One of the most challenging things to do and maintain print quality with an extrusion style printer is to print a solid object (100% fill).
A student recently came into our shop to print some small parts in PLA. They were 15mm long with solid connecting tubes 4mm in diameter, and he insisted that they had to be solid.

hex_4mmDi_15mmL sidehex_4mmDi_15mmLfront

After a few attempts using support created in Makerware, it was obvious we were going to have to create our own solution.  The issue ultimately came down to cooling time. There was just no way to run the part slow enough to prevent warping, and permanent bonding of the support to the part.  We modeled in a solid support with a gap to the part of .3mm to start.  The part fused solid, so there was definitely not enough gap. We bumped it up to .4mm for the next print.  We saw positive results on the sloped surfaces, but the horizontal surfaces still fused solid.

On the left, first attempt with our own support.  Much improved, finish, but still fused solid.  On the right, another attempt With .1mm layer resolution.  This put way to much heat into the part.

On the left, first attempt with .2mm layer height, and our own support. Much improved, finish, but still fused solid.  On the right, another attempt With .1mm layer resolution. This put even more heat into the part, making things worse.

Eventually we found the equilibrium.  A gap of .6mm between support and part on horizontal surfaces, and .3mm on surfaces at an angle worked great.

The final settings were .2mm layer height minimum, 215 degree nozzle, 20mm/min print speed.  I accidentally left MW support on without any ill effects.  Support broke out cleanly, and parts were beautiful.

The final settings were .2mm layer height minimum, 215 degree nozzle, 20mm/min print speed. I accidentally left Makerware’s support on without any ill effects. Support broke out cleanly, and parts were beautiful.

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