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Getting Started with the Printrbot Simple
by josh marinacci
Gentle reader: Congratulations on the purchase or gift of your new Printrbot Simple. I’ve really enjoyed mine and I think you will have a lot fun with yours too. If you don't have one yet, I encourage you to get one at Printrbot.com. I've found it to be a completely fun and engaging learning experience. I don't work for them; I'm just an avid fan.
My goal with this guide is not to make you an expert in 3D printing. My goal is simply to get you from assembly to your first decent print. Your prints won’t be perfect. You will still want to calibrate and tweak. You'll still have more challenging models to print; but hopefully you will be ready to experiment and start learning instead of just being frustrated.
NOTE
Differences between Simple V1 and V2
First things first: Confusion between version 1 and version 2 of the Printrbot Simple was a big source of problems for me when I started. There were significant changes between V1 and V2, and much of the advice you find in the forums is written with the V1 kit in mind.
This guide covers version 2 of the Printrbot Simple. Any kit bought in the last couple of months should be V2. If your kit came with a fan and end stops included then you have a V2. If you have a V1 then I suggest you look at the official assembly guide from Printrbot.
Mechanical Setup
The assembly guide on printrbot.com for the V2 is actually pretty good. They have nice pictures and detailed instructions. Don’t be worried if you feel like the assembly is slow. It took me about 6 hours to finish it, including a few errors. Just take it slow and ask on the forum if you need help. Really look at the pictures. They help a lot.
Before you go build it, a few words of advice. Here's a picture of the tools I used.
You really need some narrow needle nose pliers for inserting nuts into the laser cut holes. You also need 2.5mm, 1.5mm, and 1/16" Allen wrenchs or driver with hex bits. I highly suggest getting hex bits for your cordless drill. The drill will make assembly much faster, especially towards the end when you are sticking lots of wooden parts together. You also need a ruler with a metric side. Oh, and some paper towels or a rag. Your hands will get dirty from the laser cut wood and oil on the screws.
A few tips for assembly:
On step 52, leave extra slack in the stepper cable. The photo shows it being tight with only the fan cable loose. Instead, rotate the stepper 90 degrees so the cable comes out of the side rather than of the bottom. This extra slack will let you quickly remove the stepper motor later when you need to make extruder fixes.
Now, go build your bot!, then come back here.
Number one link: http://help.printrbot.com/
Glossary
Now that your printer is assembled let’s go over some important terms.
Everything on the printrbot is in metric, usually millimeters (mm). Looking from the front left-right is the x axis, in/out is the y axis, and up/down is the z-axis.
Your usable area is a 100mm cube, or about four inches. Printing happens on the print bed, which in our case is plywood. More advance printers have beds made of metal, glass, or other materials; often heated. These are upgrades you can apply later but don’t matter right now because we are printing PLA.
Filament: the spool of plastic you feed into the printer is called filament. A mechanism at the top of your printer called the extruder pulls filament into a tube called the hot end. As the name suggests, the hot end gets very hot to melt the plastic, then squirts it onto your print bed. The temperature of the hot end varies based on the plastic you are using.
Your kit came with a kind of plastic called PLA. This is a bio-plastic that melts at fairly low temperatures and does not require a heated bed. This makes it easy to work with. The other common kind of plastic you will see is ABS, which is used to make Lego among other things. ABS melts at a higher temp and requires a heated bed to cool properly. We won’t be working with ABS in this guide. Consider it an exercise for the advance reader.
When you assembled your printer you attached three contact switches which look like this. They are called the end stops. The printer software uses these to tell where the end of your bed is. This makes calibration a lot easier.
Your printer may not have the extra board on the right edge of this photo. My printer has the Simple Tower upgrade which adds extra enclosing boards.
Connecting to your computer
While the Printrbot Simple can run without a computer by using an SD card, to get started we will only use it attached to a computer. Plug the power into your printer and the wall, then attach the USB cable between the printer and your computer. If you have Mac or Linux then you won’t need any special device drivers. If you have Windows then you may need to install a special driver. Please see the instructions in Section 4 of the Printrbot Getting Started Guide (pdf)
Now download the Repetier software from here. This is the open source software that processes 3D models and sends them to your printer.
Start Repetier
Start Repetier and open the printer settings. I’m going to show Mac screenshots but Windows and Linux should look roughly the same.
This is the main screen of Repetier. Click on the Printer settings button in the toolbar.
Create a new printer
Click the ‘add’ button to create a new printer. name it Simple.
Connection
In the connection tab, change the port to the printer. It should be something like:
usbmodem12345
Baud: 250000
stop bits: 1
parity; none
transfer protocol: Force ASCII protocol
Now you can set up the other tabs.
Behavior
You can mostly leave these settings untouched. Change Z Axis Travel Feedrate to 240 and the Dump area position X to 0.
Dimension
Set the X Max, Y Max, and Print Area Width / Depth / Height to 100.
Don’t change anything on the ‘advanced’ tab. Now click Apply then OK.
Homing
You should be able to connect to your Simple over USB now. Press the connect button in the upper left toolbar, then select the Print Panel tab (right side of the screen), and press the 1 button on the X axis. This will move the X axis by one millimeter. If you get a connection error or checksum errors then scroll down to the trouble shooting section of this guide. You might have to reflash your printer. Don’t worry: it’s a pretty fast process.
If moving the X axis worked then try moving the Y and Z axis. You have full manual control over them. Now, one at a time, press the Home buttons for the X, Y. Don’t do the Z axis yet. Homing will make the printer go as far as it can in that axis until it hits the end stop. While you are at it, make sure the strings for the Y and X axes are tight. If not then tighten them up with the adjustment screws.
Before you do the Z axis: a word of advice. The assembly instructions don’t mention how far to turn the screw for the Z end stop. If you press home before adjusting this the hot end will slam into your bed. Instead slowly lower the hot end until it is almost touching the bed. Then turn the screw above the z end stop until it pushes the end stop down enough to click. Now try pressing the Z axis home button. It should go down to engage the end stop and finish with the hot end just touching the bed. Adjust the screw and press home again until there is just enough space to slip a sheet of paper between the bed and the hot end. Now your Z axis is set up.
Calibrating the Extruder
Repetier doesn’t know how much it must turn the stepper motor to pull through a certain amount of filament. It uses a default number called the E value. We will do some measurements to calculate the proper E-value for your printer.
First, turn on the hot end and heat it up to 190 C. You can see the temperature go up with the graph [picture] or the value in the status bar. When it reaches over 175 C you can start extruding. Don’t put any filament in the printer yet. Just press the extrude button set to 10mm.
Did the stepper in the extruder move? Did it turn clockwise so that it would pull filament in? Did the hobbed gear move along with the stepper? If the stepper didn’t move then you may have wiring issues. If the stepper moved but the gear didn’t then you probably need to tighten up the set screw attaching the gear to the stepper. Head down to trouble shooting for how to remove and adjust the stepper.
Assuming the extruder is working, press the extrude button for 10mm and feed the filament into your printer from the top while it runs. Extrude 10mm at a time until you see molten filament come out the bottom of the hot end. If it never comes out and the stepper starts clicking then you either have a clog in the hot end or the hobbed gear is loose and skipping for some reason.
Once you can get filament come out, you can calibrate the extruder. With a ruler measure 50 mm up from the top of the extruder and mark on the filament with a marker or piece of tape. Now set extrusion to 10mm and extrude, then measure again. If the height is now at 40mm then your printer is already calibrated. If you just built your printer then this won’t be the case. Mine went 55mm when I asked for 10mm.
Now that we know how far the printer went when it thought it was going 10mm, we can calculate a new E value so that it will actually go 10mm. Go to the manual control panel and type M501 into the G-Code text field and press the Send button. The console will show a bunch of values. The first line or so should look something like this:
< 3:15:46 PM: echo:Stored settings retrieved
< 3:15:46 PM: echo:Steps per unit:
< 3:15:46 PM: echo: M92 X63.36 Y63.36 Z2272.72 E96.00
< 3:15:46 PM: echo:Maximum feedrates (mm/s):
< 3:15:46 PM: echo: M203 X100.00 Y100.00 Z2.00 E14.00
< 3:15:46 PM: echo:Maximum Acceleration (mm/s2):
< 3:15:46 PM: echo: M201 X2000 Y2000 Z30 E10000
< 3:15:46 PM: echo:Acceleration: S=acceleration, T=retract acceleration
< 3:15:46 PM: echo: M204 S3000.00 T3000.00
< 3:15:46 PM: echo:Advanced variables: S=Min feedrate (mm/s), T=Min travel feedrate (mm/s), B=minimum segment time (ms), X=maximum XY jerk (mm/s), Z=maximum Z jerk (mm/s), E=maximum E jerk (mm/s)
< 3:15:46 PM: echo: M205 S0.00 T0.00 B20000 X20.00 Z0.40 E5.00
< 3:15:46 PM: echo:Home offset (mm):
< 3:15:46 PM: echo: M206 X0.00 Y0.00 Z0.00
< 3:15:46 PM: echo:PID settings:
< 3:15:46 PM: echo: M301 P22.20 I1.08 D114.00
< 3:15:46 PM: echo:Min position (mm):
< 3:15:46 PM: echo: M210 X0.00 Y0.00 Z0.00
< 3:15:46 PM: echo:Max position (mm):
< 3:15:46 PM: echo: M211 X205.00 Y205.00 Z200.00
The last value on that line is the E value, for extruder. Using the incorrect value and how far the printer moved in our calibration test we can calculate a new value with this equation:
(old value * software move)/hardware move = new steps.
The software move is how far we told the printer to move. The hardware move value is how far it actually moved.
When I first built my printer the E value was set to 520. According to the equation:
(520 * 10) / 55 = 95
So my new value is 95. Set the new value by typing M92 E95 into the G-Code
window, but using your E value instead of 95. Now type M500 and return to save
the new value. Type M501 to see that the value was saved.
These calibration settings are saved in the printer itself using a special chunk of memory called the EEPROM. These settings are preserved even if you cut the power or reflash the printer.
Now try your test again. Measure 50mm, extrude for 10mm, and measure.
NOTE
Hopefully your printer will move exactly 10mm this time. To be more accurate you can try testing a movement of 50mm or 100mm instead of 10mm. This will compensate for small irregularities in your filament.
Almost there! Eventually you will need to repeat the calibration process to find X, Y, and Z values, as well as level the bed. However these adjustments aren’t strictly necessary yet. The defaults that came with your printer should be okay to start. Calibrating X, Y, and Z will greatly improve the quality of your prints, but aren't needed just to get your first print done (along as they aren’t too radically off).
Slic3r setup
To turn a 3D model into instructions that the printer can use we must chop up the model into a bunch of layers. This process is called slicing. Repetier is the GUI we are using, but the actual slicing is done by a program embedded inside it called Slic3r. Before we slice the first model we must set up Slic3r. Click on the Slic3r tab and click the configure button.
The first time you open the Slic3r config it will go through a setup wizard. Follow the prompts. Compare your values to my screenshots below.
When you are done with the wizard save the new configuration as ‘Simple’.
Now switch to the Filament settings tab. Save it with the name ‘Normal’.
Switch to the Printer Settings tab. Save it with the name ‘Normal’.
Now close the Slic3r configuration dialog. Back in the main Reptier screen, choose your new profiles for Simple, Normal, and Normal in Print, Printer, and Filament settings.
Your First print
Yes, we can finally print something!
Download this 3D model from Thingiverse. It’s a test model that will reveal problems with the printer settings. On the Object Placement tab click the Add STL File button and select the model you just downloaded.
Next switch to the Slicer panel, and press the great big slice button. You should see processing messages in the console. When it’s done slicing you can press the big ‘run’ triangle button. Hopefully you will see the printer kick into action. It may take a few seconds before actually starting to print because it must heat up the hot end first.
Your first print. Don’t worry if your first print looks horrible. Here are my first five prints:
As you can see, they start pretty bad but get better. The first issue you’ll probably have is getting the print to stick to the bed. If it doesn’t stick then raise the hot end, scrape off the bad plastic, put some blue painters tape on the bed, and try again.
If the print is very gloppy, possibly so much that it sticks to the hot end instead of the bed, then you are probably over-extruding. Adjust the extrusion factor in the Slic3r settings. If you have to move the extrusion factor way down solve the problem like I did, then that means your extruder calibration is off. You need to recalibrate it.
Hopefully you will get a print that at least finishes successfully, even if it doesn’t look quite right. Congratulations, you made your first print in THREE DEE!!! You live in the future.
Most likely you’ll have a lot of tuning to do to improve the quality of your prints. The forums are filled with advice on how to do this. A few things to check:
- Calibrate your X,Y,Z axes so that moving 50mm really does move 50mm.
- Level the bed by lowering the hot end to just above the bed and moving it around. If the bed is level then the distance between the hot end and the bed will be the same at all four corners of the bed. If not you must adjust it with the leveling screws.
- Check the tightness of your X and Y strings. Any looseness can cause subtle defects in your prints. The strings will loosen up a lot over your first few prints.
- Check the actual thickness of your filament using calipers. It can be off from the stated diameter by as much as 10% which will result in over or under extrusion.
- Vibration and slipping. The printer will vibrate a bit. On a smooth surface this could cause it to move around. Put something soft but level below it, like contact paper or those rubber sheets used for lining tool drawers.
When you are ready to try something more ambitious, there is a world of things to print on Thingiverse. Here’s a few of my favorites:
Troubleshooting
How to reflash your printer.
I’ve had to reflash my printer a few times. I pulled the plug once and scrambled the brains of my printrbot. Use the upgrader app but don’t accept the default firmware it downloads. Instead, download the latest firmware from here with your web browser and drag it to the updater icon and follow the instructions on screen. This firmware is Printrbot's own slightly modified firmware for the Simple. Using the default was the source of a lot of my frustration early on because the printer would appear work but the extruder stepper would go backwards and I had many communications errors. With the correct firmware it all works perfectly.
Fixing extruder problems
Hopefully you left some slack on the cable like I mentioned above. If so then, after turning off the heat and letting it cool down, you can just take out the four screws holding the stepper in and slide it out the back. Make sure the gear is securely attached to the stepper shaft. Also make sure it is the right distance from the stepper. When you look at your printer from above the gear and roller should be centered with the opening and tube. [picture of mine]
Cleaning your extruder and hot end
If your extrusion stepper makes a loud click and the filament stops advancing then you may have a clog. Try turning the temp up to 220C, open up the filament clamp and push some extrusion through manually. If it still doesn’t come out then you definitely have a clog. You’ll have to clean it.
Cool down the hot end to room temp then unplug the printer. Unplug the hot end and remove it from the extruder head. Put the Slide off the heat shield then use a pliers and a wrench try unscrew the brass nozzle. Keep the wrench on the hex nut area half way up, and keep it still. Turn using the pliers on the nozzle. After you get it off lightly scrap off any plastic on the outside of the nozzle.
Now we turn to the tube of the hot end. If you look closely you’ll probably see a buildup of dark, possibly black, plastic clogging the tube. Clamp the tube to a vise and plug it back in, without the nozzle attached, to the power and thermistor. Turn the printer back on and crank up the heat. Hopefully the clog will just melt out. Then cool everything back down, reassemble, and you are back in business. Watch this video by Youtube user curlnizzle for a visual demonstration.
Diagnosing print quality issues
Pretty much every print quality issue comes down to calibration. Whenever you are experiencing print issues the first thing you should do is recalibrate the X, Y, Z axis and Extruder value. Also check that the strings for the X and Y axis are tight. And finally, check that the Z axis is just barely above the print bed when homed.
You can often tell what needs to be recalibrated by the particular defects in your prints. Let me show you photos of the calibration I recently did on my Simple.
I started with this calibration object. It should be exactly 25mm along each dimension.
Notice that while the corners are pretty sharp the square hole in the side isn't actually square. It is supposed to be 5mm by 5mm, but clearly isn't. This meant I needed to recalibrate my X, Y, and Z axis. You might thing I only need to adjust the Z axis, but the Z was actually pretty good. The X and Y were too narrow.
To calibrate I measured the length of the X and Y sides, discovering they were about 15% off. After calibration I reprinted the object.
Now we can see that the bottom has defects. It feels loose, as if there wasn't enough material at the bottom. Also notice defects along some of the horizontal lines higher up.
The problem now is that I'm not extruding enough material. I had set my extrusion factor to 0.6. I now see that I had previously pulled the extrusion factor down because the x and y were squished, resulting in thicker layers. With the X and Y fixed I'm now not getting enough. The fix was to set the extrusion factor back to 1.0.
Next print:
Much better. The bottom is still loose, but the layers are uniform. No defects. Here's a shot of before and after.
Now that I'm extruding the right amount material, let's figure out what's going on at the bottom.
On the left is the current print. On the right is what we want. It looks like the filament went all over the place until it stacked up enough to provide a base for the upper layers. Since our extrusion factor is okay there's only one more place to look. Bed height.
I homed the Z axis then checked the distance between the hot end and the bed. Sure enough, waaay too much space. About two millimeters. The distance should be almost 0, just enough to slip a few sheets of paper in.
To fix the Z axis I adjusted the Z end stop screw, pulled the Z axis up a few centimeters manually (with the Print Panel in Repetier), then pressed the Home button. The printer recalibrated the Z and I measured again. Still a bit high, so i adjusted the screw again and re-homed.
One more print. Perfect!
Actually, it's not quite perfect. I think the X axis is still slightly off and you can see the top layer looks slightly different than the others. Still, it's more than good enough to start building usable models like snowflakes and phone docks for Christmas.
Have fun!
Upgrades
You might want to print a few upgrades.
If you have the Simple with the Tower upgrade, then you might want this guide for the Z axis
Bed leveling screw grips http://www.thingiverse.com/thing:103519
A filament guide