Sharing well constructed CAD models II
Sharing well constructed CAD models II
(OP)
thread561-234523: Sharing well constructed CAD models.
Sometime ago I created a thread trying to encourse people to share their we constructed CAD models so that others may play around with them an possibly learn a trick or two.
Anyway the thread has been closed, but a reference to it is at the top of this one. I've got another CAD model here of a piece of round tube with a sqashed flat end,which one of my users aksed me to show him how to do, so have a look and see what you think, I'd be interested to see other peoples interpretations and also critiques of mine.
For anyone who never saw the original thread, I would recommend you have a browse through some of the excellent CAD models that people posted on there.
Enjoy
Sometime ago I created a thread trying to encourse people to share their we constructed CAD models so that others may play around with them an possibly learn a trick or two.
Anyway the thread has been closed, but a reference to it is at the top of this one. I've got another CAD model here of a piece of round tube with a sqashed flat end,which one of my users aksed me to show him how to do, so have a look and see what you think, I'd be interested to see other peoples interpretations and also critiques of mine.
For anyone who never saw the original thread, I would recommend you have a browse through some of the excellent CAD models that people posted on there.
Enjoy
Best regards
Simon (NX4.0.4.2 MP10 - TCEng 9.1.3.6.c)
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...





RE: Sharing well constructed CAD models II
RE: Sharing well constructed CAD models II
what is the purpose of the last two features (sketch & extrude)?
Thanks in advance for any reply.
Ron
Design Analyst
RE: Sharing well constructed CAD models II
I think you'll find this a slight improvement and examine geometry will tell that story for you as well. You just use a little control over the shape when you have a straight line meet and arc as one of the section curves of the freeform sheet that you're building using curve mesh.
You wouldn't normally check this but I urge you to look at the curvature comb of the edge of the sheet as it meets the flat section in your model. The funny little inflection is what may cause you some grief.
If you want to shell to 2mm thickness, while it always surprises us what NX will occasionally do, the minimum radius in your transitional surface really ought to be larger the 2mm. That is why I thought it would be better to just show how it might be controlled to achieve that outcome.
Best Regards
Hudson
www.jamb.com.au
Nil Desperandum illegitimi non carborundum
RE: Sharing well constructed CAD models II
That spring looks good, as mentioned it appears that you can ditch the last couple of features without fear of foul, but some people might like to have them included as part of a wider reference set to use for mating conditions or assembly constraints.
I have seen something similar posted here in response to questions about building springs that did similarly well with law curves. However I do think something like this really belongs in a post such as this one.
In this case I'd just like to see one enhancement to the model which would be to make it sufficiently parametric that I could use it in a part family. Presently one of the first things that I noticed was that increasing to number of coils or reducing it significantly tends to produce errors.
Best Regards
Hudson
www.jamb.com.au
Nil Desperandum illegitimi non carborundum
RE: Sharing well constructed CAD models II
Any chance of theses models in NX4 for us in the sloooooow lane.
Andy
RE: Sharing well constructed CAD models II
during lunch break I took the "Hudson-approach" to model the flattened tube in NX 4.0.4.2. The only difference between my model and Hudson's model is the continuity, which is G0 instead of G1 for the 'Trough Curve Mesh".
Could anybody be so nice to explain the differences between these different options (G0-G1-G2), because i couldn't manage to use G1 continuity?
Michaël
RE: Sharing well constructed CAD models II
G1 is tangency, whis will mean that you get a nice smooth transition between the faces which is much more desireable but the radii of each curve at the point of joining is different
G2 is curvature symetric and really aimed at people who create very high quality aesthetic surfaces which need to reflect light nicely etc. Bascally G2 cuvature is ensuring that the radius of each curve at the point if joining is identical.
There is G3 as well in later versions of NX which is even higher quality still.
Have a look at the attached image for clarification.
Best regards
Simon (NX4.0.4.2 MP10 - TCEng 9.1.3.6.c)
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...
RE: Sharing well constructed CAD models II
Best regards
Simon (NX4.0.4.2 MP10 - TCEng 9.1.3.6.c)
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...
RE: Sharing well constructed CAD models II
http://en.wikipedia.org/wiki/Geometric_continuity
The very short version below.
G0 Touching
G1 Tangency
G2 Curvature
G3 Flow
And the model in NX-3 with at least G1 continuity. I have refined the technique slightly, but on the other hand changed it simply because there are a couple of things that later versions allow me to do which the earlier ones didn't.
Best Regards
Hudson
www.jamb.com.au
Nil Desperandum illegitimi non carborundum
RE: Sharing well constructed CAD models II
it explained at lot. Still one question though, why do i have the possibility to create continuity aswell with the primary curves/lines, as with the cross strings?
I was able to put a G1 continuity at the primary strings but not at to the cross strings.
And i don't see the possibility to create G1 continuity with the bridge curves (aren't those standerd G1 or G2?).
Michael
NX4.04.2 / TCE 9.1.3.8_build_0711 / NX6.0.2.8
RE: Sharing well constructed CAD models II
I've attached your model with G1 continuity applied. I don't know for sure what gave you grief, but as a suggestion you did have the modelling tolerances set awfully darned tightly. Also perhaps in selecting curves and adjacent faces you need to turn the tangent face chaining behaviour off in the selection preferences.
You'll notice that I changed the modelling tolerances and have now managed to shell the part out to 2mm.
Otherwise great job, and since you mentioned that you had to do this during lunch break, and we can therefore assume your boss is reading this, I think you ought to be paid for taking the initiative to learn better skills!
Best Regards
Hudson
www.jamb.com.au
Nil Desperandum illegitimi non carborundum
RE: Sharing well constructed CAD models II
Basically the bridge curves are set as default as G1 if you double click on one and to open up the bridge curve dialogue, you will see two buttons, one called tangent, and one called curvature, just experiment by clicking on each one of these whilst the bridge curve is active and you will see the bridge change shape slightly.
The reason that you cannot set your cross strings to be G1 to anything is that there is no other surface to select/refernce when you create the very first surface.
However the primary strings do have a surface for you to select for G1 (the tube surface and the flat surface) however when you mirror the suface and you you now have 4 surfaces to reference when you fill in the last through curve mesh.
1. The tube face
2. The flat section face
3. The first through curves mesh
4. The mirror of the through curves mesh.
Look at hudsons model again, double click on through curves mesh (11) and notice that G1 is set in all 4 boxes, when you click on each of the buttons next the G1 box, you will see each surface highlight that has been selected.
Basically what I'm trying to say is if you want to assign G1, when doing the TCMesh, you need to reference a surface, not a string.
hope this helps.
Best regards
Simon (NX4.0.4.2 MP10 - TCEng 9.1.3.6.c)
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...
RE: Sharing well constructed CAD models II
You can see this for yourself by playing around with the studio splines. I think I've described all this before. Elsewhere on the forum, but the G number can be equated with the number of poles that need to be aligned with the adjacent object. GO touching at the ends means that no poles are aligned, G1 tangency means that the first pole is aligned and so as the continuity increases to G2 then two poles are involved, up to three for G3.
Working with single segment curves, as somebody noted the other day in another thread, you also need to increase the degree of the object in order to actually increase the number of poles until there are enough to be able to create that alignment. Which I think helps explain part of what Simon alludes to in taking about needing to have curves that meet the standard you expect of the surfaces you intend to create.
In general then to recap from that earlier post...
G1 > Degree 3
G2 > Degree 5
G3 > Degree 7,
at a minimum in common surfacing practice.
Best Regards
Hudson
www.jamb.com.au
Nil Desperandum illegitimi non carborundum
RE: Sharing well constructed CAD models II
I never toughed your bridge curves because I just didn't think to. As luck would have it we were only ever chasing G1 continuity on this model and the surface righted itself with very little encouragement from me!
Best Regards
Hudson
www.jamb.com.au
Nil Desperandum illegitimi non carborundum
RE: Sharing well constructed CAD models II
you were a great help, i learned a lot today and will keep practicing with the different posibilities. I'm sure this will improve my modeling abilities.
But to stick to the original thread, i've att. a model which use law defined splines to create a in/out spiral/wire/... . Hope you like it.
Best regards,
Michael,
NX 4.0.4.2
RE: Sharing well constructed CAD models II
I've asked it before and I'll ask it again, when are you going to go on Seimen's payroll?
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: Sharing well constructed CAD models II
The secret to creating really good sketches is using plenty of reference geometry and a clever mix of geometric constraints and expressions.
Enjoy
Best regards
Simon (NX4.0.4.2 MP10 - TCEng 9.1.3.6.c)
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...
RE: Sharing well constructed CAD models II
RE: Sharing well constructed CAD models II
I expect that Seimens are just as happy to have me help you guys for free, but whenever they do want to call I'm sure I'd be open to offers
Maybe I ought to set up an arrangement with my local Pizza parlour as did the developers of Samba at one time. The licensing being open source, there was a stage where rather than accepting donations additional support could be sought with the understanding that the gift of a voucher for a Pizza would be accepted. I suspect that some people's needs are as modest as they are honourable
Best Regards
Hudson
www.jamb.com.au
Nil Desperandum illegitimi non carborundum
RE: Sharing well constructed CAD models II
This is a great thread! Perfect for me as a relative new comer to NX. I'm just starting to use expressions and things in my work, so the working examples shown here, along with the technical information are invaluable.
Just wanted to post a message so that the thread didn't get lost again, it was about to fall off the front page!
Does anyone else think creating a forum for this topic alone would be a good idea? With each model and subsequent comments being an individual thread. Just a thought.
Thanks again for the invaluable lessons!
Mike
NX6.0.3.6
RE: Sharing well constructed CAD models II
I don't think I've posted this one before, but it's quite a cool model. Bascially the pitch of the blades is controlled by one expression. So open up the expression editor and play about with the OUTER_PITCH and see how this effects the behavior of the model. I think the max it goes to before a blend fails is 82
Enjoy
Best regards
Simon (NX4.0.4.2 MP10 - TCEng 9.1.3.6.c)
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...
RE: Sharing well constructed CAD models II
RE: Sharing well constructed CAD models II
RE: Sharing well constructed CAD models II
I'm talking about a 'Wave Washer'. These models shows off the use of such functions as Law Curve, Wrap Curve, Instance Geometry, Thicken, etc.
In both of the attached files you can edit the Inside/Outside Diameters as well as the Thickness of the material and effective Thickness of the washer by going to the Part Navigator and expanding the 'User Expression' section, double clicking a parameter and entering a new value. I've also included a pair of Datum Planes (representing the top and bottom 'faces' of the effective height of the Wave Washer) which will make it easier to Constrain the Washer in an Assembly. You can use the 'Y' Axis of the Datum CSYS for alignment.
Note that both models are in NX 5.0 format so that should help those who have not yet moved to NX 6.0.
Anyway, give them a look and have fun.
John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
http://www.siemens.com/plm
http://www.plmworld.org/museum/
To an Engineer, the glass is twice as big as it needs to be.
RE: Sharing well constructed CAD models II
Have a look at the attached .avi file which will show you how to add face reclection. Hope it helps
Best regards
Simon (NX4.0.4.2 MP10 - TCEng 9.1.3.6.c)
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...
RE: Sharing well constructed CAD models II
That reflection command is pretty neat. Any way to apply it to different components in an assembly? Seems that if you select one of the parts with reflections on the other components go into wireframe mode.
Also if you apply the reflection to the component then open the assembly where the component is used the reflection does not follow.
Rgds Rob.
RE: Sharing well constructed CAD models II
Whilst reflection is a nice way to make components look glossy and slick, this is not the main function of the command, infact it is pretty much unintentional. The relection tool is actually an analysis tool that is used by people who want to create very high quality surfaces with out any mismatched edges or unintentional inflections or imperfections in the surface.
For example any one creating the a surfaces of a car would use this tool to make sure that light flows smoothly over the surface of the car.
We've all done it ourselves, we go to buy a nice new or second hand car that's clean and shiny and you find yourself crouched looking along the sided of the car for dents in the pannels, obviously with a bright light or the sun shining on the body pannels the dents stand out very easily, and that is basically what this tool is for, checking the quality of sufaces, the fact that you can make you model look more realistic for presentations etc without having to know how to create a full bore rendering is just and added bonus.
Have a look at the attached model, spin it round an notice where at the point where some of the sheets meet, the zebra stripes are not contiguous and they don't flow smoothly, if I was a good surface modeller (I'm not, hence the poor quality) I would be most displeased with this model, they should flow smoothly, if you have one of those iPODs with the chrome back, look at the reflection of something stripey in it and see how perfect the surface is.
Best regards
Simon (NX4.0.4.2 MP10 - TCEng 9.1.3.6.c)
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...
RE: Sharing well constructed CAD models II
For those who are on slightly older versions of NX like me who still need to use datums in order to put holes through a curved surface, I have attached a model which will hopefully show you how you can create a hole which pierces surface normal to the face regardles of what you do to the controling expression. Suppress all the features and look through them one at a time.
The important bits start with the HOLE POS sketch consisting of 1 single reference line. The length of the line is controled by a named expression called PCD.
I exited the sketch and added an associative point ot the end of the line and then projected that downwards normal to the surace of the revolved face. I then added another datum (type: point and direction) using the 2 poiint option of the drop down menu within the datum command and the associatice and project points to define the plane normal.
Then simply add a hole to the datum and position it point onto point of the projected point and create your circular array.
Open the expression editor and modify the PCD expression between 300 and 60 and notice that the hole will always be normal to the face.
Enjoy.
Best regards
Simon (NX4.0.4.2 MP10 - TCEng 9.1.3.6.c)
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...
RE: Sharing well constructed CAD models II
Thanks for the tips and models.
Never knew it would do this.
Just goes to show what you can learn this software will do by getting outside of your usual methods and practices.
RE: Sharing well constructed CAD models II
The "p" value in the expressions controls the number of "strands" in the helix.
While the "q" value is a formula, it can be directly input as an integer and controls the number of coils.
Adding a multiplier to the formula for "zt" causes the model to take on a squished appearance. Use a multiplier greater than 1 to flatten the coils in the x-y direction, less than 1 to flatten in the z direction.
RE: Sharing well constructed CAD models II
Here is a spring I created with law curves. I am trying to make the spring adjustable. It's by no means perfect but it meets my requirements.
I've also played around with linking the spring expression variables so that when I change the position of items in the related assembly the spring compresses / extends. This theory works great until you need to create 2D separate views of each position!
Such a shame that arrangements is not compatible with the assembly constraints...
If anyone can model the part in a simpler way I'd be interested to see the method.
Note model created in NX V5.
RE: Sharing well constructed CAD models II
Here is a cracker for you, perhaps a little more interesting to anyone who is involved in surface modelling, although it does make pretty good reading to anyone. It would be good point of reference.
Enjoy.
p.s. whilst I'd love to take the credit for creating this beautiful model I can't, because I didn't do it.
Best regards
Simon NX4.0.4.2 MP10 - TCEng 9.1.3.6.c - (NX6.0.3.6 MP2 native)
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...
RE: Sharing well constructed CAD models II
I modified a spring I submitted on the last model sharing thread to allow for controlling the number of closed coils.
While it is constructed as a deformable part, I have found that the deformation occasionally behaves erratically when placed in an assembly.
RE: Sharing well constructed CAD models II
Nice work if you can get it! Probably you wanted to loose the reference data out of that file. I'd love to know what the intention was in relation to the STL data. It looks more like old sheet metal off CAD than a scan off clay perhaps.
Best Regards
Hudson
www.jamb.com.au
Nil Desperandum illegitimi non carborundum
RE: Sharing well constructed CAD models II
Thanks for posting the latest version of the spring. Thats what I was looking to achieve but your model is so concise. I like the addition of the 'closed coils' into the base sketch. Simple & effective, nice.
Now we all of the benefit of how to do the spring - and how not to with my attempt!! :)
RE: Sharing well constructed CAD models II
Siemens used a data set of one of our machines to launch NX5 some time ago, we also asked them to come in and demonstrate Shape Studio to our ID team with the intention of binning Alias and unifying all our CAD data under the Siemens umberella. So they took a translation of the Fastrac boonet (already a production part created using crap alias to nx work flow) and then used this to re-model the bonnet associatively using shape studio to show how quick models could be updated compared to Alias. Hence all the reference geometry.
Best regards
Simon NX4.0.4.2 MP10 - TCEng 9.1.3.6.c - (NX6.0.3.6 MP2 native)
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...
RE: Sharing well constructed CAD models II
1)MEAN DIAMETER OF SPRING
2)WIRE DIAMETER
3)FREE LENGTH
4)NUMBER OF ACTIVE COILS
5)TOTAL NUMBER OF TURNS
RE: Sharing well constructed CAD models II
thanks in advance
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kukelyk
RE: Sharing well constructed CAD models II
Thanks for sharing that excellent model with us. Here is a metric version. Adjust expression values to suit. -currently its a very small component :)
Solid Edge; I-Deas 7 to 12; NX4 & currently NX5.
RE: Sharing well constructed CAD models II
Preferences > sketch > retain dimensions (just put a tick in the box) That will then leave the dimensions visible to make referenceing them in other sketches much easier.
Best regards
Simon NX4.0.4.2 MP10 - TCEng 9.1.3.6.c - (NX6.0.3.6 MP2 native)
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...
RE: Sharing well constructed CAD models II
----
kukelyk
RE: Sharing well constructed CAD models II
OUr company standars say that supplier data should be stored as one solid lump rather than assemblies. So this limits our options when it comes to using arrangements. So to allow us to see how a part will interact with others within assembly, we create some high quality deformable parts to allow us to view differnt scenarios without having to use assemblies and arrangements.
Attached is a hinge, the secrect to a successful, robust deformable part is a sturdy well constructed CAD model. Open the file and look thorough all the feature taking note of how the sketches were created and constrained. Then edit the anlge expression between it's default zero and various other angles. Notice also that the part is one solid body, and not and assembly.
Now add the hinge to an empty part file to create a small assembly, slide the slider bar as you add it and see that a deformable part is created. You can double click on this in the part navigator and change the angle until your hearts content. Cool eh?
I have other examples if anyone wants them of springs, gas springs and rubber bushes.
Enjoy
Best regards
Simon NX4.0.4.2 MP10 - TCEng 9.1.3.6.c - (NX6.0.3.6 MP2 native)
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...
RE: Sharing well constructed CAD models II
RE: Sharing well constructed CAD models II
John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
http://www.siemens.com/plm
http://www.plmworld.org/museum/
To an Engineer, the glass is twice as big as it needs to be.
RE: Sharing well constructed CAD models II
RE: Sharing well constructed CAD models II
RE: Sharing well constructed CAD models II
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John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
http://www.siemens.com/plm
http://www.plmworld.org/museum/
To an Engineer, the glass is twice as big as it needs to be.
RE: Sharing well constructed CAD models II
RE: Sharing well constructed CAD models II
John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
http://www.siemens.com/plm
http://www.plmworld.org/museum/
To an Engineer, the glass is twice as big as it needs to be.
RE: Sharing well constructed CAD models II
Note that one of the tables may not apply since it defines a pair of variables based on the four different styles of end coils, which means that it would be easier to just create four different models and go from there. But it would still require that, based on the size of the wire, dia of the spring, type of material, number of coils, pitch of the helix, etc. that you would have to first look-up values from the two remaining tables (one table provides the Allowable Working Stress based on the material, size of the wire, and the service duty of the intended application, while the other table provides something called the Wahl Factor which compensates for the effect of torsional stress based on the ratio of the wire dia and the mean diameter of the spring) and then you will need to insert these values into at least some, but certainly not all of those equations.
While it technically could be done, in the end it would be a very tedious undertaking.
John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
http://www.siemens.com/plm
http://www.plmworld.org/museum/
To an Engineer, the glass is twice as big as it needs to be.
RE: Sharing well constructed CAD models II
Unzip this assembly file, open it and without changing the orientation, go into...
View -> Visualization -> High Quality Image...
...and set the Method to at last 'Photo-Realistic' and select the 'Start Shade' button. Note that you can hide one or the other of the two magnifying glasses to see the effects. You can also try moving either of them in or out and seeing the effects.
John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
http://www.siemens.com/plm
http://www.plmworld.org/museum/
To an Engineer, the glass is twice as big as it needs to be.
RE: Sharing well constructed CAD models II
I'm not sure who created this model originally, but we think it was one our customers in the UK (who had way too much time on his hands). The model is at least 13 or 14 years old and I used to use it for Navigation Demos (you see, there's a FARM inside the Clown's head with a fully detailed windmill and barn).
John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
http://www.siemens.com/plm
http://www.plmworld.org/museum/
To an Engineer, the glass is twice as big as it needs to be.
RE: Sharing well constructed CAD models II
Best regards
Simon NX4.0.4.2 MP10 - TCEng 9.1.3.6.c - (NX6.0.3.6 MP2 native)
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...