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By: evanisthat!
New: 10-08-2006 23:12
Updated: 10-08-2006 23:12
Views: 1454 times
A design for a modular Crab Drive system I developed a while ago.
The material is nylon and was "printed" on an SLA machine. In this particular design, the motor mounts elsewhere on the frame and is drives the wheel via the upper sproket, which turns a bevel gear which drives the sproket driving the wheel. The whole unit rotates around a delrin bearing that sits sandwhiched between the two large disks under the lower horizontal sproket. The final version is still being worked on, but will obviously not be made out of nylon (although that would be really cool, we would get owned), the wheel however, will be made from delrin. Any further questions, feel free to ask!
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Discussion
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11-08-2006 01:17
Madison
Re: pic: 108 Rapid Crab Prototyping
Out of curiousity, how quickly do the SLA machines print? I've been prototyping parts in ABS lately on a ZCorp 3D printer, but I think I've got something coming down the line that's going to be made on an SLA machine.
What are the overall dimensions of the crab module?
11-08-2006 07:27
evanisthat!
Re: pic: 108 Rapid Crab Prototyping
I actually do not know exactly how long it takes, but I always have my parts within 24 hours of submitting them. The shop that makes them also makes tons of other stuff so I am not always first priority = ( . I would guess though that it takes about 4 hours to make something large and complicated. Umm, dimensions... the overall OD of the unit is 4.5", the overall height is 9.25", the box frame is 3"X3", and all the material is 1/4" plate (eventually aluminum). Inventor's estimates its weight at just a hair under 4 pounds, including hardware.
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11-08-2006 07:45
Ben Piecuch
Re: pic: 108 Rapid Crab Prototyping
Rapid Prototyping Content:
SLA machines run fairly quickly. I believe the units we used had a 1mm thickness interval, and each layer was done in a quick flash. However, I seem to recall that the cleanup of the part(s) was the most time consuming. The nylon is not very stable (due to temperature/light) so we always painted our models. That was after all the hand-sanding and detailing. Our turn-around time was a couple days.
Swerve Content:
Looks like a nice package. Is there only the single rotational bearing through the midline of the unit, or is it supported near the top as well? Also, are you making the swerve sprocket yourself, or is that an off the shelf part? Do you have an estimate cost for a full-up module? (I'd love to hear what it cost other teams to do a similar design.) I hope to see it in 2007!
BEN
11-08-2006 16:16
Bill_Hancoc
Re: pic: 108 Rapid Crab Prototyping
wow i wish my team had the funding to be able to access a rapid prototypeing machine...we have are lucky if you can get a few things done on a bridgeport or a cnc...seeing as we dont have either of those
11-08-2006 23:00
evanisthat!
Re: pic: 108 Rapid Crab Prototyping
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Originally Posted by Ben Piecuch
Rapid Prototyping Content:
SLA machines run fairly quickly. I believe the units we used had a 1mm thickness interval, and each layer was done in a quick flash. However, I seem to recall that the cleanup of the part(s) was the most time consuming. The nylon is not very stable (due to temperature/light) so we always painted our models. That was after all the hand-sanding and detailing. Our turn-around time was a couple days. Swerve Content: Looks like a nice package. Is there only the single rotational bearing through the midline of the unit, or is it supported near the top as well? Also, are you making the swerve sprocket yourself, or is that an off the shelf part? Do you have an estimate cost for a full-up module? (I'd love to hear what it cost other teams to do a similar design.) I hope to see it in 2007! BEN |
11-08-2006 23:17
Arefin Bari
Re: pic: 108 Rapid Crab Prototyping
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Originally Posted by evanisthat!
Right now there is only one rotational bearing in the design, however a few people have commented on the stability of that during a match so in gen2 there will be 2 bearings, one low and one high. the sprocket is off the shelf but requires serious reworking, its a 70 tooth #25 chain with a 3 inch square cut in the middle... As cost goes...hmm... I have no idea. Working the parts would be the most expensive (especially the sprocket) as everything else is a standard part. When I am done reworking the whole design, I will post it with the inventor files for all to use. My final goal is to make it 2-speed, with independent swerve per side.
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... now post the picture up and go back and concentrate on school work, you gotta get to MIT remember? Good luck, Evan.
12-08-2006 20:20
Qbranch
Re: pic: 108 Rapid Crab Prototyping
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Originally Posted by Bill_Hancoc
wow i wish my team had the funding to be able to access a rapid prototypeing machine...we have are lucky if you can get a few things done on a bridgeport or a cnc...seeing as we dont have either of those
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just what i think.
-Q
12-08-2006 21:09
Jeremiah Johnson
Re: pic: 108 Rapid Crab Prototyping
I prefer a mill, too. A small, red one sitting in our machine shop. All manual. LOL... there's 3 digital ones and 4 manual ones in K-T I think... but the only one I know how to use is the one in the robotics area and I work at K-T.
12-08-2006 23:45
evanisthat!
Re: pic: 108 Rapid Crab Prototyping
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Originally Posted by Qbranch
our team has a Stratasys Maxum FDM machine, prints ABS plastic. its good for some things but, well, i'm a machinist and i think thats still the way to go for most stuff. not to mention you get things done a heck of a lot faster on a mill.
just what i think. -Q |
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13-08-2006 11:14
Billfred
Re: pic: 108 Rapid Crab Prototyping
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Originally Posted by evanisthat!
Who knows though, one day we may see an all Lexan (or some other strong plastic) robot...how cool would that be?
108 |
http://spamrobotics.com/skins/spamin...e=history#2000
14-08-2006 08:50
MattB703
Re: pic: 108 Rapid Crab Prototyping
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Originally Posted by evanisthat!
..... one day we may see an all Lexan (or some other strong plastic) robot...how cool would that be?
108 |
and
http://www.chiefdelphi.com/media/photos/12491
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