How do I fix an Aspire model with some unintended negative z values?

[Chuck Keysor]

Hello Shopbot friends:

I am designing a 3D model, and I noticed that the model went .266" below the "Z plane" when it should not go below zero at all. I found a hand full of parts in this complicated model (it has 118 model components in 11 different levels) which have slightly negative minimum z values). When each of these parts are "turned on", the over-all Z height of the model changes, as the base gets pulled under the zero modeling plane.

When I had a similar problem 2 years ago, I was told that I had messed up by using negative base heights and negative tilt angles (as shown in "component properties"). My model was so loused up (for this and resolution problems), I had to throw it away, costing me to lose over 40 hours of work. Ever since, I have NEVER used a negative base height, or a negative "tilt" angle. And now I am fearing another messed up, unrepairable model.

Trying to isolate the source of my little negative offsets (which add up), I turned off different levels, and found that all of the negative offset came from one level. But within that one level, it seems as though 4 parts (not repeatably the same) contributed the negative offset. I spent over an hour, just trying to narrow down which parts were giving me the negative offset, and couldn't really identify which parts, as it was cumulative in small increments between several parts and the changes in negative offsets associated with each suspect component were not consistent. But it seems as though each suspect part had used a "tilt". (Again, NONE were negative, and I have avoided negative values like the plague!)

I can't have my model change heights depending upon which parts I turn on or off. But I can't figure out how to identify this, and I don't know why this has happened since I have used no negative tilts or base heights in making this model. Looking at each part's component properties shows no negative values, but I can find small negative values by using the "Scale Z Height of Model" tool to inspect each part. This is murderously tedious.

What do I do? Why do I get these tiny negative offsets on individual components, when I haven't used subtractions, negative tilts or negative base heights??????? Can I block the minimum Z value of my parts from going negative?

Thank you for your suggestions! Chuck

[Brady Watson]

Chuck,
It could be something as simple as those components need to be moved up or down the tree/stack in order to get the right combination. If you want to email the Aspire file I'll take a look when I get a minute today.

Check your PM.

-B

[srwtlc]

Chuck, I've had similar results when tilting a component from the center of the component. When you do this, it tilts the component so that one side raises above the plane and the other goes below the plane.

[Chuck Keysor]

Thanks Brady and Scott!

I've sent Brady the file.... And Scott, what you said makes sense and I hadn't thought of that. I have to go now due to an obligation, but later tonight I'll go and play with the model. I know that some of the problem parts had been "baked" so I couldn't tell if they had been tilted or not.

Is there some way to tell a part to use only its absolute value, and therefor avoid this pesky negative dipping below the Z-zero plane?

Thanks again, Chuck

[mezalick]

I would suggest that you use the "Create Component from Visible Model" tool and then use the "Replace Below" gadget to remove any unwanedt "material" that is below the Z-Zero plane.
Michael

[Chuck Keysor]

Thanks Michael! I am off to a late start, but I will soon get back to my model to apply what you and Brady have recommended! Thanks so much! Chuck