Drawing vs 3D CAD Model
Drawing vs 3D CAD Model
(OP)
I have a model that will have to be cast, but it has some very complex shapes. Using Unigraphics, I am unable to get a radius into a region I KNOW they are going to need it, the program just will not put the radius into it.
So here's my question. The Model will be sent to the customer along with a drawing. If I call out a larger radius on the drawing than they find on the 3D part, will that supersede the model? Or should a notation be included on the drawing to indicate that the larger radius is prefered regardless of what the model shows.
Unfortunately due to the complex geometry of the part the Model has to be provided as well as the drawing.
Thank you for your time,
So here's my question. The Model will be sent to the customer along with a drawing. If I call out a larger radius on the drawing than they find on the 3D part, will that supersede the model? Or should a notation be included on the drawing to indicate that the larger radius is prefered regardless of what the model shows.
Unfortunately due to the complex geometry of the part the Model has to be provided as well as the drawing.
Thank you for your time,





RE: Drawing vs 3D CAD Model
If you can't get NX to give you the radius value in a dimension, then you may have a generated a shape from blends that is not a true radius, but a curved surface. Have you tried doing a cross-section at the point you want to dimension the curve at?
"Wildfires are dangerous, hard to control, and economically catastrophic."
Ben Loosli
RE: Drawing vs 3D CAD Model
They should match, period.
Actually, I think you have a bigger problem than the old Model vs Drawing battle.
If you can't get the model to the configuration you want, how could anybody make the configuration you want?
Harold G. Morgan
CATIA, QA, CNC & CMM Programmer
RE: Drawing vs 3D CAD Model
If it's manufacturer, make a note like "RADIUS X.XX IN THIS AREA PERMITTED"
If it's customer and radius is functionally required, make your best effort to model it like looslib suggested.
Either way make sure the note will be noted. Many shops tend to ignore the drawing, go purely by the model, and refer to the drawing only after something goes wrong.
RE: Drawing vs 3D CAD Model
If the drawing is going to have changes, and not the 3D model, might as well use ACAD.
Chris, CSWA
SolidWorks 14
SolidWorks Legion
RE: Drawing vs 3D CAD Model
The geometry is a constantly changing shape. I am able to get most of the draft angles and radii in, but in the location indicated by the picture the coding of UG is not permitting me to put a large enough radius, and it is failing inside the circle. I believe in practice this problem is non existent and the manufacturers would prefer the radius and it would make their job easier, but I am spending hours trying to get UG to do something it is failing to do.
What I am getting from the conversation is that the model HAS to be right and that the drawing is only present in case of problems or to provide the person receiving the part elements they can check.
Which puts me in a quandary as to how to solve this problem. *sigh*
Unless someone knows a good say to use documentation to allow the manufacturer to put in the necessary radius. I'll take this to the Siemens forum and ask for solutions on the UG side.
Thanks again
RE: Drawing vs 3D CAD Model
How much experience do you have using NX? Have you exhausted all of the different approaches you can take to create this radius, or just the blending commands? While it may take some time and effort, if you can draw it you should be able to model it.
I have never worked with a solid modeling system where the drawing was the master definition; it is always the model.
“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV
RE: Drawing vs 3D CAD Model
Is it a constant or variable radius that you need? Have you verified the integrity of the surrounding surfaces in that area? NX should be able to do this with a little investigation. It would be a good idea to pick the brains of those in the NX forum.
“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV
RE: Drawing vs 3D CAD Model
RE: Drawing vs 3D CAD Model
I have used ever option, including trying to use my own sweep sketch, but they won't join, and due to the complex geometry it isn't tangent to the two surfaces. The edge is moving in all three dimensions, and the angle on the seam is constantly changing as well. It is simply beyond the capabilities of the program as far as I can tell. And because part of the Siemens company and my company work in the same field I'm not allowed to send our models to them for help.
So yeah, that's where it is at.
RE: Drawing vs 3D CAD Model
Sometimes in situations such as this you have to go back and recreate the surface elements that are giving you problems. By doing so, you may find slightly different approaches that allow you to proceed with the radius in question.
Again, ask on the NX forum... I have been ever thankful for advice received over the years from its members when I have come across similar problems.
“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV
RE: Drawing vs 3D CAD Model
The 'examine geometry' command may also be useful.
Have you tried the different 'overflow resolution' options within the blend command?
RE: Drawing vs 3D CAD Model
2. Are you being forced to play the purchasing 'telephone game' or could you actually talk to the foundry about your issue?
3. On the drawing if you have a call out for that radii generally just make sure it is clear that it's "ALL AROUND" - perhaps even adding that to the drawing.
The casting house is probably going to do some work on the model anyway to allow for shrink etc. so it may not be a killer.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Drawing vs 3D CAD Model
Yes I've tried the different overflow options. And Examine Geometry either Passes everything or there are no results. (I have never found Examine Geometry very helpful)
I can get a radius so long as the value is smaller than .3 mm, and no casting, scratch that, no cost effective casting will be able to maintain that.
RE: Drawing vs 3D CAD Model
Thanks for everyone's help by the way.
RE: Drawing vs 3D CAD Model
While having the model ready for the foundry to take with minimal effort/matching the drawing... are good general practices at some point the effort (i.e. $) to achieve that may not be warranted.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Drawing vs 3D CAD Model
RE: Drawing vs 3D CAD Model
Time was, UG would allow users to adjust Parasolid tolerances. Tightening tolerances on the preceding features and loosening them on the fillet might get you there.
RE: Drawing vs 3D CAD Model
I took a quick look at the picture you posted. Something like this can be done with surface modelling.
If you post a section of this model, we can give you some suggestion.
You need to take a different approach as your current one leads to invalid geometries.
Best regards,
Alex
RE: Drawing vs 3D CAD Model
RE: Drawing vs 3D CAD Model
I agree that the model "should" be identical to the drawing, but here we always put a disclaimer on purchase orders stating that the drawing is the criteria for acceptance. The model may be provided, but is reference only.
RE: Drawing vs 3D CAD Model
Always wise, but that won't stop the manufacturer from carving away blindly from the CAD. If you can't reconcile CAD and drawing, best to be material-safe on the CAD model.
I've wrestled with stubborn fillets on-and-off for half my life (as many of us have). There is most certainly a brute force solution to getting a fillet in there, even if it means carving the solid up into surfaces and stitching back together. (UG/NX is particularly good for this.)
Also, it is not always the best course to use the design CAD model as the model to be used by the manufacturer. You may want to make a second model specifically for manufacturing. I usually do this and hand them a lobotomized, featureless model so they don't need to wrestle with feature regeneration time, etc.
RE: Drawing vs 3D CAD Model
RE: Drawing vs 3D CAD Model
RE: Drawing vs 3D CAD Model
“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV
RE: Drawing vs 3D CAD Model
As others have said, try te NX forum, maybe with a portion of your total part and see if someone else with NX can get the blend you need.
"Wildfires are dangerous, hard to control, and economically catastrophic."
Ben Loosli