Infinite loop when references fail...

[zpaolo]

Sometimes I run into this problem (on WF2.0), and today is one of that days...

I have an assembly with a protrusion which "uses edges" from a sketch. The sketch has been heavily modified, and the protrusion has lost its references, because the edges "used" are no more present. The trouble is that once I try to redefine the feature it says that these references are "not updated", if I update them nothing happens, if I try to eliminate the references it says there are some constraints that will not work anymore. If I chose to delete all the constraints too it says that "the length of a segment has reached zero" and nothing happens.

I could always delete the protrusion and start from scratch, but Pro|E won't allow me to do anything in this situation, I only have the references dialog open, I can't close it, I can't select other windows or exit sketcher. I usually end up quitting xtop.exe from the task manager... but I don't want to loose my work today :O Can someone help?

 

[jeff4136]

I have that happens sometime but not often enough to have learned any
elegant solutions. One thing that comes to mind that might help; try
ctrl+A instead of killing the process to cancel out of sketcher(?).

 

[zpaolo]

Thank you for the comment, I'll check it next time, this time I was lucky enough: I opened another instance of ProE and opened the part from my workspace, 'cause I was not sure if I saved it or not Turned out I have already saved it, so the usual kill of xpro was the solution...

 

[jimshaw]

zpaolo,


I would try, at all costs, to refrain from using edge references in solid models. They are unstable, and as your experience(s) show, can lead to much frustration... I know it may seem quicker the first time, but if you ever have to redo the sketch, then any time originally gained is lost...


Good Luck!


Jim

 

[zpaolo]

I would try, at all costs, to refrain from using edge references in solid models.

In fact I'm not using an edge of a solid model as a reference, I'm using an edge from a sketch to sketch a protrusion. In the end the net result is not so different (reference to the edge is created) but I can't avoid it in many cases because I use sketches to perform simple optical simulations and build solids from them :/

 

[jeff4136]

I don't agree with "at all cost".
It defeats the purpose of the functionality
like working with one hand tied behind your back.


A few things that might help ease the pain;


Edit Reference
Reroute
Replace (sketch mode Edit menu)

 

[[-Skint-]]

" I would try, at all costs, to refrain from using edge references in solid models. "


I have heard this before and like Jeff said, surely this is a feature which, ifused correctly, is a great time saver and powerful tool to have. Does anyone have any proper evidence to support this statement, becuase I have often worried about this myself. I find the edge reference tool very handy in most of the jobs I do.


So.. if I understand correctly, the work-around would be say, if you had a 20mm Rod or Bar, you would measure the diameter in the part and then if you wanted to add something to one end of it, rather than use the diameter edge as a reference you would create a 20mm circle and use that as a construction line ?


Surely this is not aparametric way of thinking ?

 

[zpaolo]

]

So.. if I understand correctly, the work-around would be say, if you had a 20mm Rod or Bar, you would measure the diameter in the part and then if you wanted to add something to one end of it, rather than use the diameter edge as a reference you would create a 20mm circle and use that as a construction line ?

I used to think that referencing to solid surfaces is more robust than referencing to edges, so in the example above instead of "use edge" you could reference the rod side surface and draw a sketched circle that snaps to that reference.

 

[[-Skint-]]

I agree, utilizing an already existing Solid Edgesis muchmore robust than sketch lines for sure. So what I wonder do PTC recommend when using the offset/copy edge feature when you have nothing but sketch entitys to reference to. Its the little things like this that make a difference isnt it.

 

[jeff4136]

> 20 mm circle


One really handy alternative; rather than referencing existing
geometry sketch the circle and create a relation to tie it to
existing features.


(One of my niggling little complaints about Pro/E: you can't,
while in sketcher relations, reference other feature parameters
or pick an existing feature to access its feature dimensions.
You can, however, use Info -> Feature to get access to (see)
dimensions to reference. You can also, after the fact, add the
relations at the feature level (vs. sketcher level)).


Paolo, as you say you're often referencing sketched features;
if you are not familiar with (sketcher mode) Edit -> Relplace
you really do need to look at it. Replacing (vs. deleting and
creating new) curves should preserve downstream dependencies.
If curve start / end directions are important you can check
with analysis functions before replacing.


Replace can also be used on dimensions (which may be referenced
by subsequent features).

 

[zpaolo]

Paolo, as you say you're often referencing sketched features;
if you are not familiar with (sketcher mode) Edit -> Relplace
you really do need to look at it.

Yes, edit/replace is useful, to tell the truth this infinite loop does not happen so often mainly because I try not to break downstream references... but when it happens it's soooo annoying

Thank you all for the comments and suggestions

 

[jimshaw]

Perhaps we are on slightly different pages, but at least the blood is flowing, . My statement was a bit presumptuous i guess...


An edge to me is the intersection of two surfaces on a solid model. Sketch entities are just that, sketch entities. And when referencing multiple features from the same sketch, the replace/edit reference functionalities are priceless. I understand what you are doing zpaolo, and I don't think there is an alternate procedure. Just be careful, i guess... I've gotten stuck in that loop, and it's not fun. I use ctrl A also, or you can delay the sketch regeneration as well. If you get through it is a testament to your ProE skills...


I took a lot of calls as an AE from people who's models blow up because they choose to "use edge" during a sketch instead of referencing the projection of an existing surface. They reasoning is, "it lets me, so why not?" At this point it becomes discipline - which is a user-dependant attribute. And now I'm ranting...