I think he means more that in the real world, if you had for example a hinged joint capable of supporting 1 tonne of loading and still continuing to pivot on its axis, it would do that up to 1 tonne. In SP joints tend to pull apart and have an artificial elasticity which allows them to slip out of axis or break completely.

I can't find a way to get around this yet either; what may be needed is an "absolute strength" type setting for joints and perhaps also a power/force rating for motors, pistons etc. Basically put, a "don't allow joints to shift out of their axis or past min/max bounds, no matter what". In addition a power control to ramp up the load that a powered joint can shift.

I don't know much about the underlying physics libraries used in SP but such a thing must be at least possible, if not implemented within the libraries.

SP is great though, please don't misunderstand my post anyone - big respect to CPhillips for this amazing software!

I had to PM the file to you as Firefox kept crashing when I tried on this thread!?

My message for anyone reading this thread:

@unknownuser said:

Subject: Can pistons be prevented from stretching?

@cphillips said:

The strength of a joint is directly related to how big (massive) the objects connected to it are. If you can post the model I can make some specific recommendations.

My browser kept crashing when I tried to attach this to the forum post so I tried here, assuming this posts it works! Odd...

My model basically needs to defy the standard physics of this I think. I can think of a few redesigns to change how the tilting mechanism works on this one although that tends to destabilise the central pillar. I know these things are possible in real life, I've seen engineering and funfair rides which do what I'm trying to do (in part at least) - I just don't know how to go about them in this. I guess in this scenario the tilter needs counterbalance, but as there is no weight control I don't see how to do this too easily.

Thanks in advance for any help, it is much appreciated!

I'm trying to simulate hydraulic pistons; I'm using them to pivot a very heavy pivoted platform which is not counterbalanced and hence is incredibly top heavy.

In the real world some hefty hydraulics would be able to maintain the load and allow the platform to be controlled but whatever I try in sketchyphysics (2) results in the joints stretching apart (be they sliders or pistons). Basically what I need is an absolutely all-powerful piston/controlled slider which has an absolute maximum and minimum and is not subject to stretching past the specified limits.

Is there anything that can be done to achieve this? I have attached an image of the funfair ride model I'm making to illustrate what I'm trying to do here.

Cheers

Entering

servo('servo41369',0)

in to the doesn't work, it simply returns to

servo(1)

which then becomes a control in the control panel

servo(1)

Am I missing something here? It seems you are using SP3, could that be why? I'm only on SP2...

Ok, I get what that would do... where would I enter such an instruction? I don't see anywhere for such things. Forgive me if I'm being dumb, I've not been using this more than a day!

Cheers.

I can't seem to find info on this anywhere in the forums so if someone knows, I'd appreciate the help.

I'm modelling a funfair ride which is all going fairly well with one exception. I can't find any way to change the default value a control will take on when you begin the physics simulation. On playing the simulation, everything just defaults to 50% of full, which moves servos, starts motors etc. Is there some way of changing this so all values for controls are set to my specifications instead of a blanket 0.5? I can't for the life of me find where to do this if it is so...

On a side note... is it possible to create controls which control other controls? E.g. controla and controlb change two pairs of servos each. Can I make controlc which can alter controla and controlb together? I realise that in that example that I could just assign all the servos to controla and use that, but I'm trying to achieve sets of movement of individually controlled joints here, not just lump everything under one control handle.

Cheers,

Simon.