Midpoints

I often find myself trying to get a midpoint on a line, but SW does
not show the midpoint. It seems very hit-and-miss whether I can get a
midpoint or not.

At the moment I am trying to put an assembly together, and orient the
assembly so the origin is in the center of everything. The reason I
want to do this is so that I can mirror components using the planes at
the origin as the mirror points.

Since I could not select any midpoints on the objects, I added a
center line as a reference, and it did allow me to select two midpoints
on my object to draw the centerline in one plane only. So, I tried to
constrain the object to the origin by selecting the midpoing of my
centerline, but SW wouldn't recognize a midpoint on this line.

Any ideas? I imagine there is a logic to what kind of line for which
SW will recognize a midpoint. Is there any way to force to SW to
recognize the midpoint of any line?

Joe Dunfee

 

Sometimes the selection order makes a difference. You can also sometimes do
a RMB and select the midpoint that way.

Also related to that, keep in mind that midplane extrusions give you a plane
at the center. I always teach that you should use midplane extrusion unless
you have some specific reason not to. You may not use that plane, but it's
there in case you do need it, and a lot of the time, I line things up down
the center.

WT

 

What release of SW are you on?

 

I am on 2005 v3.0. As I continued to work on it, I ended up making a
new sketch and then converting the edges I wanted midpoints on. Then
on that sketch I was able to snap to the midpoints of the converted
lines. The puzzling thing is that sometimes you can get midpoints on
objects, even if they are not lines on a sketch. I haven't figgured
out the logic to it yet.

I do commonly work off of planes and the world origin, knowing that
this is the easiest thing to constrain other things to.

Joe Dunfee

 

The "Select Midpoint" function is extremely quirky in SW, For example, try
this. On any line, RMB and Select Midpoint. Ok, don't do anything with
that, just hit esc or whatever. Now try to put a sketchpoint at the
midpoint of the line, and it gives you an error saying that it can't put a
point there because one already exists. Bummer. So put the point out in
space and use a midpoint relationship between the line and the point.

Anyway, I always use midpoint relations rather than trying to do anything
directly with the midpoint of a sketch entity. I had several sprs on
midpoint selection. Best to avoid it in my book.

I have a little macro on my website that draws a rectangle centered on the
origin for you. Hook it up to a hotkey, and you get a centered rectangle
just by banging on a button.

http://mysite.verizon.net/mjlombard/

matt

 

Thanks for the info. I fel I am often chasing my tail over little
things like this. Since I am not that experienced with SW, I don't
know yet when to blame the program or myself. This morning I spent
about 3 hours trying to get a piece of metal on the midpoint of this
assembly.

On a related note, my company decided against training for me, so I
am just going to need to figgure it out by trail and error (and you
guys here). The manual is never going to say something like "The
"Select Midpoint" function is extremely quirky in SW". Later today I
attempted to create an in-context weldment. But it sometimes worked and
sometimes didn't. It is possible I did something wrong, but it is
looking like it may be one of those "extremely quirky" things.

Are there any 3-rd party books that are good about warning about
things like this so we can avoid the "quirky" stuff?

Joe Dunfee

 

wrote in @f14g2000cwb.googlegroups.com:

There's also the "symmetry" mate option where you can select a plane and 2
faces, and make the faces symmetric about the plane. Usually modeling
things symmetric about the origin does the trick. Covered in the first day
of training

Perfect. Well, lets see. Training class costs say $1500. You just wasted
3 hours at say $75.hr. You only have to do that 6 or 7 more times and
youre training would have paid for itself.

Next thing you're going to tell us that you're making molds with the SW
mold tools or using the Piping module, just to hit the quirks hard.

No. Anyone who is published on this topic has generally felt the need to
be polite and politically correct, which doesn't hamper most of us here.

After a while you'll develop an intuition and just avoid certain things. I
don't mean to bust on the software too much, because overall I get the job
done with it, and sometimes it's amazing, but I do have a bald spot from
pulling my hair out and a flat forhead from banging it on the desk.