Help with Scissor

deathwish · 2 Apr 2011, 08:01

Hey guys, ive been trying to figure out sketchyphysics for all day now, and i barely got the hinge tool. so, ive decided to ask for help: ive been trying to build a scissor thing, i believe its the mechanism pantoghraphs use, im trying to create it, so i can make easy calculations (the dimenssions of the peices so i can extend it _ length) well, i just cant manage it, i cant get the hinges to move, i tried building it up based on LilDood's model, (a forklift, as it seem) and just now, ive given up U.U

ive attached the file, (i think) so you guys can see where im wrong, i dont care about the dimenssions at the time, right now, i just wanna know how its done.....

this is my file

this is LilDood's File NOT mine

hpnisse · 2 Apr 2011, 14:31

Hello!!
I see the problems in that model.
The Physics Hinges you created need to be grouped together with the beams in the scissor.
Cause if physics joint is't grouped they are static.'
Scissor2-1.skp
There you got a file that works!

deathwish · 2 Apr 2011, 16:41

hpnisse, thanks, you have no idea of how much help you just gave me
right now, i dont have time to get into this, but i will shure look into it later on today, or possibly until tomorrow. you just grouped it as in normal sketchuo group, or as in sketchyphysics "join"? nevermind, when i examine your model i will porbably answer my own questions, if i dont, i will get back to you.

one thing thou, is there a way to make the animation more... solid? without the spring action it has?

deathwish · 2 Apr 2011, 23:45

ok, i had a bit of time to mess around, and i made this:Scissor2.skp , so, i cant make the scissors follow the track, and the first one, does not contract completely, i dont know why, i know i must be doing somthing wrong in a very basic level, but please, bear with me u.u, the idea is that the beam with the piston (the one alinged to the red axis) conects to a gear, and works kinda like a piston (something like this:

)
so that for each half turn, it will expand completely, and another half turn will contract it.....

hpnisse · 3 Apr 2011, 17:53

Hello again!!
I think I understand what you want to do!
So here I made an example:
I have changed a lot, so that the grouping has improved.
If you want me to change something or think of something more I'll try to help you as far as the knowledge.
Scissor2.skp

P.S. This is translated by Google Translate, so I did not have to translate myself.

deathwish · 3 Apr 2011, 21:25

ok, so here i am again, i think i got the hang of the hinges, but now, i cant get the motor to work
i began from scratch, and the model is 10x to real world size (so the hinge animations dont take up so much space [10cm=1cm])

Scissor3.skp

deathwish · 4 Apr 2011, 03:26

ok, good that you havent got back to me, i figured it out, i hadnt either grouped or connected the motor, but now, i belive its better if i use a servo, so i changed it.

but now, when it turns and pushes, the scissors move off track, i tried placing a slider at the end, but it wont recognize the servo if i do, so, now, i ask you

i hope im not being too buggy here, this is the first time ive used SPhysics.

Scissor3.1.skp

hpnisse · 4 Apr 2011, 18:28

The problem with your models is how they are structured.
In "SketchyPhysics" there are various shapes:
default box sphere cylinder cone capsule chamfer convexhull staticmesh

These are used so the plugin knows how the models looks like.
The plugin dosn't support hollow holes, and concave objects.

So to crate a correct model you have to create objects with this shapes above and based on that create hollow objects or concave objects.
To change the "Shape" of a group you just Right-click on the object and in the bottom there is "SketchyPhysics", it includes: "State","Shape" and some other alternatives.

Look in the atachments file, it has the basic shapes in diffrent "Shapes", just play around.
PS. To see the objects mesh, Right-click on the object; "State"; "Show collision". And play the simulation, then it will appear a frame that is the accually mesh.
And if you see in my last model I created to you, I had used this "Shapes" to create a fully functional model of a scissor!!

/Its a lot of text, sorry! In this webpage there is a "handbook" and Tips&Trix to use in SketchyPhysics!

mesh in SP.skp

deathwish · 5 Apr 2011, 03:24

awsome, yea, i hadnt noticed why it seemed to crash into something when i had the wheel close

PS im just uploading the file so i can easily transfer it to my other PC later on

Scissor3.1.skp