Host Feature Request: select g-code line to "start print from here"

Hi,

I think it would be great to be able to stop a large print and then be able to resume it from the same point.
Is this possible?

Hi,

Yes, it's possible.
Use "Pause" but if you need to move X, Y or Z, write down their values before moving (if you need to) and then move wherever you need. Once you're done with what you wanted to do, move back to these values and then hit "Continue printing". The speed might off for a little time but it will be set back correctly shortly after restart.
I know this works as I did use this procedure this afternoon.

Repetier will certainly have an opinion on this. I agree it would be good to have such an option without worrying about the actual coordinates when the job was aborted. I presume the firmware can record these once the job is paused and then add/subtract whatever the manuel moves are and then therefore restart where you were before pausing.

Yeah I know about pause but I was thinking more in the lines of something like:

- you start a big print like a plate full of parts
- something happens forcing a stop middle print (power blackout, you have to go somewhere, etc ...)
- you have rough Idea where the print was when it stopped (yeah a little hard but in the end you can just count the layers)
- you home the printer, heat up the nozzle, find the line or layer start and hit "resume print"

So this would allow to interrupt the whole process, shutdown the machine and PC and with a little luck resume the print at a later point in time.

A restart may be possible, but only saying start here doesn't work. It depends on where is the head now, where are obstacles etc. If you want to to restart, you can do the following procedure:

Delete gcode before your starting point. The editor will help you showing the remaining view. Make sure the code in "prepend" is also empty.
Heat up extruder
Home x/y
Set Z position you are
G92 Z
Set Extruder to position before the line deleted
G92 E

Thats the general receipe. Depending on your problem you may need to make some deviations, which is why I can't simply add a continue here. I think it is to risky to make so many assumptions. Your head could have changed in height after that, retracted etc. Not difficult to undo but dependent on the special case.

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Well it is risky if you don't know what you are doing of course ... EMC2 implement's this however and it saved me a lot of head aches.

I thought since a layer by layer view it's possible it would not hurt to be able to start the print from one specific layer only if the machine is homed. Anyway thanks for considering.

I could add it with the assumption, that the z-position is already correct. Lowering z on a printed plate is to dangerous. Doing what I described in my last post. In most cases this would work as expected. I would show a window describing what will happen, so the user can say, yes this should work and is exactly what I want.

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Would it be similarly possible to keep writing the current filename, X/Y/Z positions, heatbed settings & last line number printed to a (non-buffered) file?

That way if repetier-host crashes and gets restarted you can automatically start it up paused, and pop up a dialog saying that a crash was detected, and ask the user if they want to resume printing from there.

Maybe also have an option to do a dry run of the last 20 lines at a layer or two higher so that the user can visually verify that the place in the program for resumption is correct.

There is no real way to automate a restart of a print. The host never knows exactly what the printer printer. This is because the firmwares have a cache which stores often 20 moves and more. So you will always need manual control of the state. Also doing a dry run on the last commands no real option as the old model is still in place. You need to make sure your hard inever get blocked by the model. Take alone the homing problem xy homing at the start might be ok but z homing depends on the print.

WIth the newest host version it is already quite easy to do. You hopefully know the last layer. The editor allows jumping to the layer start/end in the editor. You only need to enter the layer number where you enter the visualize layer and click on the layer button. Delete printed layer. Then start marking the last layer until the position where you think printing stopped. Insert a G92 Exxx to adjust extruder position, set extruder position, remove code from start that would interfere and restart.

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