Suggestions on cylindrical part mating

Ive asked this question before, and recieved mixed opinions. Say you
have a part like a cylindrical spacer. To fully constrain it, you must
stop it from rotating.

That leaves me to my question. Do most people fully constrain
everything? It takes more time to do this, but it also allows you to
scan the design tree for anything that is not constrained. If a model
has a (-) by its name, than you have to check to make sure its not
floating around. This can also take time.

So, im looking for some more opinions.

On a related note, I like the new feature in 2006 that allows you to
ignore certain interferences. It would be nice to be able to ignore
certain unconstrained parts. I know that this is easier said then done.

 

I don't constrain hardware like that. Sometimes if you have complex
motion, like a gripper at the end of a robotic arm things will refuse to
move unless you tie down a few more degrees of freedom, in which case
you have the choice to constrain the hardware or suppress it.

One way to get around the underconstrained parts is to combine them all
into a folder, so you don't see them when you scan quickly.

Daisy

 

The folder idea is pretty good. I can create a subfolder under the
existing folder I have called "Unconstrained".

If anyone else has any tips, keep them coming.

Thanks.

 

I generally don't tie down the hardware or anything else that doesn't
matter. I have learned a way of doing things such that I pretty much don't
have to wonder if I tied it down enough or not - I just know how I work.
Now, that being said, there are times I do for particular reasons. I figure
that since I am always going for the lean and mean, so why spend time
putting in mates that take time to solve when they don't do anything for you
except turn off the - sign. So, for the most part no, except for the
exceptions.

WT

 

I'm not hung up about totally constrained hardware (or sketches, for
that matter). AFA hardware goes, it seems to save more time not
constraining than is saved looking for components in need of
constraint.

If you do feel compelled to constrain the rotation, I recommend using
angle or perpendicular (especially if plane-to-plane). You can nearly
always get angle or perpendicular to work, but parallel can be
impossible in certain situations.

 

On a more philosphical note, there is a fundamental question about if
some classes of assemblies should be constrained at all. Back before
SW and IV etc. all of the parts were "frozen" in space. Individual
parts or groups of parts could be moved and positioned together. This
only required a few commands, (align X,Y,Z Delta Move X,Y,Z Rotate
around a selected point around the X,Y,Z axis) and could easily
develope good assemblies that don't need to be manipulated. The best
part about this is that once a part was positioned, there was no
question about where it was, or if it got moved etc.

I have been told that this is one of the major features of IronCAD? Not
all assemblies should be "static" but for many, this is extremely
intuitive and robust.

There are times when movement is very valuable for checking out a
design. But, there are also many times when the time spent to
constrain a complete assembly, correct errors, etc. that constraints
are way more "expensive" then just putting the parts where they belong.


Some of the suggestions that I have submitted to SW has been to improve
the freeze command so that some parts can be frozen into place but
still "manually" manipulated into position. I think an alternative
could be, (and I think that I heard that 2007 would do this) would be
to constrain parts to a 3D sketch. Then by manipulating the sketch,
manually or with equations, the assembly could be "automated" but there
would not need to be the same reliance on constraints as there is now.

For what it is worth,

Ed

 

I worked on a system (Applicon Bravo) for many years where you just
positioned the components. It had the benefit of simplicity and speed (on
old slow hardware), but I would never go back to that method.

I very much doubt SWX was the first to add assembly mates - I'm pretty sure
Bravo got them around 1997, and I recall it being a feature I'd wanted for
several years, having seen it previously on other systems - probably ProE
and I-DEAS.

As some of the other posts have suggested, I think it probably slows the
solving down if you don't fully constrain parts (in a logical fashion of
course) - particularly if other parts are dependent on their position.

I'd normally fully constrain everything, with the exception of a percentage
of fasteners, where I get too lazy to constrain their rotation.

John H