Changing Filament Mid Print?

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KeithA
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Changing Filament Mid Print?

Post by KeithA » Sat Apr 12, 2014 11:40 pm

My son made a simple item that has lettering on it. It printed fine but he was asking me if the letters could be printed a different color. Is there a way to do this? I have read a few posts else where but they were using a Makerbot, they were saying there firmware will move the hot end away when paused. I have noticed that isn't the case with my M2 and Simplify3D. It seems I can move it manually when paused so maybe that is all I need to do. I was curious if there were any commands that you can use to have it pause at a particular height. Any advice you can give me is appreciated.

Thanks

Toby
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Re: Changing Filament Mid Print?

Post by Toby » Sun Apr 13, 2014 1:33 am

It may be as simple as clicking "Pause Print" in S3D and moving the nozzle using the jog commands, then changing the filament and priming it by extruding some (also with the jog commands). I don't see a "Restart SD print" button, but maybe the pause button turns into a restart button after you press it? I'm just guessing here.

If that doesn't work a more involved way (also untried by me) that might work in S3D is this:

Assume your first color is from 0 to 10mm and your second color is from 10 to 15mm.

1. For your first color set the Layer->Stop Printing value to 10. Slice and print.
2. When it's done leave the print on the bed and reslice it, this time setting Layer->Start Printing to 10 and Layer->stop printing to 15 (or blank).
3. Change your filament and start the second print.

As far as the gcode preview, it looks like the second print will start extruding at a height of 10 mm relative to the bed. So theoretically that would give you what you want.

Probably some gotchas though. Like make sure the start sequence for the second print doesn't bump the nozzle or fan into the print that's still on the bed. Also turn off the Skirt and raft if you have them on.

Maybe take a little experimenting to figure it all out.

Let us know if you try it or find some other solution.

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jimc
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Re: Changing Filament Mid Print?

Post by jimc » Sun Apr 13, 2014 1:53 am

to confirm toby's suspicions, you can pause the print either sd or usb, use the jog panel, move the extruder to the side, do your change then hit resume print and it will jog back to where it stopped and continue. sometime it starts off slow but it will do it. the pause button changes to resume when paused. i have done this not to change colors but to change spools. you kinda need to be quick though. you dont want the motors to timeout and disable which happens if nothing is pressed for 1 minute. this time can be increased in the firmware. this reminds me that i need to do that.

Toby
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Re: Changing Filament Mid Print?

Post by Toby » Sun Apr 13, 2014 1:58 am

i guess even with the 1 minute timeout you could stay alive by jogging a mm in x or y every 45 seconds while you're working on installing the new filament.

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jimc
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Re: Changing Filament Mid Print?

Post by jimc » Sun Apr 13, 2014 2:06 am

yes, i just remember once i did what i had to do then something interrupted me for what i thought was just a few seconds and as i was reaching for the mouse.....bed dropped :roll: start print all over

ketil
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Re: Changing Filament Mid Print?

Post by ketil » Sun Apr 13, 2014 7:07 pm

You can disable the timeout in your start.gcode with M84 S0. Reenable it in your end.gcode with M84 S300 if you want. I do both, and also have a button for each in pronterface.

jsc
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Re: Changing Filament Mid Print?

Post by jsc » Sun Apr 13, 2014 9:36 pm

I've now tried and verified that restarting after pausing in Simplify3D takes it back to where you paused it and resumes correctly. Slicers often implement special syntax, like "@pause" or a particular Gcode, that will pause a print as well, so you can manually edit in a pause into the gcode. Best would be to also add in a retraction, a z lift, maybe a y move to jut the bed out... but I haven't tried any of that yet.

Alternative ideas for coloring things:

The "M2" printed logo on MakerGear's web site was apparently colored by printing natural PLA with sharpies pressed manually to the filament before intake.

For colored inset features on the top surface, print the model in PLA, then carefully lay in colored ABS dissolved in acetone. The acetone will flash off and you will be left with colored plastic inlay.

Print a stencil for the top layer and spray paint.

apk
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Re: Changing Filament Mid Print?

Post by apk » Mon Mar 07, 2016 9:31 pm

Today I tried to change filament in mid print, specifically to print raised lettering in a different color than the rest of the print.

Everything seemed to proceed as expected:

1) When I reached the layer where I wanted to change filaments, I hit "pause" in S3D.

2) Using the jog controls, I lifted the extruder 10mm and walked it off the end of the build surface.

3) Cut the existing filament about an inch from the extruder inlet, fed new filament through the guide tubing.

4) Using the jog controls, manually extruded about 200mm to purge the old filament and feed in the new filament.

5) Removed the excess extruded filament from the extruder with tweezers.

6) Hit "resume" in S3D.

Here's where things went strange. Although S3D moved the extruder back to the place where it was paused correctly, it retracted about 25mm or so of filament before it resumed printing.

As a result, even though the extruder was in the right place and seemingly attempting to extrude filament, the retraction temporarily "emptied" the nozzle, and no filament was extruded for some time. The print was essentially ruined.

Did I do something wrong?

apk
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Re: Changing Filament Mid Print?

Post by apk » Mon Mar 07, 2016 9:44 pm

I just noticed this in another thread:
Jules wrote:Okay the original discussion is in Steve's writeup below:

viewtopic.php?f=3&t=2132

:D

If you are doing a color change, and not a drop in, you need to use the color change script below, to avoid a retraction problem:

G91 ; set relative positioning
G0 Z40 ; raise Z (drop bed)
G90 ; set absolute positioning
M84 S0 ; disable idle timeout
M25 ; Pause SD Print
G92 E0 ; zero extruder
Do I have to manually send the "G92 E0" command before resuming the print?
Last edited by apk on Mon Mar 07, 2016 10:17 pm, edited 1 time in total.

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Jules
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Re: Changing Filament Mid Print?

Post by Jules » Mon Mar 07, 2016 10:08 pm

No, you save that bit of code in the G-code file for the print, then you just need to hit the Pause button in S3D a couple of times to restart the print after you have changed out the filament.

(We probably could use a separate How-To summary for the color change process, since it's kind of buried in steve's Pause Printing thread.) Check back later, I'll write up a quickie.

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