Precision Modeling LIVE!

Wait… math?


I’m just gonna model a cabin or something…


I dare you to model the running gear of a tank.

And not some made-up thing, either. An actual, real, existing tank’s running gear. And get it all right.

Go on, ya know ya wanna!


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I think a little more than 2 dimensions are missing. But with such knowledge, program, mathematics - as you wrote - you can do it ;-). Seriously, I can hardly see professional modeling with such knowledge of technical drawing. You might as well model from Dave’s drawing which doesn’t contain any dimensions. As a blueprint

Thanks, Aaron, nice Live and useful!

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Good work as usual, @TheOnlyAaron. I finished up the wrench model while you were doing that last part. I hope you’ll model it next time. I want to see how you’d go about it.

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Well… Yes, Aaron, these drawings are for students. And they are used in engineering programs that can find tangency, parallelism or the same length of lines by themselves, I wanted to see more but… As I wrote before. For fan - yes, for work, precision work - not

It was a great livestream though I didn’t watch it live, next time it would be a good idea to do it using som plug-ins like bevel or round corner and solid inspector to fix everything faster. Also please Aaron set the shortcuts before your next livestream, it made me feel a bit anxious seeing you go to the menu to enable hide rest of the model, also enabling a shortcut to show hidden geometry would’ve been useful.

I would question whether the drawing #1159 is a “studycadcam drawing”. I believe it to be an engineering drawing from the 1920-1960 time frame. In that period a part such as #1159 would most likely be cast iron. The process would be for a draftsman to prepare an engineering drawing including the functional features and machining dimensions, then a Patternmaker would have made a wooden pattern and core prints to be used by the foundry. The foundry would cast the part, them the machinist would machine the part to the specifications of the engineering drawing.

“an (intentional?) combination of missing dimensions and dimensions placed in confusing ways that force you to do deductions and math to figure them out.” No those missing dimensions were not missing at all. Yes it was intentional.

The Patternmaker had great responsibility in the manufacturing process. The wooden foundry pattern had to include “draft” and “fillets” to enable the pattern to be withdrawn from the sand mold. Patterns also had to be made oversize to allow for shrinkage of the molten metal as it solidified. The Patternmaker knew what size the fillets needed to be and he added those. Fillets were sized to avoid cracks in the metal as it cooled. He also added bosses to the part as needed to setup the part for machining, thus he had to have some machining knowledge to pattern the part in a way that it could be accurately machined.

When the casting was completed, it went to the machinist. The machinist would work to the specifications included on the engineering drawing. Those “placed in confusing ways” items were of no interest to the machinist for their work thus were never a necessary part of the engineering drawing.

Drafting procedures back then were very specific about what should be included on a drawing. Dimensions were also placed in ways dictated by conventional practices.

Enjoyed the live stream. Thanks to those that make it happen.


It was another excellent live stream @TheOnlyAaron. Perfect!

It was mentioned in the announcement; ‘ONLY native tools’. By precisely only using Native Tools you show what is possible with SU to create technical drawings. Very welcome for the less experienced designers. Thanks!


You’re wrong. This is not a technical drawing from that period. /even the signature under it with copyright proves it!

Ale ten rysunek posiada wszystkie wymiary. Wszystkie do jego wykonania w … 10 min? Nawet na desce kreślarskiej z okresu lat 1920-1960. Niestety wiedza Arrona na temat rysunku technicznego a w szczegulności zasad wymiarowania nie podołała temu zadaniu. Swoim postem zachęciłeś mnie abym zajrzał jeszcze raz na you tube. I okazało się że to nie komedia. to dramat.

“I can’t find…”

Is it just me, or is this thread kinda turning into a Monty Python bit? :thinking:


The following clearly illustrates the precision of the SU. A circle of radius j1 unit. It would seem that the surface area will be 3.14, but not in SU… Only increasing the number of sides to 117 displays the correct result with 2 places of accuracy. Of course, the volume is even worse.

EDIT Aaronie’s post is absolutely on topic since we’re talking about precise modeling in SU. It shows the precision of the program.

But I see you’re covering your tracks with the old habit. Unfortunately, the video on Youtube remains.

Thank you for the interesting historical and technical perspective!

I don’t know where they may have lifted it from but the copyright notice at the bottom clearly states ownership by

I stand by the observation that there are missing dimensions. It is impossible to create a precise 3D model from those drawings without them. But, as you explained, the omissions were intentional based on the understanding that the pattern maker and machinist would fake them in based on shared understanding of foundry and machining practices and suitable approximations.

I’ve seen drawings for many of the objects shown on that website in old technical drawing textbooks from the late 1800’s and very early 1900’s. I’ve made models of some of them based on the hand drawn work in those old books.

These are not intended as manufacturing drawings. They are intended to be used as examples for drafting education.

Yeah, some people are like that. they feel the need to spew negativity all around them. like human banelings.
Best not to engage them.

Cool live anyway.

yeah, people often assume extensions open a new world when in fact most of them actually simply make you faster. Sure, you could use an extension to chamfer or fillet, but you can also use a follow me or a solid operation. and curviloft can be replaced by knitting the faces or your object triangle after triangle (been there, done that). but it’s quicker.

Vanilla sketchup pro, or even sketchup web / ipad, as capable of a lot of things.
I mean, look what Dani makes on an ipad.


How precise? I’ve correctly derived a dimension to three decimal places* from high resolution images alone when there have been no official numbers available. It took many hours of patient weeping and the shaving of whole years off the life of my eyeballs, but it can be done if it has to be. Unless you need the dimensions to be more than three decimal places, in which case I wish you all the luck in the world.

*The dimension was later confirmed by a manufacturing contractor after my incessant whining broke his spirit and he breached an NDA to provide the actual number just to shut me up.

Most days on the train I see kids creating phenomenal art just with 'phone apps and their fingertips. You can’t keep talent down.

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One of the first lessons I was taught on construction sites when I started was not to demand millimeter accuracy.
They showed me a flexometer and told me that the large (cm) and medium (1/2 cm) lines were seen by the workers but the small (mm) lines were not.
It was very clear to me and I still keep it in mind.
It is impossible to execute a circular concrete column with the precision that we are trying to achieve with the design software. Maybe for electronics and other sectors it is required but “precision” is not always going to the third decimal place. There are times when it is better to pay attention to how things are done and not how they are drawn on the drawings.

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Absolutely. It is too easy to venture down the OCD hole, never to return. We want perfectly accurate drawings, despite the fact some of us (ahem) can’t accurately cut or weld to single decimal places.

But try sleeping at night when you know that one dimension is only 59.71" when it’s supposed to 59.715"…

:face_with_spiral_eyes: :laughing:

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honestly I would stay awake all night too if I had to use apostrophes and quote marks to mesure things :clown_face:

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