Using Extruded Aluminum to telescope.

[VThokieME04]

Team 401 did a great three segment telescoping mechanism that worked like a dream. I know this isn't the greatest picture in the world, but I'll see if I can't explain it and point you in the right direction.

In the dynamic elements section of the Item catalog are several different setups for roller guides. In order to make a telescoping mechanism you need several things: two or more pieces of extrusion to be used as your telescoping sections, shaft-clamps that fit whatever profile you're using (I'm assuming you're going with profile 5) and the shafts that fit in the shaft clamp profile. I know this is probably pretty confusing, but download the Item catalog and look at some of the pictures to match what I'm saying with the actual product.

Now last year was the first year I personally worked with Item and I was extremely impressed with their product line. If I can also throw in several suggestions. First, go with the adjustable roller bearings, part number 0.0.390.16 (assuming you're going with profile 5 extrusion). Buying the adjustable bearing unit allows you to get the right amount of pressure between the bearing and the rail that it guides on. You get less slop in your telescoping mechanism that way. Second, if you're short on weight don't buy the Item's shafts that clamp in the shaft-clamp profile. Instead, but stainless steel tubing from McMaster (5mm OD i believe, with the thickest wall available). This saved us an amazing 6 pounds last year, so it does add up. We didn't encounter any issues with binding or bearings seizing and it was probably the most robust part of our robot.

Here are two pictures that I have of the telescoping mechanism. If you'd like to see more, email me at jheaston@vt.edu

http://filebox.vt.edu/users/jheaston/FIRST/PICT0117.JPG
http://www.firstrobotics.net/04Galle...0401-1_jpg.htm