Sharing well constructed CAD models. 5

[SiW979]

Hello all

I want to start this thread to try and encourage people to perhaps share some cool parametric CAD models. Obviously I'm not talking about your company’s valuable data, but the models you may have created whilst practicing in your own time etc. I'm fortunate in that I am an NX CAD/PLM trainer so I spend a lot of time just playing with NX and learning new things that I can them pass on to our design engineers, so a lot of the models I create are nothing to with production machinery/sensitive data etc.

What I do know is that a picture, or in our case a model speaks a thousand words. How many times have you read a thread only to be lost in translation by the 4th line? Well, when ever the engineers at my company ask me a question about how to do something, I try and model it in native and email it to them so they can pick through the history and work out what is going on. I also save and keep as many .prt files that are posted here for reference. So to get the ball rolling I have attached a model of a parametric agricultural tyre. Try playing with the expressions; change the tyre diameter, the tyre width, the number of treads and the height of the treads.

One of my missions at work is to ensure that we all get the maximum return from out investment and that all divisions are working to the same level, and sharing information is a great way of doing this. You never know, you might just leant something new.

Enjoy...


Best regards

Simon (NX4.0.4.2 MP4 - TCEng 9.1.3.6.c)

http://www.jcb.com

Life shouldn't be measured by the number of breaths you take, but rather how many times it's taken away...

 

[SiW979]

Potrero

You don't need to access the expression in the assembly, you deform the part by double clicking on the deformable feature in the part navigator within the assembly. I have created a short video to illustrate how to create the deformable part so you can choose any length in between fully open and fully closed. The quality is not great because I wanted to keep the file size down, hopefully you will get the point.

Best regards

Simon (NX4.0.4.2 MP9 - TCEng 9.1.3.6.c)

http://www.jcb.com

Life shouldn't be measured by the number of breaths you take, but by the number of times when it's taken away...

 

[SiW979]

Arrangements and arrangement specific mating conditions

In the past I have had lost of requests from our engineers regarding multiple configurations of a single component in the one assembly, historically they have used reference sets to define the position but if the part is used in may instances you end up with a list of reference sets as long as your arm.

A better way is to use arrangements. Open the small assembly file which consists of a yellow stepped component with 2 holes in it and a pin.

Enjoy...

In the ANT, right click on the top level and go to arrangements, choose one and then the other and notice that pin will jump from one hole to the next.

Now right click on the pin and enter the mating conditions dialogue, notice that there are 4 mating conditions (2 mate and 2 centre) but 2 are suppressed and 2 are live, these change when the arrangement is changed.

This is a very neat way of showing multiple positions of a part, I will attach another example of a fron axle where the lock is controlled by a couple of neat expressions. There is also a short avi for you to look at to show you how I created the arrangements.

Best regards

Simon (NX4.0.4.2 MP9 - TCEng 9.1.3.6.c)

http://www.jcb.com

Life shouldn't be measured by the number of breaths you take, but by the number of times when it's taken away...

 

[SiW979]

More arrangement specific mating conditions.

Open the axle assembly that is attached to this post. Right click on the top level of the assembly and go to arrangements. There are 5 arrangements 4 of which show differnt maximum locks for LH and RH steering and 1 of which is straight ahead. They are controlled buy 2 angular expressions, lock_20 and lock_30, these are positive so inorder to turn them negative for the opposite lock I used the following expression

lock_20-(lock_20*2) which gives you -20 degrees. Have a play and see what you think.



Best regards

Simon (NX4.0.4.2 MP9 - TCEng 9.1.3.6.c)

http://www.jcb.com

Life shouldn't be measured by the number of breaths you take, but by the number of times when it's taken away...

 

[mmauldin]

Potrero

I had the same problem with the expression when I opened the gas spring file directly from the link provided. When I downloaded the file to my hard drive, opened and saved it, then used it in an assembly it worked fine.

In the case of the gas spring and the coil spring offered earlier (also a deformable part), you can create an expression in your assembly file measuring the distance between the mounting holes of the gas spring (or in the case of the coil spring, the mounting faces) and use that expression to drive the length of the springs. This way, if the assemble parts change position, perhaps a door in the open or closed position, the spring length updates automatically.

 

[ZeissMetrology]

I am often asked by our potential customers if our CMM software can make sue of NX 5 CAD models with embedded GDT. The answer is Yes but I am seeking some simple example .prt files to demonstrate this. Does anyone have a file to share with the GDT embedded? Thanks so much.

 

[hudson888]

Just with the deformable spring are you making sure to turn off partial loading before you test the deformation? It may not be the cause of the problem in this case but it can't hurt to test.


Best Regards

Hudson

www.jamb.com.au

Nil Desperandum illegitimi non carborundum

 

[SiW979]

Zeiss

Sorry, we don't do anything here like your requesting, otherwise I would happily post something for you.

Best regards

Simon (NX4.0.4.2 MP9 - TCEng 9.1.3.6.c)

http://www.jcb.com

Life shouldn't be measured by the number of breaths you take, but by the number of times when it's taken away...

 

[crazydiamond]

Hi

I am new to using deformable component. I have had success creating deformable parts and using them in assemblies by following the techniques provided by Simon (JCBCad) in this thread. The problem I've been having is with a spring I've created with closed wound ends which are ground (trimmed with datum planes). When I bring it into the assembly I can deform it as long as it is positioned as it was created. If I attempt to reposition it or mate it the part crashes or deforms with unexpected results. I would greatly appreciate if someone could tell me what I'm doing wrong.
Thanks in advance for any replies and thanks for all the previous posts on this topic. I've learned a great deal since joining this group.

Ron
Design Analyst

 

[jerry1423]

Crazy,

The datum planes that you are trimming to are probably fixed. You need to somehow associated them to the spring so that they move when the spring moves.

 

[SiW979]

The way I do it with springs is have one main controling dimension in a sketch named spring_length for example, then you can either create an offset datum plane using the named expression as the offset distance, or if the expressin controls the length of a straight line, which is the spine of the spring put 2 datums at either end using the point on curve method.

Best regards

Simon (NX4.0.4.2 MP9 - TCEng 9.1.3.6.c)

http://www.jcb.com

Life shouldn't be measured by the number of breaths you take, but by the number of times when it's taken away...

 

[mmauldin]

Ron,

It would help a great deal if you could post the model. Then we would have a better idea of what you are working with. I am particularly interested because the spring model I posted earlier has served me well in the past but just this week I used it to create a new spring, inserted that spring into an assembly, and it fell apart. Inserting the original spring model into the same assembly created no problems. I am at a loss as to why one particular combination of spring length, wire diameter, and solid height causes the deformable part to fail. I am curious if your model is similar to mine and if it is, is there a common flaw causing the failures.

 

[crazydiamond]

Simon, Jerry1423 & mmauldin

Thanks for your replies to my post.
I’ve tried removing the datum planes and the trimming operation and I still have the failure.
Here’s how I created the spring.
I start with a file which has the three primary datum planes. Next I create my expressions to generate my helix (law curve). I then create a Sketch for the ‘z law’ to control the pitch. The Sketch is created on one of the primary datum planes and uses one of the other datum planes as a horizontal reference. Next I generate the law curve using ‘by equation’ for the ‘x’ & ‘y’ and ‘by law curve’ for the ‘z’ selecting the Sketch I created. This gives me a helix with closed wound ends. While the Sketch controls the pitch it has no control over the orientation of the helix. I’m wondering if this is the problem.

mmauldin, I would love to post my model but I think my company may have a policy against that. I checked the file you posted and it is very similar to how I created my spring. One difference is that you included a datum axis to define the direction for the deformable part. Maybe this is what my spring needs. Unfortunately I won’t have much time to work on this issue today, I have some new fires to tend to.

Thanks,
Ron


Ron
Design Analyst

 

[SiW979]

Here is my spring in case it is of any interest.

Best regards

Simon (NX4.0.4.2 MP9 - TCEng 9.1.3.6.c)

http://www.jcb.com

Life shouldn't be measured by the number of breaths you take, but by the number of times when it's taken away...

 

[mmauldin]

Simon,

I checked out your spring model, very similar to the spring template I used previously. I have never encountered a failure using that model, in fact, when my newer model crashed the other day, I went back to the old one and it worked fine in the problem assembly.

Ron,

Since your model and mine are very similar in that they use a law curve to allow closed ends for the spring, I suspect that there is something fishy going on with the law curve. The extra datum axis in my model does not define the helix for modeling purposes but is there to allow aligning the spring in an assembly.

 

[crazydiamond]

After comparing my spring with the one submitted by mmauldin (bioengineer) I realized what my mistake was. When generating the Z-law with my Sketch curves I neglected to establish a base line for the law defined spline. Now it works perfect.
Thanks again to those who took the time to reply to my post and for all the rest of the valuable information posted here.

Ron
Design Analyst