How to Calibrate the Extruder on Your 3d Printer

If you're one of the many who have bought into the 3d printing craze you've probably realized they require a great deal of tinkering to get optimum results.  I'll show you how to calibrate the extruder in order to get better quality prints.  As you can see by the printed table above, a poorly calibrated extruder can have adverse effects on your prints.  These easy to follow instructions are great for beginners because all you need is about 20 minutes and some basic tools.  These instructions will be shown for a Solidoodle 2 but will work for any RepRap using Repetier Host.  The best part is, they require no permanent modifications.  Lets get started!

Step 1: What You Need

Gather the following Materials:

- A No. 1 Philips Screwdriver 
- Metric Caliper ( Metric ruler will also work)
- Sharpie or other marker
- Pen and Paper
- 3d Printer
- Computer

Optional

- Drinking Straw
- Scissors

Step 2: Remove Cover

Remove the screws holding the cover on.  This step may not be applicable for everyone.  If you have a Solidoodle there are 4 screws.  There will be two on each side, towards the front-bottom.  There will also be two screws at each bottom corner at the rear.  Carefully remove these four screws and lift the cover straight up with a slight tilt to the rear.  At this point you should also have your printer powered and connected to Repetier Host.  Under the Manual Control tab click "Heat Extruder".  This will save you from having to wait for it to heat up later.

Step 3: Measure

Mark a 100mm segment on the filament.  This can easily be achieved with a 100mm length of drinking straw or a steady hand.  Take note whether the top or bottom of the mark signifies the correct length.

Step 4: Line Up

Set Extrude length to "1" and click the down arrow until your bottom mark is lined up with the top of the extruder [this can mean top of mark or bottom depending on your measurement/mark technique].  In my picture you'll notice the top of the mark is level with the extruder.

Step 5: Extrude

Set extrude length to 100 and click the down arrow.  If everything is working properly the top mark which is 100 mm above the bottom mark should be lined up with the top of the extruder. 

Step 6: Measure

Mark the filament at the top of the extruder and measure the difference between the two marks[This may require pushing the up arrow to reverse your extruder].  If the original mark you made is lined up with the top of the extruder, skip to step 9.

Step 7: Ratio

Click on Config, then EEPROM Settings[this will be at the top of the window].  On the first line you will see "Steps per mm".  All the way to the right you will see "E:" then a number.  This number is the number of steps your extruder stepper takes to extrude 1mm of filament.

Create a ratio from the expected extrusion length [100mm] and the actual extrusion length [105.03mm].  

(expected length) x steps = (actual length) x new steps   

We know three of these numbers so we can easily solve for the new steps.  This will tell us the amount of steps the extruder must actually take in order to extrude 1mm.  We extrude 100mm for the test because the greater length amplifies the minute error.

A simpler form of the ratio is New steps=  (100*113.68)/105.03

New Steps=107.958

Type the new number in Steps per mm: and click save to EEPROM

Step 8: Clean Up

Clean up the mess from the extruder.  And re-assemble your printer.

Step 9: Conclusion

If you followed these steps correctly you should be producing much better prints.  As you can see below the extra 5mm measured makes a tremendous difference.  If you were to repeat these instructions from step one you should get no leftover extrusion when you extrude 100mm.