Major Shift Mid Print

treyco
Posts: 19
Joined: Tue Jun 26, 2018 2:53 pm

Major Shift Mid Print

Postby treyco » Mon Jul 29, 2019 6:04 pm

Can someone please explain how this happens and how to stop it from happening again. Two thirds of the way through a 18 hour print, I come in to find that it had shifted over 1/2 inch. Completely ruined the print and 12 hours of printing time. Here's a pic. Anyone know why this happens?
IMG_4450.jpg

Jetguy
Posts: 2813
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: Major Shift Mid Print

Postby Jetguy » Mon Jul 29, 2019 7:02 pm

Simple skipped step- most likely from a nozzle strike hitting some warping plastic or other layer issue.
Since it only was one major shift and then fine before and after- not likely the coupler or other issue- just 3D printing bad luck- what happens when you send a couple hundred thousand moves to an open loop control stepper motor driven XY system.

Jetguy
Posts: 2813
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: Major Shift Mid Print

Postby Jetguy » Mon Jul 29, 2019 7:34 pm

Contributing factors:
Probably ABS material since this looks like a car dash insert for a gauge cluster (user did not say what material).
Printed with support material- and that tall vertical style of support is prone to warping the taller you go. Probably should have used "grid" VS "line" support style to combat warping of such a large support structure. Any failure of the repeated vertical line structure results in warping and further failure- however, grid takes more plastic and thus more time.
Just the overall size, complexity, height, support enabled, 18 hour print time and a couple hundred thousand lines of gcode moves on an open loop stepper control system- the odds of failure increase rapidly.

You asked can you prevent this? The honest answer- the most honest answer you will ever get- NO.
Again, reading between the lines in your question and your frustration- no, you cannot send any print, let alone an 18 hour or longer print, and not run the risk of a skipped step and thus ruined print. That's where an expectation and reality just collided.

It simply is impossible for me to take that picture, that question, this printer, (and pretty much any 3D printer most are using) and tell you a way on an open loop stepper system to never skip a step. The alternative is big enough motors and drivers such that the motor never skips and the mechanics literally either bend or shear off the nozzle or the errant plastic...... and selling that to a consumer without a machine interlocking door and enclosure without a big red emergency stop?
You can cross your fingers, you can attempt to try alternate settings, you can hope, pray, do whatever, and maybe time after time, or 1 in 3 still fail. Short of ripping out the electronics, putting in a custom servo positional feedback set of motors, sensors, and drivers, not to mention a control board and firmware, and even then, the risk isn't zero. All that would do is fail and then hopefully given the right firmware pause until you the user attempted to correct the situation and prayed after the offending failure was cleared- the print could resume. If warping was the cause- then nothing short of on the fly machine vision capable of warping the design to match the as printed printed previous layers on the fly, and that's not even NASA type stuff... Besides, deafeatus purpose maximus, the print doesn't match the design- so if it completed something- that something is not the original dimensions and specs, so still a fail.

treyco
Posts: 19
Joined: Tue Jun 26, 2018 2:53 pm

Re: Major Shift Mid Print

Postby treyco » Tue Jul 30, 2019 10:00 am

Well, it happened again in exactly the same place. This is definitely not warpage. I'm printing PLA and getting a very clean print other than this shift which apparently is repeatable. I'm going to have to assume that this is a corrupted file from Ideamaker. I've re-sliced and uploaded to the printer and will try again. Will know late tonight if this is successful.

IliaT
Posts: 11
Joined: Mon Jul 01, 2019 5:09 pm

Re: Major Shift Mid Print

Postby IliaT » Tue Jul 30, 2019 4:48 pm

I do not think Raise3D pro2Plus can skip steps without braking the part or the printhead. Our 3D printer was able to tear the big part off the print tray when the part warped and interfered with the printhead. Also I saw on this forum some Raise3D pro2Plus printers brake the printhead during interference action with the part.

The part according the picture looks very clean and flat with no warping at all. Maybe try to print it with no raft if the bottom of the part is flat.


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