Why Change the Extruder?
If you are having trouble with the stock extruder, underextrusion, clogs, wobbling, or other problems, you might want to consider changing your extruder. You might also want to add dual extrusion to your printer.
What do you need to change your extruder?
You might need a new effector plate. Many people print their effector, and the effector that comes with the He3D printer is 3D printed. But I print at high temperatures, frequently, and I noted that the screws had dug into the effector, so I decided on a metal one. Here is the link: It is the item at Amazon: https://www.amazon.com/gp/product/B01ENY1RKU
You might need a locking clamp that works with your extruder. I am using this one: https://www.amazon.com/gp/product/B01I1WFCLU This is essential to attach the type of extruder that works with this plate.
You might need a new heater plug. Make sure you match your voltage. https://www.amazon.com/gp/product/B01HGIMI2G This is a 24v replacement plug that works with my system.
You might want to replace the temperature sensor. https://www.amazon.com/gp/product/B0150YLX9C
Finally, you need an extruder hotend. I bought this one: https://www.amazon.com/Witbot-Extruder-Printed-Filament-Printer/dp/B01KHFCHXA It was cheap and it seems to work OK. I used the 24 vold heater from the original hotend and the old thermistor. I reused the Kapton tape from the ones that they sent.
Now, you will need a bunch of 3mm machine screws. The 3mm screws that mounted the old effector won't work for reuse, they are too long. I have gotten screws at ACE hardware, they have a better collection than Home Depot or Lowe's. But they charge maybe 50 cents a screw. When you order the above stuff, also get a https://www.amazon.com/gp/product/B014ONCP88 - a nice assortment of M3 screws with a little box to store them in. I had eve ry screw I needed in this box.
Print a mount for your cooling fan. How did I do that? Very poorly. I designed one, printed it in PLA (mistake) and used two longer screws to hold it. It is in use now, although it is sagging. I am going to do something else and change it out. But you need to have some sort of fan that blows on your cooling fins. I finally went with this one: http://www.thingiverse.com/thing:127932
If you look through makes and find the one from Brasshopper you can see my setup, today. I have printed clips of my own design to hold the above cooling shroud and I am using it with my parametric cooling fan.
Remove the old effector. If you are not reusing your heater cartridge and thermistor, plan how you will attach the new ones? Solder? Crimp connector? Shrink Wrap or tape? Or will you get extra wire and splice it in and use new connectors?
Install the j-head, the fan onto the mount, and the mount onto the effector and J-head, somehow.
Install the effector onto the diagonal rods.
Level your printer, check to see that it is printing flat and check dimensionality. I checked for flatness and then ran auto-leveling. But this, probably slightly longer extruder hot end and the different effector plate will change your geometry. I had to change my diagonals and the endstop to build plate distance (although I did that with auto-level).
Calibrate your extruder. The new extruder will probably have different thermal characteristics. The calibration procedure is at this page. Failure to calibrate can cause too much heating or not enough. It is not hard to change the pid parameters to match the new hotend,
I hope this helps you. If you want to make a comment, put it in the discussion on this article, or edit the article, correct my errors and add your opinions and facts. This is a wiki.