Making a telescopic beam

[Burf2000]

Does anyone have some good ideas, instructions or anything else to make a very very very large telescopic beam. I want something 6 foot long + that shrinks down 2 foot?

I know one of the large technic models had a telescopic beam but I always remember it not working that well.

[Alasdair Ryan]

Thats one big telescopic boom.

I would copy the 8421 mobile crane's boom but just make it longer.

Free Instrutions for the 8421 crane can be found here.

[DLuders]

On the TexBrick website, there is a 3-section telescoping boom (with a jib) that has these details:

From http://www.gaasedal.dk/eng/Mobile_Cranes/Grove_GMK4075.html :

[freakwave]

Erik Leppen's Brickshelf Folder (Techniques) also contains telescopic booms and many more interesting things!

[Burf2000]

Thanks guys, some good ideas!