(I think I already posted here somewhere about this problem but can’t find it anymore.)
I have a problem with precision parts regarding only the inner side of printed objects.
Example:
A tube about 4,5 cm in outer diameter I can print on the outside exactly to the 10th of a millimeter.
But the inner side of the tube(4 cm inner diameter) is about 1 mm too small.
I made an spreadsheet about this bug an realized that it seems to be related to the size of the printed object. On small objects the impact is bigger an I need to correct more than on larger parts.
This is not related to some false settings in Repetier-Host like “flow” setting or filling density parameters. When I get a very good precision on the outside than this “false inside dimensions bug” is hardly related to some obvious Repetier-Host settings.
So probably this is something that one can’t correct inside Repetier-Host so it is firmware related and needs to be fixed there?
(I use Repetier-Host V1.0.6 and the latest official firmware for dualhead)
I can’t be the only one who deals with this bug?
Maybe someone with a “singlehead” setup using this fixed firmware regarding the Extruders steps/mm can test if this is fixed by that? k8xxx-3dprinters.crimed.be/w … Mod_extrud
This problem is slicer related. The slicers approximate circles with polygons. The smaller the circle the less sides in the polygon. That’s why the error is greater with small circles.
Then why are only the inner diameters affected by this?
And to test this I would make a cube and everything fits inside, need to check this I think I made some small lego bricks and they suffer on the square insides also from that bug.
Update:
So I made a quick test with a small cube 4,00 cm on the outside and 3,50 cm on the inside dimensions in blender.
The printed cube is ~ 4,015cm outside and 3,420cm inside so this is exactly the missing 1mm I refered to.
So this isn’t related to a slicer issue with approximated object dimensions.
I tested different layer hights the standard default 0,1mm all the way up to 0,5mm(printed the test cube above with 0,5mm).
This Bug occurs on all of them.
This is extremely annoying. You want to make precise parts that fit to each other like some screw tunnels etc. with a quick boolean modifier and then you have to go in and manually correct every single part. That is a total show stopper for me. I pretty much have stopped using this printer for such parts because of this.
[quote=“Zefix”]Then why are only the inner diameters affected by this?
And to test this I would make a cube and everything fits inside, need to check this I think I made some small lego bricks and they suffer on the square insides also from that bug.
Update:
So I made a quick test with a small cube 4,00 cm on the outside and 3,50 cm on the inside dimensions in blender.
The printed cube is ~ 4,015cm outside and 3,420cm inside so this is exactly the missing 1mm I refered to.
So this isn’t related to a slicer issue with approximated object dimensions.[/quote]
That’s only 0,08 cm too small inside, not 1 mm.
Too small inner circular diameters are definitely caused by the slicing software (polygons)
Easiest way to get exact dimensions is to do it experimentally.
[quote=“Zefix”]
Raby, are you getting good results on this issue?[/quote]Nope, I’m always oversizing (a bit) the holes at design time. It’s far easier than trying to adjust all the factors in play. Even when changing the filament color you can’t get the same result.
Omfg this problem seems to be a never ending nightmare and hanging around for years.
The above Link from raby gets to tons of information of many roots of that problem…from the 3d modeler program over to the slicer and maybe even some EU politicians entangled in that issue.
So every reprap/consumer filament 3D printer out there that uses the common Slicers and usual 3D modeling programs suffers more or less from that bug/feature?