Print shifting constantly

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Print shifting constantly

Postby MichaelWessels » 2013-Jul-Sat-15-Jul

I finally got my printer plus to start extruding a little more consistently, but now it is shifting between the skirt, perimeter and infill.
I am running at 220 tip temp and 70 bed temp on kapton tape on glass.

IMG_1609.JPG


The left one was done first and you can see the it shifted to the left between each step.

The right one shifted randomly, but still seems to not be able to find where it started.

I am running the first layer at 50% normal speed because I am also having an issue where the corner seem to pause and clog the tip. It seems to have minimized the issue, but you can still see two corners are a bit blobby. The prints are also going down really close to the 0 X-axis edge of my surface, even though I have it set to print at 110 X.

Any idea how I can stop the shifting in between operations? Or reduce the globbing in the corners?
Thanks
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Re: Print shifting constantly

Postby Tdeagan » 2013-Jul-Sat-15-Jul

How confident are you in your calibrations? The X axis shifting looks a lot like calibration issues and the globbing could be as well. Getting Started Guide has basic calibration instructions, holler if more would help.
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Re: Print shifting constantly

Postby Bob-StPaul » 2013-Jul-Sun-02-Jul

And making sure your belts are tight - and the drive x drive pulley. If its set to start at a random place, it is going to mover much faster when not printing then when printing - and could be skipping/jumping teeth on the drive gear. That would cause it to print offset to the previous layer.
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Re: Print shifting constantly

Postby MichaelWessels » 2013-Oct-Tue-09-Oct

Sorry it took so long to get back to this. Thanks for the information. I am pretty confident in my initial calibration. I have run through the getting started guide twice now. (I had it printing small cubes, then I moved and now its out of calibration).
I think the major issue is x-axis belt tension. It has been sitting idle for about 5 months because of class and work and summer (My room gets to 115F when I print) The lower half of the x-axis belt is quite loose. I have a new and better set of pulleys and belt that I will try to install at some point this week and try printing again.

I just wish I could get this working. I have a lot of stuff I want to print, but I don't have the spare time right now for extreme calibration. This printer has been a great tool for learning and testing patience haha.

Thanks again!
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Re: Print shifting constantly

Postby RetireeJay » 2013-Oct-Tue-11-Oct

A very common problem is the setscrew (British "grub screw") in the toothed pulley. It needs to be tightened against the exact (rotational) center of the flat on the D-shaped motor shaft. Otherwise, the motor shaft may be turning correctly but the pulley is not moving consistently with the shaft.
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Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex
Print on glass with Scotch Craft Stick or other glue stick
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Re: Print shifting constantly

Postby MichaelWessels » 2013-Oct-Fri-12-Oct

Ok so, Progress.

After putting on the new belt the shifting has gone away, yay! the issue now seems to be the first layer. As most people have. The thing with mine is that it seems to be putting down more material for the skirt, clogging tip before the actual part goes down. I tried pulling up the z a little so that it would clog less, but then it was too far to apply the first layer, again the issue of putting down more for the skirt than the part.

A second issue is the test part I threw together is a bit small for a test. Just compounding issue, with the plastic being warm still when it loops around. I will make a larger test subject and keep trying.

Main question boils down to: Is there a setting that would be making the skirt put down more material, or is it just getting clogged and slowing down the output as it goes. Temps: 230 tip. 70 Base. Stock PB+ nozzle.

First Print: only a skirt printed, then the tip clogged. Seemed to be loosing extrusion rate, upped tempt from 220-230.
IMG_1695.JPG


Second Print: More printed, but got less and less. had issue with the initial adhering of the print part. noticably less material being extruded compared to skirt. Raised the Tip for next print.
IMG_1696.JPG


Third and last Print: Better than previous. Part was laying down alright, started pulling up the corners as it infilled. Second pass pulled corner completely off and mangled part. Still looked like extruding less for part than skirt. Still maybe a bit to squished onto surface?
IMG_1697.JPG
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Re: Print shifting constantly

Postby MichaelWessels » 2013-Oct-Sun-12-Oct

Major Progress with a small tweak! On the slicer tab of repetoir there are drop down boxes for choose saved setting for each tab within slicer. One of them for the printer options was on default instead of untitled, where I was actually making the changes. So all the changes did nothing, which is why I went in circles for an hour this morning. But progress was made none the less. Did about 15 prints, these are the last three.


From left to right. A bit of a wobble in the print, making it zigzag a bit, but not a huge issue. I backed the z axis off a little in order to fight against clogging. I also spent about 20 minutes recalibrating my extruder.
If I am using repetoir and I am extruding 30mm, and then measuring and adjusting the E value in the Slicer settings, does that immediately apply to if I test it right after? Or do the slicer settings only effect the when you hit "print." I would extrude 30mm and about 31 or 32 would come out, then I would reduce it and try again. and again about 31 or 32 came out. eventually after 3 times it was a little less than 1 mm off and I left it there.

You can see that the infill is quite thick and seems to be clogging the tip a bit, especially in the middle one. just extrudes less and less as it goes.
IMG_1698.JPG


This is a close up of the one on the left. You can see that the second infill layer didn't put any material down. The hobbed bolt had already stripped the plastic I'm guessing from extruding so much on the first layer. It simply dragged a few lines into the semi warm plastic.
IMG_1699.JPG


All in all pretty successful. Basically two questions/statement.
I am assuming that it is over extruding and that I need to calibrate my E a little more closely. If this may not be the reason the first layer is so thick, please let me know.
In order to calibrate E correctly on repetoir, what do I do? Is changing the E value in the custom G code section of the Slicer config enough? Or does that only get applied when you hit print? (I was under the impression that slicer sort of overwrites most other settings as it simply tells the printer "Do this" so does repetoir see me changing the E value in Slicer for manual extrusion?
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Re: Print shifting constantly

Postby davec » 2013-Oct-Sun-14-Oct

Put your changes in the EEProm settings in Repetier-Host. Along the top bar under "config" click on EEProm and change the steps per mm. You can then save them into the EEProm. I don't put them in Slic3r unless just checking a temp setting.
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Re: Print shifting constantly

Postby RetireeJay » 2013-Oct-Sun-15-Oct

The way to make calibration constants apply immediately is to use the little command line in Repetier. You type in the very same thing (M92...), but instead of putting it in Slic3r's header you type it in the command box and click "Send".

I agree with davec, it is my strong recommendation to NOT put calibration constants in your Slic3r header. Instead, once you are satisfied that you have the correct values, you should save them to EEPROM on the board. If you are running Repetier on a Windows computer, this is easily done by using the "Config" "Firmware EEPROM" settings window. When the constants are in EEPROM, then they go into effect immediately and automatically when you turn on the Printrbot. No "Print" command needed.

If you follow my recommendation, you should REMOVE all calibration constants (M92...) from your Slic3r headers because at best they are redundant and at worst they may conflict. It is always a good idea to save information like this in a single place, because if you ever need to change it then you know exactly where to go and you only need to change it once.

This posting describes how to use the M500, M501, M502, and M503 commands if you can't use Repetier's Config window. viewtopic.php?f=18&t=2763
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Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex
Print on glass with Scotch Craft Stick or other glue stick
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Re: Print shifting constantly

Postby MichaelWessels » 2013-Oct-Mon-10-Oct

Haha! Finally got a print to go from beginning to end! Thank you for the information regarding the EEprom. The printer is much more consistent. I deleted the slicer header and the thick skirts it was printing also went away. It finally prints a consistent amount. Huge help.

So here it is, in all its messy glory.
IMG_1701.JPG


The corners are particularly thick, especially the back left and front right. Interesting that it always pauses there a fraction longer than the other corners. The back side is quite messy, but left and right are almost smooth for most of it. It was just supposed to be a 3x3x1cm cube, which it is pretty close to. The bottom layer got a bit to squished, so I raised the Z a bit, now I'm just fussing with that again.

Here is the back side, the messiest.
IMG_1704.JPG


So my question then is, what do I adjust next to refine these? I have never gotten past this point before. Only have had messy prints.
What I was thinking of doing was ensuring my bed is level for the hundredth time. Really dial in the z height to something good. Get a set of calipers and measure the x,y,z travel and set them to be more accurate, and then probably check the extrusion again.
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Re: Print shifting constantly

Postby RetireeJay » 2013-Oct-Mon-11-Oct

Yea! Progress! :D

Now it looks like you are over-extruding. Here are the settings to check:

- Filament Diameter (measure your filament at several points, checking each point twice at 90 degrees to see if it's oval, then take an overall average)

- Extrusion Multiplier (probably should be 1.0; it's pretty sensitive to small changes)

- Extrusion Calibration (with geared extruders you will be in the ballpark of 600; with direct-drive you will be in the ballpark of 100 - but you really need to measure the Extruder calibration yourself. Unlike the belts and threaded rods, individual extruders are not all exactly alike)

- Nozzle Size (probably should be 0.4mm; you would know if you have swapped it for a different nozzle)

Also check to see if you are overriding any of Slic3r's default calculated settings like trace width. Leaving these at 0 allows Slic3r to calculate your best setting.

The pause at the corners may be due to "retract" settings. You need different setting here depending on the type of plastic you are using, but as a general principle, the more motions you ask the printer to do at each layer change the longer it takes. If the filament you are using tends to "ooze" then even though you are asking it to retract you still can end up with a bit of a blob due to ooze.
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Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex
Print on glass with Scotch Craft Stick or other glue stick
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Re: Print shifting constantly

Postby MichaelWessels » 2013-Oct-Mon-12-Oct

Hey Jay!

Thanks for getting back to me so quickly. I don't have calipers yet, getting some this week, but I did measure with my ruler.
Filament Diameter: Just a hair under 3mm so I put it to 2.95
Extrusion multipler is 1.
I did the 30mm extrude test twice. Both times were almost spot on. I bumped the calibration down by 10 just to extrude a bit less. its at 560.
Nozzle size is 4mm, stock PB+
All width settings are at 0 for default in slicer.
Retraction is set to 0 so that it is off.

I lowered my temp by 10 degrees so that it is at 220. I did this because previously when I managed to get it to print, I noticed 230 was quite hot compared to what most people print ABS at. Also the hotter temp could cause oozing at any point of pausing, like the corners. This has cleaned up the print a little bit. Here are two more Prints I have done.

Second print. 225 tip temp
IMG_1709.JPG


Third Print 220 tip temp
IMG_1710.JPG


Third attempt compared to first. third is on the left, first on the right. You can see the back left and front right still build up a bit excess, but much less than before.
IMG_1711.JPG


So maybe drop it by another 5 or 10? See if I can lower that sloppyness by lowering temp?
Huge thanks to you Jay for helping me out so far. Wouldn't be printing anything without your help.
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Re: Print shifting constantly

Postby RetireeJay » 2013-Oct-Mon-13-Oct

You're getting closer! :D

I see lines that should be straight which are not straight. Is there any "play" in your X and Y axes? If you move one axis even the tiniest amount by hand, the corresponding motor shaft should also rotate a tiny amount, with never any chance for one to move without the other.

Also, is your extruder tip rigidly attached to the X carriage? If the extruder tip can wiggle without moving the carriage assembly that's holding it, then you need to find a way to tighten that up. There are postings about this where people have used different ways to shim it and make it rigid.

The print bed should be firmly attached to its support, so it can't wiggle around at all in X or Z, and it only moves in Y with the motor.
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Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex
Print on glass with Scotch Craft Stick or other glue stick
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Re: Print shifting constantly

Postby MichaelWessels » 2013-Oct-Mon-13-Oct

Both x and y seem to be pretty good. As I move each by hand the motor moves, even with very little movements. The bed is sturdy in both x and z and only moves freely in Y. The whole printer is a bit wobbly though on its feet and vibrates a bit while printing. each side is relatively uniform in how the print is being laid down. The corners are where it is wobbly and messy. I may adjust the object to be a bit larger so that I can more easily see how straight it makes each side.
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Re: Print shifting constantly

Postby Hoverhead » 2013-Oct-Sun-23-Oct

Hi, I have been having big problems with "shifting" over the last month or so and it would occur after the run had progressed for and hour or two. I've done the grub screw checking and thread locking and belt tensioning. I even slowed down the traversing accelerations.
What I think I had found was the print speeds generally were a bit on the high side and the driver chips had gotten too hot and caused slips to happen. I've slowed the print speed down a bit more and as a result finished many projects that would fail half way.
My next project of to find some way of providing cooling to the printrboard inside the Printrbot Jr. or maybe I need to see if I can extract some of the excess wire under the cover that might allow a little more circulation on the air.
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Re: Print shifting constantly

Postby Mooselake » 2013-Oct-Wed-00-Oct

Try turning down the motor current settings a bit, they shouldn't be high enough to trip an overtemp on the board. Search the forum for advice in how to adjust the motor "pots" (short for potentiometers), including pictures. Always turn the power off first.

Kirk
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Re: Print shifting constantly

Postby Hoverhead » 2013-Oct-Thu-04-Oct

Great advise. Having slowed the print speed setting far less than the max speed which I also lowered, I decided to try a run at that new max speed as I had also installed vibration damping supports from thinygverse. You wouldn't believe it but that run also slipped, only the once but that was enough. Today I opened up the top and accessed the printrboard and turned down the trim pots for the X-Mot and the Z-Mot. Both of them closer to the 11 o'clock pos. than the 12 o'clock. Great success, not only quieter with the motors signing rather than the growling they used to do but also the part printed out beautifully from the same gcode.
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