Filament change over.

I have bought a couple of new colours of filament.

Is there a procedure I need to follow to change over filaments?

thanks

H

Timing!

I was just about to ask this!

I didn't want to reverse the feed while the extruder was hot (although some printing models seem to do it) as I could end up with a melted filament in the tube causing problems later.
I assume you cannot reverse with the extruder cold, so at the moment presuming you need to cut the filament and feed in the next colour, but that seems wasteful.

I have a RepraPro Mendel but the procedure will be the same. Basically:-

1) Heat the extruder to working temp. then retract the filament sufficiently to clear the extruder body.
2) Unclip the bowden tube and pull the old filament out.
3) Re-attatch the bowden tube
4) With the extruder still hot, feed the new filament in until some comes out of the nozzle (be careful with feed rates towards the end of this process).

DO NOT try to reverse the filament feed whilst the extruder is cold, it will 'stick' in the extruder and may damage the drive stepper motor.

I have successfully inserted new filament whilst a print job was running (silly me ... should have kept an eye on the amount on the spool before starting the job!), by simply cutting off the old flament near to the feed motor and inserting the new filament as the old stuff 'dissapears' down the feed hole. Not ideal as you don't get proper filament retraction during the print, but it does work.

Harvey

I don't see why you unclip the Bowden Tube , If the filament is currently continuous from the spool to the hot end then why does unclipping the Bowden Tube Help.


Or am I missing something

H

From [www.reprappro.com] with a few extra notes.

Changing Filament

1. Heat nozzle to operating temperature.
2. Extrude a little filament, like 10mm
3. Set temperature to 100C, send M302 command (which over-rides cold extrusion) (I don't think you need M302 on Ormerod)
4. Wait for the temperature to drop to 100C, then reverse filament until it comes out of the extruder drive (about 380mm). You can do this at 600mm/min, or by hand if you wish.
5. This should pull out most of the filament, hopefully down to the nozzle. (Also useful for clearing nozzle blockages - repeat as necessary)
6. Command M84 to turn the motors off. Feed the new filament in by hand.
7. Drive/feed the filament to just before the hot end.
8. Set temperature to operating temperature
9. Command the filament to extrude short lengths at 200mm/min until it squirts out of the nozzle. You may need to hold the bowden tube straight for the filament to go down into the hot end easily.

Ian
RepRapPro tech support

Great guide Ian, worked for me - thanks!

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Hi,

I just cut the "old" filament near the extruder outlet and feed the new filament in by hand while extruding at 200° for PLA until it gets feeded by the extruder drive. Getting the filament out by reversing only caused trouble in my hot end so far.

Markus

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XBee & electronics blog: [lookmanowire.blogspot.com]

Quote
markbee
Hi,

I just cut the "old" filament near the extruder outlet and feed the new filament in by hand while extruding at 200° for PLA until it gets feeded by the extruder drive. Getting the filament out by reversing only caused trouble in my hot end so far.

Markus

I do the exact same, i'm on my 3rd reel of filament now.

Snip filament right by extruder body and remove from tubing
Feed new filament though tubing
Start coat hook printing (or similar)
As old filament is consumed feed new into extruder body
Keep pushing pressure on new filament until it appears visible in the Bowden tube

Matt

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Limited Edition Red RS Ormerod 1 #144 of 200 - RRP 1.09fw
iamburnys Ormerod Upgrades Github
Follow me on ThingiVerse My Designs

Thanks Ian - worked perfectly for me. Looking forward to a new colour!

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Ormerod 313