The Makerfarm Prusa i3 is pretty much ready to go upon assembly, however, there is still a little bit of work to do in setting up your extruder and heated bed. I won’t claim to be any expert in this, but wanted to post a few tips that might help people get set up even faster.
Tip #1: Bed Leveling
I’ve done some reading around on the topic, and I don’t think there’s any way around this… leveling the bed is a pain in the ass. The Makerfarm Prusa i3 comes with the “Bed Leveling Kit” which includes springs and socket cap screws for providing some adjustability of the bed above it’s platform. Additionally, since the Z carriage is dependent on two screw drives to raise and lower, it also requires leveling. Here is a quick overview of the steps:
- Use a level to make the Z-carriage horizontal with ground.
- The back right corner of the bed is home, so make sure that a nylon spacer is installed in that corner.
- Then use an extra spacer as a guide to adjust the springs in the other 3 corners. This gets us a bed that is more or less level with the platform.
- Adjust the Z-home position to be about the height of a piece of paper above the glass. Do this by modifying the position of the Z-stop screw and then pressing the Z-home command in Pronterface until the correct height is achieved. Once set, finger tighten nuts on either size of the screw so that it does not move.
- Now, adjust the screw in the front-right corner of the bed until the Z home position is just above the glass
- Adjust the front -left corner to the correct Z-height.
- Adjust the back-left corner to the correct Z-height.
- Position the print head in the center of the glass bed, and test the Z-home position.
- Repeat steps 5 throught 7 until all corners and the center of the bed are at the correct height.
Tip #2: Extrusion Calibration
This is a simple test to make sure that the factory installed settings for the extruder are on target. Using a set of calipers, create a thin mark to measure out 10mm of filament. Make sure your extruder is up to temperature, then extrude 10mm of filament. Inspect the mark and your measure point for accuracy. In my case, the extruder was spot-on.
If you extruded too much or too little, RichRap made a good blog post explaining what to do.
Tip #3: Printing Temperatures
After these adjustments, I was ready to begin printing the “Test Cube” geometry, which is just a cube, 24mm on each side. So, I produced the GCode in Slic3r, and got everything set with the factory temperatures input at 80 degrees C for the bed and 205 degrees C for the extruder. Quickly after beginning the print, however, I realized something was wrong when my test print detached from the bed and became a rats nest of plastic as it got moved around underneath the extruder. Figuring it must have been an anomaly, I retried it, with the same result. At this point I noticed that the bottom of the test prints were curved. When I ran another test print, I noticed that the upper right corner looked like this:
At this point, I realized that the heat settings for either the bed or the extruder were not properly matched, making my print warp as it cooled. So I dropped the bed temperature to 60 degrees C, with no luck. I tried extruding at 190 degrees C, and that didn’t help either. I went through a few iterations:
After a bit more experimentation, I finally landed on a
bed temperature of 70 degrees C, and extruder temperature of 205 degrees C (see update below). The prints were uniform, and I was able to get a full cube. Using my calipers, I measured it and came up with the results below the pictures.
|Direction||Nom. Dimension [mm]||Actual Dimension [mm]||Difference [mm]||Differenc [in]|
So, while the X and Y directions appear to be relatively accurate, the Z direction is about 0.02″ off. For now, that’s good enough for my purposes… maybe in the future I’ll work on doing some further calibration.
After a lot of trial and error, I am now printing with a bed temperature of 65ºC and an extruder temperature of 185ºC. I believe that extruder temperature fluctuations due to drafty printing rooms caused me to require a higher temperature. I have since built a printing enclosure and can now print much more reliably than at the time of this writing.