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.

[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

[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

[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.

[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.

[IKE]

Originally Posted by 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.

We have "prototyped" chassis out of posterboard in the past. If you do about 1/2 to 1/4 scale, you can cut fold and glue panels together. This softer material can help visualize where additional members may be helpful.

[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!

[Jamie Kalb]

Originally Posted by RMS11

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!

I'm not good at judging measurements from pictures, but it looks to me like the current flanges aren't big enough. But if the flanges bent off the main body of those enormous side plates were wider (or is that longer?), you could punch holes in them and press the PEM nuts in. As far as I know, many sheet metal shops can do this in-shop. Check out the 217/148 Sheet Metal video. It shows them pressing PEM nuts at about 5:05 in the video. Not time-consuming at all. Compare the ~1 second per insert to all the time you'd spend fumbling for a nut ... total. For a season.

Whenever possible, I like to add threads to a part (tapping or threaded insert) rather than using a nut. One less piece to worry about, one less piece to come loose, one less point you have to reach for assembly/maintenance. Plus installation and removal now only takes one hand!

But Andrew's 100% right about this:

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.

Having the flanges bent in rather than out definitely does make drivetrain maintenance harder. It's possible to make the plates modular enough to justify this, but you're probably better off just keeping them facing outwards.

[R.C.]

Nice Render,

Slightly curious what's the weight?

-RC

Looking good.

Also, I'll second (third?) the recommendation for using PEM nuts. We use them at my work on our sheet metal chassis, and they're wonderful to deal with. Out of 75 robots, we had one PEM nut pop loose, and the shop that pressed them fixed it for us in less than 6 hours. PEM nuts are the way to go.

How many parts in there are standardized? It's always easier for a sheet metal shop to punch out and break more similar parts than differing ones.

[Akash Rastogi]

Originally Posted by CraigHickman

Looking good.

Also, I'll second (third?) the recommendation for using PEM nuts. We use them at my work on our sheet metal chassis, and they're wonderful to deal with. Out of 75 robots, we had one PEM nut pop loose, and the shop that pressed them fixed it for us in less than 6 hours. PEM nuts are the way to go.

How many parts in there are standardized? It's always easier for a sheet metal shop to punch out and break more similar parts than differing ones.

I'll definitely check out PEM nuts.

There are only 3 different parts here. All sideplates at the same, all cross members are the same, and brackets in between plates are the same.

Originally Posted by Akash Rastogi

I'll definitely check out PEM nuts.

There are only 3 different parts here. All sideplates at the same, all cross members are the same, and brackets in between plates are the same.

Wonderful! Keep up the awesome work!

[AdamHeard]

Why not connect the two side assemblies along the bottom?