Very Poor Layers

[inventabuild]

Terrible layers from my new J-head printing PLA at 190:

[img]http://imageshack.us/scaled/thumb/802/rw1a.jpg[/img]


I'm using the same settings in Repetier-Host, EEPROM and KISSlicer that I used when my Rostock Max was brand new giving me great prints. What could be causing such poor layers now?

[inventabuild]

By the way, here is my EEPROM settings:

[img]http://imageshack.us/scaled/thumb/109/qpc0.jpg[/img]

[img]http://imageshack.us/scaled/thumb/42/1dmh.jpg[/img]

[inventabuild]

ok, maybe this picture will help pinpoint the problem. This is the worst first layer I have ever seen and it is with my new J-head:

[img]http://imageshack.us/scaled/thumb/834/j34y.jpg[/img]

[Polygonhell]

The plastic is feeding inconsistently.
Could be a lot of things.
First thing to try is increase the temperature by say 10C.

[inventabuild]

Same terrible layers + 10 C (@ 200 C)

I noticed layer quality improves a little if I reduce the layer height from 0.2 mm to 0.15 mm, but when I go back to 0.2 mm layer height the layer quality really starts to deteriorate terribly again.

[Flateric]

Slipping extruder hob or perhaps stepper thermal resets?

[Flateric]

Also one other thing....your not printing directly onto your oynx bed are you?

[inventabuild]

I don't feel the filament slippling when I grab it with wetted fingers. It seems to feed consistently, so I'm guessing the extruder hob is not slipping.

How do I do stepper thermal resets?

I'm printing on elmers glue stick applied to the borosilicate (sp?) glass from seemecnc. It worked great when the R-max was new, but now ugly layers.

[Flateric]

Ok, was just checking.

You can take a razor blade to the glass to clean it back to fresh or use a solvent of some type. I think even really hot water will take off the elmers glue stick but doesn't work as well with UHU glue stick residue.

It really looks like something is causing your hotend to starve during the prints to me. Or somehow have inconsistent feeding.

[foshon]

Judging solely on the first layer pic, you could use a good bed levelling. The skirt and perimeter both change widths far too rapidly. Also, do not depend on the same settings working for all prints. Calibration will change, print quality will change with every filament you run, even temperature changes in the room you print in can and will have a noticeable affect on your print.

My heater cartridge had worked loose recently. I didn't see it, but I did start to notice odd hot end behaviour (temps would climb then drop or stall out on heating up). I finally realized what was going on when I looked at my hot end temp graph and saw huge spikes during the print. This all was after I had many, many successful prints one after the other. These are machines, if we could depend on machines to run themselves we'd all be at the beach. Well, not the gingers, they burn easy.

[RichW]

I would suggest trying a new nozzle, or soaking your nozzle in paint stripper/carb cleaner, etc.

[Eaglezsoar]

Don't you just hate it when something works it way out of the hole before the job is finished.

[foshon]

Ok here's a breakdown as I see it.

1. Together with 4a this area shows either a start of the extrude or a complete closure of the nozzle opening. with the lines of increasing width away from this area I would assume that as the nozzle got closer it finally closed it off completely.

2. This area of rippled layering, IMHO, is caused by extrusions being too wide. What happens is the nozzle drags across previously laid plastic, stretching and curling the leading edge. Basically the nozzle is ploughing a path through the plastic. You can see as the print goes further toward the thicker perimeter area the effect goes away. This is because the nozzle is further away from the bed and the extrusion width is slightly lower. The skirt and perimeter lines are thicker because there is pent up pressure from the extrusion being blocked for the previous bit of travel, gradually releasing more plastic until area 3. In the infill, you don't have this issue as badly because pressure is not relieved by retraction and the nozzle already has overcome the barrier produced by the blockage.

See how the infill starts on the high bed side?

See how thin the layer of plastic is under the number 1 corner, gradually getting thicker towards 2? You can see the little blobs, not ripples, just above the 2 in the picture. Those are caused by the hot nozzle shaving the plastic off. It stops shaving and starts rippling as soon as the nozzle is far enough away to extrude the appropriate amount of plastic. Further down yet you have the correct nozzle to bed height to extrusion rate and the print looks much better.

If you had let this continue it would have looked much better on the next layer and even better yet on the third, because the plastic is making up for your bed levelling issue. If it was my printer, I would level the bed and then do the full extruder calibration posted by Poly. I think you will see amazing results.

[Eaglezsoar]

Foshon, I didn't know you had it in you! An absolutely fine job in diagnosing and then explaining the problem.
You, my friend, are getting scary good! (I was going to say all that but you beat me to it! Yeah, right.)
All kidding aside, that was one good writeup.

[inventabuild]

foshon

Thanks for the suggestions.

The bed is leveled with the same accuracy as when I was getting beautiful prints with my Rostock Max when it was new.

Here is what the crappy layers look like if the build continues:

[img]http://imageshack.us/scaled/thumb/802/rw1a.jpg[/img]

so there is no improvement in the layers as the build continues. All the layers look like crap and just crack apart with the slightest of twisting on the vase. I appreciate the suggestion, but I really don't think this is a bed leveling issue.

[inventabuild]

When I knock the layer thickness down to 0.15mm the layers get somewhat better, but there is still some uneven plastic flow as can be seen on the right:

[img]http://imageshack.us/scaled/thumb/594/gio0.jpg[/img]

When I bring the layer thickness back up to 0.2mm I start getting the really crappy layers again:

[img]http://imageshack.us/scaled/thumb/834/j34y.jpg[/img]

Still trying to figure this out...looking for additional suggestions.

[foshon]

If that picture is off your printer you have levelling issues. Your bed level will change, you heat and cool it how many times a week? Just look what one season does to flat level ground. It's obvious that your not extruding properly as well, which is why I suggested Poly's guide found here:

http://forum.seemecnc.com/viewtopic.php?f=54&t=1163

Carl, Thanks! I've had three different printers over the years starting with the original Prusa. I raised my MendelMax all the way to a MM1.5+. I have had a ton of filament through these machines and seen hundreds of these same issues. You are correct, every day I learn something new here that helps to connect the dots as to why things fail.

[foshon]

I just saw the picture of the tube on your image shack, is that from the extruder? If so how on earth did you manage to melt a hole through the side of it? And why is it so burnt/dark on the OUTSIDE of the tube....

[inventabuild]

foshon,

This picture you saw

[img]http://imageshack.us/scaled/thumb/585/v6ie.jpg[/img]

is from my previous j-head hot end made in China. Not sure how the in-liner appears to have melted a hole in its side. I never turned the heat up beyond 230. Maybe I was printing the first layer too close to the glass which caused back pressure and the combination of heat and pressure caused the liner to melt / blow a hole in its side?

Anyway the blown in-liner from China is why I had to buy a new j-head. Just got a new one from makerfarm.com which is the one I'm using now:

http://www.makerfarm.com/index.php/j-he ... ament.html

Still looking for suggestions...

[foshon]

Did you take apart your current one like Rich suggested, judging by the state of the old one maybe there is similar internal damage. I have seen a torn up PTFE liner cause major extrusion issues.

BTW even in the .2 layer height pic you can see the perimeter line width changing. In a perfect world it wouldn't do that. When is the last time you did a four point calibration?

[inventabuild]

I am going to take apart the hot end to see if something similar like what happened to the old hot end might be happening to the new one.

I did several four point levels in the last 24 hours in an effort to solve the terrible layers problem I'm having.

Very frustrating...

[inventabuild]

By the way, Flateric mentioned "stepper thermal resets". What are those and how do I do them?

[foshon]

I believe he is referring to the thermal protection of the drive. If the drive chips overheat they trip for a moment until they cool down. In the end it results in a constant pulsing of the effected stepper. You can cure it by mounting a heat sink on the driver chip, pointing a fan at the board, or both.

[inventabuild]

How do I check the thermistor setting in the firmware? Specifically what is the line of code in the repetier.pde file that I check to see if I'm using the correct thermistor setting?

According to Colin at makerfarm.com I should have my thermistor set to #3

[626Pilot]

How do I check the thermistor setting in the firmware? Specifically what is the line of code in the repetier.pde file that I check to see if I'm using the correct thermistor setting?

According to Colin at makerfarm.com I should have my thermistor set to #3

That would be in Configuration.h. I would make sure that's set right, flash the new firmware, then redo the PID autotunes for both the hotend and the heated bed.

Did you calibrate your tower heights with a piece of paper under the hotend, or by mounting a depth gauge to the effector platform? Depth gauge is WAY better. That and clamping a framing square to each tower got my machine aligned pretty nice.

One thing to try if you have the pen holder is to tape a piece of paper to the heated bed. Put a pen in the holder and tighten it. Move the effector a few millimeters at a time, to various locations all around the bed. Does the pen stay level, or does it either lift up and draw thinner/no lines, or start to dig furrows in the paper? (That's why you only want to move it in very small increments.)

What are you using to secure your glass plate? I designed a clip in Sketchup and printed six of them to go around the plate and that helped. Since the Onyx heated bed will bow under heating, you have to have something to clamp the glass down. (I never thought those binder clips were quite good enough.)