Slic3r is an alternative to Skeinforge for preparing STLs for printing, and is simpler, far faster, but not always the clear choice.

This is Slic3rs first page, where you load in STLs.  Skeinforge doesn’t have way to manage the placement of parts, relying on Replicator G.  Sli3r doesn’t have a 3D view, but unlike RepG it can load multiple STLs and place them around the bed to be printed at the same time.

These are the print settings.  The first is Layer Height, normally found under Carve in SF. There is an option to scale the height of the first layer up or down in relation to the rest of the print.  If you use a thicker first layer, it can help compensate for the bed being slightly off level.

Infill every N layers is good for printing at low (.2-.1) layer heights.  Because so many more layers have to be printed, it takes a lot longer to finish a print.  Low layers are all about smoother finish and details on the surface of the print.  There is no point in using high resolution for infill.  If you set this to 3 with a layer height of .1, it will print 3 perimeters at .1, and then print the fill once at .3 saving a lot of time.  Skeinforge 35 doesn’t have this ability, but the current version does, called “Skin”.

Skirt is an outline that gets drawn around the part a set distance away.  This primes the nozzle, and replaces any plastic that oozed before starting on the actual model.  You can leave this at one layer, or set it to a lot of layers to build a shell around the model.

Brim is a kind of skirt, but attached directly to the outline of the model on the first layer.  This can help keep the part from peeling off the bed.  Most of the warping force gets applied to the brim, so it may peel, but the peeling doesn’t reach the model.

Support will add plastic under overhangs greater than 45 degrees, or whatever value is set.  Skeinforge has the same setting, with the added ability to define a separate flow rate for support.  Setting a lower flow for support material makes it weaker and easier to separate from the model.

Print settings is an area that you will adjust on a case by case basis.  Perimeters is the number of outlines.  More perimeters makes a stronger, thicker wall, but takes more time. Shallow curves over the top need more perimeters to prevent gaps.  If your model has holes that will need to be tapped or drilled larger, extra perimeters will give you more material to work with.

Solid layers are the layers at the top and bottom of the print, areas of the model that won’t have anything else printed on top of them.  Fill density is the amount of fill, with 1 being solid.  The more fill you use, the longer the print will take.  I rarely go over .5, most of the time I use .2.  The less fill you use, the more solid layers you will need to cover it without drooping.  You can choose different patterns for the fill and top layers, and Slic3r has concentric, which can make an attractive top layer.

Randomize starting points is mostly for things like cylinders.  When each layer is a circle, and every layer is the same, the extruder tends to change layers at the same place every time.  There is often a little blob when that happens, and the blobs line up to make a seam up the side of the cylinder.  Randomize starting points randomizes the place where the layer change happens, so those blobs get redistributed around the circumference and become much less noticeable.

Retraction is pulling the filament back between moves so the plastic doesn’t ooze and leave strings.  These are equivalent to the settings in the Dimension tab in Skeinforge.  Slic3r adds Lift Z, which will drop the bed slightly as the extruder travels to insure that it doesn’t bump into the print along the way.  If the print is tall and narrow, it could get knocked over.

Cooling is for helping out with small layers.  If it only takes a few seconds to complete a layer, it will still be soft when the next one is extruded, and it will get pushed around leaving an uneven surface.  The fan settings aren’t relevant to the Solidoodle.  Without a fan, the best option is to slow down the print if the layer will take less than a minimum time to complete.  Skeinforge handles cooling better, and has the added option to run with extruder in circles (orbit) without extruding to give the layer some time to cool.  You can do something similar for a small print by setting a skirt to be the same number of layers as the model.  That will give the model a chance to cool while the skirt is being drawn, but uses up more plastic.

These settings are about the printer itself rather than the particular print.  Bed size tells Slic3r how big to make the bed in the first page.  The Solidoodle is set up to consider the center of the bed 0,0 so set those coordinates for the center in Slic3r to insure the print is placed properly.  Z offset does not need to be set because that gets determined by the Z Offset screw on the printer.

For filament diameter, you should actually measure with a caliper.  Slic3r automatically calculates the flow rate, and the exact diameter is very important.  Check several places over a few inches and come up with an average.  The 1.75mm filament I have been using is typically more like 1.68

Ideally the extruder should be calibrated so that when 100mm is commanded, 100mm goes into the extruder.  If the number is different, enter the ratio between them into Extrusion Mulitplier.  If I use Pronterface to extrude 80mm and it pulls in 100, then I need to set the multiplier to .8 so it extrudes 20% less plastic.

Temperature is the Temp you want to use for the whole print, with the option of setting a different temp for the first layer, generally higher to improve stickiness.  Also you can set a lower bed temp for the higher layers so there isn’t as much difference in temperature across the height of the model.

You can set the speeds to 50 to match the defaults in Skeinforge.  You can make it slow down for small outlines to improve precision and cooling, and speed up the infill to save time where quality doesn’t really matter.  I wouldn’t run infill too much faster on a honeycomb pattern, but if the infill pattern is line you should be able to get away with some fairly high speeds.  There is also the option to run the first layer at a slower speed to improve stick.

This is where the start and end gcode goes.  These are commands that the printer carries out before and after every print.  The start gcode tells the printer to go right 200mm which is far enough to hit the X endstop, then it goes back 200mm which runs it into the Y endstop.  From there it goes to a point in the middle of the platform.  I runs the bed up into the Z endstop and defines that position as 0,0,0.  Since we told Slic3r that the middle of the bed was 0,0 it built the gcode around that point.  The printer has moved to the center and declared it 0,0 so that is where the print will begin.

The end gcode generally does things like lower the bed when the print is finished, and turn off the heaters and motors.

The Advanced tab is mostly stuff that is best left automatically calculated, but there is one handy feature here, Generate extra perimeters when needed.  This is supposed to let you set a low number of perimeters like 2 (faster to print) but if it sees some shallow curves that need more perimeters to prevent gaps, it will add them automatically.

Most of the settings in Slic3r are present in Skeinforge and called the same or very similar things.  It is a good learning experience to compare them parameter by parameter and and set up Slic3r to match the Solidoodle Skeinforge profile.  Preset profiles are good starting points that serve most prints, but you will get the best results if you look through the parameters and try to understanad what they do and why they were set the way they are.


6 thoughts on “Slic3r

  1. Very useful information for a beginner like me. Thanks a lot!
    My circular printings are deformed like an oval. Is there any way to adjust the x y parameters in slic3r to correct this problem?

  2. Hi, Just purchased Solidoodle 2 Expert. Used a LOT of information from your site to get it set up – Calibrated Z-offset, leveled the bed, fixed tension of pulleys, etc. When I started to print using slic3r – it began fantastically, but in a few minutes the top temperature (ceiling) would jump up from 200 to 215 for extruder and from 100 to 115 on bed and printing would get interrupted with an error message about temperature. I checked thermistor – and it is OK. I haven’t had this problem when I sliced with Skeinforge, but Skeinforge produces pretty dodgy results in terms of quality of prints. Slic3r starting to print very well but will change temperature ceiling in the middle of print. I think it is software/setting issue but don’t know where to look. Could you advise? Thank you very much! I learned a lot from your page and looked through all your videos – VERY helpful!!!

    • Never mind, people!!! In Slic3r, settings > filament settings> filament >Temperature >first layer/other layers – Other layers was the one that would rise the temperature ceiling. I set it on 200 (since it worked good for me) and problem went away. quality of prints is astonishing!

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