Sketches don't update properly ising design tables 1

[mjs23]

I am using offset curves to create a revolved cut. The original curves are controlled by values in an Excel design table. For certain values the offset arcs are being created as compliments of the arcs that they should be.

Any ideas on how to constrain these to give me the geometry I want would be appreciated.

Thanks, Mike

 

[CorBlimeyLimey]

Not without seeing what you have to constrain to!
Do you have a website that you could place your part in for download?


CorBlimeyLimey
Barrie, Ontario
faq559-863

 

[JNR]

Ooops - replied yesterday - musta forgot to hit the submit button.

What do you mean by compliments?

Are these conics (ie true circular arcs) or are they splines? Are you getting the "other half" of the arc? Are you getting to wrong side (direction) offset? DT's are Excel spreadsheets.

Are you getting some problems with angles going over 90, 180, 270, 360 degrees in your calcs? You can deal with this in Excel. BTW: not only can you put Excel cals, etc. in the DT parameter cells, but if you leave a blank row or column below or right of the "DT" cells, SW ignores the rest of the spreadsheet and you can do anything you want out there and link to parameter cells to the results.

I was - and he did. So at least I didn't get coal.....
OK, OK, It's a reference to my holiday sig. "Be naughty - Save Santa a trip..."

 

[winston841]

Does hitting CTRL-Q buy you anything in this situation?
Is this a time depenpency issue? I've run into sutiations in the past where I've used a driven dimension to drive an equation (not recommended practice, but for the task at hand it was handy). It worked fine with the exception that I had to rebuild twice.

Like JNR, I don't know quite what you mean by "compliments of the arcs that they should be."

Hope it goes well...

 

[mjs23]

Here is a link to files that show the problem.

http://www.amteam.com/Net_File011604.zip

I have 2 arcs that I using to make a revolve cut. The arcs are controlled by an Excel table to let me vary the radii. Typically the first arc will start at 0 degrees and go ccw thru 30 degrees. The second arc starts at 30 degrees and goes ccw thru 75 degrees. The 2 arcs are not tangent. These 2 arc are then offset and used for the revolve cut.
Sometimes the different table values work just fine and sometimes arc1 starts at 30 degrees and goes ccw thru 0 degrees and arc 2 starts at 75 and goes ccw thru 30 degrees.

If I trim this geometry then the configurations that were woking stop workiing.

Thanks, Mike

 

[JNR]

I just downloaded your zip. I'll take a look. Forgive me for taking a while - I need to virus check it first (nothing personal, mjs23).

I was - and he did. So at least I didn't get coal.....
OK, OK, It's a reference to my holiday sig. "Be naughty - Save Santa a trip..."

 

[CorBlimeyLimey]

Took a very quick look last night & it appears that it's not so much your constraints causing the problem, it's more that the geometry conflicts with itself. Not sure how to describe it, but with the radii & centre points that you are using, SW can only resolve by flipping the arcs.
Will try to be more precise when I get more time to look.


CorBlimeyLimey, Barrie, Ontario.
Don't Take It Personal, Have Fun While You Learn
faq559-863

 

[JNR]

That was my second guess, CBL. Sounds about right. It might be just a case of swapping the order in the feature tree, so it can't outgrow itself. Ie: maybe the small arc is getting larger before the large one can accomodate it. I have not been able to take look yet myself - too busy. I was going to look at home, but I don't seem to be able to log in to the forum from home for some reason. ........ duh! just realized - of course - I keep cookies turn off!!!! I'm very protective of my home system. Don't have to here, Rockwell Collins does it for me

I was - and he did. So at least I didn't get coal.....
OK, OK, It's a reference to my holiday sig. "Be naughty - Save Santa a trip..."

 

[CorBlimeyLimey]

mjs23
Havn't forgotten you, just been too busy with work & Grandkids to spend too much time "researching".

Have you had any luck resolving the problem yet?


CorBlimeyLimey, Barrie, Ontario.
Don't Take It Personal, Have Fun While You Learn
faq559-863

 

[JNR]

Sorry, tried to open your file at home, but I currently have SW 2003 on my home system. I will have to wait until I load 2004. I uninstalled the beta version. Spent all day today (Saturday!!) uninstalling, re-loading and patching Oracle, SmartTeam and SolidWorks 2004 on our work systems. 5 of us going at it including the SmarTeam server...... I'm about brain dead....... We have 29 systems and growing.

I strongly suspect that if your goemetry works manually and with certain values in the DT but fails with others, it is what I suggested - the smaller arc is getting bigger that the larger one before the larger one increases in size. So it "inverts" itself. If you change the order of the features in the tree and pay careful attention to this, you might fix it. On the other hand maybe not. You might have to do the DT value inputs it in steps so it never flips. You could put some Excel Bololeans in the DT cells to prevent the arc radii from over (or under) taking eachother, and force the use to enter the second value again after one arc has been updated. A bit cumbersome, but it might work.

Example: Imagine 2 concentric circles. Diameters are 0.5 and 1.0. If I increase the samll one to 0.75, it is still INSIDE the large one and I can increase the large one to anything I like of reduce it to a smig over 0.75. But if I increase the small one to, say 1.25 BEFORE I increase the large one to say 1.75, then it will not be INSIDE for some time during the update. Because it will be 0.25 larger than the large one for a short period of time. (same happens if I reduce the large one to less then 0.5 first.) Now in your case, you probably have some other sketch geometry which tied to your arcs and that's why it blows up with certain values, because it flips over and can't get back, because it finds a logicaL solution, but not the one you want.

Hope that made some kind of sense. It is hard to describe without your actual example to base it on.

I just though of something else. It definitely depends on what configuration you have active when you switch to the new one, so.....
If you have a dummy configuration in your DT which has the small arc VERY small and the large arc VERY large, then ALWAYS switch to that one BEFORE switching to a another one, it might solve your probelm becuase they could never flip.

Heck, I 'm just guessing in the dark here. But I have seen this sort of thing happen.

John Richards Sr. Mech. Engr.
Rockwell Collins Flight Dynamics

A hobbit's lifestyle sounds rather pleasant...... it's the hairy feet that turn me off.

 

[mjs23]

Thanks for taking a look at this. I have seen the small arc inside the larger arc, and it does seem to be the difference. I don't get to chose what arcs to work with and my only solution at this point seems to be to duplicate the file. 1 file for larger arc first and 1 file for smaller arc first.I don't really want to do it that way, that's why ai was hoping someone had a really cool way to constrain the arcs.


Thanks, Mike