Dynamic block stretch

[tlawson]

Hi to all

I am trying to stretch a frame with diagonal braces while maintaining their parallel distance (file attached).

Can anyone help???

Using AutoCAD 2008

[GE13579]

Can you save the drawing down to '06 please I'm interested in having a look?..

[chrisdarmanin]

hmm... i think you can achieve that with chaining... not sure though... i'll give it a try

[chrisdarmanin]

here you go GE13579

[GE13579]

Thanks Chris!

Just trying to work out what is required? A simple stretch in the x direction? Or a mirror type of stretch? Or am I way off track??

[chrisdarmanin]

the problem i think is that when he stretches along the x axis the width of those 2 crossing beams (or whatever they are) gets thinner. that's why there is that magenta circle in the middle. its diameter is 50.

[GE13579]

Will the horizontal beams then move in the Y direction like a scissor lift? I think this is a little bit beyond my basic understanding of dynamic blocks, but I'll be interested to hear a step by step solution?..

[dbroada]

I have to admit to having trouble with this but mostly because I don't know how I would do it in autocad. The stretching part is easy but keeping the arms a set distance is beyond me at present. If I was drawing it from scratch I would construct the arms to be either trimmed or extended to size and wouldn't try to modify an existing item.

[tlawson]

Nice response so far guys. Chris seems to have a good understanding of what I need. I can stretch the top and bottom rail of the frame with a linear stretch and can stretch one diagonal line with a polar stretch but to stretch all 4 diagonals (with my limited knowledge) I would need 4 polar stretches. I am hoping it is possible to chain some of these actions together.
Drawing this manually I use my snaps (tangent to pass the circle) (tangent intersection to connect to the top or bottom rail)

[tlawson]

Not ideal but this does work using 3 grips and some tidying up with the trim command.
1. Stretch the frame with the top linear grip (range is set at 400-2000mm)
2. Next click a grip located at one end of a diagonal, drag the grip and snap it to the RED line.
3. Repeat for the other diagonal

I hope this will give someone a few ideas. Can anyone improve on this????