CAD Drawings?

Posted by Rick Gibbs, Engineer on team #145, T-Rx, from Norwich High School, Sherburne-Earlville High School and Procter & Gamble Pharmaceuticals.

Posted on 4/15/99 8:44 PM MST

I’m curious to find out how extensively teams use CAD
when designing and building their robots.

Working for a pharmaceutical company, our mechanical
engineering expertise has been limited to say the
least. Chemical engineers and chemists? We have
plenty. It’s often said that if the competition were
to design and build a big tablet, we’d win. Anyways,
until this year, when we recruited our first and only
M.E., we haven’t had any major CAD expertise to speak of.

So, are we in the minority not using CAD significantly?
Do any teams design their robot 100% by CAD?

On a similar note, here’s an idea. Is anyone
interested in posting CAD drawings of robots or
components? I know there are several robots that have
some very creative and elegant engineering. Sharing
designs could be beneficial to everyone - maybe in
next year’s designs, but more importantly in helping
teach engineering concepts in the ‘engineering-
challenged’ teams. Just a thought.

Rick Gibbs
T-Rx

Posted by Dan, Student on team #10, BSM, from Benilde-St. Margaret’s and Banner Engineering.

Posted on 4/15/99 9:03 PM MST

In Reply to: CAD Drawings? posted by Rick Gibbs on 4/15/99 8:44 PM MST:

‘On a similar note, here’s an idea. Is anyone
interested in posting CAD drawings of robots or
components? I know there are several robots that have
some very creative and elegant engineering. Sharing
designs could be beneficial to everyone - maybe in
next year’s designs, but more importantly in helping
teach engineering concepts in the ‘engineering-
challenged’ teams. Just a thought.’

I think someone should take note of what Woodie said and put some videos up explaining the designs (I’ve seen one that was of a simple drivetrain so far).
If you start posting CAD files exclusively you’ll be catering to a small market. :-Dan

Posted by Daniel, Student on team #192, Gunn Robotics Team, from Henry M Gunn Senior High School and NASA Ames.

Posted on 4/15/99 9:29 PM MST

In Reply to: CAD Drawings? posted by Rick Gibbs on 4/15/99 8:44 PM MST:

My team uses CAD for everything on the robot.

In the past, we CADed individual components before we built them, but we always turned out having bolts or even bigger parts conflicting with other components. We solved that problem this year by CADing the entire robot in one file. It was a basic three view isometric drawing and a HUGE headache. I was in charge of CADing on my team so take it from me, it’s easy to burn out. I came VERY close. But in the end it was well worth it. The parts fit together, and the clearances were right. It was a dream come true.

Unfortunately, CAD doesn’t take weight into account, so we had to take off a whole system at the end of the last week. But that’s a whole different problem. :wink:

Anyway, back to the point: Use CAD. It is amazingly useful not only for the packaging of your 'bot but also for designing. I’d never do it any other way.

-Daniel

Posted by Andy Baker, Engineer on team #45, TechnoKats, from Kokomo High School and Delphi Automotive Systems.

Posted on 4/15/99 10:09 PM MST

In Reply to: Re: CAD Drawings? posted by Daniel on 4/15/99 9:29 PM MST:

I’ll second that! I assume that many of us design these beasts using CAD.

CAD helps tremendously. I use Unigraphics (UG) to design machinery at
work, so it was a natural to use it to design parts of our robot.
This year, it was especially helpful as I designed our drive base. After
our team decided what sort of concept the drive base should be, I was
able to get into the details while using UG. Once the details formed the
machine, our team could look at prints of assembly drawings and details
so that everyone knew how the design was progressing. What we ended up
with was a 1 inch thick stack of prints which any team member could access
while they wanted to make parts and debug sub-assemblies.

Also, what CAD give you is the ability to make your own gears and sprockets.
This year, we have designed and fabricated 7 or 8 different sprockets and
gears which were wire-EDMed out of hunks of steel and aluminum. Even if you
don’t have access to a wire-EDM or a laser cutter to make your own gears,
most decent sized machine shop should have the capability to take your
file and make a gear for you.

Thie brings up a question: does anyone else design using UG?

I know that dxf and iges conversions do an OK job transferring CAD data
using the part’s wireframe and surfaces, but UG works in solids. It
sure would be nice to share kit files with another UG user.

Andy B.

Posted by Joe Johnson, Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.

Posted on 4/16/99 7:06 PM MST

In Reply to: Re: CAD Drawings? posted by Andy Baker on 4/15/99 10:09 PM MST:

Andy,

We use UG also. Which I guess is not surprising since we work for the same company (though different divisions).

I am extremely happy with the results we get from UG.

Our whole machine is not in the tube though because we have some engineers who are more comfortable with paper and pencil.

I think that it would be better to be 100% in CAD, but we have to work with the resources we have.

Joe J.

Posted by Chris, Coach on team #308, Walled Lake Monster, from Walled Lake Schools and TRW Automotive Electronics.

Posted on 4/16/99 7:04 AM MST

In Reply to: Re: CAD Drawings? posted by Daniel on 4/15/99 9:29 PM MST:

: Unfortunately, CAD doesn’t take weight into account, so we had to take off a whole system at the end of the last week. But that’s a whole different problem. :wink:

CAD can take weight into account. Do the drawings using solids and input the correct densities for each solid component. The CAD package can then calculate weight, center of gravity, moments of inertia, and all sorts of other good things.

-Chris

Posted by Daniel, Student on team #192, Gunn Robotics Team, from Henry M Gunn Senior High School and NASA Ames.

Posted on 4/16/99 6:50 PM MST

In Reply to: Re: CAD Drawings? posted by Chris on 4/16/99 7:04 AM MST:

Is that the new CAD program FIRST supplied this year? I heard you could do that but I’ve never used it before and didn’t attempt to learn the new program. Maybe I should? I’ve just been using AutoCAD. What would you suggest I use in the future?

Thanks!
-Daniel

Posted by Joe Johnson, Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.

Posted on 4/16/99 7:14 PM MST

In Reply to: Re: What program? posted by Daniel on 4/16/99 6:50 PM MST:

My favorite CAD system is Unigraphics (mostly because it is the one I am familiar with, but I think it is pretty good without regard to my particular knowledge).

The trouble with UG is that it is expensive and runs on expensive workstations.

I think that solids (blocks, cylinders, spheres etc) and parametric design (the ability to change length, width, height and location of features by changing a parameter in a table) are the key features I would look for in whatever CAD system you learn.

I have heard good things about ProEngineer (runs on PC’s but is still costly). I don’t know if AUTOCAD is really uses 3D solids and parametric design.

Joe J.

Posted by Brandon Martus, Other on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.

Posted on 4/16/99 11:28 PM MST

In Reply to: Solids and parametrics are the key features posted by Joe Johnson on 4/16/99 7:14 PM MST:

I’ve done some 3d drawing in AutoCAD. I dont remember seeing anything with parametric design (tables).
(Unless i was looking in the wrong places.
But I am sure it can do 3d solids.

: My favorite CAD system is Unigraphics (mostly because it is the one I am familiar with, but I think it is pretty good without regard to my particular knowledge).

: The trouble with UG is that it is expensive and runs on expensive workstations.

: I think that solids (blocks, cylinders, spheres etc) and parametric design (the ability to change length, width, height and location of features by changing a parameter in a table) are the key features I would look for in whatever CAD system you learn.

: I have heard good things about ProEngineer (runs on PC’s but is still costly). I don’t know if AUTOCAD is really uses 3D solids and parametric design.

: Joe J.

Posted by Kevin Sevcik of team #57, Tigers, from BT Washington and the High School for Engineering Professions sponsored by Exxon, Kellog Brown & Root, Powell Electrical.

Posted on 4/19/99 4:33 PM MST

In Reply to: Re: Solids and parametrics are the key features posted by Brandon Martus on 4/16/99 11:28 PM MST:

I don’t know where you guys have been, but FIRST provides a 3D modelling/drafting solution that’s well nigh perfect for most people. I should know, I use it. Unfortunately, my team doesn’t… but that’s another story.

FIRST provides every team with the latest copy of Mechanical Desktop. This is an add on for AutoCAD R14, so all you AutoDesk junkies won’t lose your current knowledge. Mechanical Desktop is the single most useful drafting software that I know of. I picked it up last year starting with some basic knowledge of AutoCAD R10. (Don’t ask)

If you get the tutorial manuel and just start working through it, it only takes a week or two to learn everything. Mech Desk basically allows you to go from 2D orthographic views to a 3D part. And it’s parametric, so you can change stuff later. And it lets you assemble parts into sub-assemblies, and sub-assemblies into assemblies. So you can virtually build your robot on a really powerful computer. (Pun intended) And it’s parametric, so you can change stuff that doesn’t fit. It does solid modelling, so you can calculate centers of gravity and such if you know part densities. Then, you can take the 3D parts, and quickly make 2D drawing from them to produce the parts from, if you don’t have spiffy CNC mills…

The best and newest feature is DesignSpace. It’s a totally seperate program that can work with Mech Desk. You take a Mech Desk part and tell DesignSpace what it’s made of and where loads are acting on it. Then DesignSpace can calculate where you don’t need material on the part. Automatic lightening holes from the comfort of your computer room.

Needless to say, I’m a strong advocate of CADing a robot before it’s built. Or even after. But I’m the only draftsman on my team, and no one believes me when I tell them how useful all this stuff is. Then they wonder why the 2nd robot never works quite right. Go figure. But if you’re into drafting a robot and you know AutoCAD already, I suggest hunting down your team’s copy of Mech Desk, and taking some time to learn it. It’s well worth it.

Kevin Sevcik

Posted by Daniel, Student on team #192, Gunn Robotics Team, from Henry M Gunn Senior High School and NASA Ames.

Posted on 4/19/99 8:59 PM MST

In Reply to: The Joys of Mech Desk posted by Kevin Sevcik on 4/19/99 4:33 PM MST:

Wow! Sounds great! And it’s just sitting on the shelf in our supply room collecting dust…

I’ll get right to it.

Thanks!
-Daniel

Posted by P.J. Baker, Engineer on team #177, Bobcat Robotics, from South Windsor High School and International Fuel Cells.

Posted on 4/16/99 5:48 AM MST

In Reply to: CAD Drawings? posted by Rick Gibbs on 4/15/99 8:44 PM MST:

The leader of the Bobcat’s mechanical design team this year was
Wayne ‘The Pencil’ Wnuck. I believe he is a Chem-E (I don’t work
at IFC, so I’m not sure what he does). I’m not sure that he can even
spell CAD :^).

Just a few more days…

P.J.

Posted by Ed Sparks, Engineer on team #34, DaimlerChrysler Electronics & Bob Jones High School, from Bob Jones High School and DaimlerChrysler.

Posted on 4/16/99 7:00 AM MST

In Reply to: CAD Drawings? posted by Rick Gibbs on 4/15/99 8:44 PM MST:

I think you’ll find that the longer you play this game, the more you will
depend on CAD. When we started out 3 years ago our machine was very basic.
We machined some stuff, but mostly it utilized parts ‘as-is’ from the
legal materials sources. I realized, after going to the finals, that if
we were going to run with the big dogs, we needed better equipment. I’ve
used Autocad & Microstation for years as an Electrical Engineer but I
had not drawn much in the mechanical arena. I had all summer to practice.

Last year, I needed to design a gearbox to rotate our basket and utilized
cad to generate a model, production drawings, and gear profiles that we
downloaded into our Wire EDM. There is no way I could have pulled this
off without CAD. We also figured out a better way to hold the drill
motor/transmission assembly (I can’t stand those rinky-dink drill
housings)using CAD and downloaded this design to a CNC mill that knocked
'em right out. The more I worked with CAD on this project, the more I
relized the potential to build better machines. I even went as far as
to measure everyone’s parts and build a model of that machine. It was
cool but not that useful after the fact. It did, however, impress the
students and cranked me up for this year.

Now I’m CAD crazy. This year I designed and manufactured retractable
‘landing gear’ wheels on Autocad. You’ve got to see them. Once again I
used the data to tell our CNC shop equipment what to do (I cut all of the
sprockets with a laser). I modeled most of the components in the ‘kit-of
parts’ and then went back and did last years. Best of all, I have a model
of this years machine that has helped us check for assembly problems.

I’ve got a lot of data that I would love to share with the rest of you
guys. I’ve always felt that a parts database would be a great thing have
on-line but I don’t have the resources to start one. If anyone can get
one started, I’ll send models.

I get laughed at a little and I don’t get much sleep but it pays off in
the end by inspiring the students as to what Engineering is and after
all, that’s what it’s all about…

Come see us @ Pit #34

Ed

Posted by Andy Baker, Engineer on team #45, TechnoKats, from Kokomo High School and Delphi Automotive Systems.

Posted on 4/16/99 8:36 AM MST

In Reply to: Re: CAD Drawings? posted by Ed Sparks on 4/16/99 7:00 AM MST:

: Now I’m CAD crazy. This year I designed and manufactured retractable
: ‘landing gear’ wheels on Autocad. You’ve got to see them.

: Come see us @ Pit #34

: Ed

I saw the ‘landing gear’ in Yipsi. I think I actually drooled on it.
It is the most impressive drive/wheel lift system that I’ve seen on
any 'bot.

Very impressive… and you’re a EE?

Andy B.

Posted by Ed Sparks, Engineer on team #34, DaimlerChrysler Electronics & Bob Jones High School, from Bob Jones High School and DaimlerChrysler.

Posted on 4/16/99 9:02 AM MST

In Reply to: Re: 34’s Landing Gear posted by Andy Baker on 4/16/99 8:36 AM MST:

… and you’re a EE?

Scary ain’t it …

Posted by Daniel, Student on team #192, Gunn Robotics Team, from Henry M Gunn Senior High School and NASA Ames.

Posted on 4/16/99 6:58 PM MST

In Reply to: Re: CAD Drawings? posted by Ed Sparks on 4/16/99 7:00 AM MST:

I don’t know about you, but MY mill has hand cranks. Loose hand cranks. It’s fun! You can sit there spinning the thing and maybe read a few chapters of your english homework before it gets through all the slop (by the way, that’s my secret to not having grades decline during this project). And then once you start moving the thing you get that upper body workout as an extra. Good stuff, that.

Can I have your shop?? Please???

Oh well, we make do.

-Daniel

Posted by Tom Wible, Coach on team #131, chaos, from central high school manchester and osram-sylvania.

Posted on 4/16/99 5:24 PM MST

In Reply to: CAD Drawings? posted by Rick Gibbs on 4/15/99 8:44 PM MST:

This year we were not afforded the luxury of a mechanical engineer on our team.
Instead we used another fine design tool: pencil and paper, combined with good old fashioned imagination.
The result: a robot that can do every task(well), and was number two seed by tie breaker in Hartford.
Moral of the story: CAD is great, imagination is awesome!

Tom Wible
Team 131 ‘C.H.A.O.S.’

Posted by Kate Leach, Student on team #166, Team Merrimack, from Merrimack High School and Unitrode / RS Machines.

Posted on 4/17/99 8:42 AM MST

In Reply to: CAD Drawings? posted by Rick Gibbs on 4/15/99 8:44 PM MST:

In the past I think we’ve tried to use CAD to design our whole robot, but we’ve run out of time and haven’t gotten the robot built in time and have always been working frantically in the pits trying to get it done. This year we used CAD a little bit. Just a 2-D drawing of the side view of our ‘bot and the puck. Good thing we’ve got our ME that’s working with us on a total volunteer basis (seeing as he’s unemployed and all) because if we didn’t have him, we wouldn’t have known that if we’d tried getting up on the puck with our original design, it wouldn’t have worked. We would’ve gotten stuck because our back end would have been 2’ into the ground, well according to the CAD drawing. So, we fixed our design so we wouldn’t be stuck. We hadn’t even thought of this problem before we’d put in on CAD. Over the summer I’m hoping to learn CAD a bit better than I know it now. From what I’m hearing it will really help in the design of the robot. And it might be good seeing as though I’m going into engineering and all…

-KATe-