Not enough material with the magma hotend? FIX Included

Hi all,

i'm new to this forum so the first thing i want to do is introducing me. My name ist Kai, i'm 23 years old and i'm from germany. I recently got my makerfarm prusa i3 8". After some calibration i was ready to do some testprints which went fine, but then i had a problem with the magma hotend. This was originally posted on my blog but i thought some others may have this problem too so here it is:

Two weeks have passed since i got my Makerfarm Prusa i3 Kit. I bought it together with the magma hotend which allows me to print PLA and ABS parts.

It all worked fine until yesterday when i tried another calibration print to improve my setup. First everything seemed normal, but then i noticed that the nozzle pushing out the melted abs could not keep up with the movement of the extruder and the abs was sticking to the nozzle. For this testprint i lowered the temperature to 215c which i thought could be a problem. This is a picture taken after the print.

Attachment 312

After adjusting the temperature the result was the same so i had to investigate further...

After letting it cool down i started by removing the hotend from the extruder. I wasn't able to just pull the filament out of the nozzle so i connected to the prusa using pronterface and tried to extrude some material so i could cut it off. If you try doing so you will soon be disappointed because you won't be able to extrude without heating it. To bypass this security setting you can send a simple "M302" using the pronterface command line.
Next i extruded some material and cut off the main line. Doing so i was able to see the whole magma nozzle with it's first problem. There is too much tension on the cables because they are not cleanly tied so the thermistor got pulled out of the tiny whole in the nozzle.

Attachment 314

I decided to completely remove the kapton tape and rewire everthing.

Next, connect to your prusa using pronterface and reverse extrude the rest material so you can remount the hotend to the extruder.


All done, yes! Sadly not. I did a fresh testprint but it showed exactly the same symptoms.

I pulled out the filament, ready to disassemble the extruder again when i saw arrears in the extruder feed. I took a close look at the filament i just pulled out and saw the cut i made when i disconnected the hotend. This meant that the filament is not getting into the nozzle. I cleaned the feed using a small screwdriver and then tighten the screws on the idler.

After that the testprint went good and the throughput seems to be ok now.

Note 1: Because of forum restrictions i can not upload all the pictures to clarify the process so feel free to read the original article here.
Note 2: Maybe a FAQ-Thread would be cool? :)

regards
Kai

Hi Kal,

Glad you are printing now. I gather from you post that you are talking about the hobbed bolt slipping on the filament? This is a pretty common problem on all extruders. I use a hobby knife to clean the ridges in mine. It is the first thing I do whenever I have any issues with failed prints and I always clean it when I have the extruder or hot end apart.

When you want to disassemble the hot end (or change filament), heat it first and then hit the retract button until you can pull the filament out of the extruder. I've also found the wiring to be difficult to deal with and have pulled out the occasional thermistor too. It helps to unplug the extruder stepper, the thermistor and the heating element from your control board first. Then remove the extruder and hot end together before you start working on them.

Have fun,

KDog

Thanks for your contribution, Kai. I was having the same problem with my machine today. My filament was not feeding through the hobbed bolt and as a result, the filament was being chewed through. This is a known problem as KDog has mentioned. Check out Page 28 of the Build Instructions which deals with this problem.

I found that I had to file away the edge of the idler bearing slot so that the bearing rotated freely. Just a few swipes with a small file did the job. I also greased the bearing's axle (and also the hobbed bolt bearings). I found that the tension on the idler springs was critical to obtaining a good feed and preventing the hobbed bolt cutting into the filament.

You should also take notice of the feed rate and extrusion temperatures given in the Instructions. However, you should also take heed of what has posted in relation to temperatures here http://3dprintboard.com/showthread.p...Printer-Tweaks

Yous also asked about an FAQ Thread. This sub-folder is for Tips'n'Tricks applicable to MakerFarm printers, so if you want to ask a question, or post a solution as you have done, then do it here, but make sure that the title of your post is very clear.

Old Man Emu

Quote:

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First everything seemed normal, but then i noticed that the nozzle pushing out the melted abs could not keep up with the movement of the extruder and the abs was sticking to the nozzle.

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I've had my Prusa i3 8" for about 3 months and was recently having some extrusion problems. Mine was extruding too much material and it was bunching up and warping. I finally solved it by adjusting the E-Steps. It was kind of tedious but it solved my issues. You can find a guide here: http://reprap.org/wiki/Triffid_Hunte...ibration_Guide

I'm getting really, really good prints right now. I did switch from the Magma head to the JHead because the Magma kept clogging. I might try the Magma again soon now that I'm all calibrated. Good luck getting things settled down. It looks like you are approaching it the right way and being thorough. You'll nail it.