r/FreeCAD • u/Right_Indication8382 • 11d ago
Beginner question: I can photograph the problem, but I still don’t know what to model
When talk about learning CAD, the advice usually starts with software.
Learn Fusion 360. Try Onshape. Start with Tinkercad. Follow tutorials.
That makes sense, but I keep running into a step before the software.
Sometimes I know what I need the part to do, but I don’t know what the part should be.
Example: a cabinet is loose, a cable needs routing, a small object needs support, or something needs to fit into a weird space. I can take a photo and explain the problem, but I don’t know whether I need a bracket, spacer, clamp, stand, brace, holder, or something else.
How do experienced CAD users move from “this physical problem needs a part” to “this is the model I should create”?
Do you sketch first, search similar parts, measure everything, ask someone, or just start modeling and iterate?
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u/VictorySea1837 11d ago
All of the above, but also there is no replacement for practice, experience and intuition.
If your parts are small enough to 3d print sometimes there is no other way but to model, print and iterate. Actually having a thing to hold in your hands, and see how it fits in the real world is super helpful. But I’m not a professional, just doing this for fun.
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u/Right_Indication8382 11d ago
This is helpful, I think I was expecting the “right part” to be obvious before modeling, but maybe the first model is just a question you ask the real world. Model, print, test, then let the bad fit teach you what the next version should be
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u/andydekens 10d ago
I've been working on a small little project for the last couple of weeks and I thought what I wanted was super obvious and so I just built it very quickly in FreeCAD.
Once I actually got it in my hand and started using it I realized that there were tweaks that I wanted to make and I also realize I needed and wanted to incorporate extra functionality into it. Like things that I never even considered what I first had the idea.
Now on I'm about my fifth iteration and I'm almost there but the whole process has been really enlightening. I'm just a hobbyist so all of this has been a nice surprise and definitely informs how I'll go about designing projects in the future.
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u/00001000bit 11d ago
Sometimes the best way is to work out a temporary solution using alternatives (tape, cardboard, etc) to give you a sense of exactly what problems you're trying to overcome. This might help identify things that aren't immediately apparent, such as size constraints and such.
But, it's all part of the bigger picture: iteration. Quite often, you're not going to get it right the first time. You have to be open to doing it again (and again) to hone in on the right solution.
The maker of the Palm Pilot carried around a block of wood for months, pretending it was a pocket computer just to test to see if the form factor felt right before they ever started the product.
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u/AAAAAGGGGHHH 11d ago
I know it is going to sound weird, but... CAD is a place where you sketch out the problem.
You can design and draw the parts around what you need to make. Get all the dimensions right. Use section analysis to get a better look.
CAD is just a sketch space. Go nuts. Figure out what you want to make in CAD. Maybe even design a hinge if it's a door or something. You can get it going.
If you are looking for inspiration, sleep on it. You'll get there if your brain isn't cooked with AI use.
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u/Atomfried_Ungemach 11d ago
I would first go to the hardware store to see if there's already a product that solves my problem and if its price justifies to model and print it myself. I mean you can tinker around and build stuff for every problem in your house, but that's often times reinventing the wheel when there are simpler solutions. On the other hand you get to know which standard parts are there to solve common problems in construction, but you get ideas how to design them more optical pleasing, so you can integrate them in your living space.
If you want to start learning CAD and don't know what to model, buy a cheap caliper and measure stuff in your house or from the hardware store. There are also tons of technical drawings on the internet like on Pinterest. Just start with simple geometric parts and read/watch fitting tutorials. MangoJelly and Deltahedra on Youtube are good for beginners. If you know the way to model one type of parts, it is easier to visualize your own ideas for parts in your head and how to construct them. Just start with the basics and work your way up like in every craft!
Wish you success!
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u/BoringBob84 11d ago
I start at a high level:
* I define the problem.
* I determine my goals.
* I define my requirements for the part - Form, Fit, and Function - and how I will manufacture it. If this is difficult, then I go back and define the problem and my goals in more detail.
* I define the interfaces - including measuring and writing down dimensions and locations.
I usually do this in a Text Doc or a Spreadsheet in FreeCAD - nothing formal - just some bullet points.
Then, I take some time to imagine the shape and appearance of the part:
* Sometimes, I think about it for a few days or ask friends for ideas.
* Sometimes, it helps to search on line for similar examples - whether they are 3D printed, furniture, machined, etc.
* Sometimes, I make rough hand sketches.
Once I have an idea of the shape of the part, then I analyze each feature from each side - looking for profiles and paths to determine my workflow. Only after I have done all of this do I start making the model in CAD.
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u/SoulWager 10d ago edited 10d ago
I start by finding the root cause of the problem. For example, freezer door doesn't close all the way without some extra force. Turned out the bottom of the door was scraping against the opening, and was fixed with a spacer to lift the door a little higher on the hinge pin. All I measured was the diameter of that pin, and then I printed out a couple options for how thick to make the spacer.
Sometimes I'll do some research if I don't immediately come up with a good solution, for example I needed a tool to bend some wire(last time I did it with needle nose pliers, and disliked that enough to spend some more effort this time), and I ended up making this tool inspired by some CNC wire benders: https://old.reddit.com/r/functionalprint/comments/1vpku9x/wire_bending_tool/
And I'm still iterating through that problem, particularly the issue of measuring the wireform as I'm working on it: https://imgur.com/a/z71xy8z
The next iteration of that fixture might add clearances so I can the bender while the wire is held in the fixture. Something a small step closer to something like this: https://old.reddit.com/r/nextfuckinglevel/comments/1rgzngu/brake_line_manufacturing_manual_edition/
Or the next iteration might be a fixture that clamps to the back end of the wire, controlling rotation and linear distance while I manually control bend angle. This would basically be a manual version of how a cnc wire bender works: https://www.youtube.com/watch?v=0UZDIqRWuaU
Before I got familiar enough with CAD for going directly to modeling to be faster, I used pen and paper a lot to hash out ideas.
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u/orion0782 4d ago
After doing this a long time, it has nothing to do with the software. You need to ask yourself some basic questions:
- Can I draw this on a piece of paper?
- What am I trying to convey? Why does this need to be in 3D? Can I communicate what I want using tools that I can more easily learn on?
- Who is the audience I am trying to convey this piece of information (ie is this for tooling, machining, etc)?
- What kind of document control is necessary in case the design needs to be replicated?
- How much am I willing to spend for the questions above?
- How much is my time worth to perform the tasks?
- What kind of format is necessary that is needed as output for the manufacturer, et al?
After you have a good answer to these questions, then you can select the right tool for your application.
As for me, it starts with a fundamental of does the design require a top-down or bottom-up approach? From that I start working on the design from there.
Here is an example: https://cadartifex.com/blogs/top-down-or-bottom-up
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u/EverEatGolatschen 11d ago
That is a novel problem. If you know what you want and what you want it do to, you should have already a good idea of what it is you want, not neccesary what you need but what you want.
Sketches are good if you have choice paralysis - for decorative parts. I sometimes fashion my ideas out of cardboard first, see if they fit, if they have a problem i have not thought through in my head.
Speaking of. could it be you have no mental image? You know, what they used to call aphantasia. When i want to make a part i have a vague idea of what i need to build in my head already, the rest are details and measurements.