Your problem is very likely caused by a communication error. The Creatr has a known problem in what I have referred to as the lack of a ‘Common Grounding’ making the USB very susceptible to noise and electric interference coming from the mains supply.
Unfortunately all 3D printers using Marlin Firmware (such as the Creatr, Makerbot, Ultimaker, etc, etc) have NO WAY of knowing when the crash happened and where the print exactly stopped when the crash happened. On top of that you also have software buffers in the USB/COM drivers and within the (Marlin) Firmware of the printer. There is unfortunately NO WAY to know exactly how far the gcode has been processed, at the time the crash happens. You can make an estimated guess and try to find the latest position in the gcode file as FVH suggests. Still you would have serious challenges restarting the print as you would also need to re-heat the extruder, deal with oozing, melting of the part in the proximity of the nozzle, priming the nozzle, etc, etc Just looks like you will have a ‘bad day’ when this happens.
So far for all the bad (negative) feedback. Now my suggestions on what you can do in order to prevent this happening.
1) First get yourself a ‘Surge protection - connector strip’ This will prevent electrical noise coming through the mains, interrupting your communication. Typical devices that create this type of Noise are Refrigerators, fluorescent (TL) lighting being switched On/Off, Electrical Engines such as compressors etc, etc. All of them create huge spikes on the electrical mains and cause problem. Before I personally added one of these ‘Surge protection’ devices I could not switch off the light in my room or the printer would in 90% of all cases freeze. After installing it and making sure both computer + LCD screen (or notebook) and printer are all on the same strip, I can now switch Off/On lights and devices as much as I want without the risk of the printer stalling. This is the one I purchased and is working 100% for me: http://www.conrad.com/ce/en/product/622 ... -TUV-Black
2) You will see there is an issue with the Creatr (and some other printers as well), on the subject of not having a ‘common ground’. Take a look at the Forum thread : http://creatrtips.freeforums.org/viewto ... ?f=6&t=128
In part this is caused by the MOS-FET switches for the Bed and extruders, however also by an unfortunate ‘design issue’ causing a very thin wire within the internal USB cable to become the sole grounding wire. As the internal wire is extremely thin, it is not capable of doing the job and hence there is superimposed noise on top of the communication signals. It’s up to you if you want to make the suggested mod’s, however if you are not afraid of soldering a few wires I would surly recommend you add the wires as described.
3) If you are comfortable ‘ripping everything out’ and re-build the electronics, then I would suggest you replace the Creatr Control board and go back to the ‘standard’ Arduino MEGA 2560 + RAMPS 1.4 and also add a LCD + SD unit. See Forum Thread : http://creatrtips.freeforums.org/viewto ... f=42&t=127
This one for sure may be a ‘bridge to far’ however this would upgrade your Creatr to a level where you can start tweaking and modding the machine as you like, including adding Auto-Bed Leveling http://creatrtips.freeforums.org/viewto ... ?f=8&t=160
etc if you want.
For the moment forget point 3 and concentrate on solution number 1 and 2.