Can I continue a failed print?

I have a rather large print that failed after 4 hours. It's a 6 hour print and I'm wondering if I can continue the print somehow? For some reason my extruder stropped extruding, which I have cleared the jam and it's extruding again. It actually failed in a perfect place, it just finished the last layer so it seems that I should be able to just continue printing on the flat surface, is this possible?

It will be very hard to get it perfect, but yes theoretically you can - if you know how to edit gcode.

I would do the following: 1) edit the gcode file and delete all of the code before the failed point. Take note of the position of the E axis. 2) load this edited file into your host program, 3) manually turn on your heaters to the desired temps and wait for them to reach that point, 4) raise your print head to a point higher than the partial print, 5) prime the extruder by extruding manually, 6) reset the E axis to the point noted in step 1, 7) hold your breath and press the print button. The print head speed may be off initially, but it will sort itself out. You could also take note of the last speed (F parameter) before the failure point and add that into the first G1 command - if the G1 command already has an F parameter, don't change it.

This all assumes that the print head has not been moved. You might have to do a home first to reestablish positioning. If you need to do this, make sure you move to a location where it will be safe to home without hitting the failed print. Also be aware that homing could introduce inaccuracy. Try to avoid it if you can.

Good luck!!

Incidentally, I think the best place for a failure is during infill. Happening between layers makes editing the code easier, but it also increases the chances that the restart will be noticeable in the final print.

What I have been working on is opening the file in Sketchup and cutting off everything that has already printed, then taking whats left and starting from there. I thought I would take the hot end down to where the print left off and get it a papers width between the print and the hot end. I have to now tell the printer that 3" up off the print bed is actually home, this is the part I can't figure out. I've got it all edited and new gcode loaded into Pronterface, but I just can't figure out how to tell it where it left off is home, so it starts from there.

In Pronterface, options, printer settings I see a "Z home Position" is 0.00 Do I just measure with my digital calipers from the print bed to where my print left off and (which is 37.24mm) and change the 0.00 to 37.24?

I think I'm on the right track, but my endstop is now my problem. I can tell it that 39.74 (that's my exact measurement, the 37.24 was a guess) is Z home position and it seems to work, but the machine still needs to hit the endstop and doing this manually just isn't going to work, because when I tell it to start the print, it's going to home in the back corner and will also need to hit the endstop a few times as it's getting ready. Right now I can put the hot end right over the print and manually push the endstop when it touches it, but it will be a complete guess when it gets to the back corner. Hopefully this makes sense

I noticed that the LCD screen shows the exact position of the Z axis, but not when you tell it to home. I thought about just pressing the switch when it got to 0 on the LCD, but like I said, it doesn't count the Z axis movements when you are telling it to home.

I guess I could move my carriage up and out of the way, cut my Z end stop from it's hole, drill a new hole up higher where I need it and zip tie the end stop to that hole.

I've also thought about getting a bolt that is 2" longer, so I can thread it clear down to reach the end stop where it's currently at.

I realize it's getting late, it's 11:40pm here right now and I've kept my heat bed on in hopes of maintaining the adhesion of the print to the bed. I might just shut everything down and hope that it's still stuck to the glass in the morning then just go to Lowes and get a longer bolt. That's unless someone suggests something else.

Thanks for the help!!!

Once the plastic has cooled down, it will shrink a bit. Your top layer will not be where you expect it to be. That's going to create an adhesion issue. The other adhesion challenge will come from the top plastic layer possibly being a bit colder than you have previously optimized for.

Some may find my multiple posts annoying, but maybe it will help someone else in some way down the road. I think I've decided to just find a longer screw for the endstop. This way I can possibly use it in the future for similar situations. It seems that on taller prints, this longer screw will hit the top plate where the threaded and smooth rod go through. So if anyone else decides to try this, just be aware of that. I'll post my results whether I fail or succeed.

"Once the plastic has cooled down, it will shrink a bit. Your top layer will not be where you expect it to be. That's going to create an adhesion issue. The other adhesion challenge will come from the top plastic layer possibly being a bit colder than you have previously optimized for."

I thought about this and thought I might try spraying it with hair spray to see if that will help.

Edited 1 time(s). Last edit at 12/29/2013 12:20PM by vetteguy112233.

I would never re-slice in this situation. Just edit the original g code. Your issues with homing are because you are letting the slicer add it's preamble to the resultant code. If you just edit the g code and do all of those step manually, you can eliminate those issues.

Uncle_Bob raises a good issue re shrinking. If you are going to be successful at restarting, you need to do so asap after the failure to mitigate these issues.

I'm sure I've done everything backwards/wrong, but I've got nothing to lose. I've let the print sit for 14 hours, I resliced.......but I'm waiting for the hot end to warm up right now. I'll extrude a few mm of plastic and see what happens. I couldn't find a screw long enough, so I put an allen head wrench through the hole with a piece of plastic around it, which held it in place and allowed me to move it up/down. I was able to get it to perfectly push the microswitch and it sets itself perfectly to the home position that I think is correct.

I'll post the results in a few....wish me luck!

IT'S WORKING!!!!

For the most part it worked, but because it sat so long the left side came off the glass and started creating obvious problems. It was a learning experience for me and at least I tried.

Thanks to everyone for the help and suggestions!