gr5

Does the fan spin the correct direction? It should be blowing air into the head not sucking air away from it.

As illuminarti mentioned, you have to print about 3X slower than normal (and first layer 6x slower). Do your normally print 150mm/sec with .06 layers? If so then you should be fine. Note that this print will still come out fast as it is basically printing 200% flow (personally I would try something more manageable like .6mm wall).

The Arduino can measure only 10 bits from 0 to 5V so voltages that will stay between 0v and 5v can be measured directly to within 5v/1024 or about 5mv accuracy.

If that was a typo then I have totally different advice...

WTF? That's a typo, right? Seriously? If it really printed 7mm short then something is very very wrong. With heat off place a ruler on your bed. Move the test head to a postiion over the ruler and then move the test head 50mm. It should move 50mm. Not 48. Pronterface is a very useful tool for messing around - moving an axis 10mm at a time or whatever and for examining and changing the steps/mm values.

I'm not a bridging expert. You might know more about this than me. But I thought you might find this interesting: http://umforum.ultimaker.com/index.php?/topic/1872-some-calibration-photographs/?p=25304 Post #17.

I don't know if this helps.

rhyme - I don't think you followed nacho's links. There are different types of laywood and his is designed for smaller nozzles (finer wood particles). Are you sure you got the correct spare UM2 nozzle? Or did you get the UM1 nozzle?

If you are printing this cold (which is fine!) keep the speed around 20mm/sec.

When you put the UM on it's side it's pretty obvious. I think it might have been only one screw - maybe two. Anyway it's the screw that is CLEARLY holding the cover on the the metal box. We are talking the bottom covers, right? It's very simple. Compared to changing the battery in my watch which required me to watch two videos? This is amazingly simple.

This is begging for a plugin. The plugin could for example have one temp at the bottom and another temperature at the top and you could have the plugin linearly interpolate in between. I nominate Jonny!

I know someone who got an email the moment his UM2 was shipped. My email came 2 days after it was shipped. But I just decided to do a test - I went to DHL and put the "R" number in DHL and it showed my package! So try it.

You make convincing points. It *could* be backlash/play. Or it might be something else. play: So are all the belts tight enough to get at least a very low audible pitch? Like the bass string on a string Bass (or higher - higher pitch is fine also) and also it might be play in the head or nozzle. With the nozzle cold (or your fingers protected) push the nozzle around and see if there is any play before the rods start moving. The head could be loose or the bearings that attach the head to the rods could be loose. Assuming not play: Inner diameter circles are *OFTEN* smaller than desired. I think as you lay down the layer, the PLA pulls a bit like a rubber band and the circles are "pulled" in towards the center. Also if your model only has say 10 line segments on a circle - well that decagon is effectively now a smaller circle as each line segment cuts into the circle. Plus PLA shrinks. Combine those 3 properties and you get smaller circles. You can fix by increasing your temperature - a lot - try 240C but only for the first layer. Once the first layer is almost done put it back to what you had before. Also you can try raising your bed height by a tiny bit (loosen the 3 thumb screws by a half turn maybe). This will squish the bottom layer a bit more making it closer to the .4mm wide "strings" that Cura intended. Although I might not do this last thing as the infill bottom layer looks quite good. Third point: 25% overlap is for wimps. Go for 50%, 100%, 200%, 300%, lol. Personally I use 15% and it usually works fine for me. At least on blue tape it works fine - haven't printed a bottom layer hole on glass yet.

If you loosen both pulleys on either end of the rod, then the rod can slide around and the pulleys can slide inwards. If you push both pulleys out as far as they can go and make the rod flush with the edges and then tighten the pulleys then the rod will behave but you might get a little clicking. If you move one or both pulleys in away from the edge just a few mm then maybe can you compromise where the rod is free to slide a little bit but not enough to fall out one side and the pulley's stop clicking. These pulley's positions have 2 purposes: lining up with the belts and also holding the rod from falling out. On the UM1, the rods were held with end caps so on the UM1 you could position the pulleys where they belonged. On the UM2 you have a little less freedom but if it is designed right it shouldn't matter much.

Start by taking this cover off. I did it a few days ago. Was very easy to do: In the top right corner you can see the 2 gray ribbon cables Daid was talking about.

At 190C, if I want a good looking print, then I print 20mm/sec (very slow!). I have to print slow when I print this cold. On the other hand I *often* print at 240C. The plastic flows nicely! Like honey instead of toothpaste. And I can print nice and fast e.g. 100mm/sec is easy. At 190C I can often print at 50mm/sec but I'm afraid to leave it alone and walk away because under-extrusion is SOOO easy at this cold temp. So instead I just slow it down more so I can walk away without being nervous.

It's actually very easy. It's so easy you can do 10 different things and they will all work. So for example you could always print straight onto the glass with the bed at 70C with no gluestick and for small parts this will work pretty well. If you don't want to wait for 70C you can also print at cooler temperatures with or without the gluestick. If you find your part comes off too easily you can use gluestick. If you are printing something that is artwork that sits on a table and you don't care about the bottom, you don't have to use the sponge to get the glue smoother. The problem is: there are many choices and most of them work in most situations.

This is a little worrying but I have not damaged my glass yet. Plus you get 2 sides so you get 2 chances. Also glass is not very expensive - you can get it cut to size from your local glass manufacturer. Having said that - what is the most gentle and easiest is to print at 50C on glue stick for parts that don't warp too much and print on 70C glass plate if part is large (keeping it over 55C keeps the pla soft so it can't shrink/pull very hard). Then to remove the part - the most gentle way is to wait for it to cool and if you can't remove it easily with your fingers, then soak it in water for a few minutes and the glue will dissolve.

The bottom of the prints with glue seemed quite mirror finish I thought but maybe my memory sucks. Maybe because I used warm (50C) glass?

Are you talking about the spelling "Dhaid"? His name is actually "David" but he goes by Daid on the forum. You are welcome to call him David if that is easier. I call him "Daid" so that people who don't know his name don't get confused.

You *could* lower the bed by .05mm which might reduce the click/slips but I wouldn't bother. I actually like this "feature" (is it a bug?) for the first layer as I get a perfect first layer. The clicking occurs occasionally because there isn't room to put all that filament. But then... for the remaining layers... clicking is bad. I know my test showed you could go up to 103mm/sec .2mm layer at 230C but that is an unobstructed hole. If you are doing normal printing the pressure is probably a little higher as you are pushing the plastic down onto the layer below. So I would keep it under 50mm/sec. Plus maybe my extruder is slightly (20%?) stronger than yours? I doubt that but it's a possibility. Did you use the same UM blue filament that came with your UM? All filament colors (and manufacturers) have different viscosity at a given temperature. I know you think printing faster should be less plastic but when you speed up the feed rate it *also* speeds up the extruder "axis". Marlin does 4 axis linear printing - it prints straight 4 dimensional lines where the Extruder is the 4th dimension. Why it worked in the morning, but not the afternoon? I have no idea. Probably something about the bowden. Or the extruder stepper was too hot in the afternoon? I really don't know. It shouldn't make any difference.

Some day. It's a pretty easy test for anyone to try. I was going to try nylon last night but ran out of time. Possibly tonight but I have lots of things on the schedule for tonight.

Maybe the glass has a coating? I doubt it. Try heating your print bed back up to 75C and clean with a putty knife or cloth or something. - George

Please post a picture of the ".4mm gaps". This could be caused by many things. The most likely is something called backlash which has the tell-tale pattern of every other line is touching, and then a gap (touching/gap/touching/gap repeats across the top). There are many things that cause backlash - the easiest to check is belt tension - usually short belts: Here is a photo showing backlash and how it was fixed: http://umforum.ultimaker.com/index.php?/topic/1872-some-calibration-photographs/?p=14396 The very next post explains what causes the pattern.

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