how do the work when you have 2 chains and 3 segments like 233 in 2004 and 2005
Basically, you have a pulley or sprocket on the top of the outermost segment, one at both the bottum and top of the middle segment, and an attatchment point at the bottum of the innermost segment.
The same setup is used on an 80/20 or similar material elevator, like team 25’s this year.
You might find this presentation by Greg Needel from the 2006 Conference Archives to be interesting. He covers a lot of different concepts in arm design in it, check it out, I think what your asking is covered in it.
that is one but what I mean where you have 2 complete chain segments
I havn’t actually gotten to look at anyone elses but this is one way i thought up.
http://www.boredomabounds.com/arm.gif
the red chain is attached to the bottom of the middle segment, goes over both the top and bottom of the outer segment and is powered by a sprocket (red lines). the second chain section (blue) attaches to the top of the outer segment ran over the top and bottom of the middle segment and is attached to the bottom of the inner segment.
While I have not actually used the design you showed on a FRC robot, I strung up one of my LEGO robots to use the same design as you designed and it worked perfectly. With this design, all the segments are the same precent extended as all the others.
but what do you do when you have a 3" 2" and 1" box tubing in side of one another like this http://www.chiefdelphi.com/media/photos/20400
and http://www.chiefdelphi.com/media/photos/18173
It looks more like 4-6", 2-3" and 1"… I think they have varied it slightly year to year, If you read through some of the discussions on the 04,05 and 07 robots from 233, I think it says what sizes they use. It’s the exact same principle, except the sliders are inside of each other rather than next to each other.
We (Team 343-Metal in Motion) used a three segment arm like 233 this year. We drove the first section with a lead screw and a cable was wrapped around two pullies on the second. (Similar to the diagram above). We used box tubing of 3X2" for the first stage, 2X1.5" for the second and 1X1" for the third. We had intended to do the cut outs like 233 but didn’t need the weight so we left them whole. If you’re looking for more details, PM me and I can send you the cad drawings.
This might help you out.
From our 2005 robot
EDIT: We used 3X3, 2X2 and 1X1
The design you are inquiring about for the telescoping tower used 4", 2.5", and 1" tubing. I can elaborate on the chain routing if you like.
mike d
We traditionally have used widow tape to minimize the profile when we build extension arms. This style easily fits into a three piece extension.because it is only 1/8" thick and utilizes internal pulleys.
Pete
YES please !