gr5

If this is only happening on the first layer than I wouldn't worry about it. It just means you are slightly closer to the bed than desired. If this is happening on subsequent layers then you need to print either slower or hotter or with thinner layers. What is your: layer height, print speed, temperature. And are you printing PLA? For PLA cut the speeds in half from the table here: http://umforum.ultimaker.com/index.php?/topic/3418-um2-extrusion-rates/

There is a "direction" signal that runs from the arduino to the stepper driver. If that pin has a cold solder joint it could move the Z axis in the opposite of intended direction occasionally. So it *could* be hardware.

On top of the print head there is a little red clip. That clip holds up something which is part of a larger (but still small) part. *that* part - I don't know what it is called. Let's call it the "bowden holder". The "Bowden holder" works such that you have to push down on the outer ring of the bowden holder to remove the bowden. When you push down on the bowden holder it retracts (sucks in) 4 tiny metal blades. After you remove the bowden tube you can look down into the "bowden holder" and possibly see the blades. Those blades dig into the bowden to get their grip - to "hold the bowden". It's easy to break one or more of those blades. Either bend the blades backwards or they can fall out. Also it's easy to scrape the bowden tube so that it is now smaller diameter. This scraping is almost invisible.

Very strange! Sounds like a software bug to me. It would be nice if you knew how to duplicate it (with your fingers on the power button of course!)

Before printing anything - look at it in layer view carefully. Go up and down the layers many times until you are sure there are no mistakes. I printed a simple box today which had a slicing problem (easily fixed) but it was not obvious the first time I looked at it in slice view. Fortunately I looked at it several times and noticed the problem before I printed it.

So the thing to do next is to cut power, hookup the ohmmeter to those wires at the PCB (with the cable disconnected from the pcb) and then push the head around the bed into the 4 corners to see if there is an open in one of the corners - that's what I'm expecting as you are stressing the wire in different directions as you move the head around. It's okay to push the head around with your hand.

Love it! One tiny change - for step one - simply turn off power and push the head to wherever you want it. The nice thing about this is that you are less likely to damage the bowden tube this way.

Did you look inside this gray part? Can you see the blades? Either this part is bad or the bowden tube is scraped slightly. It's difficult to see visually. You could check maybe with calipers. Personally I would ask UM support to replace both parts and while waiting I would cut 10mm off the end of the bowden and hope that's enough. These parts do not cost much money so get them replaced before your warranty runs out. Another thought: Try loosening the 4 thumb screws 5 or 10 full turns. Then push the bowden all the way down. Then tighten the 4 thumb screws. See if this helps. If it's not enough, maybe 20 full turns?

The extruder *seems* wimpier on the UM2 than the UM Original. But I could be wrong. It seems to only be able to supply half the pressure. Or maybe as Illuminarti suggests, it's because the melt chamber is so tiny that you need higher temps to print the same volume of material than the UM Original. I think it's the feeder. Anyway, so to print at higher speeds you need higher temps. In general I just print slower on my UM2 than my UM Original. About half the speed. And I get great results. When you have two printers you can afford to be more patient.

I couldn't see the pics either. You can post the pictures on this forum if you want. On the top left of this page, click "gallery", then the upload button. Then after your pics are all uploaded, make a post and click on the "my media" next to the smiley face.

It depends how you define "decent". For most prints I don't care how it looks so I print at 100mm/sec and 240C. For some prints I care more and print slower. In general, the slower you print, the better the quality. Mostly because your extrusion rate is more consistent and the pressure in the print head is lower. Also I prefer the quality of .2mm layers over .1mm layers. So maybe I'm the wrong person to answer this question, lol.

Dans les paramètres avancés, vous pouvez régler la distance entre le support et la voiture (distance Z). Je vous recommande d'augmenter la. Pour quelque chose comme cette voiture, je voudrais utiliser un dremel pour retirer le support. Habituellement, je tente d'imprimer sans soutien, mais cette voiture a besoin et c'est bien parce que le fond de la prise en charge peut être laid. Parfois, je dessine mon propre support. Pour cette voiture je conçois une forme de boîte creuse sous la voiture, donc il ya très peu à enlever.

Because Marlin plans moves 10 or 20 line segments ahead of time, changing the feedrate (not flowrate. feedrate.) can take a few seconds to actually make a difference. The same might be true of flowrate. I don't know if this is true or not. Just warning you.

SLS is far superior to SLA or FDM - you don't have to worry about overhangs and support and shrinkage is an issue but not nearly so much. Like injection molding, with FDM you need to design for the technology - while you are designing the part you often have to worry - "what's going to happen when this shrinks? What will warp?" and "how do I support this?" and so on. SLA has a much much finer resolution but still has support issues. And with injection molding there are also tons of issues - you might have to design a curve tighter or more loose in the mold so that when it cools it changes shape to the desired shape. You can't have some sections too skinny or the plastic can't get in there and so on. SLS is great but you really need a clean room, bunny suits, and so on and it's only economical if you print 100 parts at a time. And it's still covered by patents I believe. So I don't think we will have the "perfect" 3d printer in the next 5 years. Having said all that I love my UM printers. I love being able to design something and print it up and use it right away. I like the ability to customize and so on. It's just fun. But I care about functionality - not art. So we probably care about different things. The UM2 can print beautiful things but... well... it's complicated.

That's normal. It's difficult to print overhangs as you are sort of asking to print in thin air and the layer you are printing is just barely touching the layer below so it can dip down a bit and cause minor ugliness. There's lots of solutions such as never print overhangs (lol - easier said than done). For example cut the frog cad model in half, print each half and glue together. Or sometimes, for example on models of humans you can just lean them back a bit so their chin and nose don't overhang quite so steeply.

So typically if you push the print head around by hand to the 4 corners it will fail in one of them (if you have an intermittent connection).

Sure but they won't be in until Friday. I haven't seen how the UM2 temp sensor works but in the UM Original it's a themocouple (not a thermistor) and there is a tiny board with a chip in the head that converts the thermocouple voltage to a voltage between 0 and 5V to indicate temps of 0 and 500C. Linearly. I assumed the UM2 is the same. I get temp errors when the cable running from the head to the PCB has an open. The print bed I'm sure has a thermistor as it doesn't get as hot as the nozzle and so thermistors are more appropriate here. Does the bed heater work? Go to advanced menu and mess with the build plate temp.

PLA shrinks as it cools. Longer pieces shrink more. The absolute minimum shrinkage will be .3% so you could I suppose recalibrate all the X,Y steps/mm to account for this but you will find it won't work. It might work if you only print cubes or cuboids (box like shapes) but if you print for example two boxes connected by a skinny bridge, the bridge won't be strong enough to pull the side boxes together and you will get less shrinkage at the bridge. In general I just guess the shrinkage and compensate in the design. If it's a critical dimension I just print the part twice. After printing it the first time I measure everything and then compensate the model by the amount that the result was off by. For example if a surface is .5mm too far towards the center I move it out by .5mm.

I was reading a paper about PLA this morning and found this graph. .02% is 200ppm which on the graph looks like about 15/5 or 3% humidity. The graph is on page 561 of this document: http://www.jimluntllc.com/pdfs/polylactic_acid_technology.pdf So it looks like 3% humidity is your goal.

>I thought the problem was, that Cura can't know the Acceleration / Jerk settings in the firmware? It assumes you have default acceleration/jerk settings. It sounds like it was quite a bit of work but seems to work much better now.

Do you have a UM Original or UM 2?

This is a lot in one post. You might have to re-ask some of your questions and you might have to supply pictures to explain better. 1) very hot motors is normal 2) You need to show picture, sorry. 3) Go to the tune menu. Once you hit "print" you can immediately go to tune and change settings before it actually starts printing. After you exit tune menu it will start printing if up to temp. While printing you can go to tune menu and mess with other settings live (such as retraction distance! couldn't do that on a UM original!). 4) Water works fine. I usually use glass cleaner and a rag as glass cleaner evaporates faster. 5) If machine has been hot for a while I usually manually extrude before I start the print. It's buried in advance menus somewhere. "move material" maybe?

It may take 5 minutes of extruding before most of the ABS is out. It is very difficult to switch from ABS to PLA - you have to clean the print head good.

This is very unlikely a firmware issue. It is a common problem to occur on Ultimakers that are several months to a few years old. The quick fix is to switch to the other temp cable. There are 2 cables - one for each nozzle (in case you get the dual nozzle upgrade). For now - just try the other cable (you have to switch both at the print head and also underneath the printer). UM doesn't properly crimp the wires in the cable at the connector and instead solders them. This is not good because the solder makes the cable stiffer and bending (during movement during printing) can cause these tiny strands to break - one at a time. Switching to the other cable should help for a few more months. Also make sure you do as good a strain relief as possible. When the second cable breaks you can replace them both.

regarding #1. Illuminarti did a little experiment and if I remember right, the ratio of infill speed to printing speed is the same for the bottom layer. So for example if print speed is 100mm/sec and infill at 150mm/sec and bottom layer is 10mm/sec then the bottom layer infill will be at 15mm/sec. This is kind of silly. In fact the infill speed should only affect the cross hatch open infill (e.g. when 20% infill) and should not affect top and bottom infill. But that's how it is right now.