What causes these rough surfaces & strings

I have had this problem for awhile, but would like to find a solution to this problem. This is a part I am designing to go on top of my Delta printer to connect to 2060 v-slot & 3/4" EMT. I have a makerfarm i3v 10" with 1.75mm Hexagon hotend on a wades extruder & using sliC3r 0.9.9. I am printing with at .2mm layer height & 3 perimeters. Infill is.2mm rectilinear & concentric top & bottom. I am nut using support. This seems to only occur with horizontal holes and the one of the 45 degree overhangs. I thought this would be a retraction problem, but changing it from 1mm to 3mm made no difference. Maybe it still is & I did not change it enough. I also changed the travel speed from 140 to 120 with no effect.

Here are the speed settings I am using in that Slic3r:
bridge_speed = 150
external_perimeter_speed = 70%
first_layer_speed = 30%
gap_fill_speed = 50
infill_speed = 60
min_print_speed = 10
perimeter_speed = 50
retract_speed = 30
small_perimeter_speed = 50
solid_infill_speed = 60
support_material_speed = 50
top_solid_infill_speed = 50
travel_speed = 120

Here are the retraction settings.
retract_before_travel = 2
retract_layer_change = 1
retract_length = 3
retract_length_toolchange = 10
retract_lift = 0
retract_restart_extra = 0
retract_restart_extra_toolchange = 0
retract_speed = 30

Let me know if more info is needed to show the problem. Here are some photos of the part. The 1st photo shows the print orientation.Attachment 8169Attachment 8170Attachment 8171Attachment 8173

If I had to guess I would say retraction settings are not enough.

Think I saw where someone used 9 for retract_length. Does that sound like a good number to try next?

I see several things going on in your prints. The columns of material building up next to the print are due to ooze. Material is coming out of the nozzle when it's moving between islands, and it's wiping off as it touches things and building those columns. Ooze is a product of temperature and retraction.

The hairlike threads of filament stretched across between the islands is also a form of ooze, but usually a sign that the printing temperature is too high.

The rough surface is usually caused by overextrusion (extruding too much plastic). The extra material is squeezing out the sides of the print. This usually means that your ESteps value is a little high or your filament is a little larger than configured in Slic3r.

Several things to try:

First, Slic3r 0.9.9 is very, very old. It has known overextrusion problems and issues with perimeters around holes in certain circumstances. I strongly recommend upgrading to Slic3r 1.2.9 stable. I've been using it for a while now and it prints much more preciesly.

Second, try lowering your temperature a little. A few degrees at a time. If that's ABS at 250, try 245. When you get too low, the extruder may start to jam or the layers will start to separate more easily, meaning there wasn't enough latent heat to bond them together well. Usually, you have to balance threading with layer adhesion.

Third, make sure you aren't missing steps on the retract. Older MakerFarm printers (sold early this year and previously) had motors with high resistance and inductance values and this made rapid retracts impossible. At 30mm/s for the retract, the motor would miss steps, and then extra plastic would come out when restarting extrusion. If your motors get very hot while printing (60C or higher) you probably have the old motors. Try slowing your retract speed down and see if it helps. The retract should be quick and smooth. If it chatters or vibrates during retraction, you're probably missing steps. Try 10mm/s to start. Retraction won't be as effective, but it'll be better than missing steps.

If none of these things help, try reducing your ESteps value a little at a time. If you're at 590, try 570 and see if it's better. If you reduce it too much, you'll start to get gaps in your top fill.

Good luck, and let us know how it goes.

Thanks for the detail comments. I had calibrated the ESteps awhile back, but might be worth checking that again. I tried changing the retract to 9mm & lift Z to .1 with no change. This was printed with eSun PLA at 215. My extruder motor does not get too hot, so I will leave that out of the variables. Maybe I will revisit the newer version of Slic3r again. From your explanation seems like the ESteps and/or lowering the temperature would be the best bet at fixing this.

Quote:

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Originally Posted by PyramidDave

Thanks for the detail comments. I had calibrated the ESteps awhile back, but might be worth checking that again. I tried changing the retract to 9mm & lift Z to .1 with no change. This was printed with eSun PLA at 215. My extruder motor does not get too hot, so I will leave that out of the variables. Maybe I will revisit the newer version of Slic3r again. From your explanation seems like the ESteps and/or lowering the temperature would be the best bet at fixing this.

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That's where I would start.

I made a few changes & got rid of some of the problems. The columns went away, but still have a little bit of spider webs & still have some rough edges. When going through the e-step calibration. It extruded 103 instead of 100. I changed the value initially from 885 to 860, but the calcs were off 4mm the other way. After 2 Trial & errors, e-steps of 865 gave me exactly 100mm. I have switched to slic3r 1.29a after spending some time configuring the settings. I really like that new version. Thanks big time for that suggestion. I changed the temperature to 210, then 205 for eSun PLA. That did not seem to make any difference. I just printed a delta Vertex corner that took over 7 hours & it came out better than my previous tests, so I am happy with the corrections for now. When I have some more time, I will play with the temperature settings some more to see if there is a magic number there.

Quote:

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Originally Posted by PyramidDave

I made a few changes & got rid of some of the problems. The columns went away, but still have a little bit of spider webs & still have some rough edges. When going through the e-step calibration. It extruded 103 instead of 100. I changed the value initially from 885 to 860, but the calcs were off 4mm the other way. After 2 Trial & errors, e-steps of 865 gave me exactly 100mm. I have switched to slic3r 1.29a after spending some time configuring the settings. I really like that new version. Thanks big time for that suggestion. I changed the temperature to 210, then 205 for eSun PLA. That did not seem to make any difference. I just printed a delta Vertex corner that took over 7 hours & it came out better than my previous tests, so I am happy with the corrections for now. When I have some more time, I will play with the temperature settings some more to see if there is a magic number there.

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Glad to hear it's working better.

I've been doing this for years, and I'm still tweaking as I learn more and as my threshold for "good enough" goes up. :)