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Dealing with long print jobs

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Hello,

I am wondering if there are strategies/techniques for handling long print jobs?? I have projects that take 20+ hours to print. There have been a few times that a problem has occurred part way through the print, forcing me to lose huge amounts of time and PLA since the only thing I know how to do is scrap it and restart.

Once or twice the print "skipped a beat" so to speak and shifted its print location a millimeter or two. Another time we lost power. Another time there was a PLA extrusion problem. I realize these are all problems to expect on occasion, but I am hoping to find ways to address whatever issue may arise during a long print job in order to minimize its impact.

For example, is there free/inexpensive software available that can intelligently divide the project into smaller pieces/layers? Other ideas/suggestions?

Thanks.

 

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You can edit your Gcode to restart on your partially completed print. I've done it a few times. Basically, you measure the height you want to restart at, and delete all the preceding code (based on layer number and thickness) between the Start Code and that point. At the end of the Start Code, you need to reset your absolute extruder position to where the previous print attempt failed. This will make the subsequent extrude moves make sense. This would be a G92 Ennn where nnn is last E position from the deleted code.

You might be able to use the "Cut off object bottom" feature to reslice your model from the failure point up, then edit your start code to offset the new starting Z position (and reset to G92 Z0 before the printing moves). Depending on your slice settings, this might make the new bottom something other than you want in the middle of your print.

Since it is difficult to measure accurately how much model has already printed, when I had to do it, I did a few 'dry runs' with the Z height set somewhat above the printed model without extruding. You can tweak the Z start point downward in the text editor until your sure its right. When you've got it all set, be ready to fine tune your Z screw on the first layer.

It is pretty much unavoidable that there will be a line where the two prints meet.

Hope that helps.

 

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As mastory says, it's possible to continue a print if the nozzle clogs and you don't notice until hours later. The most important thing is to not let the heated bed cool because once that happens it can pop off the bed.

I've continued a few prints. To get the Z height exact though I did something different - I used pronterface and a USB cable and sent the printer G commands, e.g. "G1 Z29.7" says to move Z to 29.7mm and then I would eye it carefully and maybe move the X and Y closer to the part if I'm getting close.

I also did the G92 thing but other's don't bother and it works fine because if you ask marlin to move Z by more than, I don't know, a meter or so it just ignores that particular move and continues on. It basically does a G92 by default.

 

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Wow, thanks guys but modifying gcode and sending the printer G commands may be a bit beyond my pay grade right now :???:

I will remember this though and most likely refer back to it when I am a bit more experienced with 3D printing.

Here is what the UM2 needs (next version):

1. A "resume interrupted print" option.

2. Select the gcode file from the SD card.

3. When prompted, manually position the buildplate and print head using the spin controller on the front of the UM2.

4. UM2 determines which layer to start printing based on the position of the buildplate and skips to that spot in the gcode file.

5. UM2 fine tunes the position of the print head to a corner.

6. Printing resumes.

Thanks again!

 

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I regularly do 30-50 Hr prints, and my main problem used to be jams, but now that i do atomic pulls with white pla, i can see when my nozzle is truly clean as opposed to having the right shape when pulling it out of the nozzle. but my main problem is the plastic tangling itself on the reel, if its new then sometimes it relaxes too much after it first unwinds, and some of the plastic goes over itself and tightens and this leads to layers getting skipped or the classic printing nothing, and then printing in thin air.

1. make sure you have a clean nozzle, (really clean)

2. Try and measure out how much material you will need and either cut it off the reel, and arrange it nearby so it doenst get tangled, (but i never do this, i just cross my fingers and try to make sure the material is not getting tangled but theres much much you can do to stop this especially if you are not around when its getting jammed.

Thats it. good luck.

Ive never restarted a print, and wouldn't recommend it especially if you are a beginner.

All you would really need is a resume from sd card option and the lower head to unfinished layer option, other than that the other stuff is irrelevant in my opinion. As you are generally gonna get a weird layer there unless the height and posinion is identical to where it left off. If you cant pull these long prints off, then i would just print things smaller or lower res. bitty prints are a real dirty fix.

 

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I regularly do 30-50 Hr prints, and my main problem used to be jams, but now that i do atomic pulls with white pla, i can see when my nozzle is truly clean as opposed to having the right shape when pulling it out of the nozzle. but my main problem is the plastic tangling itself on the reel, if its new then sometimes it relaxes too much after it first unwinds, and some of the plastic goes over itself and tightens and this leads to layers getting skipped or the classic printing nothing, and then printing in thin air.

1. make sure you have a clean nozzle, (really clean)

2. Try and measure out how much material you will need and either cut it off the reel, and arrange it nearby so it doenst get tangled, (but i never do this, i just cross my fingers and try to make sure the material is not getting tangled but theres much much you can do to stop this especially if you are not around when its getting jammed.

Thats it. good luck.

Ive never restarted a print, and wouldn't recommend it especially if you are a beginner.

All you would really need is a resume from sd card option and the lower head to unfinished layer option, other than that the other stuff is irrelevant in my opinion. As you are generally gonna get a weird layer there unless the height and posinion is identical to where it left off. If you cant pull these long prints off, then i would just print things smaller or lower res. bitty prints are a real dirty fix.

 

I've just been printing for a few months now and I have not cleaned the nozzle. What do you do to clean the nozzle and get it "really clean"?

 

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