Layers splitting + offset in y axis  

Re: Layers splitting + offset in y axis

Hi Michal

Can you please let me know what material and settings you are using (layer height, temp etc.)

Thanks

Peter

Re: Layers splitting + offset in y axis

Hi Peter!

I am printing white PLA 210/50 hot end/bed temperature. I am printing 0.2mm resolution. Retraction 4mm with 90mm/s.

Let me know if you need any more settings.

Re: Layers splitting + offset in y axis

Hi Michal

With the Prusa "original", you don't need such high retraction; try 1.5 to 2mm and at 20 to 25 mm/s. Some clones with lower quality hot-ends need the higher retractions; I don't think the printers will retract at 90mm/s in any event, as it exceeds the maximum feed rates (25mm/sec according to the config files):

#define DEFAULT_MAX_FEEDRATE {500, 500, 3, 25} // (mm/sec)

You could also lower the temperatures; 210 is about the maximum for PLA which will print very well down to 195 and below (but minimum extrusion temp on this printer is 190).

Make sure that your extrusion width is set to the nozzle width (or up to 10 % greater than nozzle width) - between 0.4 and 0.44mm.

Ensure that the part fan is working from about the third layer at >=60%.

Peter

Re: Layers splitting + offset in y axis

Hi Peter,

Thank you for your advise. Unfortunately, I didn't manage to do a good print with these settings. Printer is still not printing enough material. Please see the image. I get string instead of layers. I double checked bed level and retraction settings. Now, common sense tells me if I don't get enough material it is either motor skipping steps, nozzle blocked or issue with software/firmware. But I don't know how to diagnose further. Please help 😉

Edit:
Also, I might mention that this started after a failed print I left overnight. The issue at that time was that the Y axis pulley moved towards the motor and started scratching. After that the whole nozzle was covered in PLA. I am thinking if its clogged? Although I tried take filament out and put it back in and it seem to extruding well.

Michał

Re: Layers splitting + offset in y axis

Michal

I think I see it now. The print is very porous. That is something that has happened to me, and the solution is one of two things.

Do this from point 3: https://ultimaker.com/en/manuals/149-atomic-method

That will give a clue as to whether is is the nozzle of the PTFE tube. The porosity occurred for me following an overheat (ran out of filament during a print); I ended up changing both the nozzle and the PTFE tube - something I have to do regularly on my Chinese clone.

What happens is the filament flow is restricted and then all of the filament is ejected at once with a lot of ooze and then the nozzle has air inside which is extruded with some filament and the cycle repeats. Sometimes you can heat a clicking sound from the extruder as the motor grinds the filament which is unable to feed properly.

Peter

EDIT: Printing the first layer too close to the build plate can also cause the problem.

Re: Layers splitting + offset in y axis

Peter,

Do I also have to remove PTFE tube? I will need to remove the motor to get a good grab on it.

Re: Layers splitting + offset in y axis

Peter,

I am just doing that. Look at the filament, there is a lot of air bubbles. I did it already twice, should I continue or does this give us enough answers?

EDIT:

Just saw your edit comment. I think I did that once or twice when I started printing something too close to the bed. It's just very uneven. The corners are ok but the middle tend to be slightly higher. I need to think of autolevel 🙂

Re: Layers splitting + offset in y axis

Can't quite see the tip; it should be a nice smooth 'V' shape with a very small pip on the end.

And no, you don't need autolevel and all the associated problems that go with it, you just need to get the bed to within maybe 0.1mm all over and that is easily possible.

So, let's get the extruder working nicely first. I can't see any black deposits, so there's a good chance the PTFE is OK. And hopefully, the nozzle will now be nice and clean. pre-heat the printer for PLA and load some filament. With a marker pen, make a mark on the filament 5cm above the feed hole at the top of the extruder. Connect via Pronterface and issue the GCode: G1 E50 F120

This should feed (G1) 5cm of filament (E50) at 2mm/s (F120 - mm/min).

Make sure that the filament is fed to the mark you made earlier (within 1 mm). If not, there is either a problem somewhere or an adjustment is required. Let me know please.

Peter

Edit - make sure the Z axis is quite high when feeding and make sure the filament comes out straight.

Re: Layers splitting + offset in y axis

Now on to the bed.

You can use the edge of a steel rule (or similar) as a flat edge for this.

Determine the high point of the bed; this is usually the centre. It is possible to take some of the strain off by undoing the nuts slightly in the corners, right underneath the bed, put the bed on the chassis, push down in the middle slightly while doing the nuts up again.

With the glass, this is toughened and is also not usually flat due to the manufacturing process. Determine where the high point is on the glass; you need to find the side with the high point in the middle. You will use this side as the bottom side.

Put the glass on the bed and clip it in place. test again with the rule to see if the high point is in the middle. If not then start printing. If it is, then you need to put some blue tape or similar under the front and rear edges of the glass as in this picture: prusa-i3-kit-building-calibrating-first-print-main-f6/y-axis-shift-t557.html#p4043 ( note that is under the glass to raise the front/rear edges slightly).

Using this method, you will probably have to raise the bed temp by 5 degrees as thermal transfer is not as good, but it does give a nice flat build plate.

Peter

Re: Layers splitting + offset in y axis

Peter!

Firstly, I want to thank you for all the time and advise you are giving me. I really appreciate it!

Secondly, after that cleaning process I managed to get a proper print of my test part!

Now regarding the feeding distance, I did as you asked and I am out about 1,79mm.
I have already seen a video about e-steps calibration for feeding motor but they were changing e-steps on the LCD panel and I think that is not possible on my printer. I need to warn you that if this change need to be done in firmware I am totally new to that and you will have to be patient with me 🙂 but I am a quick learner 🙂

If it comes to the bed I will give it a try but I think I will do it tomorrow or a day after. Could you please fix the link in your previous post as it didn't open for me for some reason.

Once again thank you for your help. I will update you on the progress with bed and looking forward for your comments related to calibration of feeding motor.

Michal

Re: Layers splitting + offset in y axis

Hi Michal

No problems.

DO NOT make any changes in firmware for E-motor steps. Simply put, all printers are very slightly different as is the filament used. The drive gear is man-made to certain tolerances and will be slightly different in each machine.

Some filament is softer than others and it does degrade if left unsealed; the softer the filament, the more the gear bites into it, changing the extrusion amount slightly.

In the slicer you have chosen to use, there will be a "flow tweak" parameter which for the filament you ran the test on, will need a 4% adjustment from unity. Theoretically and to get closer to that perfect print every time, you should have settings in your slicer for each filament (type and colour) that you use to accommodate its different properties (including its average diameter).

The photo of my bed with blue tape behind the glass is in the thread "Y axis shift" somewhere below this topic. Here's the link again: http://shop.prusa3d.com/forum/prusa-i3-kit-building-calibrating-first-print-main-f6/y-axis-shift-t557.html#p4043

Peter

P.S. I have tested the link and its fine for me using Chrome.

Re: Layers splitting + offset in y axis

Hi

So today happened yet another weird thing with my printer, probably connected with the previous issue.
Suddenly the printer spitted out a big chunk of filament as per picture attached.

What should I do tho fix this issue?

Michal

Re: Layers splitting + offset in y axis

Hi Michal

I have never seen anything like that!

Only reason I can think of is if there is an issue with the gcode where a feed amount/rate instruction is wrong.

Which slicer did you use, what material, temperature and layer height?

Peter

EDIT: Nice photo BTW... If that really is you, then you shouldn't be playing around with 3d printers...

Re: Layers splitting + offset in y axis

Hi Peter,

I am using Slic3r and printing PLA 1.75
0.2mm res
210 Degrees temp

Below you can find the gcode I am using.
https://www.dropbox.com/s/q547ico6ky7fde6/BB8%20Dome%20Top%20V2%20-%201mm%20gap.gcode?dl=0

P.S
Thank you! 🙂

Michal

Re: Layers splitting + offset in y axis

Hi Michal

There's nothing obvious there, except the extrusion multiplier of 1.064.

I think it's probably time for a thin wall calibration cube. See attached on how to do this.

Peter

P.S. I have a feeling that Josef may be along soon with his suggestions...

Re: Layers splitting + offset in y axis

Hi Michal,

do you have the same issue with stock FW and our bundled G-codes? This would rule out any HW issue.

Do you make the STLs you are printing yourself? Can you share one of them so I can inspect? If it is thin wall object, Slic3r can sometimes go bit crazy :-/

Re: Layers splitting + offset in y axis

Hi Josef and Peter,

I have already done the thin wall cube calibration hence the extrusion multiplier but I think I am going to do that again after all the things that have happened to the printer recently 🙂

Josef,

I have printed some other parts before, some of them were the ones you supplied along with the printer and they printed fine.
Also after that failed print I tried to print this part again and after 5h of printing it came out good.
See picture attached.

I am not sure if it was one time thing or what. It actually happened twice. First time when the print failed as I posted before and then I used pronterface to extrude 20mm of filament and at first is spit out a big chunk of filament. But since then I printed for 5h with no incidents.

Regarding the STL file I didn't create it myself. The reason I bought the 3D printer is that I want to build my own version of BB-8 droid from new Star Wars movie. There is a whole facebook group of people trying to do that and using different 3D printers. The people who created the group originally also produced all the STL files that are available to the public. If you are interested google BB-8 Builders Club. Bottom line is that I haven't created STL file but you can find it in the link below if you want to look at it.

https://www.dropbox.com/s/nf6mh0jdfttw5qv/BB8%20Dome%20Top%20V2%20-%201mm%20gap.stl?dl=0

Thank you for all the help guys!

Kind regards,
Michal Uhman

Re: Layers splitting + offset in y axis

Hi Michal,

Are you printing from SD or from the computer?

I ment the STL for the first posted file 🙂

With the second problem of sudden extrusion, does it happen if you print from SD?

We are actually landing couple printers to Czech Rebel Legion to print BB8 😉

Re: Layers splitting + offset in y axis

Ho Josef,

I am printing from SD and all the prints were done from SD so far.

I am sorry I though you mean the latest STL . Please find below the STL of the first part:

https://www.dropbox.com/s/onmthdr5fa0r00q/BB8%20Dome%20Panel%201%20v2%20mag.stl?dl=0

I knew you might be involved in some BB-8 printing shenanigans with your printers farm 🙂
I need to learn more about my printer and discover the right settings so I can build my own as well.
I have managed to print two good parts so far although had a problem with them warping and lifting from the bed even though I used the helpers disks.
I might try changing bed temperature and nozzle and see what results I am going to get.

Kind regards,
Michal