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Constraining moving pieces

Zacharyah

New member
View attachment 5725
This image shows an assembly that I made to simulate the reach of a CNC mill. The spindle (1) has a cylinder constraint to the base (2) along axis (3). The base has a planar constraint to plane (4). The connection works fine, but the annoying bit is that movement of the spindle will move the base which means it's difficult to position the spindle accurately.
Is there any way to make it so that the spindle can only move along the axis without moving the base along the plane?
 
Sorry, I realize that there is some information missing.
I'm using WF4 on Windows 7.
I'm using the ctrl-alt drag method to move the components
around when we have part's fixtured on the tombstone to
check clearances.
 
Use the drag tool (white hand) and you can control the behavior of all joints in the assembly. You can lock your base's joint and even set an specific value for your spindle to locate it as you wish.


Hope this helps


Kaz
 
Thanks, that was helpful. Not really what I was hoping for,
but it gets the job done, more or less.
I was hoping for a method to prevent one body from moving
its reference body. The issue with locking joints is that I
want to be able to quickly and dynamically position the
base(2) in between adjustments of the spindle(1). I tried
your method out and if I create a motion axis lock on the
base, I can't move it to a new position without creating a
new lock. Basically, it just takes more time and effort
than I was hoping for.
 
Yeah - it is kinda clunky to use, but it does get the job done. If you wish to have your assembly "snap" to one, or a number of, pre-set positions, set-up each one you want, using the technique I suggested, and create a "snapshot" and store it. These snapshots can be used at any time in "Standard" or Mechanisms mode, and can be used indrawings as well.
 
It seems like there should be an option to prevent a child
body from moving the parent body. I can think of plenty of
instances where you would want that, including the subject
of this post. The mannikin would really benefit from an
option like that. I can't begin to enumerate the times that
I've tried to make subtle adjustments to the position of
the mannikin and wound up moving him way out of position,
like dragging his hand a few inches and winding up with his
torso leaning way over to one side.
 
It would be nice to have a keyboard shortcut that would lock all joints not associated with the body you're clicking on to move. Better yet, we should have an option to use the connection branch of the simulation model tree to highlight all joints and lock them, then release the ones we want freed-up prior to a mouse drag.
 
Good points. That would be a helpful feature. I thought
there would be an option when you created a constraint that
would define whether or not the child could move the
parent, but being able to define that in the model tree
without going into the connection definition would be
useful.
 
Try redefining the base to add a 'fix' constraint to lock
it. Then you can redefine it again and toggle the
'Constraint Enabled' check box on the 'Fix' to allow it to
move. So, put the base in a position you want to evaluate,
fix it, drag the spindle to check clearances, redefine the
base again to disable the fix constraint, drag it to a new
position, redefine again to enable the fix, repeat.

A bit cumbersome, but I think it ought to work.
 

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