pic: Schreiber Take on West Coast Drive

[AdamHeard]

Originally Posted by Chris is me

I've seen plenty of chassis CADed with gearboxes just dropped in place, without any thought to the gearing whatsoever. There are things you can make CAD of without understanding.

There is an awful lot of "what" with no "why".

[MrForbes]

In the old days, there was a difference between a draftsman and an engineer. I think there still is.

[Madison]

I think singling out that the students are rendering pictures of their models is a pointless exercise. That process takes a small fraction of time compared to what likely goes into modeling and constraining the parts in the first place.

I think, in reality, a point that can be successfully made is that a lot of these designs are built upon completely arbitrary criteria that have no real-world implications. They all mimic one another and those that have been successful before them, but they're not designed for any other particular purpose. Teams have had success copying 60/254/968, 148/217, et. al., but they never really grasp what makes these teams opt for certain methods or materials. That's something of a problem.

I can assure you that there are many more people that know how to operate CAD than can design effectively. We have tremendous trouble where I work finding people that are qualified to do both and frequent trouble finding people qualified to do even one or the other.

All of that being said, I learned a lot of what I know about design and all of what I know about CAD from messing around and trying to improve upon things I saw here and at competitions. With time, I grew to understand more about why certain designs worked and why others didn't and experienced a fair share of failures. I've been working as a design engineer for about four years now and am pretty damned good at it as a result of what I learned here. I think these forums can continue to be useful to new people in that regard if they're clear about the intent of their design.

When folks post a new picture or idea, it'd be amazing if they also outlined the constraints they worked under while designing and evaluated if they met those goals. Allow yourselves a hard limit on weight or materials or resources and see what you come up with.

[EricH]

Originally Posted by 548swimmer

I work on new ideas instead of doing my homework, so if pencil sketches let me get back my homework in five minutes, I'd rather spend an hour CADding.

Pencil sketches can get you back to homework in under 5 minutes. The hour CADding without doing your homework, however, we BOTH know is an hour that could be better spent. [Insert discussion on how school is more important than refining CAD skills--for now--here.]

I can get you a concept drawing, by hand, on a letter-size piece of paper, in about 15 minutes. CAD for the same thing (concept) would take me about half an hour, if I was willing to fudge some things like basic shapes. Detailed CAD would take at least a week fitting it around homework; a more detailed hand drawing could between an hour and 3-4 hours, depending on the level of detail required--with fitting around homework, call it a couple of days.

I once spent about 3 days CADding something that the concept sketches took mere minutes to do. It's a lot more time intensive to CAD something.

What Andrew showed was a concept sketch. That's how you sell a product to investors or your company, or rough out an idea. When people post CAD pictures on here, they're posting production material--what will eventually be used to build the part. Could you use production material for a concept sketch? Sure, given enough time. But when the deadline's in a couple of hours, and you need to explain something, two or three concept sketches that are on time can be worth every part in the production CAD assembly, two months after the deadline.

[CENTURION]

Hahaha I usually end up doing pages and pages of sketches before even presenting an idea to my team ( I have too much free time at school )

Half of them end up being junk of course, and I can't do any of those kinds of advanced calculations (Yet), but my study hall time usually yields some pretty crazy stuff. and then if I like it enough, I'll do a quick Google Sketchup model or something on my laptop (I'm still learning "real" CAD, but have gotten quite proficient with Sketchup)

Over the past year that I've been on the team, I've been trying to get other students do do more sketches, it seems they just want to wing it, and build as they go

[R.C.]

Originally Posted by Madison

I think singling out that the students are rendering pictures of their models is a pointless exercise. That process takes a small fraction of time compared to what likely goes into modeling and constraining the parts in the first place.

I think, in reality, a point that can be successfully made is that a lot of these designs are built upon completely arbitrary criteria that have no real-world implications. They all mimic one another and those that have been successful before them, but they're not designed for any other particular purpose. Teams have had success copying 60/254/968, 148/217, et. al., but they never really grasp what makes these teams opt for certain methods or materials. That's something of a problem.

I can assure you that there are many more people that know how to operate CAD than can design effectively. We have tremendous trouble where I work finding people that are qualified to do both and frequent trouble finding people qualified to do even one or the other.

All of that being said, I learned a lot of what I know about design and all of what I know about CAD from messing around and trying to improve upon things I saw here and at competitions. With time, I grew to understand more about why certain designs worked and why others didn't and experienced a fair share of failures. I've been working as a design engineer for about four years now and am pretty damned good at it as a result of what I learned here. I think these forums can continue to be useful to new people in that regard if they're clear about the intent of their design.

When folks post a new picture or idea, it'd be amazing if they also outlined the constraints they worked under while designing and evaluated if they met those goals. Allow yourselves a hard limit on weight or materials or resources and see what you come up with.

Madison,

I agree with you here. Rendering doesn't take that much longer. Most of the time goes into making the model and only a fraction goes into rendering. Well most of the rendering process is just letting it do its own thing. It's pretty interesting to see elegant renders that show a lot of detail aka Lewis comes to mind (roboticwanderor).

Also most drawings are just copied and re-iterated. Some are just bandwagon drawings. Such as swerves and sheet. Sometimes I wish people actually thought about x resources they have and then try to improve their design based off their resources. For our team is it really really retarded to design sheet parts, but for teams like 148 its amazing since they have the ability to.

Over the years as a CAD person on CD I have learned that most of my ideas don't work and if they do, not well. These forums have taught me a lot about material properties, clean design, and working toward simplicity. It just takes some patience and the right people to help you understand what your doing wrong.

Andrew I love your napkin sketch. Most if not all my drawings are roughly sketched in my notepad and drawn over and over till I find "THAT" model. It saves a lot of time already having something to base your CAD off of. I'm sure a lot of teams take this approach already: Napkin -> Whiteboard -> Paper -> CAD -> CAM or Sponsor -> Part.

-RC

[sdcantrell56]

I am echoing a lot of the sentiments voiced on here. Too many people seem to be designing things without really thinking about what their team can actually produce and what would be the best for them. Specifically, all the sheet metal and west coast style drivetrains lately. While I agree many of the teams that do west coast and sheet metal drive trains do very well with them, it is because they understand all of the intricacies of the design and have the resources to implement it properly. Teams should do like RC says and really focus on designing for their resources and for their goals. While I greatly admire the "simplicity: of west coast drives and love the integrated design of the 148 style sheet chassis, chances are you will not see a 1771 chassis out of anything but wood. We have tried other things and for us we can achieve the most optimized chassis building with laser cut plywood.

Secondly, the idea that Andrew brought up about people spending so much time on CAD and not actually thinking through the design is alarming. The design that comes to mind right now is a west coast one seen in the past week that is beautifully rendered and has jags, battery, etc included but doesnt have any bearing blocks, axles, or tensioners. Basically it is missing all of the crucial parts of a chassis and the most important parts of a drivetrain. The time spent plugging in all the existing models would be much better spent actually figuring out the drive train specifics.

We at 114 try to use WAD (Whiteboard Aided Design) before we move to the computers. Once students can understand the goal of their design, they use CAD for what it is: A tool to enact a design. CAD is simply a step that is used to bring a design to reality, and nothing more.

The design is more than the CAD. The design is the thought, the sketches, and the math involved in bringing the mechanism to reality.

[kgzak]

Originally Posted by CraigHickman

We at 114 try to use WAD (Whiteboard Aided Design) before we move to the computers. Once students can understand the goal of their design, they use CAD for what it is: A tool to enact a design. CAD is simply a step that is used to bring a design to reality, and nothing more.

The design is more than the CAD. The design is the thought, the sketches, and the math involved in bringing the mechanism to reality.

That is pretty much what I have done for everyone of my designs except I use paper and a pencil. I only recently learned CAD so Most of my ideas have had to be given to CAD people. In my opinion that helped because my drawings had to be done so that others could turn it into CAD.

[Mike Schreiber]

Originally Posted by ttldomination

If you don't know how it works, how did you create the CAD in the first place?

The argument here is the base definition of pointless.

My argument is that if you say it goes this fast and they say how'd you get that number and you are stumped, what have you accomplished? You aren't getting that job.

The students who post well thought out designs with chain runs planned, ratios thought out, structural consideration, etc. are doing wonderful. They know how it works. I'm not saying you need every number, but if there's a number given it needs to be backed up. Pulling 11ft/sec out of nowhere is pointless. There are people who don't know how it works who are posting stuff. As Chris said:

Originally Posted by Chris is me

I've seen plenty of chassis CADed with gearboxes just dropped in place, without any thought to the gearing whatsoever. There are things you can make CAD of without understanding.

Chris' situation is what I'm referring to as the base definition of pointless. The students who learned mate and downloaded a bunch of stuff of AM...

Yes learning the basics of CAD is important. But there aren't many people who sit around and CAD all day without knowing anything about what they're drawing. There's a lot of those on CD.

As Adam said...A lot of "what" and very little "why"

Do I believe saying anything about these students posting random things will do anything? Not even the slightest.

[IKE]

If it is not hurting their grades, then what is really the issue with people cadding up ideas and submitting them for criticism and critique. Granted about 50% of the responses could be run from Auto-pilot, but so be it. I am sure that each one fo the students that threw their hat in the ring got some good advice. I really like Schreiber's sketch because it reminds us to do some figuring first, but we should all turn the snarkiness down just a bit on students that are excited about drawing up their ideas. While most would pass as loose interpretations of role model designs, they have brought up a lot of good responses like chain tensioner planning and design, chassis stiffness, how to make your chassis rock...
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Warning: Slight thread Hijack

Maybe those that are tired of seeing renders should work on a compliation paper of different 6WD designs, fabrication techniques, andd what teams love and hate about them. I know a couple posters in this thread have already done some great work on this material. Adding to their material and other presentations like Patton's and a few others would be great.

SAE will often do a compiling of papers on subjects that have a common theme and individually are good, but as a whole are more powerful than the sum of their parts. Imagine a 6+WD Chassis book that showcases/benchmarks some of the different ways about doing a 6+WD. Talk with the teams that have these and what they like and dislike about them. You could compile a nice set of papers on:

Architectures: Basic architectures and benchmarking. 6, 8, 10+ WD architectures. Live or dead axles. Cantilevered or fully supported. Direct Drive or chain...
Chain tensioners: types and the pros/cons of different tensioning systems along with the importance of having just the right tension.
Chassis Dynamics: the "why won't my bot turn?" paper along with several others. Pros&Cons of chassis Flex.
Construction and Fabrication techniques: KOP, Sheet metal, welded frame, 8020 frame, wood, plastic...
Power Transmission: Design guidelines for speed/traction philosophies. Designing powertrains with COTS. Custom gearboxes. Chains vs. Belts vs. Geardives.

If this book or collection existed, then you could just point up&coming chassis designers to the collection and off they can go.

IKE

[Andrew Schreiber]

Originally Posted by ttldomination

If you don't know how it works, how did you create the CAD in the first place?

The argument here is the base definition of pointless. One side is arguing that simple tools are alright as long as you have the skills to implement your goals, while the other sides is arguing that the tools are needed as well.

I guess I'm an alumni now, so I would prefer the students on my team have the know how of the skills and the ability to present their ideas/skills in a professional manner.

- Sunny

Oh, I am not arguing that the tools are pointless. I am arguing that the tools are pointless without the skills and knowledge to use them. The word I used, crutch, implies that it is an aid. There are times when a crutch is the appropriate solution to a problem. There are also times when you don't need one.

I would also like to point out a drawing that caught a bit of attention in 2006. http://www.chiefdelphi.com/media/photos/22693 Anthony didn't draw the detail of a spur gear and caught a bit of flack for saying it was frivolous. Why should we have to design every single gear tooth in cad? You know the size of the gear what is the issue?

My point is, use the right tool for the job. For me sketching a quick idea was the right tool at the time. I wasn't really sure how I wanted to position things. I did a couple other sketches that you don't see. On one I don't direct drive the middle wheel. A couple where I sketched in the battery. You know, I did about 4 different sketches in about 7-10 minutes. Would it be possible in CAD? Sure, but it would take me a bit longer, heck, 2 minutes of that would be loading Solidworks.

[Tom Bottiglieri]

So if one of the students you 'mentor' was excited enough about their team to CAD up a full robot component, you would also scold them with sarcastic put downs... right?

[Andrew Schreiber]

Originally Posted by Tom Bottiglieri

So if one of the students you 'mentor' was excited enough about their team to CAD up a full robot component, you would also scold them with sarcastic put downs... right?

Depends, if they brought it to me and said, "How do I figure out how I should drive the wheels?" I would be happy and bend over backwards to help them out. If they brought something to me making wild claims with no facts, yeah, I would be irritated by them, depending on the student I may make snide remarks.

[Chris is me]

Originally Posted by Andrew Schreiber

Depends, if they brought it to me and said, "How do I figure out how I should drive the wheels?" I would be happy and bend over backwards to help them out. If they brought something to me making wild claims with no facts, yeah, I would be irritated by them, depending on the student I may make snide remarks.

Well, they're getting excited about using science and technology to solve a tough problem...