? quoting wil5on
Are you even using phys constraints, or just rope ents? I dont think the rope ents have any physical presence. Use a phys_lengthconstraint for each rope to stop the ropes from stretching, and as Omega said, use a constraintsystem for all the constraints otherwise you may get weird stuff going on.
Also, I notice your physbox isnt falling to the ground immediately. Have you got motion disabled on it? Thats probably a bad idea if you want it to move...
I have phys_lengthconstraints for each of the ropes, yes. Basically, Iv done this in the same way as shown in the Tire Swing Tutorial in the tutorials section, and iv tried this before without the moving upper platform, and it works. In this one, the underneath platform is suspended properly, and it actually wobbles and dangles if you use the phsycannon to blast it, (as if the upper platform is directly above it and not moving).
In answer to Dr. Brasso, i would have used the phys_tracktrain for the lower platform too, but wil5on is correct, i want the lower platform to swing around realistically. I'll edit this post when i try everyones ideas (except the tracktrain one 
).
Cheers for the help lads.
-edit: iv added a constraint system but it makes no difference, also no, i dont have motion disabled ticked. This is a mystery and a half! Im considering just posting the .vmf so people can have a look at it first hand. But thats only if i cant figure this mother out.
-edit 2: iv just tried making the tracktrain the parent of the phsybox, and that makes it move underneath in the way i wanted, but for some reason as soon as anything phsyical happens to the physbox (like a blast from the physgun, or when i jump onto it) it goes back to the first problem and doesnt move. But its not like it just stops where it is, it actually goes back to where it began and stays there. Hmm..
-edit 3 (IMPORTANT): Ok guys iv managed to get it to work how i wanted now, all i had to do was assign both the platform and the tracktrain as entities 1 & 2 for each of the length constraints, so that's that sorted. New problem, however.. When i start the map, the physbox starts off swinging, and i cant quite figure out how to make it stay still to begin with.
-FINAL EDIT!: All done fellers! For some reason the problem was that the train was still a parent of the physbox, but as soon as i changed that the platform started off stationary. All the problems are now fixed! Thanks again dudes.
Peace
