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SnowEagle
(@snoweagle)
Trusted Member
Centering

I have a round disk on the build plate, and I want to put a hole into it at the center using a Negative Volume Cylinder. How do I Center in onto the round disk?

 

Posted : 05/05/2022 1:21 pm
Neophyl
(@neophyl)
Illustrious Member
RE: Centering

Use the Part manipulation fields located on the right hand side below the Object tree.

A perfectly circular disc will have its centre defined as 0,0,0  (at least for a stl imported in, can be different for other file types).  So when you right click on your disc and select add negative volume modifier it will place it off to one side usually.  However the positions of modifiers are based on the coordinates of the object they have been added to rather than an absolute on the build plater.  So if you want a modifier to be in the centre of an object then the part manipulation fields for location just need to be set to 0,0 (for x/y).  You can adjust z so it completely goes through the disc and out the bottom if needed so that will usually be 0 too but you could set a slight negative like -1.

Dont forget to use the tree on the right to select JUST your negative volume modifier and not the object as a whole or you will be adjusting the Object group rather than the modifier part.

Posted : 05/05/2022 2:00 pm
SnowEagle
(@snoweagle)
Trusted Member
Topic starter answered:
RE: Centering

That worked Great. Thanks!

Posted : 05/05/2022 5:29 pm
SnowEagle
(@snoweagle)
Trusted Member
Topic starter answered:
RE: Centering (Follow-up Question)

After I centered the Negative Volume Cylinder and sliced it, I get the file ready to print - g-code file.

Is there a way to select the File and Negative Volume Cylinder and combine them to make the hole and save as a stl file?

Posted : 05/05/2022 9:27 pm
Neophyl
(@neophyl)
Illustrious Member
RE: Centering

No. Modifiers alter the parameters of a slice, they don’t edit the underlying geometry. This is the function of proper CAD and why anyone who prints should be at least passingly familiar with at least one cad program. 
Just about any of them should be able to handle a Boolean difference operation. 2 second job in something like Blender once you are familiar with the program. Unfortunately the learning process isn’t anywhere near that quick. 

Posted : 06/05/2022 5:07 am
SnowEagle
(@snoweagle)
Trusted Member
Topic starter answered:
RE: Centering

Thanks for the info!

I tried to use Tinkercad to make the modification but, "The shape's mesh is too complex."

Posted : 06/05/2022 10:52 am
Robin
(@robin)
Noble Member
RE: Centering

For super easy geometries like that, you should have a look at OpenSCAD. Even without much coding experience you will have your STL in no time.

Chapter one of the tutorial includes everything you need: https://openscad.org/documentation.html#tutorial

 

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Find out why this is pinned in the general section!

Posted : 06/05/2022 11:06 am
Neophyl
(@neophyl)
Illustrious Member
RE: Centering

I take it your 'round disc' has some complex surface geometry ?

Posted : 06/05/2022 11:06 am
SnowEagle
(@snoweagle)
Trusted Member
Topic starter answered:
RE: Centering

Yes, it does, it's a UFO.

Posted : 06/05/2022 10:50 pm
NewShockerGuy
(@newshockerguy)
Active Member
RE: Centering
Posted by: @neophyl

Use the Part manipulation fields located on the right hand side below the Object tree.

A perfectly circular disc will have its centre defined as 0,0,0  (at least for a stl imported in, can be different for other file types).  So when you right click on your disc and select add negative volume modifier it will place it off to one side usually.  However the positions of modifiers are based on the coordinates of the object they have been added to rather than an absolute on the build plater.  So if you want a modifier to be in the centre of an object then the part manipulation fields for location just need to be set to 0,0 (for x/y).  You can adjust z so it completely goes through the disc and out the bottom if needed so that will usually be 0 too but you could set a slight negative like -1.

Dont forget to use the tree on the right to select JUST your negative volume modifier and not the object as a whole or you will be adjusting the Object group rather than the modifier part.

THANK YOU so much for this!!

I can't even tell you how long (hours) I was messing with slowly aligning and modifying things only to be off slightly or have more area in one spot than the other..etc.

I was like let me google this and hope something pops up and here we are!  Amazing.  Thank you and I wish I would have found this sooner.  I wanted to do exactly what the OP did and put a negative modifyer in a circle and have it be perfectly centered.

 

-Nigel

Posted : 16/07/2023 2:45 am
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