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The first image on the actual paper really tells the whole story. CAD for mechanical design, by necessity, requires pretty immense specificity. It is more onero

The first image on the actual paper really tells the whole story. CAD for mechanical design, by necessity, requires pretty immense specificity. It is more onerous to type out "now raise the height of the torus relative to the base 4mm" than to click on "extrude" and type 4 or drag a handle. Injecting a natural language layer into the workflow is just not optimal. CAD itself is not a difficult tool to learn and use effectively. There are essentially no layers of abstraction that an LLM can assist in cutting through, and no obfuscated rules or languages to learn. I think of it this way. If there was someone sitting at my computer, and I had to do all of my CAD design by explaining what I wanted them to do verbally, I'd rip out my hair. LLMs are doing for programmers what virtual CAD did to the drafter 35+ years ago, optimizing the effort expanded to create the thing already in your brain

rehevkor5 4mo ago
While you're probably right about >90% of situations that fluent CAD users face, I think you might be suffering from a lack of imagination about situations where an LLM could help do work which would otherwise be tedious or mistake-prone. And then you have the non-fluent CAD users, just like the non-programmers who are now vibe-coding: this stuff can be a game changer for them even if it's far from "good" right now.
abdullahkhalids 4mo ago
> If there was someone sitting at my computer, and I had to do all of my CAD design by explaining what I wanted them to do verbally, I'd rip out my hair. Isn't this how a lot of machine shops operate, or how things operate internally in larger manufacturing factories? Customer/person-from-different-team comes in and explains what they want to do. Maybe they have some sketches or pictures of similar parts. Then there is back and forth with the CAD guy to build the thing. One critical difference is that the CAD guy is usually smart and you have to explain to them things at a more high level, along with some written down hard numbers that need to be obeyed.
coldtea 4mo ago
>I think of it this way. If there was someone sitting at my computer, and I had to do all of my CAD design by explaining what I wanted them to do verbally, I'd rip out my hair. I, on the other hand, have used LLM + OpenSCAD to design stuff - while I pulled my hair out everytime I had to sit and write OpenSCAD primitives or use a UI CAD like FreeCAD or Fusion360 and their horrible unintuitive interfaces.
8note 4mo ago
virtual cad did something major compared to drafting - you switched from only being able to represent certain views of an object, to having a stored full representation of the object. you could sculpt a model à la ILM for star wars or the architecture models, but the only way to have a copy of the object was to make one. the virtual cad also brought in the ability to do analysis with FEA and get approximately smooth undestandings of the stress and strain on the piece, rather than manually calculating the critical points and stress raisers for doing analysis
jjk166 4mo ago
Definitely for fine adjustment you're going to still use the manual CAD tools, but you can describe things much faster than you can model them. Good prompt engineering is important here as much as for any other AI use case. For example let's say I need a parametric model of an involute gear with a 14.5 degree pitch angle and a 0.5 inch hub with an 8-32 set screw where the OD, number of teeth, face length, and shaft diameter are all variable. It takes seconds to write the prompt and then adjust the variables to what I want whereas it would take tens of minutes to actually model even for a highly skilled drafstman. The time savings get more extreme the more the modelling work is looking up information online. For example if I wanted a model of a lightbulb electrical connector, 95% of the work is just going to be googling. Technically you could have an LLM just tell you all the dimensions you need and then model it yourself, but that's definitely still going to be slower and you have to put in the effort to figure out what each dimension refers to. It makes sense just to cut out the middleman. Add in the fact that CAD is in fact a difficult tool to use and learn effectively. There is a subset of the population that is very good at picturing and orientating objects in 3D space in their minds, and engineering is mostly limited to these folks. For those whose minds work differently, CAD is extremely tricky to learn. An alternate method of interacting with models that does most of the heavy lifting such that a person only needs to tweak a near complete model could be extremely helpful to many people who would like the benefits of CAD design but have struggled to learn the software. It's no different than AI generated art opening digital art to those who are not good with digital artistry software.
- zonkerdonker 4mo ago
  https://www.mcmaster.com/6325K113/ https://www.mcmaster.com/6325K113/ Download model, done. Not attempting to be sassy, sorry, but maybe I can explain my point a bit better. If you are making something complex enough to warrant you yourself designing it (something unique, custom, new), then CAD on its own is the best tool (right now!). I have models with thousands of parametric features linked to hundreds of other parts in an assembly. I would need to write a novel to achieve those same features with an LLM. If what you want to make is simple enough that an LLM would be able to nearly one-shot it, then that model either: 1. Already exists somewhere (like the gear above) or 2. Is simple enough that a couple hours of training videos will give you all the skills you need to make it yourself

rehevkor5 4mo ago

While you're probably right about >90% of situations that fluent CAD users face, I think you might be suffering from a lack of imagination about situations where an LLM could help do work which would otherwise be tedious or mistake-prone. And then you have the non-fluent CAD users, just like the non-programmers who are now vibe-coding: this stuff can be a game changer for them even if it's far from "good" right now.

abdullahkhalids 4mo ago

> If there was someone sitting at my computer, and I had to do all of my CAD design by explaining what I wanted them to do verbally, I'd rip out my hair. Isn't this how a lot of machine shops operate, or how things operate internally in larger manufacturing factories? Customer/person-from-different-team comes in and explains what they want to do. Maybe they have some sketches or pictures of similar parts. Then there is back and forth with the CAD guy to build the thing. One critical difference is that the CAD guy is usually smart and you have to explain to them things at a more high level, along with some written down hard numbers that need to be obeyed.

coldtea 4mo ago

>I think of it this way. If there was someone sitting at my computer, and I had to do all of my CAD design by explaining what I wanted them to do verbally, I'd rip out my hair. I, on the other hand, have used LLM + OpenSCAD to design stuff - while I pulled my hair out everytime I had to sit and write OpenSCAD primitives or use a UI CAD like FreeCAD or Fusion360 and their horrible unintuitive interfaces.

8note 4mo ago

virtual cad did something major compared to drafting - you switched from only being able to represent certain views of an object, to having a stored full representation of the object. you could sculpt a model à la ILM for star wars or the architecture models, but the only way to have a copy of the object was to make one. the virtual cad also brought in the ability to do analysis with FEA and get approximately smooth undestandings of the stress and strain on the piece, rather than manually calculating the critical points and stress raisers for doing analysis

jjk166 4mo ago

Definitely for fine adjustment you're going to still use the manual CAD tools, but you can describe things much faster than you can model them. Good prompt engineering is important here as much as for any other AI use case. For example let's say I need a parametric model of an involute gear with a 14.5 degree pitch angle and a 0.5 inch hub with an 8-32 set screw where the OD, number of teeth, face length, and shaft diameter are all variable. It takes seconds to write the prompt and then adjust the variables to what I want whereas it would take tens of minutes to actually model even for a highly skilled drafstman. The time savings get more extreme the more the modelling work is looking up information online. For example if I wanted a model of a lightbulb electrical connector, 95% of the work is just going to be googling. Technically you could have an LLM just tell you all the dimensions you need and then model it yourself, but that's definitely still going to be slower and you have to put in the effort to figure out what each dimension refers to. It makes sense just to cut out the middleman. Add in the fact that CAD is in fact a difficult tool to use and learn effectively. There is a subset of the population that is very good at picturing and orientating objects in 3D space in their minds, and engineering is mostly limited to these folks. For those whose minds work differently, CAD is extremely tricky to learn. An alternate method of interacting with models that does most of the heavy lifting such that a person only needs to tweak a near complete model could be extremely helpful to many people who would like the benefits of CAD design but have struggled to learn the software. It's no different than AI generated art opening digital art to those who are not good with digital artistry software.

zonkerdonker 4mo ago
https://www.mcmaster.com/6325K113/ https://www.mcmaster.com/6325K113/ Download model, done. Not attempting to be sassy, sorry, but maybe I can explain my point a bit better. If you are making something complex enough to warrant you yourself designing it (something unique, custom, new), then CAD on its own is the best tool (right now!). I have models with thousands of parametric features linked to hundreds of other parts in an assembly. I would need to write a novel to achieve those same features with an LLM. If what you want to make is simple enough that an LLM would be able to nearly one-shot it, then that model either: 1. Already exists somewhere (like the gear above) or 2. Is simple enough that a couple hours of training videos will give you all the skills you need to make it yourself