Making an Add-on for Precision Drawing Tools (CAD)

I’ll look into how to do that…

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Added automatic Button enabling/disabling where appropriate, like:

Object in Object Mode.

Object in Edit Mode.

We are thinking about a proper manual, “what format and where” are the two questions we are wrestling with, any thoughts please?

We have also moved all the button labels to the messages file, so any can be translated/altered. I have not found out how to make a “settings” function for PDT, any hints anyone, like an add-on I could study for the right way to do this?

Cheers, Clock.


I’m observing_you,
So I can tell you what happens and what will happen.
You are now expanding your knowledge and confidence in blender coding and you are going deep and deep.
But at some point you will discover something that will revolutionize your way of doing things and at that point your mind can no longer do without wanting to rewrite everything according to this revolutionary idea …
You will probably just decide to rewrite a PDT 2.0, the revenge. :joy:

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Oh shit, I am being watched, this is not good! I am, however, being kept on the straight and narrow path to enlightenment, by my good friend @ermo so all is well. We are planning Version 1.2 where there will be new features, but that is some time away, we need to get this one right first. And we need a proper manual, so that will keep us busy for now.

Maybe Version 1.2, “The Draughtsman Strikes Back” :laughing:

Cheers, Clock.


OK, I have found this:

Now I can look at Add-on Preferences, phew! that took some finding…

Cheers, Clock.


We are toying with the idea, well I am and need to clear this with @ermo, of having a Preferences selector that says something like “Blender Polygon Modeller”, or “CAD Draughting Modeller” as two choices that sets the contentious button names to:

Global, Relative, Polar, Perpendicular, Intersection, Bevel
Absolute, Delta, Direction, Normal, Convergence, Fillet

Also, elements are normally referred to in CAD terms as Points, Lines and Polygons, do we need to change anything here, or is everyone happy with Vertices, Edges & Faces.

Any thoughts please? also what else do you good folks think should be in the Add-on Preferences?

For those who don’t know, a “Polygon” is either a closed 2 dimensional shape, existing in a 2, or 3 dimensional world, having at least three sides, or is one of these:

You will note the parrot has escaped… :rofl::rofl:

Cheers, Clock. :wink:


We have started the Wiki for this, rather than have this all on the website:

I should be really grateful if some of you good people could look at this and tell me if it readable, logical, does it explain properly, is it fit for purpose? It is sometimes difficult to write a manual for something you completely understand yourself, so some other views on this would be nice.

I think things like “Am I over-explaining this”, “Am I leaving out important information”, “Is this succinct”, etc. are all important considerations to how a manual is perceived by a User rather than the Developer.

Cheers, Clock.


OK, so no-one wants to tell me how crap my Wiki is then. :grin:

I have started to look at Add-on Preferences and came up with this:

Now you can set the path and library file (you might have lots of library files in one folder) in the Preferences, then work from there. In the image above I have appended a Collection called “Trials” which contains the engine assembly you see in the 3D viewport.

As soon as you press Return, the Parts Library Selectors are updated.

I need to work out how you can invoke the Path selector, that would be a better way to do things, but I haven’t got there yet, so I just type in the path for now.

Cheers, Clock. :mantelpiece_clock:


Well that was easy:

pdt_library_path : StringProperty(
        name="Parts Library", default="", description="Parts Library File",
         maxlen=1024, subtype='FILE_PATH'



The new Wiki looks great at first glance.
Well organised, detailled, plenty of pictures… all I would hope for in terms of good documentation :slight_smile:


Thank you and welcome to DevTalk!

Cheers, Clock

my stupid mind, used to scrolling vertically in and with classic wikis, hadn’t seen the menu on the right, and I had believed that the wiki was under development …
But now I have investigated better and I have seen all your work that has now become really professional, and remembering where you started from, I must say only, great job!
I think you’re ready for blendernation community. :rocket:

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I found this guy on youtube that tries to create a model in a precise way … it uses interesting tricks to get results on the meshes … maybe you can give it a look … and maybe you could create some tools that use similar techniques to get results (obviously I mean, automating interleaving processes … especially to create holes in the meshes …)

@nokipaike That is a long-winded way to do this job IMHO, I will do it my way, before I go on holiday for a month, or when I get back. I will use PDT to do it.

Release 1.1.5

In the meantime, @ermo and I have now made a Version 1.1.5 Release Candidate on our GitHub in the Latest Release page.

Many thanks to @ermo for all his efforts in changing my amateur mess into a releasable product. We have also worked on the Wiki and code structure, so hopefully you will all be able to use it easily! To that end, if anyone wants to test it for us, that would be greatly appreciated.

Cheers, Clock & Ermo.


OK, so just under 5 mins 30 seconds with PDT, but then I wrote it, so I should be fast with it, that time included finding all the dimensions from the youtube vid, shown in Isometric View:

Nice mech. topology, yum, yum :yum::yum:

Seriously, CAD techniques produce faster results and better topology for precision work, but you can’t use Sub-Div modifiers, but then you wouldn’t want to… I did not start with a cube, I started with a single vertex BTW.

Cheers, Clock. :grin:


Hey, I’m confused, but didn’t you say that you left for now?

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So I finally had the opportunity to review the PDT Wiki on GitHub. My first impression is, good. Very good; well organized, easy to read, and quite in-depth. If I had any critique to make from a new user perspective it would be that that it is quite in-depth from the point of view of a developer with CAD experience.

The tool’s description is informative, and the examples are inspiring but neither teach “me” how to actually use PDT. Thus I humbly request some step by step tutorials; time permitting.

I would have loved to have seen how you assembled the “model in a precise way” example utilizing PDT. Unfortunately, from experience, I do not have any screen/video capture software suggestions to offer, per your previous request. I am surprised no one offered any suggestions. When I did a general search OBS (Open Broadcaster Software) kept coming up though it might be overkill for making simple tutorials.

I also in my searching found that there is a tutorial series from FXhome the makers of Hitfilm Express that covers the process of doing video recording, and editing for a “gaming channel”. I imagine the techniques, give or take some green screening, would be similar for a tutorial series. I only mention this particular series from this particular software because I have some limited but positive experience with Hitfilm Express and their tutorials.

Also, I guess, gulp, I am offering to help with editing tutorials if you or another user records the step by step screen capture video(s).

Anyhow, as always, very impressed with the development of PDT, giving two thumbs up to its wiki, and looking forward to learning how to incorporate it into my workflow.



@dcbCreative Thank you for those comments, I. take on-board all you have said, and can reassure you that tutorials are part of our future plans.

However, Mrs. C and I are going on holiday 1st November for a month and I have a load of time pressures before then, not least of which is that the European Aviation people have decided, in their infinite wisdom, that we owners of gliders must now have new aircraft log books and we must hand-write in them every air directive ever issued for our aircraft, mine is 56 years old, so I say “Thank You” to EASA… My glider has just undergone it’s three year major inspection and there is a lot of paperwork to do associated with that before I can fly her again.

Then there is the packing, etc. etc. So I will get around to tutorials on my return, but have to say I did try doing these once and ended up swearing, because I got the words wrong, not good and doesn’t look professional!

Thank you for the offer to help with tutorials, I will certainly take you up on this, once I get home and start this. On the matter of the Precision thing, I only had time to do it, not detail how, but I will do this after our trip. As for the Wiki, I just wanted to get the basics in place, so we had something to go with the Add-on, there is much work still to do and detailed worked examples are one of those things.

Cheers, Clock. :beers:

PS. Thank you to everyone who has encouraged and supported us through this journey with PDT.


Just wanted to add that people should feel free to clone the wiki and suggest improvements in the form of github pull-requests. The same goes for the code naturally.

If people play around with PDT and can’t get a specific function to work the way they expect it to, we very much encourage you to leave a note here (possibly with a short video) so that we may engage in dialogue and – if necessary – transform it into a proper, actionable github issue that we can assign to a release as part of the release process.

And yes, @clockmender is quite an experienced hand when it comes to CAD and Mechanical Design, which means that some of the tricks of the trade he uses are effectively “silent knowledge” that may not be immediately obvious to someone who wasn’t trained as a draughtsman.

Please note that I myself am still getting my head around many of these tricks and processes, as I was only trained in SolidWorks, which approaches the design process quite differently. I enjoy the challenge though, and will do my best to act as a proxy for the “new-to-Blender-and-old-school-CAD-neophyte” to the eventual benefit of everyone (or so I hope!).

While @Clockmender is away, I have promised to handle bugs and issues as best I can. From a release perspective, we have agreed to go into feature-freeze and will focus on stabilizing and polishing off any rough edges in both the code and the documentation.


Opps. I just realized I neglected to include a link to the tutorial series mentioned in my last reply.

I edited it, but there is the link as well: How to Create a Gaming Channel - Game On, by FXhome

As for tutorials, no-worries-no-hurries, I just was just attempting to provided some constructive forward thinking feedback about the wiki. It is quite obvious that you and @ermo have your hands full with development already. Someday though, when time permits, I look forward to learning a some Blender style CAD tricks from you.

It is the currently busiest time of the year for me at the office thus excluding this weekend I haven’t had the opportunity to play with Blender as much as I would like. Learning to use PDT is though on the top of my to-do list for the weeks ahead. I make no promises of impressive results but I intend to to take notes as I dabble with the aid of the new PDT wiki and hopefully can script a few basic tutorials myself. From the point of view of a Blender / CAD novice.

In the meantime, May you and Mrs C enjoy your holiday. Should you encounter any more chatty penguins or photogenic flying fish be sure to share the experience.