alaris2

I can second Daid's comments through experience. adjusting the bed to be perfectly level is a thankless task and it seems no matter how hard you try it's never quite perfect. the 0.3mm first layer seems to solve it as long as the temperature is high enough and the flow rate is sufficient. (if they're not, the part will either not stick and make a terrible mess on the hotend as it drags it around, or curl slowly off the bed and give an 'old cheese sandwich' effect to your object). I've replaced tape 3 times in the last 20 or so prints. mostly my own fault due to experimentation.

great tip Daid. tried that last night and the stringing is reduced to mere whiskers. also tried your suggestions for changes to the first layer (as per another post) at the same time and they work well too. it seems that whilst I/we can print at 180C - 230C the low temperature prints are not as strong structurally and tend to have adhesion problems (with the bed and with other layers) - hot prints tend to burn the PLA a bit but otherwise are OK. it seems 200C is a good place to be. remind me - why were we trying to get down to 185C again?

so are you saying you've heated the hot end to 190C or whatever first and then executed the gcode to extrude 10mm? I'll give that a try, thanks!

thanks all, filament diameter - check. temperature - switched back to 200C (altho white PLA seems to burn slightly at this temperature) can I check the steps-per-E procedure - am I doing this right? 1) release catch on the extruder, 2) heat up hot-end, pull filament back out until it reaches the extruder 3) pop off the bowden tube at the extruder end 4) line the filament up with the top of the quick release fitting and apply the extruder catch again 5) use Cura to extrude 100mm 6) measure with steel rule, enter actual extrusion and lo and behold the E is calculated. is that right? whilst it checks the extruder is working properly it says nothing about how much filament can be pushed through the hot end.. I agree with your under-extruding statement which was why I tried changing the packing density to see if I could fool it into pushing a bit more filament out.

Daid, are you saying we can set different values for the first layer in the next release of Cura? "I've set the first layer to 20mm/s, 0.3mm and with 220C then it really sticks well for me." 'cos you normally print at 180C don't you? or did you just manually insert some extra gcode for that?

what was the conclusion here? I'm down to 180C but experiencing some problems with parts curling and lifting off the bed which might be temperature related, I need to run more tests. I also have the 'swoopy' fan. you're right, it looks great, but the fan isn't capable of generating the pressure and most of the air blows back out the fan side instead of at the head side. it's also extremely difficult to access the head for cleaning and there's several design faults (walls too thin to print reliably, curvature of working end doesn't deflect the air correctly..) it looks great, but I can't recommend it. I'm going to redesign the fan shroud myself.

what's the best way to determine if it's loose belts/backlash? I don't think cura is to blame, although as an experiment I tried some different settings to see if I could improve matters. (I'll try printing slower tomorrow, right now I'm having a different problem which is that the edges of prints are curling off the bed during printing which makes it hard to complete prints without them getting kicked off the bed) http://i177.photobucket.com/albums/w228 ... r/keyg.jpg shows what printrun reckons the top surface looks like. pretty solid really, no problems there. but http://i177.photobucket.com/albums/w228 ... 100577.jpg shows what happens. the top print is with the settings I mentioned in the first post - the walls separate from the infill on the right bottom edge of that photo and you can see almost 1mm gap present between them. however the circles are perfectly circular. oddly the wall separating from the infill seems to happen predominantly on the X axis, but only ever on the 'falling edge' so to speak. ie. as you scan from left to right, it's wall, infill, wall. and the first wall touches the infill, but the last wall doesn't. the left keyhole is printed with similar settings - layer height 0.2mm, walls 0.8mm, top thickness 0.8mm, fill 20%, speed 70mm/s, temp 190C, packing density 1.0 the right keyhole is a significant improvement - but note the 'hatching' effect of the top layer is still very visible and there are gaps towards the bottom right of the print. settings for this were height 0.1mm, walls 0.4mm, thickness 0.8mm, fill 20%, speed 70mm/s, temp 190, packing density 1.2 I'm printing with PLA, but turning the packing density up and wall thickness down seems to help considerably. (layer height makes the edges look better but shouldn't affect the top surface) I've also tried temperatures as low as 180C but the results were visually identical.

same problem on Cura RC2 (so I don't think the problem is software related). perhaps there's a way I can improve the quality of the top surface by extruding more material? fiddling with the filament diameter, E or the packing density perhaps?

I started a sort of related thread viewtopic.php?f=7&t=699 the idea here was to show prints that went wrong and what we did to fix them. it's a slightly different question from 'I have a bad print, what have I done wrong?' because there might be 100 possible answers to that

I've been playing with settings in Cura and can now print at 70mm/s 195C. however I've noticed for a while that the infill (20%) does not always touch the outer walls of my print - sometimes to the extent where the infill and outer wall are separate (almost 1mm gap) I thought this might be a problem with the XY alignment or tension so printed some circles and measured them. the diameter varies by less than 0.5mm all round the circle, so presumably this is good. the other (perhaps related?) problem is that top surfaces of objects never look very good when printed. they don't look solid - sometimes missing small bits or you can see the random zigzag infill through them. this isn't helped by the outer edges not joinging with the infill of course. what sort of quality of top surface should I be expecting - it should be fairly smooth solid and flat shouldn't it? I wondered if this was extruder related - but if I extrude 100mm of filament with the Cura setup, I get 100mm exactly - does that exclude extruder problems, or could I have missed something? this is Cura RC1, marlin 1.0.0.0 (I'll try and get a photo posted if this isn't clear enough?)

Thanks Daid - you're a mine of information. I found this this morning - http://www.flickr.com/groups/3d-print-failures/ unfortunately gives few indications as to why the prints failed - some of the pictures do have comments however.

is anyone aware of a tool to take an STL (or OBJ or 3DS, it doesn't really matter, it's a list of triangle faces essentially) and turn it into a sequence of bitmap slices (at whatever layer height might be required). ? I think I remember the resin printer boys having some tool like this.. but the second part of my question is equally important - does anyone know how to turn that set of bitmaps back into STL (or similar) ? the reason for asking is that I'd like to write some clever software that works on the slices and optimizes and makes certain improvements to them - this would be easy if I had slices to work with - but then I need to get back to something that can be printed so I have to convert back to STL ultimately. bit of a tail wagging the dog exercise I appreciate, but any info gratefully received. thanks, nik

do we expect buffer underruns if the PC isn't doing anything other than sending gcode? I hadn't realized this would result in blobs..

mine is also very very noisy. I read somewhere on here that it's upside down and should be mounted the other way up to be quieter, but your post suggests this 'fix' has already been applied. I was going to remove the wooden board holding the fan and run it either way up and see if it makes any difference in volume, otherwise was about to post as you have. I found the plasticated card assembly for this fan to be a bit less like 'origami' and a bit more like a mess with lots of blue tape over it.. glad it's out of sight.

I'm curious about the under extrusion one Daid - out of interest what did you do to fix it? was it the thumbwheel on the back or wrong filament diameter or what? for reference for other folks, I'll include http://s177.photobucket.com/albums/w228 ... ultimaker/ some close up prints of what happens when the filament diameter varies by 0.3mm (good PLA appears to vary by <0.05mm) (the silver one is the bad PLA, white is good) also an image marked #1 of what happens if you don't have the extruder thumbwheel tight enough and/or temperature high enough the birds nest sitting on top of #2 happens when the temperature is too high and your print just got kicked off the bed..

has anyone tried to collate a bunch of links or photos of "this is what my print looked like when the following fault occurred"? (this is a different question from "my print looks like this, what's the fault?" because this might have multiple answers) If someone's already done this then please point me in the right direction. it seems such a resource might be extremely useful. for example, I'd be curious to know how a print degrades when the belt tension is wrong, when the temperature is wrong, etc. so that I can recognize a problem when it arises. (yes I could just set all the settings wrong and print lots of mistakes but no point duplicating work if someone else has already done it..)

a happy ending to this topic - I bought some new PLA which varies by less than 0.05mm across the filament. this stuff works properly and the before and after can be seen at http://s177.photobucket.com/albums/w228 ... ultimaker/ still a few very minor things to try and understand to get my prints looking as good as Daid's tho.. nik

I found those bugs too.. python throws exceptions because on first time install Cura puts 0 in the first box and nothing in the second box. as a result it throws some error about 'startswith'.. anyway the work around is to type 100 in the first box and 850 in the next box. then hit save, then hit the extrude button. measure the extrusion and enter the real value and it will re-calculate E for you. moral is to watch the dos box and see what errors are being thrown up there.. best of luck, nik

the steps/mm was set to default 50 - that print is the consistency of a spiders web, I was amazed it held together and it would make excellent support, but it was caused by the thumbwheel on the extrude feeder being set too loose, which caused me to have to set the E number in cura to about 1100 or so before I got 100mm filament fed through. the temperature was set to 210 or 200C (from memory, ie a bit too low really to properly melt the PLA). i'm not sure it's reproducible enough to be useful unfortunately..

thanks all. you reckon the silver is no good either Daid? I'll try a different print and see what happens.. my temperature probe is really loose in the metalwork, so it won't be getting good contact and probably doesn't register the right temperature, that would make a lot of sense. maybe some thermal grease or something might help here.. presumably temperature regulation won't be great if I can't monitor the temperature properly and variations might cause those strange defects? or is the general consensus that it's definitely feed rate vs filament diameter related? I'll give slic3r a go and see what happens too, I've heard some quite good things about it.

So I'd really appreciate some (constructive) critique of my ultimaking so far. I've levelled beds, finally managed to get the extruder knob to the right tightness, fought with firmware, removed repg 026, installed cura and marlin, worked around some bugs in cura, calibrated the E, played with many temperatures and finally have something printing. but it's not exactly what I was hoping for. http://i177.photobucket.com/albums/w228 ... mtrial.png #1 was my first attempt - the extruder knob wasn't tight enough so it wouldn't feed properly, temperature was probably too low (200 - how does anyone print this low? I can't get the PLA to flow until I reach almost 230?). it's a vase3 made almost entirely from strings and blobs. I only left it running so long because it amused me to watch and I wondered how long before it fell to pieces. #2 is a more serious print at 210C, but I stopped it because I found the diameter of the silver PLA supplied with my UM seems to vary from 2.72 to 2.94mm - I'd calibrated it for 2.90 and it was making a mess. is this normal? I then recalibrated for 2.85mm.. #3 almost looks like a real object. the temperature is now 230C. when the print starts, the extruder 'pees' all over the place, again I'm not sure if this is normal or not. at any other temperature nothing comes out the extruder during this part.. but the print starts really well, good clean lines for maybe the first 10 layers. then it's OK for quite a bit longer before reaching the purple ringed area. I don't understand what happens here - the print turns into strings and blobs again, but sorts itself out after a few more layers. any suggestions? and then there's the weird cyan ringed area - the strange diagonal deformations appear to be caused by part of the interior wall in some unexplained way.. then it went mad and made a birds nest on top for me. I left the room for a moment and stopped watching it so it threw a hissy fit. jealous machine. oh, and how are you supposed to remove the print from the blue tape? it always seems to stick so well that my efforts to remove the object actually snapped it off near the base (that's why there's a fracture line a few layers up). I guess I'm missing a trick. sorry if these questions are all answered elsewhere but I couldn't find anything other than suggestions the silver PLA might not be fit for purpose. all the best, nik.

other than 'Ultimaker PLA' there's no batch code or anything on my silver. it came with the machine which shipped here a couple of weeks ago. I just noticed it says <=220 degrees on it too. which is strange, since I can't even make it come out the extruder below 230 degrees! does the gcode take care of the extruder rate and filament thickness? if so, modifying it on the fly does sound tricky.. if you could just get away with changing the extruder motor speed with a single command you might be able to compensate?

Maplin sell a cheap but good digital caliper. I used it for measuring the filament that came with my new Ultimaker. used to be £10 but I think they charge £20 now. I bought 3 and was going to make a 3-axis CNC machine but never got around to it. why is this relevant? because this particular caliper has accessible pins and a described waveform for reading the values via an Arduino or similar - you could mount it and have it reading the filament size and feeding it to a CPU. having just paid lots of money for my new Ultimaker and finding the silver filament supplied with it varies from 2.79 to 2.92mm and makes some atrocious prints, I'd be all for automatic calibration.. gonna have to throw this filament away I fear ;(