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filling an undercut


filling an undercut

Good morning
I have a bezel that I am setting up for injection molding.
The bezel is symmetrical about a centerline.
It was originally setup for vacuum forming and ends up with aan undercut on opposite sides of c'line
The original drawing was designed outside by a firm that does industrial design.
They sent the file as a step.
Now when I try to fill these undercuts I get an error.
If I extrude the fill it works on one side but gives an error " part fills its self" and fails.
So I tried to mirror the first fill and it fails also.
The whole part is a merge the way it was brought in.
Any ideas on a Friday?


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Use the Import data doctor and remove the surface in repair mode.

Kevin Audibert
Design Engineer
GE Energy
Industrial Solutions
41 Woodford Ave.
Plainville Ct. 06062
Axiem International Consultant


Try increasing your accuracy by reducing your accuracy number to say .0005. If that doesn't work try reducing it by .0001 steps.

Mr. Harry L. Archer Jr. P.E.
Naval Surface Warfare Center Indian Head
Explosive Ordnance Disposal Technology Division
Cartridge & Propellant Actuated Devices

With such little data on the actual geometry there are several things that can help with undercuts.

If you can create a good surface, you can use the replace functionality to fix the undercut.

I have also been successful in creating draft. Use your pull plan to define the 0 for the draft angle and you don't have to worry about what the angle is and you can just apply the value that you want it to be.

Just suggestions...

Ronald B. Grabau
Roseville, CA


This isn't the answer to your question directly, but if time and money allow I would remodel the part in Pro/E (Creo Elements Pro) so you have modifiable geometry when other things need changing or fixed instead of whittling on a chunk of dumb geometry. It is usually quicker to remodel a part when the design intent is clear or established and thus you have a better idea of how you want to control the part and features. You also have all the main geometry in the STEP file to use as your guide.

One possible direct fix is simply creating the same feature on the other end of the part if the mirror feature is not working for accuracy issues or other reasons.

Good Luck,
Mark A. Peterson
Design Engineer
Varel International

21-Topaz II


Sorry I didn't respond on Friday.

I'd contact the ID firm for the native file, if it's in a format you can read. I suspect that you may not have access to the firm, the file may not have been made in Creo or they may not be willing to supply the native file. It's worth asking, however. Ideally, it would have been made in Creo/Proe with your start parts and you would already have the naive, but it seems too late for that.

Another approach to repairing what you have would be to cut the part in half, if fully symmetric, add the extrude to fill the undercut, and then re-mirror the entire part. You can also try creating surface copies of the successful filled geometry, mirror the quilt and solidify that.

Ultimately, if this is a part you are going to live with, remodeling is going to serve you better in the long run.

Good luck,

Doug Schaefer | Experienced Mechanical Design Engineer