gr5

Well it could also be filament that varies in diameter by quite a bit. But I guess it would have to vary by so much that you would see it visually (30% thinner or thicker). So try cleaning the Z screw - especially where it is inside the nut when the bed is within 5cm from the nozzle - in otherwords especially the top 1/3 of the z screw. Try cleaning it with wd-40 maybe and a rag and maybe a toothbrush or paint brush. Try to get it completely clean and then grease it back up - just one drop of grease should be fine. You use the green grease that came with it? I think any grease is fine. Does the platform rub anywhere else? check that the platform doesn't touch the spool holder - actually just remove the Damn spool holder - it causes more trouble than it's worth I think. check all around above/below the glass - the entire stage - check to see if it touches something that would make it bounce or jiggle or hang up. The z stepper controller might be overheating and causing it to be weaker than desired such that some of the microsteps are ignored until it gets to a full step. Maybe remove the bottom cover and put a fan blowing on the printer - it can print upside down just fine so tilt it over a bit so a window fan can blow some air under there for a test print.

Also the red arrow in the photo above seems to be pointing out some underextrusion. Typically when it is just one or two layers it is caused by a tangle on the filament spool.

I'm confused - is your "step" always the same distance from the print bed (indicating hardware error)? Or did the "step" (#2) move upwards to a new spot (indicating something more complicated interaction with the model)? If #2 then it could be a clockwise versus counterclockwise issue that shows up errors caused by backlash. This is common on flat surfaces but never on curved surfaces that move out and then back in or vice-versa.

There are a few really great gcode viewer programs. I recommend repetier host - it's very easy to use and you can highlight just one layer at a time and see the movement through that layer in another color. It's also free, and a quick small download.

The vertical holes - you need to exaggerate them by about .3 to .5mm to get the to be the right size. The walls may be too think to print. If they are close - just lie to Cura and tell it you have a .35 nozzle. In fact start with .3mm and if that shows walls in slice view then gradually increase until you find the moment where the walls disappear. .35 is pretty safe - the quality will be reasonable. But much smaller and the quality of the object will get quite bad so you could then buy a smaller nozzle. Stores for smaller nozzles very depending on country - what country are you in? Please update this in your profile.

You are getting over extrusion on some layers and under on others. It could be a bunch of things: 1) feeder issues that change but slow enough that a whole layer is under/over extruded. 2) Temp issues where the temp is oscillating chaotically by at least 20C. You get underextrsusion when cold and over when hot. 3) Z movement issues where the bed isn't moving a consistent distance so you get over extrusion when it doesn't move far enough and underextrusion when it moves too far. It really could be any of these 3 so you need to eliminate 2 of them. #2 is the easiest to eliminate - you can just look at the temp reading. The actual temp may be 10C off of the reading but if it's oscillating then the reading should do sudden jumps in temp by more than 1C - in other words it might read 210C and then 212C skipping over 211C. This should never happen and indicates the sensor path has a loose/bad connection (usually inside the sensor). #1 seems the least likely so if you can elminate temp issues that leaves Z issues. Something would be making the Z table misbehave - grab the bed with power off and slide it up firmly (grab with 2 hands near the back on either side). and down. repeat many times trying to feel for stickiness or something weird. when you say you "greased everything" I hope you only greased the Z screw and oiled the rest. If not remove any grease from the Z rods with wd40 and then re-oil them.

for what you are doing I expect the form printers to be worth it. For most people - probably not. I user my printer for more mechanical things and the variety of filaments I can use (nylon, flex filaments, pla, colors, durability, strength) just blows away the resin printers. For a while I believe it was only 4 drab colors - now there are more resins including a "tough" resin which seems to degrade quickly (over a few weeks) for some people. And a flexible resin. Working with those resin's just doesn't compare to the UM. But the resolution on the form1 and form2 is outstanding.

You could try drilling it out but I don't think there's much you can do after 1000 hours. What's an olsson block? yikes. It allows you to print with larger or smaller nozzles. Go here: 3dsolex.com

Not really - I mean it's a stepper motor so the magnets in it alternate easy/hard/easy/hard but there are 10 steps per millimeter so when pulling at any reasonable speed it just feels like a pleasant hum or vibration. If it feels like it sticks more suddenly then that's strange. Maybe the filament was ground down and has a "bite" out of it at that point? Maybe something strange is going on - maybe your motor isn't square and the shaft is tilted a bit - this can happen on some UM2's because there is a tiny hex nut under the motor *inside* the rear panel. If that is rotated wrong it pushes on the extruder stepper and tilts it and makes the filament twist as it goes through the bowden and causes problems. Or something else wrong with the extruder - maybe you should print the IrobertI feeder? It's a great feeder and one of it's features is you shouldn't have to buy and screws or hardware more than you already have in the feeder.

Ah - yes then you definitely need a new ptfe. About 10 euros from 3dsolex.

Just for fun - with power off - try moving the bed up and down by hand. To move it down is easy. To move it up grab on left and right side near the back of the bed and pull up firmly (the printer may lift off the table for a moment). Repeat this several times and try to feel for a regular resistance on each rotation or a noise that repeats once per rotation. Did your printer come with a tiny squeeze tube of green grease? If so consider cleaning the screw completely with wd40 - especially near the top - then grease it with about one or two pea-sized drops of grease.

Marlin won't let you print at 170C. If temp dips to 169C then the extruder will stop. So 180C is the lowest you can safely go. Or maybe 175C. Okay - you convinced me it's a Z problem. I know it looks "melty" but I think that's just a very glossy look. Or maybe it's just a glossy kind of filament. Those regular lines are too regular to be anything else. What happens is the Z axis isn't moving the entire .1mm or .2mm so you get over extrusion for a layer and it sticks out. I would contact support.ultimaker.com - your ticket will automatically go to fbrc8.com in memphis. Send them a link to this topic so they can see all the things you tried. Tell them gr5 says you need a complete new Z kit - vertical rods, vertical screw, z motor, z bearings and Z nut. It's a lot of parts but when you get this problem it could be any one of those. Actually because the problem is so regular I would just get a new Z nut and maybe a Z screw. The distance between those "bad layers" appears to be very consistent - possibly every 3mm (the screw I believe moves up 3mm for each rotation? Maybe? I forget - that was the UMO I think - the UM2 moves farther maybe? Anyway I think support.ultimaker.com is going to help you much faster than any other method at this point because you need to start swapping out Z parts. It's much easier to do than you might think.

On the center picture above - that red circle is showing "ringing". Which printer do you have? Please note this in your profile settings. Ringing happens because the printer is moving right-to-left in that part of the photo. When the printer hits that corner hard as the print head moves in the new direction, the old direction has stopped suddenly and it vibrates. The bumps get farther apart as the head speeds up. The best fix for this is usually to change filaments, change temperature or if you are patient, lower the acceleration to 1000 mm/sec/sec and that will go away. But you might then get other quality issues - especially at corners. 3000 mm/sec/sec might be good enough for you. If you print this part with a matte surface instead of glossy you won't be able to see any of these "ringing" issues or other "buckle" issues. Unfortunately there are not many companies who sell matt finish filaments. Woodfill and stonefill are two that come to mind.

All 6 pulleys per axis? Most people say they "tightened pulleys" but they only did 4 of them. It's the other 2 - the ones on the short belt that are the problem 90% of the time. You want them tight as hell - the tool should twist a bit.

Damn - why you order the nozzle bundle - you should be getting an olsson block if you are going to pay that much! Just get the ptfe from 3dsolex.com. Do you really have 6 months of printing already? I had the impression this machine was still new. ptfe parts may look fine but they can be very soft at 220C when they degrade. So it's hard to tell. Anyway seeing your photo of the cell phone case it looks like it has HUNDREDS of retractions each layer. Your problem *might* be a partially clogged nozzle - and this is good practice to find the exact right temperature for atomic pulls (you might want 85C or 95C just keep playing with that). HOWEVER, I still think your main problem is too many retractions. Just change the "minimum extrusion before retracting" in cura to 0.45 and reslice and I bet it won't grind. Did you ever try that? I posted this advice as the very first suggestion maybe? And it won't cost you any money!

Which printer um2go? Can you show an overhead shot please when it is at this initial position? I'm guessing the screws jiggled loose in shipping that are the set screws for the pulleys. Most likely the Y stepper motor pulley. Tighten the hell out of that - you might need to remove the cover to get at it or even remove the motor but I don't think that's necessary. To get through the stupid start up procedure I would just tell the printer it's homed fine - just keep continuing through those menus. You can relevel the build plate after this is fixed - just go to menu MAINTENANCE BUILDPLATE.

@bagell-orb - on aug 27 you posted that this bug was fixed. I think you can ignore this thread.

Did you use the supplied STL file? It had a VERY small cylindrical area that was getting no infill even though there was room for it. It could be that this bug was fixed recently.

Is it possible that your filament broke into 2 pieces in the bowden? This has been a common problem in the last few months with brittle filament. There is no ceramic part. There's the bowden which touches the white part which is teflon. Then that touches the heater block which is brass and is integrated with the nozzle. What country are you in? You can get the teflon part in USA at fbrc8.com (official utlimaker parts reseller) or my store (not official but cheaper) gr5.org/store. You can definitely drill out the white teflon part. I have done this. You want a 1/8" drill bit. These teflon parts are not expensive though. By several. The newer UM2 printers come with some spare ones. It's possible that you never get the filament past the white part or the next part but it seems unlikely. Is your 3rd fan working in the back? If not this would cause the symptoms you see - the PLA softens due to retraction, enters cracks above and below the white teflon part. Then they cool enough to get stuck there and now the filament won't go up or down.

cloakfiend - I agree that heat can do this and is probably axislab's problem but in this other guys case he has a much more extreme case of varying layer thickness - by what looks like a factor of 2X (double extruding). I think this is more likely a Z issue but I still want to rule out that he set layer height to .4mm and it is in fact a heat issue like you say.

I'm not certain that's a good pull. It should be shaped like the inside of the nozzle exactly. I think this pull is leaving behind lots of filament. Try 5C cooler repeatedly until the pull doesn't work and then go up 5C. It should be about 5 -10 pounds pulling force to get it out. Having said that, there is another possible cause for gound-flat filament - and that is retractions. You didn't mention if your part was retraction heavy. You can look at the failed layer in Cura slice view and each vertical blue line is a retraction. More than 10 retractions per minute might be enough. There is a 3rd cause for ground-flat filament and that is heat - if the weather is hot and your extruder motor is hot the filament can soften. I doubt this is the issue as I assume the weather is cool in the UK.

If it *is* a Z problem you might be able to prove it by printing something exactly 10mm tall and then measuring it after it's done. It looks like the bed might not be moving down occasionally. Some recent boards have a problem with the driver where uses too much current and it overheats and there is a simple fix to reduce the current - just edit the gcode file and add this line to it: M907 Z1000 That lowers the max Z current to 1000ma (I think the default is 1300).

@joseph-kim - what's your layer height? It looks like .4mm? What's your nozzle diameter? Is it the standard .4mm or did you change nozzles? Please post *all* your settings. You should be able to "save profile" to an ini file and post that.

>I believe the ceramic in the hot end has some >sort of bump on it which stops retracted filament from going through again. You would have to do about 20mm retraction for that to happen - I strongly doubt this is an issue. The typical 4.5mm retraction simply reduces pressure and doesn't actually retract down at the tip of the hot end. Most of the motion is happening in the bowden only.

If you have a UM2 and the extruder is skipping backwards it usually jsut means you are printing too cold or too hot but there are a dozen other causes. Here are top recommended speeds for .2mm layers (twice as fast for .1mm layers): 20mm/sec at 200C 30mm/sec at 210C 40mm/sec at 225C 50mm/sec at 240C The printer can do double these speeds but with huge difficulty and usually with a loss in part quality due to underextrusion. Different colors print best at quite different temperatures and due to imperfect temp sensors, some printers print 10C cool so use these values as an initial starting guideline and if you are still underextruding try raising the temp. But don't go over 240C with PLA.