Major shifting in prints, Makerbot Z-18

[runninred57]

I have a prototype model I needed to mock up for a car build the company is doing. It’s a large piece that will really test the Z-18’s limits. I started the print and realized the print had significantly shifted near the beginning of the process, “no problem”, I thought," as long as it doesn’t shift like that in a more critical location". Then I ran out of filament, changed the roll and continued on, now the printer began printing at that original location, the one it started at prior to “the shift”. Since there were no supports of course it just started printing in mid-air and turned into a mess quickly. I ask if there is anyone who may have encountered such a thing in the past. This seams to me that it isn’t a belt issue because the shift is in a diagonal direction and is an almost perfect 45 degree angle, I don’t think both belts shifted the same amount at the same time, that just seams too coincidental. Mind you this is a huge print so the slicing took a half hour alone, and the over-all print time is around 70 hrs.

[Richard_20]

I have a STACKER3D printer I could try to print it. Rhluttrell@rocketmail.com

[carlosap]

I have a gb2 24x24x24 inches if you ever need a large and inexpensive print. I experienced shifting on my prusa 3d printer i found that one of the belts (y axis in my case) was too loose i tighten it and hadn’t had problem since

[OCTheatrical]

I’ve had a couple of shifts on my Z-18 where spool changes occur and its normally by a a mm or so which is deeply irritating and I feel your pain, I now always buy the XL or XXL spools for print over a 900g just to ensure I don’t risk it

Just out of interest how did you transfer the file?

I’ve found my print reliability has been much better if I export the print to USB and print locally - I just feel theres something not right in the file transfer for larger files - dont forget the inbuilt memory is pretty small and print STLs like this can be around 40mb…

[carlosap]

If I do 10+ hour prints I always save the gcode to a usb and run it from the printer. can you home x and y after the filament change? what slicer are you using? the longest print I did was a 20" diameter by 16" tall it took around 98 hours and the gcode wasnt bigger than 10mb.

[OCTheatrical]

On the Z18 so long as the extruder goes into its “Dock” it knows its postion, I only get odd moments when it doesnt dock properly.

Personally use Makerware / Simplyfy 3D

[Skimbal]

I’ve seen this occasionally on my Z-18. The head probably got caught on a piece of curling support material at the beginning of the print and shifted out of position. When the spool ran out and the head went back to the loading area, it re-homed its X-Y position and ‘corrected’ for the error.

I have two suggestions for you:

1) Consider sourcing larger spools of filament. Push Plastic here in the US sells spools up to 55 lbs for a reasonable price per pound.

2) For prints like this that use extreem amounts of support material, consider adding a custom support structure to the model using Meshmixer’s Overhangs tool. It will be dramatically more efficient in time and material.

-Michael Curry

[runninred57]

Thanks for the comment! I’m trying meshmixer’s software and it seams way better than makerbot’s

[MCdesigns]

I am sure you have already done this but re-tighten all the set screws on the gantry. I have had problems where they felt right but they had just enough play to shift sometimes.

[toybuilder]

It sounds like the Z-18 uses limit switches to re-establish its homing location, and when your print shifted near the start of your print, you were essentially printing the object “in the wrong place”. When the printer then resumed and returned to the correct location, your in-progress print which was consistently in the wrong location no longer matched to the true correct location.

[BHAMHUB3D]

It started printing at the right place immediately upon resuming the print when the filament was changed. I’m pretty sure the MBs re-home during a pause and/or filament change. Sounds to me like the slicing/gcode is good, but the stepper driver overheated/slipped at the point it shifted. I really don’t know how to resolve that though. A shift like that usually means the stepper driver overheated. It is odd that x and y both shifted together though not impossible. Are you running the print particularly fast? I have resolved hot stepper drivers with a small fan on (directly pointed at the driver heat sinks - they are tiny) other printers where the drivers were more accesible than the MBs. I know you have a lot invested in this part and it’s a long print, but my best suggestion is to slow it down some. If you can get to the mainboard easily, point a small computer fan at the drivers. I hope you are able to get it printed!

[BHAMHUB3D]

I would also do as the others suggest and be sure all your belts and pulleys are snug.

[BHAMHUB3D]

I have a MB replicator and it has never shifted on me. Check to make sure the power supply fan is operational. I’ve never disassembled mine so I don’t know much about the internals but maybe a fan somewhere has malfunctioned and causing the driver to overheat.

considering the x and y both shifted at the same time, I find it likely the nozzle got snagged on the print itself (like another person suggested)

[Perry_1]

So, your printer, probably due to a mechanical issue, shifted the print. The printer can’t know this happened, and continued to print.

When it hit the limit switches so you could add more filament, the printer is put back to the original xyz, and continued the print.

The layer shift is a mystery you need to fix, but the behaviour after the filament change is expected.