(newbie 1st post) Cutout with rounded edges

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(newbie 1st post) Cutout with rounded edges

unmechanical
Hey there,
 
new to OpenSCAD (and CNC in general).
 
I have found a couple tutorials of how to make a cube with rounded edges, but that's not what I'm after ;)
I have a wooden plate for an enclosure, and it needs a cutout in the shape of the cross section of a typical pill / capsule, i.e. a long-ish rectangle with a half circle at each end.
The out-side of that plate should have rounded-off edges (i.e. that side will be pointing UP on the CNC table)
 
How would I do that with OpenSCAD primitives?
A box for the plate, and then subtract a box and 2 cylinders from it, sometihg like that? (ok, that would not have rounded edges)

And how would I, in a clever way automatically calculating this independently from some detail changes, (re-)position the whole thing such that the center of that cutout is at the origin (0,0) of the model?
(I have no clue, but my gut feeling tells, me, homing in on that (center marking) should be easier, after getting the orientation of a clamped-down wood plate right enough, than going from corners with some edge sensing tool, that I don't have yet anyway)
 
OT side note: any recommendations for free or affordable CAM software for this kind of stuff, and tools helping to calculate feed parameters and such?
I have zero clue about all of this.
 

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Re: (newbie 1st post) Cutout with rounded edges

nophead
To make the outside I would take the hull of four rounded cylinders placed at the corners. You can find those in my library:  https://github.com/nophead/NopSCADlib#Rounded_cylinder

To make the slot I would subtract the hull of two cylinders, or use my slot module https://github.com/nophead/NopSCADlib#Polyholes

If I wanted the slot at the origin I would simply model it at 0,0 and place the corners where they should be relative to that.

On Sun, 13 Oct 2019 at 15:51, <[hidden email]> wrote:
Hey there,
 
new to OpenSCAD (and CNC in general).
 
I have found a couple tutorials of how to make a cube with rounded edges, but that's not what I'm after ;)
I have a wooden plate for an enclosure, and it needs a cutout in the shape of the cross section of a typical pill / capsule, i.e. a long-ish rectangle with a half circle at each end.
The out-side of that plate should have rounded-off edges (i.e. that side will be pointing UP on the CNC table)
 
How would I do that with OpenSCAD primitives?
A box for the plate, and then subtract a box and 2 cylinders from it, sometihg like that? (ok, that would not have rounded edges)

And how would I, in a clever way automatically calculating this independently from some detail changes, (re-)position the whole thing such that the center of that cutout is at the origin (0,0) of the model?
(I have no clue, but my gut feeling tells, me, homing in on that (center marking) should be easier, after getting the orientation of a clamped-down wood plate right enough, than going from corners with some edge sensing tool, that I don't have yet anyway)
 
OT side note: any recommendations for free or affordable CAM software for this kind of stuff, and tools helping to calculate feed parameters and such?
I have zero clue about all of this.
 
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polyholes

adrianv
nophead wrote
> To make the slot I would subtract the hull of two cylinders, or use my
> slot
> module https://github.com/nophead/NopSCADlib#Polyholes

Has this evolved since the original hydroraptor post?  I tried it a month
ago on my Prusa Mk3 and the polyholes weren't even close to the right size.
Of course, at this point I don't remember exactly what was wrong, and I have
three unmarked test prints with different size holes.  



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Re: polyholes

nophead
Polyholes should always print the correct size if square holes print the right size on your printer. If not the printers needs calibrating or the slicer settings are wrong.

The way it works is the vertex count is reduced enough to ensure the corners don't cut into the circle even when the plastic cuts the corner, so the hole diameter is set by the flat sides of the polygon. They are outset correctly to be on the circle, so if your printer prints straight lines in the right place the hole should be accurate.

On Sun, 13 Oct 2019 at 16:23, adrianv <[hidden email]> wrote:
nophead wrote
> To make the slot I would subtract the hull of two cylinders, or use my
> slot
> module https://github.com/nophead/NopSCADlib#Polyholes

Has this evolved since the original hydroraptor post?  I tried it a month
ago on my Prusa Mk3 and the polyholes weren't even close to the right size.
Of course, at this point I don't remember exactly what was wrong, and I have
three unmarked test prints with different size holes. 



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Re: polyholes

adrianv
I scrutinized my code and realized it doesn't match the code on hydraraptor.
It seems the code I actually tested came from here:
https://gilesbathgate.com/2016/02/07/polyholes-revisited/  and it looks like
I got the same result you did when testing this code: all holes too big.



nophead wrote

> Polyholes should always print the correct size if square holes print the
> right size on your printer. If not the printers needs calibrating or the
> slicer settings are wrong.
>
> The way it works is the vertex count is reduced enough to ensure the
> corners don't cut into the circle even when the plastic cuts the corner,
> so
> the hole diameter is set by the flat sides of the polygon. They are outset
> correctly to be on the circle, so if your printer prints straight lines in
> the right place the hole should be accurate.
>
> On Sun, 13 Oct 2019 at 16:23, adrianv &lt;

> avm4@

> &gt; wrote:
>
>> nophead wrote
>> > To make the slot I would subtract the hull of two cylinders, or use my
>> > slot
>> > module https://github.com/nophead/NopSCADlib#Polyholes
>>
>> Has this evolved since the original hydroraptor post?  I tried it a month
>> ago on my Prusa Mk3 and the polyholes weren't even close to the right
>> size.
>> Of course, at this point I don't remember exactly what was wrong, and I
>> have
>> three unmarked test prints with different size holes.
>>
>>
>>
>> --
>> Sent from: http://forum.openscad.org/
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> Discuss@.openscad

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Re: polyholes

nophead
Yes that was an interesting conversation with Giles.


When printed with single outlines, or with the multiple outlines doing the outer perimeters first, that always gives the correct size for me.

On Mon, 14 Oct 2019 at 00:01, adrianv <[hidden email]> wrote:
I scrutinized my code and realized it doesn't match the code on hydraraptor.
It seems the code I actually tested came from here:
https://gilesbathgate.com/2016/02/07/polyholes-revisited/  and it looks like
I got the same result you did when testing this code: all holes too big.



nophead wrote
> Polyholes should always print the correct size if square holes print the
> right size on your printer. If not the printers needs calibrating or the
> slicer settings are wrong.
>
> The way it works is the vertex count is reduced enough to ensure the
> corners don't cut into the circle even when the plastic cuts the corner,
> so
> the hole diameter is set by the flat sides of the polygon. They are outset
> correctly to be on the circle, so if your printer prints straight lines in
> the right place the hole should be accurate.
>
> On Sun, 13 Oct 2019 at 16:23, adrianv &lt;

> avm4@

> &gt; wrote:
>
>> nophead wrote
>> > To make the slot I would subtract the hull of two cylinders, or use my
>> > slot
>> > module https://github.com/nophead/NopSCADlib#Polyholes
>>
>> Has this evolved since the original hydroraptor post?  I tried it a month
>> ago on my Prusa Mk3 and the polyholes weren't even close to the right
>> size.
>> Of course, at this point I don't remember exactly what was wrong, and I
>> have
>> three unmarked test prints with different size holes.
>>
>>
>>
>> --
>> Sent from: http://forum.openscad.org/
>>
>> _______________________________________________
>> OpenSCAD mailing list
>>

> Discuss@.openscad

>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>>
>
> _______________________________________________
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> Discuss@.openscad

> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org





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