gr5

This seems like a pretty advanced project for a beginner. Even ultimaker didn't tackle it until the UM3. Also the UM2 maintains it's level for months (forever?) so I'm not sure how useful this would be. Good luck though!

It depends on how low quality you are willing to go and how much money you are willing to spend. For me, it would probably be the prusa i3. But maybe that's too expensive for you. I wouldn't want quality any worse than that machine and I think it's the best deal for that level of quality. If you want to spend a bit more then of course go for the UMO. Even better, get a used printer. The price is lower and the quality is better.

As long as it pauses then you can just change the filament manually. I don't use that auto change filament - it's easier to just use "the wedge" (on youmagine) and remove and feed by hand. You also get to feel the resistance and if there is a tiny (almost invisible) thread of filament in the bowden jamming the filament then you will notice during this step.

Sounds interesting! Please keep us updated.

It's not too close. If it's too close it still extrudes but so thin it's almost transparent. It *is* possible it's to *far* from the glass. That's basically what it looks like when it's too far but I don't understand how the outer trace is the correct distance yet the infill is the wrong distance. Seems more likely it just stopped extruding after it finished the outside. The filament may have ground up at the feeder and now it can't extrude at all. But the cause might several of the possibilities above. For example your gnurled teeth are no longer sharp or your teflon isolator has softened. Either of those things or other's above will make sense that some filaments are fine and some aren't. But the ones that are "fine" are probably just barely fine. For example UM gray might be more viscous and require 20% more pressure to get through the nozzle.

You can heat it in an oven but you have to stay below the softening temp of PVA. I measured this but lost my notes so I'll have to measure it again some day. But I was surprised at how it softens at a very low temperature similar to PLA. I remember it was within 10C the same as PLA but I forget if it was higher or lower. PLA softens around 55C. I strongly doubt PVA is that low so it's probably around 60C. But could be 50C. Anyway I would set my oven temp to 60C and leave it in there for many hours. When drying filament out that can handle 100C (boiling temp for water) it dries out very fast. But 60C is going to take much longer! Don't use a gas oven as that produces a lot of moisture and I'm guessing it won't dry as well in a gas oven (not certain - maybe it somehow works anyway?).

> . And making an overflat first layer creates elephant foot and accuracy issues. True. I don't call it elephant foot - I call it mini-brim but we are talking about the same thing. That's the tradeoff between sticking extra well and having no mini-brim.

If it's 1 ohm when disconnected, then yes. It is damaged. Get a new one. I sell them for $28 in my store: http://thegr5store.com/store/index.php/temp-sensor.html But your temp sensor is hopefully still under warranty since it never worked.

I disagree with Neo about nozzle being too close. The closer the nozzle the better the material sticks to the glass. But Neo's other advice is good. I have a video for anyone else who is looking into this same problem. It's long but I spent many hours editing it down to the essentials. My parts always stick to the glass. So well that occasionally the parts rips off a tiny piece of glass.

One more thing - I think this particular print would benefit from a larger nozzle. Try a 0.6mm nozzle.

I would cut this part small and just print wing tips with a few hexagons as a test piece and do lots of tests. Brassfill is difficult to print - it has so much brass in it that it doesn't stick to itself as well as typical PLA. First thing I would change is to get all your speeds the same. Having an outer wall speed different than inner is asking for trouble. They will have different pressure in the nozzle and it takes a few second to switch to the new pressure causing over and underextrusion and those gaps in your top layer. higher flow sounds great. Keeping printing speed under 30mm/sec will help. And keep travel speed fast like 250mm/sec. Having more top layers will help also. You might not need much fan since you don't seem to have any overhangs or bridging. Not sure. Fans can also help top layer bridging over infill. So I suppose make sure fan is at 100% by the time you get to the lowest hexagon top - meaning whichever top of a hexagon is lowest - you want fan at 100% by the time the nozzle gets to that Z height.

Well putting the feeder on the head helps a lot with flexible filaments. The friction between the bowden and a rubbery filament is high. Adding oil to the filament helps immensely. But if you want to keep the feeder on the printer then the iRoberti feeder is great. You need to include the part that doesn't let the filament bend. That part could use some improvement! That might be a good project.

Maybe the tension is bad in the feeder. Some materials are a little softer and so the gnurled sleeve digs into those better. Or maybe you printed some CF filament and now the diamonds in the gnurled sleeve are worn smooth. How does the pattern look on the filament if you look through the bowden? You want it somewhere in between these two but more like the one on the right: There are MANY other causes of underextrusion - you might simply be "on the edge" with the other filaments also but it's more obvious with silver as maybe it needs 5C higher temperature. Here is a list of things that can cause underextrusion: As far as underextrusion causes - there's just so damn many. none of the issues seem to cause more than 20% of problems so you need to know the top 5 issues to cover 75% of the possibilities and 1/4 people still won't have the right issue. Some of the top issues: 1) Print slower and hotter! Here are top recommended speeds for .2mm layers (twice as fast for .1mm layers) and .4mm nozzle: 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. 2) Shell width confusion. Shell width must be a multiple of nozzle size. For example if nozzle size is .4mm and shell width is 1mm cura will make the printer do 2 passes with .5mm line width which is possible but requires you to slow down much more to make a .5mm line out of a .4mm nozzle. If you really want this then set nozzle size to .5mm so it's clear what you are asking Cura to do for you. 3) Isolator - this is most common if you've printed extra hot (>240C) for a few hours or regular temps (220C) for 500 hours. It gets soft and compresses the filament under pressure. It's the white part touching the heater block. It's very hard to test when not under full pressure (spring and bowden) so sometimes it's best to just replace it. Also if you notice parts of it are very soft (the blacker end where it touches higher heat) then it's too old and needs replacing. 4) Curved filament at end of spool - if you are past half way on spool, try a fresh spool as a test. 5) curved angle feeding into feeder - put the filament on the floor -makes a MASSIVE difference. 6) Head too tight? Bizarrely MANY people loosen the 4 screws on the head by just a bit maybe 1/2 mm and suddenly they can print just fine! Has to do with pressure on the white teflon isolator. 6b) Bowden pushing too hard - for the same reason you don't want the bowden pushing too hard on the isolator. 6c) Spring pushing too hard. Although you want a gap you want as small as possible a gap between teflon isolator and steel isolator nut such that the spring is compressed as little as possible. 7) clogged nozzle - the number one problem of course - even if it seems clear. There can be build up on the inside of the nozzle that only burning with a flame can turn to ash and remove. Sometimes a grain of sand gets in there but that's more obvious (it just won't print). Atomic method (cold pull) helps but occasionally you need to remove the entire heater block/nozzle assembly and use flame. Or soak it in acetone overnight (after removing 90% of the material with cold pull). 8) Temp Sensor bad - even the good ones vary by +/- 5C and bad ones can be any amount off - they usually read high and a working sensor can (rarely) fail high slowly over time. Meaning the sensor thinks you are at 220C but actually you are at 170C. At 170C the plastic is so viscous it can barely get out of the nozzle. You can verify your temp sensor using this simple video at youtube - on you tube search for this: mrZbX-SfftU 9) feeder spring issues - too tight, too loose 10) Other feeder issues, one of the nuts holding machine together often interferes with the feeder motor tilting it enough so that it still works but not very well. Other things that tilt the feeder motor, sleeve misaligned so it doesn't get a good grip. Gunk clogging the mechanism in there. 11) Filament diameter too big - 3mm is too much. 3mm filament is usually 2.85mm nominal or sometimes 2.9mm +/- .05. But some manufacturers (especially in china) make true 3.0mm filament with a tolerance of .1mm which is useless in an Ultimaker. It will print for a few meters and then clog so tight in the bowden you will have to remove the bowden from both ends to get the filament out. Throw that filament in the trash! It will save you weeks of pain 11b) Something wedged in with the filament. I was setting up 5 printers at once and ran filament change on all of them. One was slowly moving the filament through the tube and was almost to the head when I pushed the button and it sped up and ground the filament badly. I didn't think it was a problem and went ahead and printed something but there was a ground up spot followed by a flap of filament that got jammed in the bowden tube. Having the "plus" upgrade or using the IRobertI feeder helps you feel this with your hand by sliding the filament through the bowden a bit to see if it is stuck. 12) Hot weather. If air is above 30C or even possibly 25C, the air temperature combined with the extruder temperature can soften the filament inside the feeder such that it is getting squeezed flat as it passes through the feeder - this is obvious as you can see the problem in the bowden. The fix is to add a desk fan blowing on the back of the printer. Not an issue on the UM2 "plus" series. 13) Crimped bowden. At least one person had an issue where the bowden was crimped a bit too much at the feeder and although the printer worked fine when new it eventually got worse and had underextrusion on random layers. it's easy to pull the bowden out of the feeder end and examine it. 14) Small nozzle. Rumor has it some of the .4mm nozzles are closer to .35mm. Not sure if this is actually true. I'm a bit skeptical but try a .6mm nozzle maybe. 15) CF filament. The knurled sleeve in the extruder can get ground down smooth - particularly from carbon fill. 4 spools of CF will destroy not just nozzles but the knurled sleeve also. Look at it visually where the filament touches the "pyramids". Make sure the pyramids are sharp. 16) Hot feeder driver. I've seen a more recent problem in the forums (>=2015) where people's stepper drivers get too hot - this is mostly a problem with the Z axis but also with the feeder. The high temps means the driver appears to shut down for a well under a second - maybe there is a temp sensor built into the driver chip? The solution from Ultimaker is that they lowered all the currents to their stepper drivers in the newer firmware. Another solution is to remove the cover and use desk fan to get a tiny bit of air movement under there. TinkerMarlin lets you set the currents from the menu system or you can send a gcode to lower the current. Ultimaker lowered the default currents in July of 2015 from 1300ma to 1200ma for X,Y,Z but left extruder at 1250. Other people (I think the support team of a major reseller but I forget) recommend X,Y,Z go down to 1000mA. M907 E1250 Above sets the extruder max current to the default - 1250mA. So try 900mA. This will only change until next power cycle so if you like your new value and want to save it use M500. You can just put these into an otherwise empty gcode file and "print" this and it will change. Or get tinkergnome marlin! You will wonder how you lived without it: https://github.com/TinkerGnome/Ultimaker2Marlin/releases M907 E900 M500

The proper solution would be for Cura to insert a comment on EVERY layer change that says expected remaining time. Then Marlin can make a more intelligent calculation based on how long it took so far and how long cura *thought* it would take so far. Instead there is only a single comment at the top of the gcode file. So if the top of your part is very fast to print such as robot antenna then it will give you an estimate that is too high (will print much faster than marlin expects) but if you have the opposite - say you print a cow with skinny legs and then a large body - it will tend to error in the other direction saying it's a minute left when it still has 4 minutes. I find that the original estimate by Cura is extremely accurate if you don't change the feedrate.

Also note that the failure mechanism for teflon is that it looks fine and is the right shape but it is softer under pressure. But only the portions of the teflon that got hot so the "top" and the outside might be fine but inside it might now be softer (even when cold) than it should be. Again, get the part from 3dsolex or a partner and not Ultimaker because although Ultimaker switched to the newer, more expensive teflon for the UM2 and UM3 I don't think they switched for the UMO yet (it's possible). The 3dsolex web store is down this week but you can just email them at "sales" at 3dsolex.com. Or pick a nearby reseller that has the UMO part. I think they are about 15€ maybe. You can tell just by looking at the teflon - older style is pure white. Newer material is more translucent. It looks darker if you put it on black paper. "Pearly"?

Exactly. Or the bowden is loose and slides up and down. Or not properly seated in the teflon. Or the brass fittings aren't all the way touching each other or not touching the teflon inside the peek part. By measuring the filament that comes out of the head - it *might* be possible to figure out where the enlargement corresponds to. But it's difficult because the PLA likely stretched as it pulled out. So maybe measure from the tip. But then that is also tricky because you can't see how far the nozzle is drilled on the inside.

Well I recommend you print the wedge: https://www.youmagine.com/designs/the-wedge With your working nozzle. Then insert it into the side with the pva core. Do some cold pulls where you heat to about 210C, push the pva in hard, release the wedge to hold it in and let it cool to about 90C (not sure ideal cold temperature). Then put the wedge back in and pull hard. If it won't come out, raise by 5C at a time and let sit for 30 seconds and try again. If it comes out easily and doesn't bring the clog out then try a lower temperature. I've never tried cold pulls with PVA as I haven't had a clog yet. Also get a needle smaller than .4mm (such as one from my store) and insert that into the tip of the nozzle. Also you *can* take the core apart but it's very very easy to destroy. Once you take the nozzle out you can heat in a flame and burn all the pva to ash. Or just soak it in a cup of water for 24 hours (not sure if that works with "cooked" pva). I'm still relatively new to PVA but these techniques work with PLA just fine. I have a UM3 and have printed many things with it but I haven't had a clog yet.

If you attach the bowden correctly it shouldn't slide up and down. To do it right you have to insert it all the way while pushing down on the outer clip and then lift them up and do all this with the 4 screws loose about 1 full turn and then tighten the 4 screws 1 full turn. anyway I'm thinking your white teflon part has died. I suggest you get one from 3dsolex (not ultimaker) because the 3d solex ones are made out of a newer kind of teflon that handles higher temperatures. Or at a minimum you take the head apart and try to figure out where the filament is leaking into.

lol.

Hopefully you understand the difference between "flat" and "level". If not look it up or think about it. Just because your bed is flat doesn't mean your gantry is. Sometimes the entire printer is warped during shipping and one corner is or lower than the other 3 causing the print head to also be lower or higher in that corner. You c an try bending the frame back or you can try putting a shim under the glass such as a washer or pieces of paper. First you have to understand the problem exactly (where are the high/low spots even after leveling perfectly at the 3 screws).

Measure the resistance of the sensor when it is not connected to your printer. It should be about 108 ohms at room temperature. If it is below 100 ohms or about 120 ohms then it's not the right kind of sensor. If it *does* measure 108 ohms then you probably did not insert it properly into the board or it isn't making good contact.

How thick is your bottom layer? 0.3mm? That's the default - just checking. It's probably not the temperature of the glass. More likely the glass is either not quite level or not quite flat. Or your gantry isn't flat. Glass can be warped and can be corrected by inserting a thin shim such as a washer or a few pieces of paper in the "low" corner(s). But usually the glass is warped less than the first layer thickness. Still this seems quite possible. Try putting a metal straight edge on your glass in various angles to see if that corner is low/high. It could still be the gantry above. The 4 rods in the outer edges of the printer might not all be in the same plane. Especially if your printer was shipped using DHL which apparently hires elephants to stand on the corner of each package as part of some critical shipping process. But all shippers seem to use the elephants occasionally. Does your printer sit flat on the table or does it rock?

Examine the tiny pyramids in the gnurled sleeve in the feeder. They can go from pointy to rounded after years of printing. Or after only hours of printing CF filament. You want the feeder tight. Tight enough that you can see a pattern in the filament. One of these is a little too tight and the other too loose. You want the tension more like the one on the right but not necessarily quite that tight. Are you certain the bowden is all the way in? It can get caught up on the edge of the teflon part. If you have that stupid aluminum spacer I recommend you get rid of it and print one instead or drill a hole in it so you can see what's inside. https://www.youmagine.com/designs/um2-spring-replacement Also experiment a little - cut off the end of the filament so you don't keep grinding the same exact spot in the feeder. Then insert it and when it gets to the end stop it right away and use "move material". Move the material down until it stops. If it's not coming out of the nozzle move it up and push the bowden every which way as you move it back down to get over the various sharp rims it can hang up on.

Please explain more. The question is too basic. The direct answer is "you change the nozzle whenever you want to". Are you asking about what to do in cura when you change a nozzle? Or are you asking which prints come out better with which nozzle? .6mm prints about twice as fast as .4mm and .8mm prints about 4X as fast a .4mm but you get lower resolution on sharp corners. If you are printing a solid cylinder there is no loss in resolution by using a larger nozzle. But a cube will have rounded corners and will be more and more rounded the larger the nozzle.

I get the same globs all the time but they never cause clogs. @neotko? Ideas?