Some years or so ago I had the chance to purchase the CorelCad programme very cheaply. I was in the mistaken belief, that I would be a small step from CorelDraw to CorelCad. It wasn't so, the more that there was no handbook included in delivery.
In the past two years I had to learn it autodidactically and – much to my astonishment – I archieved first successes rather soon and so I could design most parts form my current project with ease.
Now, my projects have become more and more demanding, and recently I am confronted with a problem I can't find any solution. I thought, I will ask all the 3D professionals here in my familiar surroundings, although I do not think, anybody uses CorelCad too.
What's the problem:
Whenever I am saving a drawing with roundings or bevels on my harddisk, there are more or less distinctive anomalies when I reopen them. This is also the case, when I saved them as STL files.
Here an example (bevore and after saving).
(https://images40.fotki.com/v1648/photos/4/3824994/14463210/Sprocket_neu_1-vi.png) (https://images14.fotki.com/v1676/photos/4/3824994/14463210/Sprocket_neu_2-vi.png)
May be someone has an idea what it might be and could explaine me whats wrong here in simple words (remember, I am a CAD novice ;-)
Thanks in advance
Peter
Look for multiple identical objects occupying the same space. I'm not a Corel user, but none of the modeling programs like duplicate objects in the same location.
Now that Eric has written that, I have enough confidence to agree and add that it looks as though some planes in your drawing may be slightly twisted. In SketchUp I sometimes encountered similar issues and it was always because I had made a tiny alignment error somewhere. I'm sure somebody with more knowledge than I can explain it more clearly and correctly. -- Russ
Thank you Eric and Russ
May be it helps, when I show here my approach:
1 Construction of the base in revolving the cross section
(https://images41.fotki.com/v1673/photos/4/3824994/14463210/1-vi.png)
2 Construction of the « cone » in the same manner :
(https://images20.fotki.com/v1672/photos/4/3824994/14463210/2-vi.png)
3 Rounding off the corners (0.75/0.50/0.25mm)
(https://images15.fotki.com/v1674/photos/4/3824994/14463210/3-vi.png)
4 I aligned the «cone» inserted it in the base and finally subtracted it.
(https://images14.fotki.com/v1676/photos/4/3824994/14463210/4-vi.png)
Ok, and finally it looks crumpled like this:
(https://images14.fotki.com/v1676/photos/4/3824994/14463210/021120713_49_13HohlraumPrint3D1-vi.png)
Peter, it looks to be a boolean subtraction function issue. Boolean functions are the creation of a new form through the addition, subtraction or blending of separate forms. I am not at all familiar with Corelcad but boolean functions in any CAD program can be problematic, especially when filleted edges are involved. Your "cone" form is actually quite a complex shape with all the different radii. As an experiment, try removing the radii along the edges, the filleted edges, then try your subtraction... see if that gives you a cleaner result. If so, then fillet those edges on the final form. As a general rule, whenever I create a complex part in CAD, filleting the edges is always the final step in the process, after completing all the boolean functions.
I agree completely now that you've outlined your sequence. Subtractions work best with as simple a form as possible. And fillet last.
Hi
I wouldn't have thought to receive a reaction at all! Thank you very much for your support. I followed your advice in the hope of having understood everything right.
Alas, the result is about the same ☹. Hmm, but I am rather sure you were right! The problem lies at the different radii...
(https://images15.fotki.com/v1674/photos/4/3824994/14463210/7-vi.png)
Hmmm.... try another experiment. Use your existing subtraction form (without the fillets) and try a subtraction on the end of a simple circular column shape, basically a primitive. If that works, it will tell us that the subtraction form is ok and CorelCad can handle it. If not, it will tell us that either the subtraction form is the problem or that CorelCad is unable to process the subtraction properly for some reason or you're pushing its abilities. If it's successful, then try it on a simple revolved form to test whether CorelCad has the ability to process the function properly on a revolved component. I notice you've added more complexity to the main component; gear teeth, bolt heads and so on. It is always best to perform complex subtractions on the simplest forms possible, so perhaps you will need to attempt this particular subtraction operation earlier in the process. The sequence of performing complex functions is important for proper results and often, you have to experiment with different sequences to achieve the desired result.
The other strategy I've used in the past is to do all of the subtractions, fillets, etc. on a segment of the overall circular form, and then do a polar array of the resultant to get the full form. The goal is the same as everyone has suggested - trying to keep the forms as simple as possible when doing complex functions like additions, subtractions, etc.
I really appreciate your help – thank you very much!!! What I did last night: I created a simple revolved object. It has the maximum dimensions of the later shape. Later I would substract all the unnecessary parts.
From this form I substracted a «core» without roundings. These roundings were made after the substaction on the main object.
The result ... the same problem. Arrrgh!!!
(https://images46.fotki.com/v1671/photos/4/3824994/14463210/9-vi.png)
Just annother idea:
Might be the problem that I have to round some edges of the «core» with different radii?
(https://images20.fotki.com/v1672/photos/4/3824994/14463210/3B-vi.jpg)
Try adding the ribs instead of the subtraction method. And do it in such a way that they overlap with the base body. For example, by extending them to the outer diameter. Then they should automatically boolean with the main body. At least that's the case with Onshape, which I work with.
Bernhard
Hi Bernhard
Thanks for your input. Inserting the ribs was my first attempt. And it was a succes -at least partly.
(https://images14.fotki.com/v1676/photos/4/3824994/14463210/Sprocket_3-vi.png)
Those ribs are part of a cast core and have to blend in smoothly in every direction. There are a lot of rounded edges, some of them with small, others with rather large radii. Here the ,,rib adding methode" reached its limits. Working with smaller radii and omitting some of the edges worked more or less. But this does not fully comply with the original!
What I overlooked up to now completely is the item with overlapping the base body. I always placed the ribs on top of the base...
I will give it a try...
Woohoo... well done Peter! At least you're getting closer to the desired result. Bernhard had the right idea. An additive approach can sometimes work better than a subtractive one as it generally uses less application and processing resources. You've also determined that Corelcad's subtractive boolean function is somewhat limited, useful knowledge for any future projects.
Things become more and more mysterious. Some month ago I draw this submarine replacement sail for my brother. It was uploded and printed by Shapeways without problems.
Now I wanted to add some slight improvements and opened the file. See what happend...
Here the stl. file uploaded at Shapeways:
(https://images14.fotki.com/v1676/photos/4/3824994/14463210/File_103-vi.png)
And here the same as I found it tomorrow on my harddisk (bulge marked with an arrow):
(https://images20.fotki.com/v1672/photos/4/3824994/14463210/File_102V-vi.png)
Might a virus launch such an anomaly? ???
Confused, Peter
Curious... Have you updated Corelcad or added a plug-in of some sort to it, or made any substantive changes to your computer after completing the original drawing?
Quote from: WP Rayner on December 15, 2021, 06:11:39 AM
Have you updated Corelcad or added a plug-in of some sort to it
No, I didn't make any changes, as I am not so familiar with that complex matter. Meanwhile I have checked some further files. Most of them with more then one rounding or chamfer are unusably now :'(
Here another example (and not a complex one):
(https://images34.fotki.com/v1633/photos/4/3824994/14463210/Sonar_2-vi.png)
Have you recently changed any preferences in the software?
Some programs have a setting for the number of facets on curves, and changing that can affect objects that are already modeled.
Other programs describe the setting as "smoothness" or a similar term.
What platform are you using Peter, MAC or PC? Has there been a major update or change in your operating system since you completed the original drawings? For example: perhaps you are using PC and the original drawings were completed under Windows 10, but you are now running Windows 11. Has there been an update or change to your graphics card or its driver? Any of these changes hold the potential of causing compatibility issues with the CAD software, particularly a major system upgrade. A possible solution would be to do a complete uninstall of Corelcad, reboot, then do a clean reinstall.
Quote from: WP Rayner on December 16, 2021, 07:56:14 AM
A possible solution would be to do a complete uninstall of Corelcad, reboot, then do a clean reinstall.
You seem to be right! And there are signs of movement in this matter. Today I received some informations from the Corel support team. I have to do some modifications deep in the bowels of my program. I do not know, if I a able to do that properly, but at least it is a glimmer of hope !
However, I wonder now how this could happen... ???
Thank you very much and I will inform here if the miracle has taken place ::)
I'm on the verge of seeing the light at the end of the tunnel. I just opened a support ticket at CorelDraw and after two weeks email exchange (Huh !) the problem could be detected. It's a program error that will be eliminated in future versions of CorelCad ( ;D )
At the moment it can be avoided in saving the files in an older file format – as simple as that.
It should be mentioned that all «older» files remain unusable now... :-[
Maybe you need a different, more reliable, CAD program ...? -- Russ
I was about to make the decision to purchase Corel CAD. When I read this I'm glad I didn't.
Unfortunately the development of CAD, 3D modelling, imaging, video, and design applications are driven by major software companies such as Autodesk, Dassault, Siemens, Nemetschek, Maxon, and Adobe. Their products define and drive the industries and if you want to produce professional level work or need to interface with other industry-related services, you have little choice but to bite the bullet and purchase one of their products. Fortunately for imaging, video, and design needs, there are alternates available, i.e. Affinity Photo, which work very well at far less cost, driven of course by a large public demand for more affordable applications in those disciplines. However, there is not a large public demand for CAD or 3D modelling applications, CAD especially, so the big players continue to control the field. Corel products try to fill the lower cost need, but are universally shunned by the profession. For CAD there is always SketchUp, which has a free version. The Pro version requires an annual subscription but is much more affordable than anything by the major producers. There is a lot of good work that has been done with SketchUp and it plays well with pro-level products. For 3D modelling, Blender is an excellent open-source alternative, but it's not a 3D CAD application. It's a no-cost alternative to 3ds Max, Maya, Cinema 4D and so on, and it holds its own in the industry. A lot of excellent work has been done in Blender. I suspect there are other low-cost 3D CAD apps available, perhaps some of the other modellers here will have suggestions for other alternates.
Tank you very much for your thoughts!!! Sure you're right, and I should look for an alternative. But maybe I have to explain why I chose CorelCad.
The main reason was that I believed I could easily switch from CoreDraw to CorelCad. It wasn't so! Furthermore, because there was no handbook provided I had (and still have) to self-study steps by step with the help of tutorial from other programs. Then I try to adapt them.
Secondly, I was able to purchase the CoreCad education edition for around € 90, because I was still working as a teacher at the time.
To be honest, I can't afford a more expensive program right now, and I really would not like to change to a completely new software where I have to start from scratch again. So, I have to continue with CorelCad in the full knowledge, that there would be better programs (even free ones) around.
What I don't understand is: There is a program error and up to this day, nobody realizes this. Seems, that I am the only one on earth working with CorelCad :-\
Hi Peter,
I know about at least 2 other model builders who work with Corel CAD and how you came to it via the Education Edition. Unfortunately I do not have the possibility to purchase Education Edition versions. That's why I'm also looking for a free CAD software version.
Paul suggested SketchUp. Several past and some present forum members use it. I have fooled around with the free online version and it seems to work about as well as the free program they used to offer and did everything I need a 3-D CAD program to do. At the moment they offer the free version to hobbyists and only charge the professionals. It's not very hard to learn so maybe you should try it out. -- Russ
I completely understand your reasoning Peter. Hopefully the developers will be able to correct the flaw in the software. Not being able to work with older files is a major drawback, can't understand their reasoning on that.
Concerning a handbook, I don't know of any CAD or 3D modelling program that comes with a handbook. Their instructional resources tend to be web-based and designed to obfuscate rather than educate. After over seventeen years of working with 3D CAD and modelling programs I can count on one hand the number of times I've found the answer I'm seeking in the program's online documentation. I find independent tutorials to be a much better resource and much quicker to find an answer to whatever problem I've encountered. The tutorials are written for users by users, not developers.
I also started my 3D design career with SketchUp. The operation is quite intuitive and relatively quick to learn. However, I quickly realized that this program was originally developed not for technical, but for architectural projects. Moreover, it is not possible to create a 2D manufacturing drawing from a 3D model. Furthermore, it is difficult or impossible to create files for 3D printing.
I have therefore switched to Onshape. This is a free, cloud-based solution. Disadvantage: in the free version all documents are public. The operation is not that easy, but there is a good online help and many tutorials. So far I am very happy with the choice. In my current project, the Hulett Ore Unloader, which has really complex and extensive assemblies, I have not yet found any weaknesses.
Bernhard
Quote from: WP Rayner on January 12, 2022, 12:16:14 PM
Concerning a handbook, I don't know of any CAD or 3D modelling program that comes with a handbook.
I find independent tutorials to be a much better resource and much quicker to find an answer to whatever problem I've encountered. The tutorials are written for users by users, not developers.
It's amazing, even in this modelers forum I get more help and tips then from the company's support. Obviously there are other experts here as well ;)
Paul, I'm glad to read here, that I am not the only one without handbook. Then I will have to learn by tutorials, although until now I haven't found so much about CorelCad. At least thanks to a tutorial I was able to generate some letters on an curved surface yesterday. That's already a success... ;D
(https://images46.fotki.com/v1671/photos/4/3824994/14463210/Idler-vi.jpg)
Good job on the lettering Peter. That's always a challenge especially when applying curved lines of text onto a radiused surface.