HOW TO SUCCEED WHEN PRINTING WITH ABS
ABS is one of the most commonly used, and most versatile materials available in 3D printing today. If you're new to the scene though, it can be a bit daunting to start with. However, the payoff is worth it. Learning to print well with ABS is essential if you want strong, heat resistant parts.
Table Of Contents
• What is ABS?
• Getting that first layer right
• Printing on glass with Kapton/PET Tape
• If your first layer is not sticking
• Getting the Temperature right
• What to look for
• Changing Filament
• What to do when things go wrong
What is ABS?
Lego bricks made from ABS
ABS or Acrylonitrile Butadiene Styrene is a common thermoplastic. It’s a popular plastic for injection molding and it’s used to make legos, instruments, sports equipment and more.
If you’re used to printing with PLA, you’ll probably find ABS a little trickier to print with. There are a couple more steps required for each print, and it has a different set of printing settings. However, you need not despair. ABS is a strong and heat resistant filament, with awesome post processing options. With this article under your belt, things will be printing your way.
Getting that first layer right
As we discussed in our PLA article, getting the first layer down is the most important part of the print. Here are the key points:
1. You need the print bed (or print surface) to be level.
2. You need the extruder to be homed to the correct height from the bed.
3. You need a good adhesive to assist your ABS in sticking to the bed.
4. And of course, making sure that your extruder is heated to the right temperature.
Printing on glass with Kapton/PET tape
In order to print with ABS, you need a temperature controlled bed. The recommended bed temperature for ABS is 110.
Instead of printing directly on the glass, it’s better to print with Kapton/PET tape. This makes it easier to clean the bed after you’ve been printing for a while, as you can simply remove the tape, clearing any leftover adhesive or filament.
Having your bed level and extruder at the right height is extremely important when printing on tape. If your extruder is too far from the glass your ABS simply will not stick. If the extruder is too low the glass it will completely block the extrusion of material and may cause a jam after extended periods.
You should also make sure that you have an adhesive of some sort. ABS requires something to bind itself to during the first layer of the print. The most commonly used adhesives are glue sticks, ABS slurry, and hairspray. We prefer hairspray because it’s easy to apply and smells nice. Make sure you get the kind with a plastic base. (We have used "Aqua Net Extra Super Hold")
Freshly applied PET tape
If your first layer is not sticking:
1. Make sure the bed is level.
2. Make sure the bed is hot enough.
3. Make sure that the ambient temperature of the print environment isn’t too hot or cold (or else adjust accordingly).
4. Make sure you put the adhesive on the bed.
5. Make sure the print head is close enough to make a nice squished first layer.
6. Make sure you run the extruder enough before your print starts so there is filament going onto the bed during the entire first layer. In MatterControl you can set how much material you would like to extrude before the print starts, either with loops, or if your an expert GCode commands.
Kapton/PET tape is a great way to print ABS. It makes a great shiny bottom layer and the heated bed ensures that your parts stay nice and flat.
Getting the temperature right
When working with a new roll of filament for the first time, we generally like to start out printing at about 230c and then adjusting the temperature up or down by 5 degree increments until we get the quality of the print and the strength of the part to be in good balance with each other.
What to look for
If the temperature is too high:
You will see more strings between the separate parts of your print and you may notice that the extruder leaks out a lot of plastic while moving between separate areas of the print. If this happens you should try to incrementally lower the temperature by 5 degrees until the extruder is not leaking so much material.
Sometimes you will have a material that is simply less viscous than ABS and will leak more even at lower temperatures. We recommend you increase the retraction a few millimeters (3-4 seems like a good number for most every ABS we have tried).
If the temperature is too cold:
You will either see that the filament is not sticking to the previous layer and you are getting a rough surface, or you will get a part that is not strong and can be pulled apart easily. In either case, you should increase the temperature by 5 degrees and try again until you get good line segments on every layer and have a strong part when done printing.
A print gone cold. Check your retraction and heat for clean prints.
Changing filament
When switching ABS colors:
1. While the extruder is cold set the heat to 120c and wait for it to heat up.
2. When you reach 120c remove the current filament from the extruder. You may be able to back it out by hand or you may need to reverse the extruder.
3. If you are having trouble removing the filament, increase the temperature to 180c and try again.
4. Clean the extruder gear and blow out any particles from the extruder entrance.
5. Increase the heat and load the new filament normally.
6. Run the new color through the extruder until it runs clean and the new color is all that is coming out of the extruder. If you are switching from a dark color (such as black) to a light color (like white or natural) you may want to extrude for a few minutes to be you sure don't have any dark contamination.
7. Print something that you don't care if it has bits of the previous color in it, or run the extruder for several minutes. It may take as much as 10 to 15 minutes of extrusion before you can have confidence that there won't be dark material mixed with lighter material.
Note: We recommended removing the filament when soft rather than when fully melted so that there is a lower possibility of depositing melted material onto the extruder drive gear or leaving meterial high up the melt chamber entrance. Both of which can cause jamming and are hard to clean out. Soft removal also helps ensure that you get everything out of the extruder tip.
What to do when things go wrong
There are a few key things to check when your prints aren't working. But before we look at solutions we need to have a brief description of your symptoms.
"I can't get the first layer to stick."
1. Make sure the extruder is at the right height. Adjust the limit switch or extruder to 0 height
2. Make sure the print bed is level. Level the bed.
3. Make sure you’re printing at the right temperature and that your bed is the right temperature.
4. Check the ambient temperature of your environment. If it’s too cold or too hot outside, your print can vary drastically!
"The part has bad internal layers and top surfaces."
1. Check the extrusion temperature (you may need to increase it by 5 degree bumps).
2. Check the filament tension.
3. Clean the filament drive gear.
4. Decrease your speed.
5. Make sure your part is properly cooled.
"The outside edges of my parts have lots of little bumps on them."
1. Make sure your printer is getting enough data. If printing from a computer, ensure that the computer is not too busy to feed the printer commands. If the printer is pausing it is usually due to the printer being too busy.
2. Print from the SD card. On some printers you can try and print from the SD card. This often helps the printer have enough data to run more smoothly.
However, don't be too quick to assume the problem is in your ABS. With the right settings and patience hobbyists have succeeded in printing all sorts of materials many of which have very low viscosity. You should be able to get usable parts even with some lower quality filament.
"Tall sections of my prints look melted or squished together."
1. Turn on "Cooling". If your printer has a fan you should enable "Cooling" in the print settings.
2. Get a small fan. If your printer does not have an integrated fan you should look into getting a small desk fan. This can help dramatically with tall sections of your print or when "bridging" (printing top layers that span gaps).
“My part is curling off the bed.”
1. Make sure that you have a good amount of adhesive on the bed and that you’re applying a fresh layer with every print. In addition, turn on a brim. Having a brim that extends out a bit helps give the part a large base to work with, as well as having more to adhere to.
"My printer will not extrude any material."
1. Make sure your hot end is getting hot. Check to make sure the hot end is heating at all. If it is not, you need to have your printer serviced. It is likely that you have a loose connection, or your electronics have been fried (assuming the printer is still connected and responding to your host software).
2. Clean the drive gear and adjust tension. The first thing we are going to do is clean the filament touching drive gear and ensure that we have proper tension against the filament. Usually improper tension or a clogged drive gear will make the print look more like the picture we have for low temperature filament, but it sometimes does prevent extrusion all together. Clean the pinch wheel with a wire brush, and make sure your tension is good and solid (too much can also prevent extrusion and is more common with direct drives [the motor is directly connected to the drive gear] but less common with geared drives).
3. Remove the current filament. It may be that you have a small particle in your extruder tip jamming the plastic. Use the change filament technique described above to pull out any particles that are in the extruder tip.
4. Check for and remove jams between the extruder and hot end. This is the most extreme type of problem because now it's time to take things apart. Sometimes heat can creep up the filament in the extruder and cause a bulge that then cools and prevents any further extrusion. This is usually at the junction between the extruder and hot end. Take off the extruder and remove all the ABS you can (you may need the hot end hot to get all the material out.) If you can't get out all the filament by pulling, you may need to try and drive it down through the hot end. We usually use a small allen wrench. If this fails you can try and drill out the extruder or hot end but you may need to replace parts. Be sure to take precautions against being shocked or burned. If you are not qualified to do this work, find someone who is, rather than risk injury.