alaris2

ooh, this should be interesting to try. I've had dwindle switched off until now. That retraction looks pretty aggressive compared with the default Cura settings!

very nice Daid. Ian -> Hexagon (from Daz) it's free and handles cad and organic shapes.

I'd be interested in how people are tackling the 'first layer' problem with PLA and the print quality they get. (i'm assuming no heated bed) for those not already aware, the problem is that if the bed is perfectly levelled using: 1) the tin foil method - the nozzle is too close to the bed for the first layer. if you have Cura on default settings of 0.3mm for first layer, you'll get a mess. I have mine set to 0.2mm and backed off the bed by a quarter screw turn. pros: this results in perfect adhesion and no warping, cons: it's almost impossible to get the print off the bed without destroying the blue tape it sticks so well, and the first layer is (measured) 0.05mm not 0.2mm since it's been squashed into the tape. this is not only a problem if you want a really accurate part made, but it means there's lots of excess material when you print the second and third layers which can lead to a lumpy bumpy ride for the head as it runs over the excess pla and grinds against the print. regardless of this, the print quality is excellent, so it's my current setup. 2) the just slide a piece of card under the nozzle method - the nozzle is a little too far away. I'm guessing Daid uses this method, since when I do it this way I find I need the first layer to be 0.3mm and the fan switched off to get better adhesion. pros: slightly more accurate part, no bumpy rides cons: prone to warping, doesn't always adhere, especially with support so I'm curious what methods people are using and whether anyone has found a 'perfect' solution?

I had a discussion with Daid on exactly this topic a few days ago involving circles and triangles. it sounds like Daid has already found a solution to your problem, but it's worth being aware that if your model consists of two solids that intersect, some packages export stl that will look correct on screen but slice to give inside out prints (or negative space as you called it). the solution, in my case, was to use booleans to ensure that no individual parts of the model overlapped. I could also have union'd them all into a single part for the same effect. netfabb was pretty useless in this case - it just tried to close all the holes and messed things up. what i really wanted was a 'make my model the way it looks on screen' button. which doesn't exist.

you may not need to drop it by much. I have my black PLA running at 211 with perfect results. it depends how accurate the temperature readings are too of course.

I have a thermal camera so can take some proper measurements if you really want, but at a rough guess I'd say the extruder motors are getting to just under 60C if I give them a really good work out (lots of retraction and 100mm/s build). X and Y are considerably cooler, 40-50C would be my guess. 100C sounds bad. spec. for typical coil potting varnish is 105C max with an assumed 40C max ambient temperature (..is this where you saw the 40C maybe?) set the build speed really slow would be the best way to reduce heat - or modify the box - drill some holes and mount a fan on the inside next the motor and then enclose the motor from the rest of the chamber.

Thanks Daid - I found a workaround, altho I admit I don't understand why the model should slice like this.. imagine a fish shape - a circle with a triangle (tail) that intersects it. make a smaller hole in the center of the fish (another circle). If you extrude this shape, the cylinder and triangle are two separate things and instead of the hole printing as a hole, it prints solid whereas the outer solid prints hollow.. except the perimeter! netfabb claims there are openings and helpfully closes them all, thus rendering everything solid. which was not at all what i wanted. solution was to boolean the circle with the triangle, thus cutting away the part of the triangle that intersected the circle. trouble is, it's still 2 things. and Cura lays down the entire circle first, then goes back afterwards to lay down the triangle (for each layer) this results in a retraction and layer adhesion problems and is clearly suboptimal - I would have thought it would lay down the entire outline since it's a continuous shape. anyway, it printed, just the tail won't be very strong i suspect.

I get a migraine from the PLA fumes too if the temp is too high. I'm not convinced either plastic is totally safe (despite what is sometimes said) so print with the window open. as far as steppers overheating - I believe the main problems are delamination of the coil wires (which will lead to shorts) and with extreme overheat, locking of the parts due to thermal expansion. I suspect the torque curves will degrade in some way with excessive heat but I'm not an expert on this. I have seen inside a stepper that failed due to delamination of the wires - they're covered in a sort of varnish which just melts if the temp gets too high. it was quite a mess inside. usually of course it's the stepper drivers that overheat and that's the more understood issue.

my observation was that 2mm worked OK, but the problem is in re-priming the nozzle - I can get no hair prints, but just after retraction any fine details are lost - this is really bad news on the first layer where sometimes the PLA won't stick to the bed. I tried re-priming with an extra 0.5mm but that leads to a different sort of stringing. I intend to get some 4mm ID tube as soon as possible - where did you get yours from fj?

given there's no fan on the hotend and you are now chambered... isn't there significant danger of overheating the steppers?

so I finally found a file that failed to slice and print properly under Cura. it displays fine, but prints 'inside out' in that hollow parts are solid and vice-versa. what's the correct way to report files like this - would you prefer them mailed to you Daid or just reported as bugs on the Cura wiki page (assuming I can edit or leave messages there..) or perhaps, more useful (to me) - what's the quickest way to 'fix' broken files - are there any packages available that 'clean up' bad stl files for printing? it's probably something inside out or non-manifold or whatever, but I'm not in a position to edit the file myself.. thanks, nik

nice work Ian. looks like you have an entire village there, and a scale 50ft woman too - are you making a b-movie?

have you checked the filament diameter Ian? if it's close or exceeds 3mm there's a problem.. should be about 2.89mm with a +-0.05 tolerance (ideally better)

I had this exact problem yesterday - but it wasn't Cura at fault - I'd taken a mesh model and used a boolean to cut a hole in it which deformed the geometry and made weird triangular cuts into the model.

nice work fj! I've been debating how best to resolve this issue myself.

well, let me ask why do you want so many fans? I don't think it's necessary - I was about to upgrade my (single) fan to a 20mm one to give me more space. the 50mm one is blowing most of the air back out of the shroud anyway!

Weird thing just happened - I have an old fashioned incandescent bulb lamp sitting next to my Ultimaker so I can check the print quality better. It was on, was printing away just fine.. then I switched it off. Ultimaker stopped dead and refused to print further. no errors displayed anywhere - I can only assume it introduced some sort of power glitch and the arduino hung? has anyone else experienced this?

thought I'd add a 'me too' to this thread. my machine has been working perfectly for maybe 30+ hrs, then suddenly tonight it stopped feeding. the symptoms are worth being aware of - the shoelace pattern on the filament is normal, indicating the extruder is working correctly, apply some manual force and the filament does move through, but let go and it stops. the extruder doesn't have enough force to move the filament through. the reason? filament had varied slightly from the 2.88mm it started at, to 3.01mm at this point. I removed the filament to see exactly what gael posted a photo of earlier in this thread. it was hard work pulling the filament out - not just out of the hot end but out of the tube. conclusion: the fault is definitely the ID of the tube. as the filament varies the print quality varies (I've posted photos of this before) - this may actually be because of increased friction I now realize. I really don't want to have to mod the hot end - but I see no alternatively (other than throwing this filament away). does anyone have any nice hotend mods they'd like to share - if I'm making one change I might as well make a few.. has anyone made a quick release interchangeable head yet? I saw Daid working on something related a while ago..

I see what you mean - it does say *extra* length in Cura but I missed that subtlety. yes, I would have suck 2, blow 2.5 I guess, at 50mm/s. and yes, the blob at the start of the outline was my guess too - since the strings start from the opposite side from where you'd normally expect. I had observed (in my earlier photo) that z layers vary in quality. it seems the layer after a layer involving retraction isn't quite primed enough, leading to loss of material along edges in particular. I'll try the same print with your 3.5mm settings tonight and see if there's any noticeable difference for me. you really think the shim on the quick coupling makes a big difference? easy enough to print one and try I guess. cheers, nik

are you still priming with 2mm after? I went back and re-read your original post and realized you were doing that, but I was repriming with 0mm. I tried a prime of 0.5mm just to see what would happen - and the strings came back. I don't think I understand that observation since I expected the prime to occur after it reached the destination - not in anticipation of it! anyway your pyramid looks much better. someone else was saying vibration was affecting the quality of their prints too..

good thinking Ian - these are probably very small (2mm?) I'll do some measuring. I might try http://www.thingiverse.com/thing:8781 as well - it won't take much misalignment to cause trouble I suspect.

I thought the google one was deprecated so we could all discuss and improve the Ultimaker on one forum (this one). I barely have time to read all the posts here...! thanks tho Robert - that's some interesting work there, altho I think I'd blame most of the faults on calibration and slicer software. I tried printing that object with my 'default' settings, de-stringing courtesy of Daid. http://i177.photobucket.com/albums/w228 ... 100771.jpg http://i177.photobucket.com/albums/w228 ... 100772.jpg apart from a gnats whisker of a string near the bottom, the print is totally string free. there's no post work done on this model (as you can tell!) the only problem I seem to see in prints is variable print quality in z as evidenced here. regardless of whether there are retractions or not (a solid print would have had the same issues). it seems to be caused by subtle variations in filament width but can lead to structural failure as you can see in one of the pillars. amusingly, it managed to recover the broken pillar and starts building in thin air further up which was great fun to watch. that nasty blob on top is caused by the default end gcode which moves straight up, slowly peeing PLA all over the top of the model. I should change that to home XY first. this is a stock Ultimaker without ultipanel but with the following mods. 1) machine oil instead of grease 2) mauritius fan instead of stock (which makes a huge difference on a pointy object like this) 3) tensioned and calibrated so it's V2 bolt, not v3. doesn't mean the v3 isn't better, but I can't see any justification to buy one just yet.. PS. the lightbulb is pretty nifty tho flo! like to see one in glow in the dark PLA.

so I thought I'd see what gives first when I up the printing speed, more for fun than anything.. at 90mm/s I started noticing the first little inaccuracies creeping in, and a little investigation showed the cause to be the left steel guide shaft (for want of a better description - what's the proper name for this?). anyway, at speed I noticed even when well oiled the shaft would move 2mm towards the front of the machine and hit on the wooden end cover, the be driven back to the back wooden cover, making a tap tap tap noise and introducing some inaccuracy when putting down layers. anyone else noticed this? anyone else know how best to fix it? I was thinking of putting a small washer or something on the other side of the cover plate to take up the excess space, but it will introduce friction of course...

wha? I must have blinked and missed something. what's this about a new v3 bolt and extruder shim? is there another thread on this already? what's the supposed advantages - the retraction appears to work perfectly already?

thanks Daid - I'll give it a try. it's not very obvious tho!