Non-uniformity in a 100% infill printed slab
I'm trying to print a perfectly uniform slab (15 cm x 15 cm x 1cm) of PLA (100% infill, rectilinear pattern) for a radiation physics clinical application. I'm using 1.75 mm Prusa PLA, 0.20mm layers. To verify the uniformity of the print, I'm using a CT scanner, which shows me a relative density image.
Regardless of what shape I print, the edges (and within 1 cm of the edge) are always more dense than the middle of the object (see attached image, where white is dense, black is less dense).
So I'm just wondering if anyone has any ideas on how to make the print more uniform throughout? I realize many users do not worry too much about this!
I've did wonder if the printer is extruding slightly more material at the edges of the print as it slows down to make the turn. Infill print speed has was set to the default (170 mm/s), but I've just started a print with an infill print speed of 60 mm/s to see if it makes any difference. Maybe the filament in the centre is being printed too quickly and is 'stretching' in a sense? We shall see.
Any other ideas would be appreciated. Thanks in advance!
Re: Non-uniformity in a 100% infill printed slab
try different infill patterns
Re: Non-uniformity in a 100% infill printed slab
What is the scale on that image? It's kinda meaningless without one. You may very well just be seeing bed variances.
Also look at your first layer; the edges always tend to squish/blend a bit more than the center from deceleration and flow dynamics. Does that match with your image?
Re: Non-uniformity in a 100% infill printed slab
This square slab in the image is 15 x 15 cm, and 1 cm thick. The non-uniformity is seen throughout all the layers (this image is from the z=5 mm plane).
Would the bed temperature variance still have an effect at z=5mm and higher?
I will try a more complex infill, however, it seems that printing them at 100% is not an option in Slic3r, and it defaults to rectilinear.
Re: Non-uniformity in a 100% infill printed slab
I meant the scale from white to black, not the dimension. Are we looking at a uniformity variance of 0.0-0.05 or 0-500?
Re: Non-uniformity in a 100% infill printed slab
Try changing your all your print speeds to be the same, reduce perimeters to 1 and set top, bottom and infil pattern to rectilinear.
Re: Non-uniformity in a 100% infill printed slab
could it just be layer lines and outer artifacts causing it?
I have a Prusa,therefore I research.
Re: Non-uniformity in a 100% infill printed slab
Have you considered making the slab with enough top and bottom layers, to preclude any infill layers?
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK