Robot Arm C

[illusionist]

For those of you using SketchUp, how do you model things like Vex parts? Is there a download or something for special parts?

[chalker7]

For those of you using SketchUp, how do you model things like Vex parts? Is there a download or something for special parts?

Looks like someone already drew quite a few of the Vex parts and posted them on the Model warehouse. http://sketchup.google.com/3dwarehouse/ ... 62&ct=mdcc

If you haven't really started with 3D design and are just messing around with sketchup, I'd suggest following through some of their tutorial videos. They are very good and will get you started quickly. http://sketchup.google.com/intl/en/training/videos.html

They also have a number of self-paced tutorials that operate within the software that work, but aren't quite as detailed as the videos. http://sketchup.google.com/3dwarehouse/ ... l=en&ct=lc

[illusionist]

Thanks for the response. How much do you think the Event Supervisor will care if the drawings don't match up exactly? For example, we're using parts from the Vexplorer Kit, and although the exact parts aren't available in SketchUp, parts from that link you gave can be easily substituted.

[chalker7]

Thanks for the response. How much do you think the Event Supervisor will care if the drawings don't match up exactly? For example, we're using parts from the Vexplorer Kit, and although the exact parts aren't available in SketchUp, parts from that link you gave can be easily substituted.

That is going to depend entirely on the supervisor, you should contact them if you have a deep concern about it. If I were judging the event (which I will not be, do don't take this as a clarification or anything official), I would be fine with the substitution.

[Primate]

Thanks for the response. How much do you think the Event Supervisor will care if the drawings don't match up exactly? For example, we're using parts from the Vexplorer Kit, and although the exact parts aren't available in SketchUp, parts from that link you gave can be easily substituted.

That is going to depend entirely on the supervisor, you should contact them if you have a deep concern about it. If I were judging the event (which I will not be, do don't take this as a clarification or anything official), I would be fine with the substitution.

Considering we got full credit for hand-drawn stickish figures at regionals, I can't imagine anyone getting fussy about slightly-different parts, even at the state or national level.

[jander14indoor]

Yeaahhhh!!!! Technical documentation, glad to see some serious conversation about it!!

OK, reasonably open disclosure, I'm the guy chalker7 mentioned who's the full time engineer on the committee who's behind this stuff. I work at Ford where I'm the Powertrain Integration Manager on a variety of products.

Soapbox for a moment. I'll tell you, before we build part one, we have a full 3-d model, detailed Bill of Materials, simulation models, and word descriptions on what we're doing. You just can't afford to build things in a competitive production environment unless you have a pretty good understanding on where you are going. Yes, there are a lot of detailed changes, fixes, etc before we finish, but without good technical documentation, you wouldn't know where you started, where you are, or where you are going. Its a real pain when something slips through and a test car is built that has something in it other than what was planned. Very hard to explain what went wrong, or even be confident everything is right if you don't track what you build.

Climbing of the engineering soapbox, let me preach on the practical side. I'm a jackleg mechanic in my spare time, can't even park my cars in my garage for the tools and stuff I've accumulated. I also build things based scavenging my spares/lefovers. I've found it saves a bunch of time even then if at least sketch out where I'm going and what I need to get there. And I mean SKETCH, I can't hardly draw worth a darn. I do a simple bill of materials to guide my search through the junk piles and make sure I have what I need before I start building as I hate to stop in the middle to run to the hardware store and pick to two bolts. I also use the sketch and parts list to keep me on track if I'm building anything vaguely complicated (and a robot arm is far beyond vaguely complicated). Oh, and with computers nowaday, if its beyond vaguely complicated, I'll use CAD software to plan where I'm going. From good CAD software you can pull your BOM almost automatically.

As to time spent on the documentation itself. If you do it FIRST, you'll spend less time building and have a better product. Changes are just a normal part of engineering development. Just strikethrough and change. Heck, I'd be more impressed by that than neatly typed and drawn stuff that doesn't show process. Don't sweat neat. Chalker7, myself and others were VERY careful not to make neat, computer drawn or anything like that part of the rules or scoreable. The scoring impact is significant, but not overyly complex or gotcha (I hope).

Of course there may be event supervisors out there who think differently, but that's a risk with any event. We tried to make our intent clear, but welcome suggestions to improve on the language. Expect some sort of technical documentation in the event as it is apparently having the effect we wanted based on this discussion.

Jeff Anderson
Livonia, MI

[Primate]

Thanks for the insights! Any recommendations for CAD software for a project like this?

[chalker7]

Thanks for the insights! Any recommendations for CAD software for a project like this?

Google sketchup: http://sketchup.google.com/
and Autodesk 123D: http://www.123dapp.com/
are the best free applications available currently. 123D is more powerful and I prefer it, but sketchup has a larger user base and extremely healthy forums that will guide you through whatever project you want to create.

[Flavorflav]

I would suggest that 5 hours is quite a bit of time for something that you know is not going to be tested. I like the action plan well enough, but I think the materials list was a bit much. We used Vex, and there are an awful lot of bearings, axles and gears to list in a decent bot. It also would have been a big waste of time to do it in advance. We entered three Bots, and two of them had fairly major design changes in the process. You see, the kids building them are not actually engineers - they are kids, and they don't really know what they are going to do until they start. I agree that it is important to visualize things in advance and I sometimes make them sketch things before they begin, but most of them are so bad at it that it is barely worthwhile. I usually end up having them pantomime what they are thinking of with bits of scrap metal or dowels or something. Their process may not be the one used by engineers, but it was effective - all three of them medalled and they enjoyed the whole process, except for the documentation.

[illusionist]

Another question about modelling (sorry for asking so many!)-
I know this will depend on the event supervisor and all, but suppose I use a flat rectangle box to represent a Vex plate. Would I have to make the holes in it and everything, or will it be fine if I use flat boxes and label them?