How to upgrade an extruder.

Hi I have a Prusa I3B and am having problems with the extruder and I am probably going to buy a new one. The one I have right now is a stepper motor driven mk8 from Geeetech. If I want to change it do I have to buy the same model of extruder or can I get a different one? What would you recommend to be the best extruder for use on the printer.

Edited 1 time(s). Last edit at 09/11/2015 06:35AM by SkeptikRC.

Maybe it's a good idea to start troubleshooting your current extruder problems before considering replacing it. There might be an easy fix and you may learn how it works along the way, making it easier to repair or optimize as you go.

There are many things to consider when changing a hotend Bowden or wades extruder, direct drive or geared, do you want to include auto bed leveling, led lights, print cooling fan etc.

Quote
imqqmi
Maybe it's a good idea to start troubleshooting your current extruder problems before considering replacing it. There might be an easy fix and you may learn how it works along the way, making it easier to repair or optimize as you go.

There are many things to consider when changing a hotend Bowden or wades extruder, direct drive or geared, do you want to include auto bed leveling, led lights, print cooling fan etc.

Thanks for the reply, I was a bit irritated with it but after some thought I decided to open it up. Looks like I had the temp to high and the PTFE tube melted. I'm going to buy some new tubing and some new nozzles.

Hi,

You can replace any component for another, it's no big deal.
But you're right, you need to make your extruder work properly first.
Repraps are not plug and play machines.
They need time consuming calibration,
and some experience to set up temperature, feed&speed settings...

You don't want to try extreme values.
First check everything is well assembled and work properly.
The filament must pass thru fluently by hand,
or the motor will have some trouble to do better.
Try it cold with the nozzle out, then at temperature with the nozzle in.
Then keep it warm for a wile and try again.
If the cold end gets too warm after a while,
you will feel the difference, and maybe pushin the filament will be impossible.
That should mean the extruder does not cool down properly.
Maybe the fan is lazy, or the heatsink not in contact enough.

If everything above is ok, try with the motor,
and check it moves fluently, with no vibrations and no overheat of the motor itself.
If the motor jams or get too warm, check the motor powering (drivers output).
The motor should be around your body temperature to the touch.
You don't want to feel heavy vibrations too, just a soft operating feeling.

If everything above is ok, start feeding calibration.
100mm asked should be 100mm of filament extruded.
Put a mark on the filament at 150mm, ask for 100mm then measure the remaining.
Apply a rule of three to your motor's steps per mm settings.
Refine as much as needed, and get as precise as you can.

If everything above is ok you can try a print.
Start with average values for the filament and the machine.
185°C for PLA and 60mm/s for example.
Check the bed adhesion is ok, then go.
You should print roughly the expected shape.
Then refine parameters : low or raise a parameter just a bit,
on a small calibration part, and see if it's any better.
If not, try in the different direction.
There's a lot of calibration parts you can print at purpose.
Prepare to print a lot of them and refine parameters
until you can get an acceptable result to your eyes.

Then the big fun can begin

++JM

Edited 1 time(s). Last edit at 09/12/2015 07:20AM by J-Max.

I have the i3, and I've upgraded my extruder to greg's wade with bowden addon, mounted the motor extruder at top of te frame, inline with filament spool, I'm in the process of modifying the greg's wade gear extruder to run a worm gear to drive the filament.