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This is a monocoque frame with treads that I designed last offseason. I was sorting through some folders and found the render and thought I'd share it. The frame shown is made entirely from one sheet aside from the two crossbars. Looking back on it now, I don't like the crossbar design, but I thought I'd share it anyways.
Rendered in Inventor 2009.
Discussion
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06-08-2009 17:17
sgreco
Re: pic: Monocoque Treads
Wow, very nice render.
Excuse my ignorance, but how do you get power to the tread itself?
Good stuff though, I like it.
06-08-2009 17:27
Akash Rastogi
Re: pic: Monocoque Treads
That looks amazing Andy. 
I'll definitely have to take a crack at replicating that next week. RC's thinking the same thing right now probably. 
06-08-2009 17:32
R.C.
Re: pic: Monocoque Treads
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Originally Posted by Akash Rastogi
That looks amazing Andy.
I'll definitely have to take a crack at replicating that next week. RC's thinking the same thing right now probably. |
But Andy, that looks SICK. ME LIKEEEE.-RC
06-08-2009 17:42
sdcantrell56
Re: pic: Monocoque Treads
That is an absolutely beautiful render. I too am curious about how the tread is driven though.
06-08-2009 17:58
EricH
Re: pic: Monocoque Treads
It looks like the drive system is in the middle, where what seems to be an axle pokes out from a bearing. I'd say right above that is where the drive goes. Am I correct?
06-08-2009 18:45
AndyB
Re: pic: Monocoque Treads
Yes Eric, you are correct. If you look closely, a bit of shaft is sticking out of the middle into the bay of the frame. I think my original intentions were to use a Gen 2 AM shifter but the shaft is standard 1/2" keyed, so direct drive would be possible as well.
06-08-2009 21:53
Akash Rastogi
Re: pic: Monocoque Treads
What's the wall thickness of the various rails and the electronics pan?
06-08-2009 23:20
AndyB
Re: pic: Monocoque Treads
I'm not 100% sure on that. I found the cad file of the design and noticed that the wall thickness was .1in, but that's hardly accurate. In a design like this, I'd probably use .08-.09" for 6061 aluminum or .03-.05" for some sort of galvanized steel. I'd probably use sheet steel just because it's readily available to us.
I've never actually worked with sheet steel within FIRST robotics. I tried doing some research on it but couldn't find much in terms of second hand experience. I've used chromoly steel back when I was with 269 but the properties of chromoly extrusion and galvanized sheet steel are probably pretty different as well. I've heard the number 3x the weight/strength when compared to aluminum but I have no clue if that's correct or not. It was with chromoly extrusion compared to aluminum extrusion which is why we could use .035" wall thickness extrusion.
So to answer your question Akash, .08-.09" Aluminum or .03-.05" Steel.
Something interesting to point out now that I'm looking at the design more up close is how the rollers are set up. There are no crossbars inside the tread modules to add support. At least not any supports designed solely as crossbars... the axles for each roller are dead and the UHMW or UDPE rollers spin freely on them. This way, the roller acts as a crossbar support as well.
06-08-2009 23:59
Nick Lawrence
Re: pic: Monocoque Treads
That kind of reminds me of the 2006 robots that NiagaraFIRST built.
-Nick
07-08-2009 00:03
Akash Rastogi
Re: pic: Monocoque Treads
Its also pretty similar to the frame 25 uses on their beautiful drivetrains.
07-08-2009 00:10
artdutra04
Re: pic: Monocoque Treads
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Originally Posted by AndyB
I'm not 100% sure on that. I found the cad file of the design and noticed that the wall thickness was .1in, but that's hardly accurate. In a design like this, I'd probably use .08-.09" for 6061 aluminum or .03-.05" for some sort of galvanized steel. I'd probably use sheet steel just because it's readily available to us.
I've never actually worked with sheet steel within FIRST robotics. I tried doing some research on it but couldn't find much in terms of second hand experience. I've used chromoly steel back when I was with 269 but the properties of chromoly extrusion and galvanized sheet steel are probably pretty different as well. I've heard the number 3x the weight/strength when compared to aluminum but I have no clue if that's correct or not. It was with chromoly extrusion compared to aluminum extrusion which is why we could use .035" wall thickness extrusion. So to answer your question Akash, .08-.09" Aluminum or .03-.05" Steel. ... |
Depending on the actual alloy used however, these figures will vary.
07-08-2009 00:29
AndyB
Re: pic: Monocoque Treads
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Originally Posted by Akash Rastogi
Its also pretty similar to the frame 25 uses on their beautiful drivetrains.
|
I actually think I drew the most inspiration from team 1024's 2008 chassis as far as the fold pattern goes. However, I definitly took a few looks at the NiagraFIRST 06' bots while designing this as well. At the time, we were seriously considering building this drive system. I contacted Karthik regarding belt selection and he highly recommended Gates belting over Brecoflex.
During kickoff last year, when they announced the slick floor surface, our team all looked at eachother with huge smiles because we thought for sure this design would be coming to life... and then 5 seconds later, they announced the rover wheels mandate.
07-08-2009 00:34
Akash Rastogi
Re: pic: Monocoque Treads
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Originally Posted by AndyB
I actually think I drew the most inspiration from team 1024's 2008 chassis as far as the fold pattern goes.
Thanks for the info Art. I'll keep that in mind for future sheet steel projects. |
Mind sending the CAD over for reference?
07-08-2009 00:47
AndyB
Re: pic: Monocoque Treads
You can download the cad at:
http://www.andyburchardt.com/robotic...MonoTreads.rar
Speaking of 25, I have been looking closely at their 2006 drive lately. I like their use of ITEM/8020 with sheet/plate aluminum.
07-08-2009 01:00
Akash Rastogi
Re: pic: Monocoque Treads
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Originally Posted by AndyB
You can download the cad at:
http://www.andyburchardt.com/robotic...MonoTreads.rar Speaking of 25, I have been looking closely at their 2006 drive lately. I like their use of ITEM/8020 with sheet/plate aluminum. |
I could def see myself converting this frame a little to use the Skyway bead-lok wheels 25 uses.
http://www.chiefdelphi.com/media/photos/19942
Some people definitely underestimate the use of 80/20.
Btw, did you use any additional rendering software/add-ins with SW for this?
07-08-2009 01:05
R.C.
Re: pic: Monocoque Treads
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Originally Posted by Akash Rastogi
Sweet, thanks a lot
Btw, did you use any additional rendering software/add-ins with SW for this? |
07-08-2009 01:14
Akash Rastogi
Re: pic: Monocoque Treads
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Originally Posted by rc_cola1323
Andy uses Inventor 2009
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Then I am definitely speechless. Best. Inventor. Rendering. Ever.
k, I'm done commenting now
07-08-2009 01:44
AndyB
Re: pic: Monocoque Treads
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Originally Posted by rc_cola1323
Andy uses Inventor 2009
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Thanks all for the kind words.
07-08-2009 09:00
Peter Matteson
Re: pic: Monocoque Treads
Looks beautiful. A couple of questions though.
Why one sheet of material, do you have access to a shop where handling a piece of material that big is practical?
Second have you considered beading the base pan dimpling the holes for added structure?
Great work.
Pete
07-08-2009 12:16
AndyB
Re: pic: Monocoque Treads
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Originally Posted by Peter Matteson
Looks beautiful. A couple of questions though.
Why one sheet of material, do you have access to a shop where handling a piece of material that big is practical? Second have you considered beading the base pan dimpling the holes for added structure? Great work. Pete |
Yes, we do have a shop where bending something like this would be fairly simple. If you take a closer look at the main shell, all of the folds are in one direction. We also have access to a CNC router.
As far as beading and dimpling go, I never really considered it. I'm not sure that we have the kind of tools to do something like that, but it's a very interesting idea.
Come to think of it, the base pan could probably be pretty open... again, similar to 1024's 2006 frame.
07-08-2009 13:50
cbale2000
Re: pic: Monocoque Treads
Nice looking chassis you've got there (and a VERY sweet render)!
Any estimates on how much it would weigh?
10-08-2009 13:59
AndyB
Re: pic: Monocoque Treads
What you see weighs about 20lbs. The frame is aluminum and the rollers are UHMW.
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