Cutting Tools  

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travis.duckworth8
(@travis-duckworth8)
Active Member

Okay so I'm having a problem in building an object in STL format. What I really need is a circular cutting tool to cut this Center from my build. I want to reuse it.

Are there any other cutting tool options aside from plane cut and Boolean cuts in any known build programs for STL files?

 or is there a way or is there a way for me to achieve a circular cut via one of those cutting option?

Posted : 14/04/2020 3:12 pm
Neophyl
(@neophyl)
Noble Member

What are you trying to achieve ?  I use blender and you can easily do a Boolean operation to remove whatever shape you want. You can even do it non destructively if you don’t apply the Boolean on your model, it will apply it on export so you get your ‘hole’ in the output stl but you can move the modifier later and re-export if you need to. 
for splits you can put a box over the part where you want to split and then you duplicate the original object, apply a Boolean cut to the first object and a Boolean keep on the second copy. That way you end up with a perfectly split object, you can move the box (or other shape you are using for your modifier) later and adjust the position of the cut. You then export the 2 halves of your object. 
Takes a bit of getting used to but it’s not that hard. 

Posted : 14/04/2020 5:13 pm
travis.duckworth8
(@travis-duckworth8)
Active Member

@neophyl

Hey thanks, I actually don't know how to do a Boolean operation cut.

But what I'm trying to do is cut the center out of an object that has a slot in it. I want to be able to rotate that slot on an axis at various degrees then reattach it to the original object.

This post was modified 4 months ago by travis.duckworth8
Posted : 14/04/2020 5:58 pm
travis.duckworth8
(@travis-duckworth8)
Active Member

Also I'm somewhat familiar with meshmixer, can this be achieved in meshmixer?

Posted : 14/04/2020 6:02 pm
Neophyl
(@neophyl)
Noble Member

I’m not familiar with mesh mixer so I don’t know. 
Zip up and attach your stl.  Might get a better idea of what you mean but from the sound of it I can’t see why it’s not possible. I’ll give it a go and if I can do something with it I’ll attach a blend file that you can play with and alter the rotation angle. As blender is free the software won’t cost you anything. 

Posted : 14/04/2020 6:19 pm
travis.duckworth8
(@travis-duckworth8)
Active Member

@neophyl

Thank you so much, I'm at work right now but will be home in about 5 hours. I'll attach and send it then.

Posted : 14/04/2020 6:24 pm
Neophyl
(@neophyl)
Noble Member

I’ll probably be asleep by then 🙂 as I’m in the uk but I have blender and slicer installed at work too so I’ll take a look in the morning. 

Posted : 14/04/2020 6:50 pm
travis.duckworth8
(@travis-duckworth8)
Active Member

rcbm

Okay that should be the file, let me know if it didnt send, cheers from the u.s.

Posted : 14/04/2020 11:18 pm
Neophyl
(@neophyl)
Noble Member

Ok, hopefully there should be a zipped folder attached.  It contains 2 blender files showing 2 different ways of doing it.  The zip also contains 2 exports to stl for the 2 methods, both just recreate the disc with the slot at the same angle but changing the angle should now be very simple.

Firstly the model was imported and the objects centre of mass was moved to be in the middle of the object, and then that centre was placed to xyz at zero.  This places the object in a better position for the later steps.  I also reduced the geometry at this point to clean it up a little before starting.

Method 1 was to duplicate the rcbm model and on one of them cut out the centre and on the second cut away the outer.  This resulted in 2 models that fit perfectly within each other.  The problem with this is that when sliced its 2 actual objects so the parts aren't well connected as the perimeters abut but there's a gap.  So the outer edge of the inner disc was expanded in X and Y a little causing the inner and outer to 'overlap'.  When both are selected and exported while it is 2 objects, slicer has no trouble slicing them as one object (I checked).

This method has the disadvantage of its messy with 2 objects overlapping, it is also a bigger file size when exported.  Of course the reverse is true, in that you could use split to parts in Prusa Slicer and move/rotate the 2 parts individually.  This would allow you to change the angle within slicer.   To change the slot angle in Blender just select the inner object and rotate it around the z axis however many degrees you want.  Theres a control panel for that so you can just type the angle in.  As its centre is aligned with the centre of the outer object they rotate around a common point (0,0,0).  Then select both objects, file>export stl and export them making sure that you tick 'Selected Only'.  That will give you a new stl with the slot at the new angle.  Make sure to give it a suitable name as you don't want to overwrite the old one.

Method 2 I started with the same positioning and clean up steps but then I actually deleted the slot from the model entirely.  I then placed a modifier in the correct position and using a Boolean difference used it to cut out the slot from the disc object.  This way when exported there is only one object and its a cleaner geometry.  You can just rotate the modifier around its z axis and the cut out position will change as the boolean hasn't been applied (once you apply it, its locked so try not to do that unless needed).  Like method 1 Ive made the origins for the object and modifier both be at 0,0,0 so it rotates around a common centre.  When you export as stl it applies the boolean modifier to the output stl file but your original is still untouched.  Method 2 would be my preferred way as it gives the cleaner output model.  

I used Blender 2.81a so you should be able to load the files in with that, although I see that 2.82a is out now.

Give them a go and if you have any questions just ask.  Disc with slot

Posted : 15/04/2020 10:06 am
travis.duckworth8
(@travis-duckworth8)
Active Member

@neophyl

Wow man, really appreciate it. I should be able to perform the process on my own now, thanks again for all the help.

Posted : 15/04/2020 2:06 pm
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