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If you *do* use blue tape, after placing down the tape you must wash it with a small amount of isopropyl alcohol to remove the waxy surface. I agree with Robert that "not using tape" is probably better.

I have tried tape on glass on the UM2 and it works just fine. This is caused because of shrinking. When something like the bottom portion of the spider's abdomen is printed, as the upper layers are pulled inwards, the sides go up and the head hits it as it tries to print. There are 2 solutions. You may need to do both solutions: 1) Heat. Keep the bed near the glass temperature of the plastic so that it doesn't shrink so much (70C for PLA, 100C for ABS). This might be sufficient. You might want to also reduce the fans to 50% and add a box over the top of the machine or a piece of plastic covering the front of the machine so that the air near the spider stays warm but hopefully this is not necessary. 2) Support. Usually support holds the parts *up*. In your case you need to hold the part *down*. I recommend meshmixer and add support in the places where the print head was hitting the spider. This solution alone is also probably enough to fix your problem. More on meshmixer: http://www.extrudable.me/2013/12/28/meshmixer-2-0-best-newcomer-in-a-supporting-role/ pay particular attention to how to rotate your part in the "annoyances & limitaions" section and also note that there is a small error where he set layer height to "0.5" mm and it should be the layer height you print at e.g. .2 or .1mm.

If the Right X limit switch shorted then Marlin (the firmware) refuses to move the X axis to the right and will ignore all those moves. When you tell it to move left it will move left. When you tell it to move right it won't because it thinks the head hit the switch (even though it is nowhere near it). The symptoms are similar to but different from the DIR signal broken. When the DIR signal is broken, if you tell the head to move it always moves, but always in the same direction. Very very similar symptom but slightly different. So if you tell the head to move 10mm left, 10mm right, 10mm left, 10mm right then DIR problem: head moves 40mm in one direction (4 10mm moves) Limit problem: head moves 20mm in one direction (2 10mm moves) edit: Changed "Y" to "X" axis. The same problem can occur for any of x,y or z axes if there is a bad signal.

>I mean 0.05 mm Wow. I can't even measure that with my calipers. I think you can get pretty close to .05mm but it will probably require tweaking the model. The biggest error at some point is going to be shrinking related (unless you buy PLA45). Because the shrinking is happening as you print it is complicated and changes the shape of the print in a complicated manner. Similarly with play (backlash). It matters which direction the head approaches from. In general, to get .05mm accuracy you will need to print everything twice. The first time you print it "close" to spec. Then you get out your calipers, measure all the errors and adjust in CAD and then print again. That's really the only way I know to do this. After a while you get good at predicting how much an error will be and your first print will be very very close. For example my parts are usually a little thicker on the bottom 3 or so layers. Some people call that the "elephants foot". You can measure this and add a chamfer (correct word?) in CAD and end up with a perfectly vertical part with no elephants foot. Other manufacturing processes have the same issues. For example injection molding has worse problems. For example if you want a 90 degree corner you have to make the mold have a slightly different angle and then when it shrinks it ends up being 90 degrees. Also the entire mold has to be about .3% larger than final part for injection molded PLA.

@tonycstech I feel like you don't understand Illuminarti's point. Look at a few layers in layer view and look at about how far the moves are when you *don't* want retractoin and then look at how far the head moves (approximately) for those where you *do* want retraction. If you are lucky - and usually - most of the ones where you don't want retraction are very short - maybe less than 1mm or maybe less than 5mm. And most of the ones where you *do* want retraction span a large gap. Maybe 10mm and maybe the moves are farther than the gap - maybe 15mm. Then pick a threshold between these values - say 9mm and make that the "minimum distance". That way moves less than 9mm will not do retraction and moves longer than 9mm will do retraction. That is Illuminarti's point. I think he and I are getting frustrated because you don't seem to understand that. We thought if you simply looked at the settings you would understand the point. But maybe we are both wrong. Maybe you already understand this and maybe there is no threshold that will work for your part. I just know that this usually works for me. I agree - it would be nice if there was more control. Daid who wrote Cura likes to keep the options as simple as possible and strongly resists more options in the GUI. There are already 5 or so options related to retraction.

By the way - another way to measure this is to print a wall where the lower part of the wall is approached from one side of the bed and the upper half of the wall is approached from the other side of the bed. Very similar to your test but you end up with a part where you can use calipers. One way to do this is to print two square columns where one of the columns stops half way up and hope cura slices it in such a way that when it switches from the short column to the tall column it starts on the edge closest to the other column. You can force cura to do this by messing with thickness of skin (2 versus 3 passes or .8mm versus 1.2mm thick).

Very cool test. I haven't measured my backlash (aka play) but .1mm sounds about right to me - but again - I don't know. Usually most of the backlash is in the short belt which is also the easier belt to tighten. If you tighten the long belts too much you will increase friction so much that you will start to increase backlash again (bizarre but true!). So as you are tightening the belts, push the head around to make sure the friction doesn't increase drastically. There is a nice video that explains how tight to make the long belts based on pitch made by Erik himself (one of the founders):

It's like a wooden guitar. When you put new strings on it they stretch a little and you have to retune the guitar before every song. After a day you only have to retune once per day. After a month - if you don't play it - it keeps it's tuning for months. Similarly for the bed - a brand new Ultimaker printer needs leveling more often. The frame itself is fine - I don't think that needs any strengthening - it's just those 2 support arms and how they attach to the vertical rods. Plus you get very good at levelling after a while. Like other's have said - you can level while it is printing the skirt. I've done that also. And most things don't have a super critical bottom layer height so for most things levelling isn't quite as crucial.

I strongly suspect this is a USB issue. I would spend the $10 and get a USB hub to buffer the signal just to see if that helps. Or try a different computer and maybe a more expensive (and short) USB cable. Many UM1 and UM2 users have had issues that sound exactly like this (randomly stops printing for no apparent reason and just sits there making an ugly blob) and fixed it by changing one of those 3 things (cable, usb buffer/hub, computer).

It's no big deal as long as you have access to soap and water to clean your fingers after.

The um2 is very tough. Don't worry so much. Before powering on I recommend you push the black print head around. If it doesn't move then look for cable ties holding it in place. Pretty much all the servos and mechanism is designed to run uncontrolled and slam into the end and nothing should get damaged (other than anything you might stick in there like your hand).

I have no idea but hopefully Daid will read this post now that you posted more details. Do you have access to a second computer that you could try?

Could it be that the motor is turning but the piece that touches the filament is not turning? There is a tiny set screw there - maybe it is loose?

I usually only have to level once per day now but when it was newer I had to level every few hours. If the first layer is .3mm then you don't have to get it perfect but if you are printing say smart phone covers you will want the first layer perfect. I have only levelled my UM2 on day one (a few times) and haven't touched levelling since!

After you do that if Cura still can't connect here are few things to try: 1) When you connect or disconnect the USB, windows should make a two note sound. The pitch goes up when you connect USB and down (second note lower) when you disconnect. That should happen even without the arduino driver. 2) If that is working, try running device manager. I have windows 8.0 with "winShell" so I'm not sure how you do it on win8.1. I just hit windows key and type "device manager" and after a few seconds windows finds it for me and I click it. If the arduino driver is working, the Arduino (which is inside the UM2) will show up in the "com ports" section. If it isn't working it will show up in the "USB" section and with a yellow caution/error symbol. You know it's the arduino because if you unplug the USB it goes away and when you plug it back in it comes back.

Like you said, when you install Cura at some point it runs a separate installer that installs the Arduino driver. You can instead install the arduino IDE which also installs the arduino driver: http://arduino.cc/en/main/software I recommend the 1.0.5 windows installer.

The UM2 is still relatively new and UM hasn't published all the details of how to build your own, yet (they plan to do this later this year). So I don't know what the temp sensor is. I guess one could probably figure it out by looking in the comments in configuration.h here: https://github.com/Ultimaker/SecretMarlin Let us know if you figure it out. Oh - also I deleted your other thread/topic for you.

What is the maximum retraction speed you have tried so far? And what is the speed you use now?

@vinay - everything sounds mostly normal except the extruder is skipping back during your print. So first of all the sounds in the first video sound fine. I don't see the stepper turning. Is it? Obviously it is supposed to turn. But the sounds it makes are normal. In the second video it looks like you are printing fine. I can hear occasional retraction, but I also hear when the extruder motor skips backwards. You should look at it - you should have videoed the stepper then but I'm pretty sure I know what is happening. What speed/temp/layer height are you printing at? You should either print thinner layers, print slower, or higher temp because your extruder stepper is slipping occasionally. The extruder stepper is designed to skip backwards if the pressure gets too high in the print head. This is usually caused by printing too much volume of PLA too fast.

This is a strange problem. I'll throw out some possibilities: 1) Some materials have lower resistance at higher temps and some have higher resistance. If your HB has lower resistance, then maybe when it gets hot enough it is using too much power from your power supply. When the bed starts failing - check your voltage at the power supply. Or maybe the power supply simply heats up and gets overloaded. So again, check the output power at the power supply. I think this is the most likely problem - the power supply. It could even be turning on and off 5 times per second. 2) Bad solder joint - when it gets hot, it expands and causes an open. This could be on the UM PCB, or anywhere in between. I know you "checked the voltage" and said it oscillates a few times per second but where did you check? Maybe there is a bad cable? Check *at* the mosfet and if it's fine there but bad at the board do a search to find the intermittent open. 3) PWM mode - I know you said you PIDTEMPBED is commented out in configuration.h but what you describe sounds amazingly close to PWM mode. I would double check configuration.h to see if it is *not* comment out somewhere else. And then rebuild using ginge builder and re-upload. It sounds very suspicious to me. Maybe you accidentally uploaded default firmware with Cura recently?

No. It means one of the days that week. No later than Feb 7. And DHL apparently works weekends so I would expect you would get it by Feb 10 but I don't know much about shipping by DHL to hong kong.

lol! :lol: :lol: :lol:

By the way - please explain how I would grind the filament to dust if I *wanted* to do this (more that I want to avoid!). Do I make it tighter or looser to make it grind more? Right now it is as it came from factory which is *almost* all the way loose (white square tension indicator at the top).

Well I'm not certain you've got a thin layer of gunk inside your nozzle but that seems most likely. If it were me I would just print at a slow speed but if you really want to see if cleaning out the nozzle helps... Very carefully. See? I'm so helpful I haven't done it yet. The nozzle is integrated with the heat chamber so you'll also have to remove the heater and thermocouple. Better to do it now before the whole thing is fused I suppose. Read post #18 and look at picture: http://umforum.ultimaker.com/index.php?/topic/3037-ultimaker-2-printing-issue/?p=22333 And post #8 has a very important note: http://umforum.ultimaker.com/index.php?/topic/3971-more-clogging-issues/?p=31744 More notes: http://umforum.ultimaker.com/index.php?/topic/3749-clogged-um2/?p=30178

Very nice print by the way. I hope you end up painting it.