Moving 3D Objects...very slow :(

Hello,

I've hit a problem with AutoCAD which is making it unusable I've modelled the tail fin of a glider by lofting five or six cross-sections together - AutoCAD had a really hard time doing it for some reason. In the end, I had to split the fin down the middle, loft each half sperately and then union the two resulting objects back together again.

Now, I've cut a slot out the fin and created the corresponding object that came out of the slot by using subtract and intersect, but when I select either object to move it (or copy it), the processor goes to 100% load and the cursor only reponds to the mouse once every twenty seconds or so.

To try and work around this, I've set the UCS origin to the point I want to move one of the objects to, but when I copy the object, specify the base point and then enter the co-ordinates as 0,0,0 the object moves to where I want it but, on pressing enter to confirm, the copy operation just quits with no error and no object copied.

I've checked the 3DCONFIG "tune log" and my computer's within the minimum requirements. All other 3D objects in my drawing (and there are dozens!) work fine without this phenomenal lag. The objects causing the problem aren't massive and, in fact, one of them is only a tiny piece of its original self (after the intersect operation).

So, is there any way I can reduce the processor load or bring the speed of this operation back up to something usable? I'm sure it's something that AutoCAD doesn't like about these objects rather than my machine not being up to the job (it's a Core i5, 2.53Ghz, 6GB RAM, running 64bit Windows 7 and gets a 4.9 WEI rating, so nothing brilliant, but not stone-age, either).

Any help would be very much appreciated

What's the overall file size of the drawing?

Have you done a -purge of the drawing?

Can you attach a copy of the drawing to your next post that has a few of the more problematic objects in it?

About 8MB - I'll try and attach it...

Just a need a few of the more problematic objects. 8MB far exceeds that max file size for this site. Another option would be to use a file sharing website such as Dropbox and post a link to the file here.

The CAD file upload keeps quitting on me - either my connection is too slow (I'm getting under 1Mb at the moment...) or the file's too large.

I've put it on Google Drive:

https://drive.google.com/file/d/0B_fYK-ebo_xocXd4QlR2cmxyY0k/view?usp=sharing

...hopefully that works.

Also hopefully, the file should open zoomed in on where the problem is. If not, the UCS origin is on the object giving me the problem. You should be able to see a red object next to the green tail-fin object. Trying to move or copy either causes my computer to lock up - see if it does the same for you.

Thanks for your help with this

It's your Solid History on the more complex objects. Select the objects giving you trouble and set it to None. Watch video here:

http://screencast.com/t/AruLw5YIrjzN

That's brilliant! Thanks very much for that - pretty weird seeing my own CAD on a video posted back to me

I wouldn't have guessed at that fixing my problem in a billion years

The amount of help I'm getting off the kind souls on this forum is truely above and beyond - thanks very much again!

No problem. Just paying it forward from all the helped I've received through the years.

Good modeling BTW. Would love to see a final rendered output of your design.

-TZ

Thanks very much - this is a sort of "learn how to use CAD in 3D" project I've set myself. The plan is to 3d print the glider in sections that clip/lock/twist together - I've printed some bits already to check they work. I'll certainly upload the finished render when I get there - I'll attach a picture of the final printed model if it works

Thanks again

TZ, turning off Record for a solid object is a great tip. I did not know about that feature.

SweptAway, I took a close look at the cross sections of the airfoil for the wing. How did you construct them? After exploding one of them you can see that they are composed of a series of very short line segments. If you did not use splines you should consider using them in the future. They will yield a better quality and smaller file size model.

When creating a spline you can use one of two methods, fit or CV (Control Vertices). I usually use Fit for my first approximation then use SPLINEDIT to make adjustments to the CV's. Once you have moved a CV the Fit points are lost but that is usually ok. As a comparison, the picture below shows one of your airfoil cross sections in yellow (the blue grips show vertices), and a spline equivalent in green.

When creating a spline your goal should be to use as few CV's as possible. You can always move or delete them after you have created the spline. Adjusting the tension (weight in AutoCAD terms) is tricky in AutoCAD. Other programs give you better tools like handles. The spacing of CV's takes practice. Long straight or large curvature portions of a curve will require fewer CV's than sharp corners. When transitioning from a flat portion of a curve it is best to gradually change the distance between CV's rather than do an abrupt transition. I like to think of it as putting on the breaks as I approach a tight corner. Good luck! ~lrm

Hi lrm,

thanks for your advice - I had a devil's own job getting the aerofoil sections right. I started by approximating them using splines, but then had rescale the one I'd drawn to suit the different section sizes at the wing-root and wing-tip. I created a WBLOCK from the one I'd drawn and then re-inserted it at the scales required, but couldn't get the loft function to extrude between them. To get around this, I exploded the inserted WBLOCK's and the converted them to single polylines - this is probably where they ended up as a hundred an one individual lines...I was quite pleased that the lofting had worked at that point, so didn't go back to do it any better...I'll certainly follow your instructions in the future, though.

I'm still reading up on producing rendered images, but in the meantime, as promised, here is the finished version of the glider as I intend to send it to the printer - I have red and black filament, hence the colours chosen

https://drive.google.com/file/d/0B_fYK-ebo_xobWdUUEcyT1pULVU/view?usp=sharing

Again, thanks for your help and interest

I would recommend not making WBLOCKs of the cross sections of the "aerofoil". I would suggest creating one aerofoil as a single spline and then convert it to a region. Copy the region in the direction perpendicular to the plane of the aerofoil and scale as desired (making sure your base point is in the plane of the copied section). You should have no problem using the loft command with multiple regions copied from single region.

Of course in real-life successive wing cross sections are not simple scalings of a master cross section. To get more accurate cross sections I would copy the original spline and edit the spline to the desired shape and then convert it to a region.