vonhofs.com/files/shrinkage_calcs.xls

 

[mcgowanp]

Hey Scott, fairplay for sharing all your info!!!


Paddy
Edited by: mcgowanp