Color changing process midprint and weird happenings (Page 1 of 2)

The extruder acting wierd is the fact that it is working on absolute coordinates.  It knows where it is after you have been extruding, and tries to get to the extruder coordinates in the gcode, which is behind where you left it.

Color changing is a good reason to go ahead and switch to Repetier.  What I did with my lithoplanes was enter a @pause command after the last layer of the outgoing color.  Before the pause command I also entered an X move to place the extruder over the dump area without hitting the endstop, and set the temp to 100.  This way if I wasn't around, it wouldn't sit on the print, oozing and burning plastic.

When it hits a pause, Repetier brings up a dialog with a Resume button, but still lets you control the printer.  I change the filament, purge the old color, then press Resume and it picks right back up again.

I did the slicing in KISSlicer which enters and extruder reset (G92 E0) at the beginning of every layer.  Repetier might keep track of what you have done with the extruder and compensate, but I don't know for certain.  With that G92 E0 at the beginning of the layer it doesn't matter.

It automatically goes back, or rather it goes to the next position in the gcode.  So long as you don't home or hit the endstop, it still knows where it is and can find the next position.  Also I think Repetier is doing something to help the process.  If I try this while printing from SD, it doesn't work so well.  In fact it turned the motors off on pause, which I didn't realize until I bumped the carriage and then I was screwed.  Each of those lessons (don't home and don't use SD card) were worth 2.5 hours of printing each.

I have been experimenting with dual color printing, and so far the @pause command has been ignored once.  But that may have been a coding problem on my end.  I have not had the slow print on resume of the job on 3 different dual color prints.

Here you go, just a simple test, black on grey.

Just a thought on printing  two colors .This may not be feasible but here goes. If I wanted a base for an object one color and the object another color, print the base and then leave that print  on the print bed and print the new object another color on top of the base.You would have to "fool" the printer into thinking that the base in actually the print bed. Any thoughts on this?

You would have to do something like that that if they were two different files, or not using Repetier.  It is far easier to combine them into a single STL and insert the @pause command into the gcode at the layer where the color changes and then resume after you have swapped filaments and purged the old color.

Satman I setup my repetier to do a G1 X203 Z40 after an @pause command.  Then I just change and purge the filament and hit, Continue print.  Been making money doing custom printing name plaques for some people that go to PDXLan you can check them out here.

http://www.pdxlan.net/forums/viewtopic.php?t=17242

All the money generated from those sales is going to go into building/buying a even better 3d printer

@pause goes into the code at the point/layer you want to pause the print to change the filament.  The G1 X203 Z40 was intereted into the area in the gcode editor under the drop down "run on pause"  that makes it so the only thing you have to add to your gcode is @pause. Also executes teh X and Z move when you manually press the pause button.

If you were to add all the code into the gcode it would look like this.

G1 X203 Z40
@pause

The @pause has to come after the move you command.

OK am understanding a bit more, but does the @pause command supposed to pause the print automatically when it reaches the @pause line?

nlancaster,now I got it  lol , I was using upper case pause.Thanks for all your help.

My first try at using the @pause technique, very similar to above but at a smaller scale.  Making a very gimmicky thing, a 3D-printed business card.  Probably the reasons it came out only just sort of okay include that I haven't yet done a Y-backlash calibration (need to buy a dial indicator) and that I haven't yet learned how to set up Slic3r settings to adjust flow rate.  This also takes forever -- the print is only about 23 minutes, but I spent that much time on switching filament back and forth before and after (takes an age to clear black out to print in white).  Still, it looks pretty impressive.

Sliced at 1mm vertical resolution since this whole thing is about a half-millimeter thick.  I figured out using the G-Code Editor's "Show Layer Range" settings where the layers switch between the solid white background and the raised lettering (just to confirm that it was where I expected based on how thick I'd made the layers).  Then by clicking on lines in the gcode I found where layer 4 started, and added "@pause" in just before it did.  Printed in white until the pause, then manually controlled the head to move it up and over so I could change filament without the goop ending up on the model -- making careful notes about how much movement so I move back to exactly the same spot.  Also changed extruder temp to 205 for black since it prints better.  Once I'd run enough black to work out the white, I moved it back to the same spot and resumed printing.  Easy-peasy.

What I ought to be doing, once I know how to make Slic3r settings perfectly adapted to each filament, is slice it separately with each settings, then use a text editor to merge the relevant bits of the two gcodes produced with a @pause in between them.  After I learn enough to be able to understand the articles about calibrating the extruder and flow rates, I'll have to try that.

By way of contrast, here's the one-color version.

(The discoloration here just shows I didn't clean off some of the green from the outside of my extruder before doing this print, but it's okay, it was just a test run.)

Thanks, good thing to know -- I assumed it didn't, but I didn't actually test it.