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Here are examples where the bed is too close to the nozzle (0mm off the bed) to too far apart (.35mm example where it completely fails similar to your print). I prefer a skirt like the blue filament above where it is well squished and sticks well. The more squished it is the better it sticks. On rare occasions I can't have even .1mm of brim on the part so I can't squish it at all for dimensional reasons - so parts fit. In those rare cases I am more for the red line amount of thickness.

You aren't squishing your bottom layer enough. There's "level" and then there's "level". The latest leveling procedure with the card makes it so that when the z=0.3mm the nozzle is 0.3mm off the glass and that is where it prints the bottom level (by default in Cura anyway) and that is how much filament is extruded (enough to make a bottom layer .3mm thick). This works great when you need dimensionally PERFECT parts - where the absolute bottom layer can't have a skirt - not even .1mm of skirt (not visible without a microscope or micrometer). However this results in parts that don't stick well. So instead I level things a little lower (a lot lower). This way the bottom layer is extruding pancake-like brim or skirt. To achieve this - anytime after doing the leveling procedure (I rarely run it anymore) just adjust the 3 screws counter clockwise about a half turn. The next time you print something make sure the brim or skirt is squished flatter than nominal. It will stick much better.

@IRobertI - It's like no one can hear you. I can hear you. @p-trax why would you set the filament diameter in cura and not on the printer itself?

You can either modify the endstop or you can modify the part that hits the endstop. I found modifying the part that hits the endstop easier.

Yes. new topic please. Put a summary at the top of what you are worried about at the moment (photos of the latest banding) and then post a link to it from this topic so we can all go over there and subscribe to it (or not). I think your over/under extrusion theory has merit and you should check the nozzle temperature for a few minutes while it's printing to see if it is oscillating. You may need to adjust your PID values on your nozzle.

The head uses a thermocouple and then it goes through a circuit board that translates the nozzle temp to a voltage from 0 to 5V where 0v=0C and 5V=500C. With an error of 15% a temp reading of 210C would actually be 180C. That's significant. You can print PLA at 180-240C but I wouldn't go outside that. So until you fix this try printing more like 240C (210C actual).

The vibrations I believe are mostly from the belts which can stretch a bit like a rubber band so I don't think that would help. Putting a box of sand with interior baffles on the print head should help but then you will have to lower the acceleration also most likely. Some newer boards limit "true jerk" and don't have these problems such as the tinyG controller board.

This is not hard to do. What cad software are you using? You want relatively large threads like this part: http://www.thingiverse.com/thing:925556

There's no easy answer. 1) If you only care about 2 of the 4 sides then print with one of those sides facing down and the other facing up. You need of course to adjust leveling 10X better than normal so don't use the normal leveling procedure and instead adjust by turning the 3 leveling screws equal amounts up or down until the skirt laid down is exactly .4mm wide (assuming your nozzle is a .4mm nozzle). 2) You could print the part in a few pieces and glue them together or have them press fit together. 3) You can measure the error accurately and then change the shape in cad to account for this. This works much better than you would think. Basically remove a few layers off the bottom of each of those protruding cylinders. It sounds crazy but it works pretty well if you are printing consistently. 4) You can get rid of that stringing on the sides (but not the bottoms) of the cylinders by making sure fan is at 100% well before it gets to those "bumps". Also lower printing temp by 10C or 20C to around 190C or 200C and also consider a different filament. This filament appears to be one of the softer formulations that "string" more than average.

The AREF pin is used by the ADC on the arduino and is the reference for value 1023. I'm thinking instead of being at 5V for some reason it is closer to 4.5V.

Did you ever check the analog reference? It's the AREF pin. The top left pin here:

The firmware (not cura) does homing. Cura just writes out a simple gcode to tell the printer to home. The printer's firmware is supposed to know which direction to move the axis to hit the homing limit switch and which switch goes with which axis home position and once homing is complete the firmware should know the position of home: (0,0) on an ultimaker. Something like (-100, -100) on a delta printer typically.

very strange. Maybe it reboots on temperature to nozzle? Try turning on only nozzle heat - see if it reboots for that also. Do you have the right power supply? Possibly using um2go supply on um2ext?

Start with voltages. Locate 24V and power circuit that steps down voltage to arduino.

The Z screw is triple helix. So it goes down 3 "bumps" for every rotation. So it seems most likely that this is a coincidence. For example if the Z screw was warped in the shape of a "C" I would expect patterns to repeat once every 3 bumps on the z screw - not every bump. But maybe I didn't think of something.

Yes. That it occurs at the same height for the same model doesn't rule out layer adhesion. If it occurs at the same heights but for completely unrelated models (say a simple cylinder then yes, it's probably a Z axis issus (warped Z screw, z screw with dirt or dust at those spots, bad Z rods). But I still think it's bad layer adhesion because HIPS has a higher glass temp than PLA (about 100C versus about 60C) and with all higher-glass-temp materials it's easy to get bad layer adhesion that looks exactly like this. Usually turning off the fan fixes layer adhesion issues but then you get ugly overhangs.

There are definitely quite a few extra signals. I'm not sure which ones are extra but the ones on EXP2 look more likely as some of the ones on EXP1 might be used dual purpose. So double check that. That connector you link to is a .1 inch spacing which is almost certainly correct. So I can't actually verify anything but I think you are on the right track. Edit: oops - exp1 and exp2 I guess are for the display and sdcard reader. But I'm sure there are more signals available somewhere.

The plastics we use (PLA, Nylon, ABS) are non-newtonian in that they stick to themselves. Like, hmm, honey? More sticky. Like mucus or snot. So it's hard to get droplets. When water comes out of a faucet at very slow speeds it breaks up into droplets. Not so easy with plastics which stick to themselves much more. You'd need to mix it with pressurized air or something and spray it straight up and have it fall back down maybe. Something like that.

Even better - once you level it once don't re-run the procedure and instead just turn the knobs until you get perfect bottom layer. Here's my bottom layer guide: Here are examples where the bed is too close to the nozzle (0mm off the bed) to too far apart (.35mm example where it completely fails similar to your print). I prefer a skirt like the blue filament above where it is well squished and sticks well. The more squished it is the better it sticks. On rare occasions I can't have even .1mm of brim on the part so I can't squish it at all for dimensional reasons - so parts fit. In those rare cases I am more for the red line amount of thickness.

It may be that cura won't be able to connect until you fix the MAXTEMP problem.

You have a display. That's great. That means you don't have to print through USB (which is more difficult). MAXTEMP is probably the most serious issue here. Something is wrong with the temp sensor. There should be a green terminal connector on top of the print head that has 2 screws and 2 wires going to it. Check that the wires aren't loose. The temp sensor is a bit complicated - there is a thermocouple inside the print head. The 2 wires for that go up to the tiny circuit board on the print head and get converted to a voltage. I hope you are good with electric circuits or there is someone you know who can fix very simple circuits. The output voltage of this tiny board is 0V to 5V where 0V=0C and 5V = 500C and linear in between. So at room temperature it should be about 200mv. If that is at the correct voltage then it probably is not connected properly on the circuit board underneath the printer.

@dbotos - I'm a bit confused. Didn't you already prove that the correct voltage arrives at the ADC? But that the ADC reads back the wrong value? If that's true then it's definitely a hardware issue (bad arduino). I have the same thing - UMO with the HBK. The firmware works fine for me.

that's fantastic news. It's probably just dirt on the Z screw. Clean it completely with WD40, dry it and then put on some fresh grease (just a pea sized drop).

1.5 is much thicker than 1mm so that should be good with a .4mm nozzle. Make sure nozzle is set to .4mm and shell is set to a multiple of .4 (such as .4 or .8mm). If there is no "red" in xray view in cura and it still isn't printing these walls (move through the layers with the slider to be sure and give it time to draw the "current" selected layer) then you are probably wrong about the 1.5mm wall thickness.

This plug looks pretty simple - consider trying tinkercad and do it yourself.