The real question here is why are you CADing pneumatics? If it’s to layout your system, you’re probably better off just using a pen and paper or CAD (cardboard aided design), rather than spending time making everything in the computer. You can’t legally use custom pneumatic devices and there are a number of places to get CAD models from, so there’s no real reason to have to design your own components. So what are you trying to get out of a CAD program for pneumatics design?
As a rookie team, they used pen/paper and cardboard modeling last year with graphic drawing for the pneumatic “schematic” last year. This year, we are looking to step up the level of the team. What do you use for electrical?
We generally use pen/paper and cardboard to layout our electrical and pneumatic systems. There’s really no reason to make it more complicated than that.
CADing the mechanics is definitely important. Leaving space for electronics and pneumatics is important and if adding them into your CAD model helps, then great. But there’s really no reason to model the systems independently of the robot. That’s just adding work for no real gain.
While I agree that your 3D CAD model is not the best tool for making a schematic or even a layout of the pneumatic or electrical systems, I do think there is great value in including the major components in the CAD model.
For one thing, they take up space and despite the best efforts of saying “leave this spot empty” the space for the electronics really needs to be reserved in order to make sure that you will have access. In addition, if you do the layout well, you can CAD the bolt holes in the electronics tray for the components and have those cut when you make that tray. Plus, if you add lightening cutouts in your tray, you can make sure you still have some material to bolt your components to.
Modelling pneumatic cylinders is also a good idea. These components need to have the attachments considered as well as the extended, retracted positions. You want to be able to make sure they have clearance to other components and that you have adequately thought through how the components are going to move. Finally, you want to make sure that the cylinders are adequately protected and not exposed to bending of the rods due to hard hits with the field elements or other robots.
Wiring and tubing is hard to model. But if you don’t think about where those wires and tubes are going to be routed, you will end up with a spaghetti of wires and tubes running through your robot. You can really optimize the layout of the electronics and pneumatic systems if you think about where the wires need to run. We have had the cleanest layouts when we start to position the electronics components in the directions closest to the elements they are interfacing with (i.e. locating motor controllers in the direction of the motors they are controlling) so that you do not have a lot of criss-crossing wires running around your robot.
We have not been very successful with that on our team and by the end of the build, we generally have a pretty messy “pit” in the middle of the bot. We have been trying to get better every year and I would say that we are getting better, but we have found that in order to account for this stuff, we really need to start including these in the CAD model at some level.
In general I agree about adding electronics/pneumatics components. But if that’s what we’re talking about then you should already have a CAD software you’re working with. It doesn’t make sense to be asking for a CAD software recommendation if you’re already designing your robot in CAD.
I also agree that you definitely should be thinking about where your wires and tubes will go while designing. But adding all of them into your CAD model is really just a waste of time. You can get the exact same results by laying stuff out with cardboard and string and/or drawing a diagram by hand. The hours and hours you’d put into modeling them in CAD could better be spent on a few thousand other things.
Well, I agree that you don’t need to use a separate tool for CADing the pneumatic and electrical bits. You seemed to turn the question around on @btaira asking him why he was CADing them at all. But perhaps I read that wrong. Sorry for the confusion.
Having said that, we are actually seriously considering doing our wiring diagram in a wiring diagramming software next year in an attempt to get better control over everything. We want to have a proper reference to use for troubleshooting and also be able to edit it and keep it up to date as the robot changes throughout the season. The extra work upfront hopefully will be worth it if we can update it relatively easily and keep it neat as the season goes along.
If you really want to. SMC has free software for 2d schematics. It is very similar to Visio.
How much time does your team want to (can afford to) invest in learning a tool where you will only use a tiny fraction of its capabilities and get something that may only be marginally better than what can be achieved with pencil and paper or a spreadsheet? Are there more important things that a second year team should put their efforts into learning that would give a greater return i.e. fundraising, team organization, mechanism design…
For perspective, the companies I have worked for drew out the equipment wiring in AutoCAD 2D (any decent drawing program would have worked) then made wiring tables using EXCEL for products with 10 X more wires than a complicated FRC robot. The tables included details such as the signal names, wire sizes, the wire colour and length of each wire, the connectors and labels at each end and any special considerations. It doesn’t have to be more complicated than that.
Thanks. The team is working on the items described above with structured fundraising, outreach, Solidworks training for mechanical, etc. On the electrical side, they are getting good with the tools (ferrules, crimpers, soldering, etc). They also have basic capabilities with the multimeter, DC current probe, IR thermometer and oscilloscope. Some are starting to pick up Solidworks Electrical.
It sounds like some teams will use 2D CAD. No mention of 3D cad. If you are not using CAD, then the next method seems to be Visio/PPT/image processing program and with icons. The fallback is Corrugated Assisted Design with waxed string.
Then, if we wanted to create a pneumatic schematic, we could use the program mentioned above but it sounds like very few teams even do this.
Thanks for your inputs!
As @AriMB stated, it is worthwhile to include the electrical and pneumatic components in the 3D CAD. It is possible to add the wires to the 3D CAD but it is very time consuming, even for professional users with a lot of experience with the CAD tools. In addition to making a wiring table, it is valuable to consider the layout of the electrical and pneumatic components in your 3D CAD. You want to ensure that they are accessible for manufacturability and serviceability issues. You should be able to visualize where the wiring and pneumatic tubes can go without getting pinched by moving parts etc. Pay particular attention to minimizing the length of the loop from the battery to the main breaker to the PDP and back to the battery.
Major components (battery, pdb, speed controllers…) are worth using off-the-shelf CAD models for and placing in the CAD. Don’t add wires & tubes, just give clearance.
Speaking as a professional user who has modeled wiring harnesses, THIS. It’s very easy to spend a completely dispropotionate amount of time on modeling the wires to the amount of benefit there is to having them in the CAD. This is FRC, you’re hand-fabricating one to three harnesses, not ordering thousands from a supplier, you don’t need every length and connector placement to be accurate.
If you want a Gold Star for FRC, model a couple pipes through the critical areas where you know you’ll need a large trunk of cables as “keep out” areas. And then show off your CAD to judges.
The ME’s I have worked with have generally done what @s-neff advocates. They only drew in a few of the really big, expensive cables (3/0 & 4/0, 3/4’-1" dia., depending on insulation thickness) that absolutely must be kept short, have large bend radius restrictions and will be difficult for the manufacturing people to wrestle into place.
I would recommend that the pressure switch be moved to the input of the storage tank. A blockage in the storage system would never satisfy the cutoff pressure and the compressor would continue to run forever.
I also need to caution everyone that certain valves are not guaranteed to function 100% of the time below certain operating pressures. If they are operated at <40 psi for instance, there is a likely hood that the pilot valve will get stuck midway in the valve housing causing the valve to try and operate in both modes at once. Please check the spec sheets for your devices.
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