Top Layer Is No Longer Smooth

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Top Layer Is No Longer Smooth

Postby Radioman1017 » 2017-Aug-Tue-01-Aug

Hey all,

I'm starting to have issues getting a decent top layer on my Metal Plus. For the last year, I've had pretty good luck getting very smooth top surfaces. Now all of a sudden, the tops are terrible. lots of lines and a definite lack of cohesion with the outside edge. I'm hoping you can see it in the picture.

IMG_1868.JPG


The lines seem very tall. It's not the "extruder looks like it was drug through mud" issue where the Z axis is too close to the bed. I thought maybe it was temperature and that maybe the plastic just wasn't melting enough. I'm using esun PLA + which recommends 205 - 225 degrees. I've gone up and down in that range and it's not making a difference. I've done fill from 10 - 40% and 3 - 5 top layers. I'm using Slic3r with Repetier to print. Nothing changes. I'm kind of at a loss. What's odd, is that while I'm printing, the layers underneath are fine. really smooth, until I get to the top. That's when it goes to shit.

Anyone have any ideas?

Thanks,

Mark
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Top Layer Is No Longer Smooth

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Re: Top Layer Is No Longer Smooth

Postby RetireeJay » 2017-Aug-Tue-06-Aug

Did this problem suddenly crop up when you started using a new spool of plastic? Do you have any other spools you could try, to see if the problem is independent of the spool? If it's spool-dependent, a likely candidate is the need to adjust the Extrusion calibration because filaments from different spools can have different diameters. That's an adjustment you normally make in Slic3r (although you can also adjust the flow rate in Repetier). I use digital calipers, measuring twice to get the largest and smallest "diameter" of the filament (which is generally slightly oval), take the average of the two, and plug that into Slic3r as the diameter of the filament.
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Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex
Print on glass with Scotch Craft Stick or other glue stick
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RetireeJay
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Re: Top Layer Is No Longer Smooth

Postby Radioman1017 » 2017-Aug-Tue-10-Aug

In 2 years of 3D printing I have never really gotten the hang of the filament measurement. I have a digital caliper and when I measure I definitely see the oval shape you're referring to. This morning, I measured a diameter of 1.70, turned the caliper 90 degrees and registered 1.78. So for that spot I'd be at 1.74. I went up another inch or two and came up with 1.74 / 1.80 so that'd be 1.76. Do you then average the two to get to 1.75? (Which is where I started from in the first place?)

mark
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Radioman1017
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Re: Top Layer Is No Longer Smooth

Postby RetireeJay » 2017-Aug-Tue-14-Aug

I agree with your calculations. What I do is cut off three pieces about 1" long and measure min/max on all three. Add all six readings together and divide by 6. The reason for cutting off short pieces is that it makes it easier to be sure the caliper is in fact exactly perpendicular to the long axis of the filament.
  • 0

Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex
Print on glass with Scotch Craft Stick or other glue stick
User avatar
RetireeJay
My next printer is...
 
Posts: 4776
Joined: 2013-Jan-Wed-13-Jan
Location: Greenville, SC
Reputation: 477

Re: Top Layer Is No Longer Smooth

Postby themzlab » 2017-Aug-Tue-17-Aug

quick and dirty, you can set the extrusion ratio to 90% and see if it improves, or 110% (except in this case that may be way too high). Since you are extruding rows of plastics you shouldn't expect perfectly smooth imo. I think the ideal has little ridges, too little extrusion and you have air gaps, over extrusion and you get some smooth but also some bad features where the extra plastic will squirt out.
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