Slic3r

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.

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Damp filament

This is what it looks like when filament absorbs too much moisture.  The water steams when the plastic is extruded, leaving bubbles and ragged edges.  I left the spool out overnight, which usually isn’t a problem.  I don’t know if the green happens to be more prone to absorption or not.  I did notice that Solidoodle ships the spools shrink wrapped rather than in bags with desiccant.

I’ve had it in the tub with the dehumidifier rod for several days, and if it is still bubbling, I will try unspooling a couple layers and hope that the filament is drier further in the spool.  If not, I can try drying it in the oven.

 

 

Work Space

 

Here is a short tour of the work space I have set up for 3D printing-

Here is the link to the hooks I use for holding up the filament reels – http://www.thingiverse.com/thing:17443

One other thing I forgot to mention which you can see in the video is the pail I have hung near the printer.  I’m always pulling plastic off the nozzle, and bits of failed prints from the bed, and it’s handy to have something close by to throw it in.  The bigger the better because it becomes a pile of plastic spaghetti and spiderwebs that springs back up every time you try to crush it down.

Another print I need to do soon is a filament reel like this one – http://www.thingiverse.com/thing:19122.  Some places like Ultimachine sell filament in 1lb quantities which is great if you want a variety of colors.  However they come as loose coils rather than spools.  If you feed plastic off the coil to the side it will quickly become a twisted tangled mess that can take hours to sort out.  The coil needs to turn to avoid putting twists into the filament.  Running it onto empty spools doesn’t work too well because the filament is set into the diameter of the coil, and resists being wound into the smaller diameter of a spool (PLA is especially bad about that).

Confessions of a 3D printing newbie – what not to do

Hi all, Ian has graciously let me join in the fun here. I’m a complete 3D printing novice, who just got their first printer in the mail last Friday.

3D printing is not mature technology – it’s still the frontier of printing technology. And while the Solidoodle is pretty user friendly, making it work is still a bit of a task. So, based on my complete inexperience, here are some hints.

So, first things first – don’t leap straight into printing. The very first thing you should do once everything is plugged in and working is play around with the manual control buttons in Pronterface.

Actually, the very first thing you should do, at least in the version of the software I downloaded, is change the default heater temp for ABS to 200 degrees, and the default bed temperature to 100 degrees. A few people have experienced blow ups when using the default temperature.

If you’ve never printed anything before, start with something really simple. I used a 20mm calibration box, which is one of the examples from ReplicatorG.

It took me about five tries to get one of these succesfully printed. The first three or four goes the print head height was wrong, so I had to adjust the Z-stop screw (at the back right of the case, about 2/3 of the way up).

 

Here you can see the first attempt on the left, which I interrupted after a couple of minutes. Why?

 

Because of a very complex process called ‘impatience’. You’re meant to wait until the heated bed temperature reaches about 85 degrees, but I pressed ‘Print’ when it was still only about 60. This meant that the plastic cooled too fast, and the corners lifted up off the print bed. The second attempt, on the right, shows what it looks like if you wait until the temperature is right.

(You also need to wait until the hot end temperature is right as well, but that’s a much quicker thing to heat up).

 

Here’s my second print (of the Mini Solidoodle) in progress. Again, you can see from the front left that I didn’t learn my lesson, and had started printing too soon again.

But the real problem happened a few minutes later.

 

You can see that the top layer has been ‘yanked’ backwards. This happened because the printer got a jam in filament spool, and it couldn’t move the way it wanted to. I stopped this print here.

But I wasn’t done being impatient yet. It’s best to wait to turn off the heated bed and wait a few minutes before trying to remove the print, to let the plastic cool and pop off a little. You also don’t want to put the scraper too far under the print. Why?

 

Because you’ll end up with this, torn Kapton tape. Fortunately I had a spare, so I was able to take this off and replace it with a new layer.

That seemed to be the end of my problems so far. I’ve now been able to print a Dog Bone Cookie Cutter:

 

And a Penguin:

 

(OK, I’m still not all the way there – you can see the raft printed onto both of these – you don’t need a raft, but I’d forgotten to turn it off in Skeinforge, and decided to keep going anyway).

Basic Settings

There are a lot of settings in Skeinforge, which can be intimidating, but there are only a few that really matter.  You access the different categories of settings through the rows of buttons.

Raft-

 

If you don’t have heated build platform, you will want to use Raft. This is a first layer made of wide, thick lines designed to stick hard onto the bed and prevent warping from the plastic peeling up.  Aside from turning the raft on or off, there is no need to change any of the settings that determine how it is drawn.

The next layer up from the raft is the interface.  This is a looser, thinner set of lines that go between the raft and object, to make the raft easier to peel away from it.  Turning down the temperature and flow rate a little can help keep it from sticking too hard.

Object First Layer settings affect the first layer of the model itself.  If you are not using the raft, you can change the settings for the first layer only, to help it stick to the bed better.  Feed rate is the speed the extruder moves over the platform.  The multiplier determines how much faster or slower it goes compared to the overall Feed Rate set under the Speed Tab.  Flow Rate is the speed the plastic is extruded.  The multiplier sets the speed in relation to the overall Flow Rate set in the speed tab.  A 1 means 100%, or the same speed.  .8 is 80%, 1.2 would be 120%.

You can help the first layer of the model stick by slowing the feed rate a little, or raising the flow rate to push a little more plastic down.  Most of the time you would leave this alone, because you can use the Z offset screw on the printer to control the stickiness of the first layer.

Fill

A model is built in 3 parts.  The solid layers at the top and bottom, the walls (perimeters or shells) and the fill.

 

Extra Shells determines how many outlines are drawn to create the sides of the part.  The more shells you have, the thicker the walls.  If the model has a gradual curve to the top, such as a fillet, you may need more than 2-3 shells.  If you don’t have enough shells, then as the curve nears horizontal one layer may be set far enough back from the layer below that it doesn’t reach the innermost shell of that lower layer, leaving a gap.  You can see that happening around the neck and ear of the yoda print below.

Infill-

Infill is the plastic inside the “solid” portion of the object.  There is no need to fill it completely with plastic, and Infill Solidity Ratio is where you determine how dense the fill is.    The higher the ratio, the longer it will take to print because of all the lines that must be drawn.  It doesn’t take much to make a strong part.  Large amounts of fill will be able to apply more force to the sides of the part as the plastic shrinks, and increase the chances of warping.  .2 (20%) is a good number to start with.

The Grid settings determine the shape of the fill pattern.  Hexagonal and Rectangular are strong, but Line can print faster.

The last setting under fill you want to think about is Solid Surface Thickness.  This is the number of layers used to make the top and bottom of the model.  The first layer is usually sparse because the threads tend to droop into the fill, depending on how loose the fill pattern is.  Each layer will droop less than the last until there is a solid top.  The more sparse the fill is, the more solid layers you will need to cover it.  3 solid layers is a good starting point.

Speed

Most of the time you won’t need to adjust anything here.  Feed Rate is how fast the extruder moves, and Flow Rate is how much plastic it pushes through.  If you are finding that the threads are squished together on solid layers and pushing up plastic that the extruder is dragging through, then flow rate might be too high.  If the threads are barely touching and you see gaps between them, then Flow Rate might be too low.  Don’t judge this by the first layer however, because this can be affected by the distance between the nozzle and bed, as set by the Z screw.

If there is a problem with the extruder pausing around complex perimeters, as in the first Yoda post, you can help this by slowing down the printing of the perimeters.  Setting Perimeter Feed Rate below 1 will slow down the extruder so it can print the outlines with more precision.

Temperature

Most of the time, 195 is a good temperature for ABS.  Higher temperatures stick better, so if you are having problems, you can try setting the Object First Layer temps to 210.  If you are using a raft, the set Base Temperature to 210 (Base is another term for Raft). Object Next Layers is everything else, so set that to 195.

Something that may come up is the need to cool.  If you have a model with small areas like narrow columns, it might only take a few seconds to draw each layer.  As a result plastic will be extruded onto a layer that is still slightly melted, pushing it around.  Minimum layer time assures that each layer will have at least 15 seconds (or whatever is set) to cool down, either by the extruder running circles doing nothing for awhile, or it could slow down the Feed Rate so the layer takes longer to draw.

For most things, the defaults will work, but this should give you an idea of what you might adjust on a part to part basis.  The main ones will be Solid Layer Thickness, Infill Solidity Ratio, and Extra Shells.

 

 

Software Walk Through

Here is a basic walk through of taking a model from download to print, using a design I made on Tinkercad.  I download it, clean it with Netfabb, orient it in Replicator G, slice with Skeinforge and print in Pronterface.

There is a missing step however.  After modifying the reprap.xml in Replicator G, you have to go back and select Solidoodle 2 from the list of Other Printers.  You might also have to quit and restart Replicator G to get the resized platform to show up.  My install of RepG seemed to remember that I had used a Solidoodle profile before and brought it up automatically.

This is a lot of different programs to use, and everything can be simplified using other software like Repetier Host which will orient, slice and print all by itself.  There are some issues that need to be addressed when using that one with the Solidoodle, and I will cover it later.

More Yodas

The Yoda prints weren’t coming out right in large part because the printer was making so many short fast moves that it kept getting ahead of the computer and had to stop and wait for more commands, oozing plastic and leaving blobs in the mean time.  The simple solution then, is to slow down the printer.

Slic3r lets you define different speeds for perimeters, fill, and solid layers.  I dopped the perimeter speed down to 25mm/s, and raised the fill speed up to 80mm/s to keep the print time from going up too much.  I also changed the fill pattern to lines, which are simple enough that the printer isn’t trying to change direction a lot at high speed.  I dropped the temperature from 210 to 195.  When the plastic is cooler it resists drooping a lot better.  If it gets too cool however it might not bond as strongly to the lower layers, so there is a balance to be struck.

I also set it to print 4 perimeters so there wouldn’t be gaps between layers at the top of curves, like his shoulders.  I enabled supports as well.

The chin could certainly use support, but I could do without the inside ears and under eyelids.  Here it is with the support cut off.  Some brushing with acetone would turn the white bits back to green.

I ran the print again with the same settings but no support.  There were a couple of dropped loops under the chin and ears, but nothing really critical.

You can see a little bit of rough texture under the cheeks where gravity was pulling down on the threads a bit.  Now that I have 3 different Yodas, I can experiment with some options for finishing them.