Looking to improve my CAD skills and take them to the next level this season. I haven’t done any substantial FRC cad but I’ve worked on cadding stuff like gearboxes to try and work my way up. Any tips to help improve?
It won’t help with actual designs, but for speed I highly suggest setting up custom keyboard shortcuts. Instead of wasting time going through menus or memorizing button locations, set easy to hit keyboard shortcuts. I know Solidworks allows you to also set mouse shortcuts when holding right click, but I don’t know about other programs.
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I’m reminded of a sign at an old sandwich shop near the University of South Carolina: Perfect Practice Makes Perfect
Obviously, more CAD makes for more practice…but only sharing it with an experienced mentor or here on CD or somewhere like that is going to tell you where you can improve.
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I’ll look into doing that tomorrow
Ok appreciate it, I just don’t know what to CAD right now, Like I said I’ve been working on a drivetrain gearbox but I just don’t know what I’m doing. I tried starting with meshing the gears with the motors just to see how it would go but then it never really worked.
Well, post that! Screenshots are common and easy, though if you’ve got an Onshape or GrabCAD link that’s even better since it lets people poke around more easily. If your form is straight on that, then you’re probably going to move on to other things on the right footing.
Cool I definitely will. Don’t have my laptop on me right now but first thing in the morning I will
In my book the best things to practice with are actual FRC things. CAD a West Coast Drive. CAD a coaxial swerve drive. CAD a fuel shooter. CAD a 2018 climber. CAD whole robots from CADathons and precious games.
Focus on making sub assemblies modular. Get in the habits of designing around critical dimensions, including everything (fasteners), and worrying about weight.
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Re-iterating what others have said, the more you do the better you will become. That goes for everything in life and applies very well to CAD.
You mentioned that you don’t know what you are doing. This leads me to think one of the best ways for you to start to improve might be to watch others do CAD. Watching how others do it and the approach they use will help you understand why they are making the decisions they are and will help solidify the “what” you are supposed to do.
When I started, I watched the “973 RAMP Cascade elevator” videos on youtube. You might search “First robotics competition cad tutorial” to find more videos. You can also look at the 971 Cad tutorials on youtube or their website like this one https://www.youtube.com/watch?v=4Eg2b4-jtqA. I haven’t watched them in awhile but I am sure they would be fruitful.
Additionally, you need to become acquainted with your software. For example, it took me a year to learn about featurescripts in onshape. Now, I can make any length extrusion in less than 20 seconds. Or knowing how to make a standard fastener or make multiple parts that are based off of one sketch or import COTS components (MkCad). These things are shortcuts I have found in Onshape, but the overall idea remains the same - become comfortable with your Cad platform and optimize your workflow. It will make your CAD more structured and organized and producing cad will take less time/you will be able to get more done in the same amount of time.
To do this, you need to answer some questions about your CAD software: what is the easiest (and most parametric) way of making holes and other features in your software? What diameter holes should you use for different bolts or for bearings and bushings and other common robot objects? In what way does your software create crayola-cad (2d planning sketches)? How can you get your software to relate different features of different parts? etc. This list is no where near comprehensive. What I’m trying to say is you need to understand your software to a T to excel at CAD. If you don’t understand something, ask!
Overall, (IMO) you need to do a couple of things to get good at CAD.
- Understand Design of Robot Components
- Understand Your Software
- Create a workflow tailored to your CAD platform and follow it
- work on your skills through practice
- get feedback on your designs and ask for help when you need it
This is a general outline on how I have guided others on how to learn CAD. Ultimately only through hard work and dedication will you get better. I hope this helps, feel free to ask more questions.
Bio/Disclaimer: am an Onshape fanboy and self taught CAD-er. I am now the Captain of my team’s CAD subgroup and have spent the last five months teaching CAD to newbies.
P.S. I highly recommend using Spectrum Robotics’ Design sheet. So so so useful. http://blog.spectrum3847.org/2017/12/spectrum-robot-design-sheet.html
And more to it, understand the design of your team’s robot components. If your team has no access to precision machining, it doesn’t make sense to try to make fancy pocketed custom gearboxes that would require CNC work. But it would make sense to understand how COTS gussets and planetary gearboxes integrate.
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Use the S shortcut in SolidWorks/OnShape.
Practice, practice, practice.
If you’re trying to make something that maybe your team could use, start researching that subject and make multiple designs. Then go back and fix it and improve it. <— I do this all the time when I design something, it helps when you want to cad something more efficiently.
Another thing I do is pick a random object in your house and CAD it; I tried to CAD a tent which was not the easiest thing to design and figured out a bunch new controls and features on my CAD program. Does it help? Yes. Did it matter, No. Experience is the only valuable thing that you can get.
You can use jvn’s design calc for gear ratios.
Also you can watch behind the bumpers and try to cad them to improve your cad skills
Summary is know your teams limits and then draw your competition robot’s cad
Set up your workflow, try things, but most of all try to use the most of it. For me (in SOLIDWORKS) that means:
- Put everything on the “S” key so you aren’t going to menus (also, hitting S puts keyboard focus on the search bar - put the search bar on command search, so when you need a niche command you can just search for it)
- Use SharpKeys to rebind caps lock to ctrl, ctrl to enter, backtick/tilde to delete. This way you have all the frequently used things to manipulate menus and modify selections (escape, delete, tab, ctrl, shift, enter) at your left hand on the keyboard, and ctrl is in an ergonomically friendly location. Alternatively get one of those fancy spacemouses with button pads. But I think they’re overrated especially in SOLIDWORKS.
- Strip all the graphics down, remove all the animations
Everyone’s milage varies. Some people like dedicated shortcuts, I like S-key. Find what works.
Additionally, practice the following:
- Top-down modeling (if this works with your team’s workflow). Pay particular attention that you don’t make unmaintainable models (i.e. circular references that break everything when you change something). Once you’ve built a model start screwing with it and trying to break it.
- Designing sketches with proper design intent (read: every dimension/constraint you add in the model is something you directly care about, not a happenstance, and you should never be doing math to input a dimension) (also- learn about how you can change how dimensions are added to circles- you can make it so that you dimension from a tangent of the circle, not just the centrepoint)
- Skeleton/layout sketches. This helps with the above two points- if you can make a layout sketch showing the general idea of the part, it will enable you to change the part easily later on, and also reduce time wasted CAD-ing something that actually won’t work out. The most powerful tool in a 3D CAD package is still the 2D sketcher, IMO.
- Machinist-friendly drawings. The more frustrating a drawing is, the more likely it is to be wrong. Learn about the different callouts and conventions. Ordinate dimensioning schemes, reference dimensions, hole callouts (and maybe some very basic GD&T) can reduce the frustration and speed up communication.
- You don’t need to add fasteners or motors always and when you do, they can usually just be low-poly spaceclaims. Defeature your parts… looking at you, McMaster-Carr SOLIDWORKS models of screws with the threads cut into them. Screws with modeled threads will bring the mightiest of computers to their knees.
Some principles to remember because a lot of people see pretty pictures and forget why they’re making them:
- CAD is first and foremost a communication tool. It exists to help talk to your teammates about a design. Adding fasteners can help but sometimes you just need to get it done. Naming your features and sketches can convey what your thought process is so when (not if) you need to hand off your work to someone else it’s easy.
- CAD is secondly an experimentation and validation tool. You should build CAD that you can change and tweak. You don’t get it right the first time so don’t build CAD that’s too rigid.
- CAD is lastly a manufacturing prep tool - the last stage of an idea before making prints, CAM, or exports for 3D prints. Make sure it’s accurate for these processes and called out appropriately on a drawing.
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