Why do my FreeCAD models break? - "Topological Naming Problem"
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- Опубліковано 22 жов 2024
- Wonder why your models sometimes break when you modify something?
Can they be fixed?
What the heck is the "Topological Naming Problem"?
If you've been using FreeCAD for a little while and you're frustrated, this video might be just what you're looking for.
Parts of this video move very quickly, it's not a tutorial about how to model in FreeCAD, it is purely about the topological naming problem, how to fix issues caused by it and how to avoid them all together.
If you're new to FreeCAD, check out some of my other modelling videos before watching this one.
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I'm disappointed the fix wasn't considered for the 0.19 release. Having used FreeCAD for years, this has consistently been the single biggest problem with using the software. I also think it will be the biggest problem getting new users to adopt the software.
It's not that is wasn't considered. The problem is that realthunder needs to separate it from his fork, to make it into a manageable (or even multiple) pull request(s). His fork is tens of thousands of lines of codes spanning the whole code base. It's impossible to review for other developers with limited available time. Already, his App::Link work was merged into 0.19 and it was a lot of work, to make sure it played well with all the other workbenches. As an end user, I understand the frustration of not seeing this and other cool stuff merged into FreeCAD's main branch already. But we cannot know what all of this requires on the other side. That being said, with FC 0.19 releasing soon, I believe merging of the topological naming code will be in the works for 0.20.
@@normandchamberland1503 As a developer I understand, and I think the FreeCAD maintainers are doing an amazing job. But as a user... Now! Now! Now! Sadly, life doesn't work that way,,,
@@DavesRocketShop yeah because this issue does not exist to that degree in aps i use like fusion360. references can have hick ups so you just re-associate and done
@@normandchamberland1503 but good to know that this is actively worked on. RT build and work is really making FC more usable and approachable. I saw the same with Blender - once the UI got better the adoption rate increased.
Autodesk is helping by trying to manipulate users into spending $500/year.
That will boost the user base and development of FreeCAD.
Apparently, Autodesk only wants to do business with wealthy corporate clients, not regular people.
Putting up with some bugs in FreeCAD is well worth it, give it a few years, it'll get sorted out.
And hopefully, some day, Autodesk will be put out of business. Companies like that should not exist. Corporate culture and business models like theirs like that should not exist. They try to be gate keepers, limiting access to tools to only the wealthy. F 'em.
Another outstanding video sir. These are of real benefit to the FreeCAD community, myself included. Thank you for making these. Keep 'em coming!!!
Great video and pretty much what I have learned in the forums and reading the wiki for the last month since ejecting myself from Fusion 360. I am wondering what are the downsides of just downloading realthunder's branch and happily continuing on using that instead of the 0.19? Are there aspects about his branch that make the files not compatible if you build a model there and then try to go back to the official FC version? If so, and they are well known, maybe you could do a little video pointing out the differences between them? Thanks for the effort on this and other videos - I am slowly coming up the curve with FC but it would be a real nightmare without videos like this.
l'll have to watch this again because I'm a little hard of thinking, but you've certainly got the knack of talking sense - I currently use DesignSpark Mechanical - which is brilliant but I need an easier way of making adjustable models. I got a long way with this with FreeCAD but gave up on it and returned to DSM because I got sick of the time squandered on broken models. Edit: I've just had a quick fly through the RealThunder version. I had no idea there was a version of FreeCAD that works! I tried your method to stop models breaking, but being able to just get on with designing using the RealThunder version is fantastic. Thank you for mentioning it, it looks like I'll be able to migrate to FreeCAD now. Sorry I am only able to like your video once, there ought to be a more emphatic like button for this!
It's definitely an annoying issue until you work out how to deal with it, I fought with it for years before I bothered to actually research why. It's hard to move to any new tool and customisable/parametric design is definitely not a simple concept.
If you don't have any luck or continue to get frustrated, I highly recommend trying RealThunder's Linkstage3 branch, the new topological model is on par with or better than a lot of commercial offerings. You can still break things, but it's only a small fraction of the time and it's easier to fix.
I guess one way I could try to really summarise the "correct" workflow for 0.19 is;
Every sketch must have an absolute position rather than a position relative to part of the body, which means every sketch must be started on an origin plane, then offset and rotated as needed.
I hope at least some of this made sense, if there is anything I can do to help, please let me know.
Good luck!
I've been doing the plane fix for a while. Thanks for the tip on the Real Thunder.
Wow. I'd call it the "Name continuity problem" instead. Such issues show the difference between a creation program (where edits are difficult or break things) and an editor (where you can ideally change - edit - anything you want). Thanks for pointing out ways to deal with this huge issue in FreeCAD. By the way, I'm loving the open source nature of FreeCAD and appreciate all the work of the various developers.
Well it took a while but it looks like TNP gets finally fixed this year.
With V22...
Thanks, it's a very good description of how and why.
I started learning 3D modeling recently using FreeCAD and already started to experience breakages due to the topological naming problem. I was able to fix them, but it's tedious.
Your workaround is very good: referencing meaningful dimensions instead is semantically better than faces IMO, but won't work for filets or complex paths coming from the output of various features.
Thanks for highlighting that realthunder's fork is build to solve the that! I'll switch to it and report issues now !
Also, subscribed 😃
I agree. There are other topo naming problems that arise even when following this workaround. (Like the pads themselves getting mixed if pads are deleted/added?)
Did you find those all fixed in real thunder branch?
Thank you. My FreeCAD model broke and this video was very helpful in helping me understand why.
I appreciate the bits of humor thrown in. :)
Excellent video! Really appreciate your explanation for why and how you showed to combat! Thanks!
OMG, thank you! I was pulling my hair out trying to figure out why making a revision to my model was causing everything to break and features moving to entirely incorrect places.
I'm so glad that I was able to help.
You can also try RealThunder's experimental Linkstage3 build (link in the description) if you're having issues with more complicated designs and placing datum plane's/offsetting sketches to the right places.
Wooh, definitively the best videos on FreeCAD i saw on youtube ! Thanks.
Tha ks for the kind words!
It's great to hear a Bazz. (read Oz-Trail-Ian) accent making such an informed and clearly articulated analytical video. I'm an FC newbie and, after many montha of bashing my old head against the Blender wall, I now know that this is the package GP draughting package I've been looking for!
Well done mate, Cheers, pk (Central Vic.)
Cheers bloke!
Sorry Brodie, I'm an old fart trying to be 'current'; it's ok, after more than 50 years of programming I'm truely used to failure.
Cheers Lassie, p.
@@nedbazzvictoria6948 no worries, I quite enjoyed the comment 😄
@@BrodieFairhall
Thanks Brodie, you are clearly (I assume) in Oz, what state? (and I don't mean 'stoned', 'happy' etc).
I guess the benefit of being able to sketch with respect to external geometries is "theoretically" as the base geometries change, the sketches and features that depend on them would also change in response. But you could get around this by making the model parametric anyways? I'm probably not in the majority, but I feel like defining the relationships explicitly as parameters external from the model would be more future proof and easier to change.
That's exactly how I design most things, with a spreadsheet and using absolute references only.
Chamfers and fillets become a little more complicated / tedious to do this way, but things just don't break.
Yes, that's how I do it. I don't base sketches on generated geometry at all. Everything is defined numerically in a spreadsheet and/or a set of master sketches.
I've never really come across the TNP.
Brodie, I'm now a subscriber:- you'd be very surprised to learn more that we have in common !! PK - Ned, Oz, Central VIC -- I'll find you somehow.
Very good explanation. I had just heard about this problem but have not had time to properly explore the issue. Hopefully we will have a nice solution to this problem in the stable packages some day.
I have found that it doesn't even require adding or removing faces. Simply changing a dimension can cause the topology to be rearranged, even if no new edges or faces are created. This not only breaks subsequent features, it breaks assemblies. I have also found that if you modify a dimension up the tree that causes a datum plane to be hanging out in space, this is a Big Deal that I was unable to solve without deleting all subsequent features and rebuilding it. This is still an issue in 0.20. Hoping for 0.21? 0.22?
The 0.21 Dev version has the first lot of topo fixes from real thunder added in. After 0.20 came out they committed to having the tnp fix in 0.21.
@@BrodieFairhall Great news! Thank you!
There are 2 distinct types of objects in FreeCAD fixed and volatile. If you don't distinguish you will fight for ever.
Fillets and chamfers just have to deal with both, so that struggle isn't easy. Always do them last.
Excellent description - thanks
Excellent video (and funny too!), I am no longer confused. Good to know about that fork too. Wasn't the correct pad at 6:08 supposed to be Pad002?
Thanks! And you're correct, pad isn't even on the same body the new sketch is going on.
@@BrodieFairhall Cool, I just wanted to make sure I wasn't missing something re. the label vs. the underlying object name.
Oh wow nice - you can use the name of a command and extract values - I did not know that.
Even before I started using freecad, I saw another video explaining this, and got that forked version, it is a bit different when following your videos, but I could find a way around, and it seems like for the 1.0 verison they will finally fix this
The topo naming fix is being rolled into the current development version. So FreeCAD 0.21 will have the fix 😊
What is the benefit of using an extra datum plane instead of simply creating the sketch and off-setting it directly?
I typically offset sketches, a datum plane was easier to visually demonstrate for a video though.
Datum planes are really nice when you have a complicated offset with rotation that you may want to re-use to base multiple sketches on.
Also I know there is quiet some drama in the background at freecad, there still is one thing for me: This is not a "problem", this is a bug, a deal breaking bug. I'll stick with RealThunder till it's fixed. Great video never the less ;)
Realthunder is an absolute genius.
Amazing tutorial. Thanks from a fellow Australian
Geat work! Thanks.
What do i have to look for in the changelog to see if this is implemented?
Anything related to "Topological Naming".
There is currently a PR waiting to be merged for FreeCAD 0.20 github.com/FreeCAD/FreeCAD/pull/4752
Hopefully it is merged soon, while I will still design using absolute references for most things, there are some workbenches & tools that basically require it to guarantee there won't be issues with changes (such as surface) and part design tools like fillet, chamfer, Draft and thickness.
@@BrodieFairhall Thanks for that information!
I'm just thinking about using a branch with this fix included because the annoyance of breaking everything over and over again is bigger than the risk of incompatibility for me. I just broke models from 0.17, so i'm kinda used to it ;)
Thank you again, this should help me switching to FreeCAD
0:12 ... i actually read all the error messages .... why? .. because I am used to FreeCAD, so just a few of them are no issue to me!
In general I have no longer had the topo problem on the latest 0.19 version of Nov 2020 with Asm3 workbench. Had major topo problems earlier no have had non for chages on a transformer model for 16 changes of details on variants.
Hoping the topo issue is being put to rest.
Do you ever use the FEM plugin? I've been breaking my mesh in many different ways. I have now come to a point where I can make the structures I need to.
I use the FEM workbench on occasion to find the highest points of stress on some of my designs and improve them.
@@BrodieFairhall I appreciate the quick response.
So I've come to a realization that my problem still stems from topological naming problems. When A2+, or part fusion, compound or boolean result in topological naming issues that I cannot resolve. Now what I've come to realize is that by building my object from just one part FEM and Gmsh have no issues.
I wonder how you are able to have the model tree as overlay in the 3d view. Do you need an addon for that?
This seems to be a nice feature.
It's the glass add-on, you can get it with the addon manager. Make sure you read the instructions on how to use it too
@@BrodieFairhall Thank you very much
Great Video. Thank you!
Very helpful, thank you
Hey are you still working with FreeCAD or have you given up on it already? I'm rooting for it pretty hard but it seems like even in 0.20.1 RealThunder's fixes haven't reached FreeCAD yet...
I still use FreeCAD for all my 3D CAD work. I'm even presenting at this conference about it in a month hopin.com/events/freecad-and-free-cae-users-conference/registration
The team committed to getting the topo naming fix added into 0.21 and you can check out the progress here (github.com/FreeCAD/FreeCAD/tree/development/toponaming)
@@BrodieFairhall sounds great!
I'm really looking forward to FreeCAD 1.0 (the Version where FreeCAD finally overtakes proprietary software). But I guess this will either never happend or will take 30 years or more from now :/
That can happen with a different strategy. Publish 1.0 asap with what is available, instead of waiting for new features. Rapid development needs lots of developers. And that in turn needs a big user base. 1.0 releases attract a lot of users who are weary of alphas and betas. Only application and feature stability needs to be guaranteed. More features can be added to 1.0 branch as long as they don't break the workflow. Meanwhile a 2.x development branch can be started to be that version which overtakes proprietary software in the long term.
This was more or less the story of blender too. It wasn't much of a competition against commercial software up to version 2.5. But users were confident in its stability and therefore had good developer attention. It consistently improved to a level where 2.9 series is very competent against proprietary alternatives.
@@gokuldastvm I don't know if that would change anything. Have you ever tried the mainline FreeCAD 0.19? It's not even usable. RealThunders branch is at least usable but still far from perfect.
@@blendarious I do use FreeCAD 0.19. A 1.0 release won't change anything when you look at it from a feature point of view. What it would achieve is to get more people to try it out and pitch in for development. This kind of change is evident from other FOSS projects that made such a transition.
Hey Brodie, I've been looking for you; tried to 'join' Facebook - was banned for "trying to create multiple accounts" !! I can appeal but they want a real photo (they 'promise' not to use it - NO thanks, tried Mastadon - no joy - no Brodie, tried Patreon -same - almost joined BIG OOPS - any other hints? am I spelling something wrong? I have some lovely stories to share with you from AutoKEY to the Car insustry. Cheers, p. ps "Happy New Year Brodie", p
GOT IT "MASRERDON" and (lately), "Fosstodon", catcha soon Brodie, p.
could you do threads next? I have been using free cad for about 2 months now and decided to hit up windows and try fusion 360, threaded objects are so much easier to do there, of course I'm not about to start using fusion so I would be very interested in learning how to do threads efficiently in free cad.
Funny you should say this, I'm recording a short video on that today (it will take me up to a week to out it out)
Thanks a lot mate, I appreciate your work!
@@BrodieFairhall Up to a week, OK :D
@@SianaGearz Life gets in the way sometimes.
What’s your view on placing darum planes on shape binders you got from faces ?
If you want to avoid topo problems in 0.19, my stance is that datum planes go on an origin plane only.
Shape binders will break in the same way that a sketch on a face will.
Sub-shape binders can have their "Bind Mode" set to "detached", which theoretically removes the referencing issues because the face is no longer referenced, but it also means that if you change the surface it is bound to, the sub-shape binder won't update.
I see yeah good points.
Btw do you have a good explanation of shape and sun shape binder ? I fail to grasp the clear differences.
Is shape binder the only way to make a reference to a different body ?
TNP is so much not an issue in fusion - i hopes real thunders work makes it into matter
I don't have an explanation that would fit nicely in a comment, there are some good explanations, I think AndrewCad has a good video on it.
Unfortunately the answer is, don't reference bodies, that's really it (I'm not just talking about FreeCAD either, for customisable and highly parametric parts in fusion or inventor I'd still only use absolute references).
Instead of referencing anything, I'd recommend looking at using spreadsheets and / or mastersketches.
There is a pull request in the FreeCAD 0.20 Dev repo to include the toponaming fix, it's an enormous PR so it will take a little time for it to be merged, I'm hoping in the next month or so.
@@cekuhnen ua-cam.com/video/MCY5IrWrHrU/v-deo.html
Here is the Shape Binder vs. Sub Shape Binder explanation from the Andrew Cad channel. It's a really good explanation of the differences between them.
I watched it few times and still struggle they seems to basically so 90 the same
I should stop crash learning it
How do we download real thunders version when i go to your link there are about 15 different links which is it? or is it all of them is there an easy way for non software engineers to do this
Hi, im still learning.. should i create and name a number datum planes as i start opening a new file? if i have a good idea where they will be?
If you know where all the datum planes need to be, there is absolutely no reason you can't create them before creating any geometry. It's more personal preference, if doing that suits you, go for it.
Whhaaaaaat! Well that explains a lot. Thank you.
Apparently FreeCAD ver 1.0 whenever that comes out will have that fixed.
It's fixed in the current Dev version.
Very interesting video! Love FreeCAD, but this is one of the weaker points. When they fix this, I think a lot of new users will flow in.
There is a Topo Naming fix PR for FreeCAD 0.20. So it shouldn't be a problem much longer
@@BrodieFairhall Thanks. Looking forward to it! 👍
While not the point of this video, I can't stop but laugh at the 'claim your prize' error and all the following terminal/bluescreen stuff that showed up 😂
I'm glad, because I probably spent more time on that part of the video than the educational content.
Is this fixed in 0.20 ?
The fix is partially implemented in the 0.21 Dev version and of course in realthunder's linkstage 3 branch.
The fix didn't make it into 0.20.
I thing the problem is most important problem for freecad.
This seems to say it's a "name space" problem, the faces exist in a global name space not a local sketch name space which is where they should live as they are a product of an operation on a sketch also not sure why I can't explicitly name a face.
It has been fixed and is in the Dev branch as well as RealThunder's Linkstage 3 fork, if you want to check out how it was resolved.
I'm puzzled with this so trivial problem in FreeCAD, is it that hard to give an absolute references to geometric objects? I mean, programming speaking, just set a big hexadecimal number (64 bits) randomly generated, then check it if already exists (1 in billion), if not, set that reference as writings on a stone. BAM!, Problem solved! :idea: :idea: :idea:
This is unbelievable! :lol: :lol: :lol:
It's a fair bit more complicated than that unfortunately, otherwise it would have been solved back in 0.17.
Don't worry though - forum.freecadweb.org/viewtopic.php?f=10&t=66407
@@BrodieFairhall Maybe because it was programmed in a slow language as python, in C++ scanning references, in this case already compartmented in shape names, is pretty fast. So, I believe this has to do with the chosen programming language being too slow (ex. Python)!
@@Popart-xh2fd not the issue at all.
WHY the names change? This shouldn't happen
This happens in a lot of CAD software actually, essentially it's because the model is being re-built from the last part you change each time you change something. I'll be surprised if RealThunder's new topology model isn't merged into the main branch of FreeCAD immediately after 0.19 is released as stable (which should be very soon)
attention devs : FIX THIS !!
Sev 1 priority 1. No new features until this is fixed. Real thunder models aren't compatible.
FIX THIS !!
FIX THIS !!
FIX THIS !!
FIX THIS !!
FIX THIS !!
FIX THIS !!
FIX THIS !!
FIX THIS !!
FIX THIS !!
There are no datum planes in sketches, are there? I use sketches for constraints.
4:38 This workaround might work, but I encounter similar errors when adding geometry to a sketch: my tool paths get mixed up as to which faces they use. I don't know how to fix it, or how to even know if topo naming is the problem.
I'm not even sketching on a face.
It really messed up work flow and ability to edit designs. Took me a day to figure out what happened. "Oh it might be topo naming". Arg!
Linkstage 3 is a highly experimental version, so you can't expect things to just work between the two. There is a compatibility option in Linkstage3 that you can select that will disable multi part bodies to make the files compatible, but it won't prevent topo naming issues from occuring if you haven't designed with that in mind (even using Linkstage 3 or any other similar cad software, such as fusion, you should still use absolute references for sketches, not sketching on faces if you want a robust model you can change dramatically).
I use 0.19 for commercial work, because I understand the topo naming problem, it isn't an issue at all. I don't use Linkstage3 for commercial work as features can change at any minute.
If you've been following along with FreeCAD Dev, the realthunder robust topo naming fix has been merged with the 0.20 Dev version, which you can download and use (remember, it's an early Dev version, so it's not as stable as 0.19). The topo naming fix won't be added to 0.19.
As for sketches and datum plane's, you put a sketch on a datum plane, you can't put a datum plane in a sketch. You can still use master sketches for constraints and not have topo naming issues.
If you like Linkstage 3, just use Linkstage 3.
Also, look at the size of the core Dev team, it's tiny, almost all of them have full time day jobs too. So, maybe consider contributing or donating to help them move FreeCAD along faster, as they don't have time to come and dig through my UA-cam comments to see you demanding fixes. (The forum is the best place to get information and help)
@@BrodieFairhall Man I'm sorry for the rant. I do appreciate all their work. I have submitted bugs in the past, but in the end they weren't fixed for various reasons.
And thank you for the response! I'm using v.19 and not sketching on planes.
Even using shape binders, I still get bugs if I rotate that hex shape with lines constrained to recreate the shape in another sketch. Seems like the edges are renamed depending on rotation (topo naming? Idk). Maybe I'm not doing it "the right way". That is part of the problem: too many ways to achieve a result, and only a few are the "right way".
@@TheRainHarvester shape binders aren't topologically safe by default, remember, you're still selecting a face or edge of a model to create it. Everything must be created referencing the origin, not an object.
Sometimes the easiest thing to do is just copy and paste sketches.
A few things I really hate about FreeCAD:
- So many devs do their own stuff instead of working tight together to make the most awesome software possible (general Linux problem)
- They try to be good at all which results in being not good at anything (They should focus on Part Design, Assembly, Sketcher & TechDraw)
- Missing important features like Extrusion/Cut feature with face selection & Measuring tool for lines, circles, distances of any kind (see Fusion360)
PS: realthunder should join the mainline -> Support him @patreon
Why do you feel they should they focus only on Part Design, Sketcher & TechDraw? Are they the Workbenches you personally use?
Everyone codes on their own branch of FreeCAD, realthunder is such a prolific coder that they can't keep up with his changes fast enough. Every pull request has to be fully reviewed before merging with main. Also, he sounds pretty "mainline", as he gets an equal split of all donations received by the project. wiki.freecadweb.org/Donate/en
Have you considered forking FreeCAD and adding a measuring tool yourself?
There are some measurement tools but they are less polished. There are some tools for it in the Tools menu, there are a few items in one of the menus in the Part workbench. There is a separate inspection workbench. And there is a macro you can download for volume/area calculations for a body.
@@VorpalGun The measurement tools in Part workbench are very basic and I don't need 8945702 workbenches + 90834 Addons. Just one well thought Part Design workbench with all necessary features is enough.
So many of them (there are 3 main devs) are doing it for free.
@@paulg3336 Only 3?! They should try to become a part of Linux Foundation, Blender Team, etc. That's the only way to get way more devs working full time on FreeCAD
Who in the right mind thinks that changing set names that work as some sort of ID should EVER change?
It's not really "changing" the ID's and when you look into how it works, it's a little more complicated to do than it initially seems. The issue is that every time you make a change, it rebuilds the object from that point and the ID's are created each time this happens. My understanding of how the Topo naming fix works, is before a change is applied, FreeCAD works backward through the nodes and notes which actions rely on geometry that was previously created and when it rebuilds, it tries to ensure the same ID gets applied to each piece of referenced geometry.
@@BrodieFairhall Thanks for the explanation! I wonder how other CAD software handles this …
until the freecad community fixes these problems OFFICIALLY, people will always try to use ANYTHING other than freecad.
freecad is nice and all, but it leaves a sour taste in your mouth that makes you realize what a royal mess it is, even if the potential is IMMENSE.
You have to realize that a lot of modellers don't make parametric models to begin with, so this would be much less of an issue for them.
Ridiculous.