Best way to make a small change?

I modeled this stand to hold a wireless charger that has protruding ring on the back. After 3D printing, the ring area is a bit too tight. I probably need to shave off another .25mm. I tried creating a circular solid .125 mm dia bigger and boolean subtracting, but the operation failed.

Any suggestions on the best way to do this?

If you upload a file when you ask questions you will usually receive an answer very fast. This looks like a simple fix but without your file I cannot tell you what I did.

Thanks for your response.
Here it is. I’ve tried everything I can and now I give up. There may be some geometry problems on the right side that I can’t see. I was able to split the left and use Boolean subtract. However, that procedure failed on the left side. I’ve reverted to an earlier version to up load. The red curve is the new boundary I need.

Charger_VER_4MM.3dm (733.5 KB)

Hi CalypsoArt -

Join the object up into a solid.
Extrude your circle down ro that ‘floor’ level as a solid.
BooleanDifference, MergeAllFaces

Charger_VER_4MM_PG.3dm (550.2 KB)


Or a super easy option- scale the whole model by like 2% or something! If the other dimensions are not critical.

Thanks Pascal, but that is what I’ve been trying. I keep getting “Boolean Difference failed” The only time it worked was when I used BD separately on the left arc. It did not work on the right, or using the complete circle. I don’t know how it worked for you? If there was bad geometry, shouldn’t you have the same problem?

Could it be some tolerance setting, or such?

Hi CalypsoArt - the file as sent needed to be joined up into a closed object - as is, it will fail. yes, because there are two surfaces not joined into the object in the area of the intersection.


I selected all the objects and used the Join command. Is the that the wrong command?
This the file that is failing.

Charger_VER_4MM_error_test.3dm (723.3 KB)

That’s the right command but it doesn;t make the boolean work.
Your problem stems from the fact that your model is out of tolerance.

I suggest not using booleans because you end up wasting enormous amounts of time when they fail and they fail often. If you do the operations manually you will quickly discover where the problem is

You can either loosen your tolerance or just extend the cutting surface upward so that the out of tolerance edges don’t mess things up.

Here is how I set it up for trimming and joining.
Chargerx.3dm (523.9 KB)

Notice I eliminated the surfaces that are not part of the solution.
Then just select both objects and run Trim and click on the parts that get trimmed off. Then run join.

I’ll experiment with this at work tomorrow. But two questions.

  1. Pascal used Boolean on the file and it worked for him.
  2. I’ve only used trim to trim curves. crossing other curves. If I’m understanding you, you are trimming surfaces with surfaces?

I’m bored at work… just gave it a go, my workflow was-
1- join your model into 1 polysurface (selall, join)
2- extrude your offset curve down as a capped cylinder (a solid)
3- boolean difference or boolean split, take your pick…
4- merge all faces to remove joint lines

as pascal mentioned- it works fine.
No tolerance issues my end.

Yes you can trim surfaces with surfaces, but in this case it would be trimming polysurfaces with polysurfaces. You just click on the parts that get removed and then join what is left There is nothing booleans can do that you cannot do yourself.

The two solids in the last file that you posted will not boolean because of the out of tolerance edges. You can use the Intersect command to see that the 2 solids don’t produce complete intersection curves.

yep- as jim said, your 2 shapes don’t intersect. If you scale1d or move face the top of the cylinder so it is not flush with your object, it will boolean.

Got it now.