Why do components move when I go into sketch editor?

[Noah_Katz]

I'm trying to align the four mounting holes of two vacuum motors to what will be a plywood mounting plate.

After that I will project geometry from the motor bodies to make cutouts in the plate for them to protrude through.

The following two pic's show how the two sets of 4 holes in the sketch don't line up with the raised bosses on the round fan housings.

The motors' bolt pattern is rotated 11 deg, so I rotated the motors by that amount.

[Another question: In order to get the handles to show up when hitting M for the Move command, I had to activate the motor component. If I just highlighted it in the browser, the form window came up, not the handles; is it supposed to be that way?]

Motors rotated 11 deg: 

When I went into a sketch that I had previously started (it's at the end of the timeline), the motors rotated back:

Why?

I rotated them back, grounded one, and made them a rigid group:

I went into the sketch editor again and the rotated them back again:

What the heck?!

I tried rotating one of the motors while in sketch mode, but it wouldn't move.

Fair enough, since it's constrained.

But when I exited sketch mode it *had* moved.

I noticed that when I go into the sketch editor that the ground on the motor disappeared. grr

I rotated the motor again and put the ground back, but somewhere in that process I got bumped out of sketch mode and when I go back the motor is misaligned again.

I'm totally bewildered and frustrated.

[michallach81]

Recording a screencast would be much better, but my guess is that before creating a sketch you've moved (rotate) your components. Did you make a snapshot of that new position for components? If not, creating sketch will reposition moved components back to original (not mentioning scenario when you editing sketch that was created prior to a move command). There should be a warning, but there was an option do dismiss this warning from appearing.

[Noah_Katz]

I could have made a screencast, but didn't think anyone would have the patience to watch me klutz around for 10 min.

I don't think I rotated them before making the sketch, because it was only when I made the sketch that I saw that one hole on each motor would fall right on the O.D. of the big circle, as seen in the 2nd pic.

But even if I did, why doesn't the ground and rigid group keep it in place, and why does the ground get deleted when I go into the sketch?

Also, I didn't get the message that something had moved and the option to continue or capture position.

It surprised me that I didn't, as I get those unexpectedly a lot, and on top of that, after rotating the motors I *didn't* get that message.

[michallach81]

Try to record a screencast.

[Noah_Katz]

Bedtime, will do that tomorrow

thanks

[michallach81 · Accepted solution]

I've read your post again, and you're clearly trying to break the time. If you edit sketch that was created before "move" it will show the state of components at the moment of that sketch creation. When we editing "old" features Fusion rewind time (look at the timeline ribbon while editing "old" feature).

[Noah_Katz]

Ahhh

Well this is a Catch 22.

I tried dragging the sketch to be before the move in the timeline, but got a Compute Failed message, and the sketch rotated.

But since I didn't know the motors would need to be rotated until after starting the sketch, what am I supposed to do?

I could delete the sketch, rotate the motors, and create the sketch again; not too bad in this simple case but would be a real pain if it was more complicated.

In my previous CAD s/w, editing features would not roll the history back, and you could project points and edges from current geometry, though it wouldn't be associative, which in many cases isn't an issue.

Is there an option to not have the timeline roll back?

[michallach81]

Be serious, if your sketch drives some geometry, that geometry can't drive that sketch. Such loop is impossible.

[etfrench]

One way is to create a sketch and project the moved geometry/faces, break the links, then move this sketch earlier in the timeline than the original sketch. 

Another method depends on your organization.  If the sketch is in the same component as the body, then it will move with the body and holes and other features will remain aligned.

Third way is to exit timeline mode and use direct modeling.  You will lose a lot of the parametric functionality, but components stay where you put them

[Noah_Katz]

>  if your sketch drives some geometry, that geometry can't drive that sketch

No, the sketch is the latest feature, driven by the motor geometry.

I don't see why I can't move the motor Position feature back in the timeline before the motor plate sketch; what's the logical conflict? 

[Noah_Katz]

> One way is to create a sketch and project the moved geometry/faces, break the links, then move this sketch earlier in the timeline than the original sketch.

I don't follow; if I'm going to create another sketch, I'll rotate the motors first and then the sketch will be what I want.

Which I guess is what I'll do, but here I'm trying to understand how F360 works.

[Noah_Katz]

More perplexities:

Upon opening the file this morning, the motors and the sketch are aligned the way I want!

However, as shown in the screencast, when I open the sketch, the motors rotate, and when I exit the sketch they rotate back.

I tried grounding the motors, but then the got the Continue/Capture Position message, which then puts that after the sketch in the timeline.

So back to where I was.

Is there a way to know that F360 has saved a move and is going to spring it on you, and delete it if desired?

There was no Capture Position icon in the Position tab at the upper right.

[etfrench]

I was assuming the original sketch with the motor position also contained other details about the mount which wouldn't be rotated with the motor.  The purpose for making the second sketch and moving it to a position earlier in the timeline is to be able to modify the original sketch geometry based on the rotated motor position.  It isn't about creating a new motor component in a rotated position, although that is possible.

[Noah_Katz]

Regardless, why couldn't I move the sketch to before the motors were moved?

I did some searching and found several videos where AD people did just that, so why do I have a problem doing it?