pic: Schreiber Take on West Coast Drive

[548swimmer]

Originally Posted by Jared341

I am struggling with why having a high CoG would prevent you from flipping in the event of a collision.

If anything, lowering the traction of your wheels would seem to do the most good since it would prevent your entire robot from becoming a lever arm rooted in the ground.

Think about free body diagrams. The forces always go to the center of mass (in this case, gravity), of the object. A CG directly in line with the bumper zone will create a force applied that is parallel to the ground. This eliminates the levering issue, as well as flipping.

[Andrew Schreiber]

Originally Posted by JesseK

Andrew, I don't know a single employer who would take a napkin sketch and arbitrary numbers over a full CAD given a choice between the two. It's a shame that you're mocking everyone who requests feedback on various frame designs while also learning.

CAD is never a crutch; it's simply one of the many pieces to the equation of a high quality product.

Am I looking for a job designing gearboxes? Do I work in that field? No. But I do know that most employers would rather me take the 30 seconds it takes to draw a rough sketch of an idea to make sure it would work than spend 2 hrs in CAD.

Would you call a lot of what has been posted recently full CAD or would you call it a bunch of cookie cutter components tossed together? I would say the latter. And yes, I am going to mock them. I am ok with them learning, heaven knows I still am, but this constant stream of "West Coast Drive" CADs that are only differentiable by their color is irritating. Sure, I could have put more time into my drawing but the important parts are there in my opinion. Wheel placement (having them overhung), chain placement, approximate weight, and a reasonable gearing based upon simple calculations. (Which I will be redoing thanks to Jared's post)

CAD used as a tool to help further a design is a tool. CAD used to assemble parts that you downloaded off the internet and then making a pretty picture without any understanding of what you are doing is a crutch.

Originally Posted by JesseK

If you re-read Andrew's post as if you were brand new to these forums, you may find that (specifically) the final paragraph is incredibly off-putting to someone trying to do a CAD by themselves for the first time, not knowing what they're really supposed to know in order to do things correctly. Andrew has exemplified the common CD knowledge paradox. Sure, all of the recent CAD prototypes are 'pretty', and most of them are missing details, yet the negative implications of Andrew's tone are as common as the missing details themselves.

Yes, my last paragraph was meant to be that way. I, as a mentor whose job it is to inspire (not teach) students, would be floored if we were to have dozens of students asking how to properly do calculations for drive trains or arms. They have their college years to learn CAD (and will probably have to relearn a different piece of software for their jobs). Instead they are designing systems that, in all likelihood, will not work because they made some mistake that would have been solved had they first taken the time to do a quick sketch on a white board. So, if I turn off a couple people from jumping right into CAD I am fine with that as long as it also gets some people thinking about doing the math.

[548swimmer]

Originally Posted by Andrew Schreiber

Yes, my last paragraph was meant to be that way. I, as a mentor whose job it is to inspire (not teach) students, would be floored if we were to have dozens of students asking how to properly do calculations for drive trains or arms. They have their college years to learn CAD (and will probably have to relearn a different piece of software for their jobs). Instead they are designing systems that, in all likelihood, will not work because they made some mistake that would have been solved had they first taken the time to do a quick sketch on a white board. So, if I turn off a couple people from jumping right into CAD I am fine with that as long as it also gets some people thinking about doing the math.

I know that I posted my designs to receive structural feedback, not feedback involving gear ratios and the math involved in the traction. I'm all for sketching by hand, but there is some structural feed back you just can't get off of a napkin.

[Andrew Schreiber]

Originally Posted by 548swimmer

I know that I posted my designs to receive structural feedback, not feedback involving gear ratios and the math involved in the traction. I'm all for sketching by hand, but there is some structural feed back you just can't get off of a napkin.

Which would be "doing the math" would it not be? I disagree that there is structural feedback you can't get off a napkin since the lightening of 2337's hanging system was a napkin* sketch but I will give you the benefit of the doubt. The ones that bother me are the ones that say, "We go X fps" and then when questioned about that number are unable to tell us their ratios. To me it screams that they pulled a number out of their behind.


*Actually, I think Spaz Dad used the back of another sheet of paper

[AdamHeard]

Originally Posted by 548swimmer

I know that I posted my designs to receive structural feedback, not feedback involving gear ratios and the math involved in the traction. I'm all for sketching by hand, but there is some structural feed back you just can't get off of a napkin.

I disagree there as well. A good, clean, efficient design should have a frame that can be sketched by hand and explained in 30 seconds or less.

A frame can still be strong if it doesn't meet that requirement, but that means it's probably pretty inefficient and complex.

[548swimmer]

Originally Posted by Andrew Schreiber

Which would be "doing the math" would it not be? I disagree that there is structural feedback you can't get off a napkin since the lightening of 2337's hanging system was a napkin* sketch but I will give you the benefit of the doubt. The ones that bother me are the ones that say, "We go X fps" and then when questioned about that number are unable to tell us their ratios. To me it screams that they pulled a number out of their behind.


*Actually, I think Spaz Dad used the back of another sheet of paper

I agree that things such as lightening patterns can be done easily on sheets of paper, but more complex mechanisms such as our kicker pull-back mechanism should be done primarily in CAD.

[Chris is me]

Originally Posted by 548swimmer

I agree that things such as lightening patterns can be done easily on sheets of paper, but more complex mechanisms such as our kicker pull-back mechanism should be done primarily in CAD.

You can make a winch on paper...

[EricH]

You'd be surprised at how many things can be done on paper quickly, including "complex" mechanisms like kicker pull-backs.

Let's go back in time a few years, to the airplane and tank designs of WWII. Did they have computers? No. At least, not that were capable of running CAD programs other than number-crunching to do analysis and things of that nature. So, how do you think they designed all their engines, landing gear, treads, guns, turret-turning devices, and all that sort of thing to create the given airplane or tank?

Yep, on paper, with enough accuracy to use them to make and assemble parts that worked, a few thousand times over per part.

How about the interrupter gear in WWI, which allowed a plane to shoot through its own propeller without damaging itself? Paper, and relatively complex. And I'd be willing to bet that Mr. Fokker, if placed in the modern world and told to sketch the interrupter gear, or even create a production drawing of it, could do it faster and just as accurately as a good CADder.

The point is, while CAD is nice because it can quickly turn a part model into a machining drawing (or, with assistance from other programs, into code for a CNC to make the part), pencil and paper is just as effective in the hands of someone who knows how to use it well.

"Don't underestimate the ability of a highly skilled technician with simple tools..." --Dave Lavery, in response to someone saying something about not having good enough tools in http://www.chiefdelphi.com/forums/sh...661#post119661

[548swimmer]

Originally Posted by Chris is me

You can make a winch on paper...

How long would it take you to change the spacing of your sprockets used in the pull back on paper?

How long would it take to create a piece you can water-jet with your paper sketch? About as long as it would take you to just CAD it originally.

I'm all for conceptual sketches being done on paper, but it seems unintelligent to not utilize all of your resources (CAD).

[548swimmer]

Originally Posted by EricH

You'd be surprised at how many things can be done on paper quickly, including "complex" mechanisms like kicker pull-backs.

Let's go back in time a few years, to the airplane and tank designs of WWII. Did they have computers? No. At least, not that were capable of running CAD programs other than number-crunching to do analysis and things of that nature. So, how do you think they designed all their engines, landing gear, treads, guns, turret-turning devices, and all that sort of thing to create the given airplane or tank?

Yep, on paper, with enough accuracy to use them to make and assemble parts that worked, a few thousand times over per part.

How about the interrupter gear in WWI, which allowed a plane to shoot through its own propeller without damaging itself? Paper, and relatively complex. And I'd be willing to bet that Mr. Fokker, if placed in the modern world and told to sketch the interrupter gear, or even create a production drawing of it, could do it faster and just as accurately as a good CADder.

The point is, while CAD is nice because it can quickly turn a part model into a machining drawing (or, with assistance from other programs, into code for a CNC to make the part), pencil and paper is just as effective in the hands of someone who knows how to use it well.

"Don't underestimate the ability of a highly skilled technician with simple tools..." --Dave Lavery, in response to someone saying something about not having good enough tools in http://www.chiefdelphi.com/forums/sh...661#post119661

Didn't see this when I hit reply...

Paper and pencil is to those times as CAD is to modern times. Sure, there are still uses for hand drafting in today's environment, but CADding is becoming more and more important. I'm not suggesting you eliminate all drafting instruction, but that you consider what will be most useful in the future.

[Mike Schreiber]

Originally Posted by JesseK

Andrew, I don't know a single employer who would take a napkin sketch and arbitrary numbers over a full CAD given a choice between the two. It's a shame that you're mocking everyone who requests feedback on various frame designs while also learning.

CAD is never a crutch; it's simply one of the many pieces to the equation of a high quality product.

I don't know a single employer who would hire someone based on a full CAD with no explanation and no knowledge of how it works. It's all about the interview and if you can't explain/justify your design decisions you're not getting that job.

[548swimmer]

Originally Posted by ICanCountTo19

I don't know a single employer who would hire someone based on a full CAD with no explanation and no knowledge of how it works. It's all about the interview and if you can't explain/justify your design decisions you're not getting that job.

Why would you think that someone who knows only CAD would have no knowledge of how to design (I'm assuming this is the "it"). I would be highly surprised if anyone who knows only CAD would have an issue making a pencil sketch such as the picture for this post. Many of the drivetrain ideas posted on here are done in CAD simply because it takes more time. 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.

[ttldomination]

Originally Posted by ICanCountTo19

I don't know a single employer who would hire someone based on a full CAD with no explanation and no knowledge of how it works. It's all about the interview and if you can't explain/justify your design decisions you're not getting that job.

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

[548swimmer]

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

Thank you!

[Chris is me]

Originally Posted by ttldomination

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

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.