Using Extruded Aluminum to telescope.

[Yan Wang]

I posted a picture on CD of our 2004 robot's sliding nylon piece of our scissor lift. We manufactured it.

http://www.chiefdelphi.com/forums/pi...&quiet=Verbose

[WizardOfAz]

Originally Posted by Dzdconfusd

We have done many arms using either nested Al tubing or monocoque. We make slide bearings out of HDPE tosit between the inner and outer arm. We also use window tape to run the arm in and out. Just a coup[le ideas to ponder...

Can you elaborate a bit on "window tape"?

Do you use it as a spring to extend the arm, then pull it back some other way? Or do you push with it? Or what? Can you say where you get it, what product?

Thanks

[Cody Carey]

Three years ago my team Had to manufacture our own sliders out of nylon, it was tedious work, but they held up well. You want to also watch out for how you have your mast arranged, because if you use a lot of cable and oulleys the upkeep on it is horrid .

[Peter Matteson]

Originally Posted by WizardOfAz

Can you elaborate a bit on "window tape"?

Do you use it as a spring to extend the arm, then pull it back some other way? Or do you push with it? Or what? Can you say where you get it, what product?

Thanks

Window tape used to come in the KOP (until 2001?). It is a black nylon ribbon about 1/8" thick that has rectangular cutouts in it that keep it tracking on pulleys. I believe it is available through Small Parts. (Don't remember because we have so much of it we haven't bought it in a while.)

We have a design that allows us to use the "track" on the tape to both extend and retract the arm with a motor driving it. We drive the arm up the tape more or less. Below are the best 2 picture I could find on our website. We have used this mechanism in 98, 99, 01, and 03. I'll see about getting some better pictures of it at tonight's meeting.

http://www.swindsor.k12.ct.us/Highsc...t_Pit_engpoint

http://www.swindsor.k12.ct.us/Highsc..._Pit_fromabove

Edit: Forgot the URL of our homepage. http://www.swindsor.k12.ct.us/Highsc...s/clubs/first/

[petek]

Cybersonics has been making telescoping structures out of extrusions for years, mostly 8020 1010, though we used Bosch 2020 last year. Instead of using linear bearings, they just interlock parallel extrusions and apply a little lithium grease.

The engineer in me cringes every time I look at how we do it, but it's simple, it works and is very light weight. I think the key to this working is the hard anodized coating on the aluminum keeps it from galling. Needless to say, I wouldn't expect this to work for a real long time, but the only problem we've had (besides cringing engineers) is when the strut gets bent, but that would be a problem with linear guide bearings, too.

[Peter Matteson]

Here are the pictures I promised. They are of the base and end of two different telescoping arms we have made. Our 1999 bot which has an Al monocoque design. And our 2003 robot which use extruded Al box. If you look carefully at the pictures labeled shoulder and wrist end you should be able to discover how this works.

Pete

[WizardOfAz]

Thanks for posting the pix, makes the use of the window tape clear.