pic: Rastogi 8wd Iteration 1.2

[Akash Rastogi]

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[Dkt01]

Looks great. If I didn't know better, I'd think you had built it already and this was a picture of it.

[gyaniv]

Looks great!!!

I have couple of questions for you:...

Does the 4 outer wheels raised?

If the wheels are raised why not going for 8WD instead of 4WD?

Why did you decide to use 4 dual-nano (have no idea what it is but i figured it is a gearbox) instead of 2 gearboxes and using chain/belt to convert the power? might save some weight over there.

I don't know much about sheet-metal drive-train but wouldn't it be wiser to bent the sheet-metal towards the robot instead outwards? My opinion is that it will be much safer, more easy to work with, and stronger. But as i said, i don't know much about sheet-metal drive-train, so i also want to hear an expert on that question...

Thank you

[Brandon Holley]

Why are the hex shafts so long? Just curious, I'm sure its just something you haven't gotten to yet.

Looks good. Designing in sheet metal is a very good thing to learn if your planning on becoming a mechanical engineer of some sorts. I cannot tell you how many sheet metal parts I've designed for my various jobs I've had. It comes in handy for other parts too that aren't necessarily made of "metal" (ie: polycarb, other such plastics) which may be created using the same techniques as standard sheet metal parts.


Also very handy with sheet metal are PEM fasteners. If you can master their usage, you can create really sleek sheet metal designs.


Have you done any FEA on the frame? Its sometimes difficult to gauge the "strength" of a design from sheet metal, especially when first starting to design in sheet. My only comment would be to add a cross member lower on the frame to add another axis of stability, however it may be unnecessary, thats what analysis is for!

Brando

[jamie_1930]

Originally Posted by gyaniv

Looks great!!!

I have couple of questions for you:...

Does the 4 outer wheels raised?

If the wheels are raised why not going for 8WD instead of 4WD?

Why did you decide to use 4 dual-nano (have no idea what it is but i figured it is a gearbox) instead of 2 gearboxes and using chain/belt to convert the power? might save some weight over there.

I don't know much about sheet-metal drive-train but wouldn't it be wiser to bent the sheet-metal towards the robot instead outwards? My opinion is that it will be much safer, more easy to work with, and stronger. But as i said, i don't know much about sheet-metal drive-train, so i also want to hear an expert on that question...

Thank you

I immediately questioned why the metal was bent out and all though I don't have his answer to it in my opinion it is better to bend out because when you bolt things to the top it allows easier access to the nuts than reaching your hand around to the inside.

[apalrd]

With little experience designing sheet metal chassis, I will share my opinions anway.

1. Any reason for folding out instead of in? Without that pesky bolt heads frame perimeter rule, there should be no reason to cover the bolt heads.

2. What material is the dead axle? I assume a 3/8" pipe, taped at the end, with a bolt holding it in.

3. Again, why the dual-nano?
3a. You could alternatively make the distance between the two side plates exactly the width of an AM Shifter, then put an AM Shifter inside (with the chassis sides as the side plates). Or, you could just use an SuperShifter or Toughbox as you do now, with a live axle, then chain the other side.

4. Why the bump-climbing notch? Assuming there is less terrain then this game...

5. I like the render. Looks very real.

[Akash Rastogi]

Originally Posted by Brandon Holley

Why are the hex shafts so long? Just curious, I'm sure its just something you haven't gotten to yet.

Yup, just didn't get to that yet, its just the standard AM model length.

Originally Posted by Brandon Holley

Have you done any FEA on the frame? Its sometimes difficult to gauge the "strength" of a design from sheet metal, especially when first starting to design in sheet. My only comment would be to add a cross member lower on the frame to add another axis of stability, however it may be unnecessary, thats what analysis is for!

I haven't learned proper testing, that's a big part of CAD I plan to learn shortly.

Originally Posted by gyaniv

If the wheels are raised why not going for 8WD instead of 4WD?

I'm not sure what you mean. The center 4 wheels are lowered 3/16" for barely a rock.

Originally Posted by gyaniv

Why did you decide to use 4 dual-nano (have no idea what it is but i figured it is a gearbox) instead of 2 gearboxes and using chain/belt to convert the power? might save some weight over there.

I'm just trying out new nano configurations and it decreases chain usage. I haven't calculated how much power I'm getting to the wheels as apposed to using a single gearbox with dual CIMs per side.

Originally Posted by gyaniv

I don't know much about sheet-metal drive-train but wouldn't it be wiser to bent the sheet-metal towards the robot instead outwards? My opinion is that it will be much safer, more easy to work with, and stronger. But as i said, i don't know much about sheet-metal drive-train, so i also want to hear an expert on that question...

This is a question I have for the experts too. Right now I'm just creating "shells" for the main structures as I've seen done with team 1902's 2008 and 2010 frames. I assume it is actually easier to work with the frame pieces this way because you have more access to the open surfaces of the material.

Originally Posted by apalrd

3a. You could alternatively make the distance between the two side plates exactly the width of an AM Shifter, then put an AM Shifter inside (with the chassis sides as the side plates). Or, you could just use an SuperShifter or Toughbox as you do now, with a live axle, then chain the other side.

I definitely like this idea. Right now I was just going for something that is direct drive, but I'm liking the built in SuperShifter idea a lot.

Thanks for the questions. More suggestions and advice are welcome and appreciated.

[Chris is me]

edit: akash is a ninja delete plz

[sgreco]

I would say you're fine for powering from four separate locations as opposed to one central spot on each side. If it shortens the chain runs and makes maintenance easier, it's a good trade-off.

I can't see the stress tests for this, but as a typical rule of design you want the most support in the middle, as that's where it'll break first. I would take out some of the pocketing in the middle, it'll likely only add fractions of a pound anyway.

Overall it looks great though. Your rendering and designing skills have gotten really good, great job.

[Jamie Kalb]

Originally Posted by jamie_1930

I immediately questioned why the metal was bent out and all though I don't have his answer to it in my opinion it is better to bend out because when you bolt things to the top it allows easier access to the nuts than reaching your hand around to the inside.

If you've got PEM nuts inserted in the flanges to bolt things to the top, you never need to reach under the flange to hold a nut...

*hint - Akash, PEM nuts are good - hint*

Looks really good, though. Really imposing. Keep it up!

[Chris is me]

I'm of the opinion it would be faster to stress test a prototype then it would be to run complete and thorough FEAs on stuff like this anyway. We should just build one.

[RMS11]

Originally Posted by Jamie Kalb

If you've got PEM nuts inserted in the flanges to bolt things to the top, you never need to reach under the flange to hold a nut...

*hint - Akash, PEM nuts are good - hint*

Looks really good, though. Really imposing. Keep it up!

Where here would you attempt to use PEM nuts. I was looking at them on mcmaster, and they look cool, but pressing all of them seems time consuming when you could just use rivets or a nut and bolt instead. In the long run it might save a bit of time though... Any other big advantages of them? thanks!

[rulesall2]

Something I've noticed, only because we ran into the same problem this year, is that you have effectively created a giant piece of C-channel. Moving those cross-braces down to form an I-beam shape or adding ones near the bottom should strengthen the design a bit. Just some thoughts, but I like where this is heading.


.

[Andrew Remmers]

Originally Posted by Akash Rastogi

This is a question I have for the experts too. Right now I'm just creating "shells" for the main structures as I've seen done with team 1902's 2008 and 2010 frames. I assume it is actually easier to work with the frame pieces this way because you have more access to the open surfaces of the material.

Being on 1902 I can say that when the flanges are facing outward it is significantly easier to run maintenance on the drive train. Considering that the space you are working with is already very small it is difficult to get to all the components even on the robot we have this year. I can only imagine what it would have been like if it were the other way around, having that "obstacle" in the way would have made some points of repair for us very difficult especially when we had a master link failure at Florida.

Also what I think with the flanges facing inward towards each other means you would have to design enough space for your chain/belt to run depending on your configuration. Which means you might have less space elsewhere for another mechanism or something like that.


BTW very nice render It has inspired me to get finished with my school work faster so i can finally get around to designing my own sheet metal drive train!

[Akash Rastogi]

Originally Posted by Joyride_67_1902

Being on 1902 I can say that when the flanges are facing outward it is significantly easier to run maintenance on the drive train. Considering that the space you are working with is already very small it is difficult to get to all the components even on the robot we have this year. I can only imagine what it would have been like if it were the other way around, having that "obstacle" in the way would have made some points of repair for us very difficult especially when we had a master link failure at Florida.

Also what I think with the flanges facing inward towards each other means you would have to design enough space for your chain/belt to run depending on your configuration. Which means you might have less space elsewhere for another mechanism or something like that.

BTW very nice render It has inspired me to get finished with my school work faster so i can finally get around to designing my own sheet metal drive train!

Ah thanks for the insight Andrew.

You might also like this. I tried to copy it from one of the pictures that was posted of your 2010 bot.