madoverlord

I am fooling around with modified cooling fan setups on my ultimaker. Does anyone know what the max recommended current draw for the fan driver is? I wouldn't want to put a bigger fan on and overload things!

Thanks for the tips about alcohol and the gcode, I'll try them. My experience testing layer heights is that 0.1mm is better than both 0.2 and 0.6. My preliminary hypothesis is that the 0.2 layers have more thermal mass, so they tend to have worse quality under the overhang, and the 0.6 layers cool too fast and tend to curl up.

I decided to do some tests to see how well Cura and my Ultimaker could handle overhangs, using a variant of a calibration model I found on Thingiverse (http://www.thingiverse.com/apps/customizer/run?thing_id=58218&code=aede3fe580c5b5328a88c5749fe73508) My best results were at 210c where I was able to get perfect overhangs -- both unsupported and bridged -- at 69 degrees with .1mm layers @ 50mm/sec. I set the wall thickness to 3mm and Cura nicely obliged me by laying down the wall from the inside out, which no doubt helped. Past that point I started to get imperfections on the underside and upward curling on the unsupported spans, but given those limitations I got up to 80 degrees, which is much further than I'd expected. Any advice on how to tweak things to improve on this would be appreciated. However, that is not the main reason for this post. In the process of doing these tests, two possible improvements to Cura occurred to me. 1) Almost every time I start a print when the hot end needs to warm up, the initial adhesion is bad for the first 30 seconds or so. It might be interesting to have an option that would have Cura lay out a pattern in a corner away from the main print job to get past this critical time period. In the case of this particular model, I needed brim because it had little support area, so the first few rings of the brim would mess up, but then it would "catch". Something as simple as being able to specify extra rings of brim/border might do the trick, though sometimes the filament drags across the middle 2) Adhesion seems better at higher temperatures. Consider an option to specify a different temperature for the first layer. Usually this would be higher, but in the case of models with a lot of contact with the bed, you might want it lower to make removal easier.

Actually, I found that brim was the solution to an adhesion problem with a smaller part that had multiple points of contact with the bed -- in this case a level-2 Menger Sponge rotated so two of the vertexes went through the Z axis and then cut to form a triangular base (which is composed of smaller triangles). On the initial print, several of the triangles detacted; brim provided extra support enabling them to stick to the bed until they joined up into the larger structure. Furthermore, brim has the advantage of being much easier to clean than raft, and provides a much better bottom surface to the model -- a big win if you're printing sections for later assembly. The downside of brim is that it's a bit finicky to clean it from within "fjords" -- thus the suggestion.

I'm having a lot of fun with the new Cura, and the new "brim" option is certainly an improvement. However, it occurred to me when cleaning some brim off a print that instead of a continuous brim, a series of small tabs (say, 5mm x 5mm?) that alternated around the outer perimeter of the model (as long as they didn't intersect with the model or another tab) might be just as good, and much easer to remove (by just bending the tabs)

Two things: 1) The XZ and YZ swap feature seems to have disappeared in the latest Cura release. This was REALLY REALLY handy, especially when I was doing complex models that I had to cut into individual segments to print. I reverted to 12.12 simply because this feature had been removed. 2) Ability to individually set top and bottom thickness. Often when I am printing multiple parts of an object to be glued together, I don't want the bottom at all, I want a hollow shell. Depending on the part, I often have to set a thick wall in order to ensure the top of the part fills in.

The acetone wasn't to dissolve any leftover PLA. I just figured it might loosen any leftover burned ashes. Basically, "couldn't hurt, might help"

OK, happy to report that the problem is solved. As per snowygrouch's suggestion, I removed the tip and "candled" it, then ran a hot wire through the orifice. I also used an old drill bit to auger out the inside of the tip (heated tip and drill bit, inserted into tip and rotated to extract leftover plastic). I then put the tip in a toaster oven for 30 minutes at 400F, soaked it in acetone overnight (because why the hell not?) and lightly sandpapered the cone of the tip to remove any residual carbonized crap. After reattaching the tip, I turned the temp up to 250, waited 10 minutes, and then manually fed a little filament, and it started extruding. After it stopped, I fed it a little more, and repeated this cycle several times. I then reduced the temp down to 220 and did more extrusion cycles. First test print had some irregularities in filament thickness, but I let it run for several layers and it seemed to settle down, so I cancelled the print and restarted it. The result speaks for itself... https://www.dropbox.com/s/8zp6nzlscx0fggf/IMG_0434.JPG Many thanks to everyone who has contributed to helping me address this issue.

I can easily remove the nozzle, it's cleaning it out that is the issue. The plug is likely right at the tip. THF is a possibility, but it's pricey ($30 for 500ml on ebay). Anyone else have suggestions?

Alas, the thermocouple seems to be fine. I immersed it in boiled water and got 95C.

OK, I disassembled the hot end, cleaned it completely, and put it back together again. I followed the advice given above about manually turning the extruder gear, and plastic did start extruding. I re-zeroed and re-leveled the bed, and started a print. The perimeter line had a big blob at the start, and the normal behavior (a thin thread from the home position to the start of the perimeter) did not occur. The perimeter was a bit thin, and the same could be said about the first layer, the filament lines being laid down were thinner than normal, and seemed to be getting thinner -- my guess is that the flow was not as large as it normally would be. I stopped the print on the first layer, rehomed the head, lowered the bed, and tried to manually turn the extruder gear to extrude a bit more filament. No filament extruded, it was blocked again! I reversed direction on the gear, and the 2.89mm filament came out of the hot end without any resistance. I tried manual feeding, no luck. Upon close inspection, I could see a plug of plastic that reached right up to the bowden tube. As you can see from the linked photo, it has a lip on it that appears to be where plastic got between the tube and the teflon part. https://www.dropbox.com/s/2swy38ifvtgkqg7/IMG_0431.jpg I removed this obstruction and reassembled, but the extruder is still blocked. My guess at this point is that there is some obstruction in the tip that I have not been able to remove, and that this is causing the thin feed followed by a backup and a clog. Does anyone have any advice as to how to completely clean the tip and/or determine if it needs to be replaced?

The Cura defaults, as set by the first run wizard. Print speed 50 mm/s, Temp 220, Filament diameter 2.89, packing density 1.0, retraction enabled, 0.2mm layer height, various wall thicknesses depending on the print. The only setting I have changed from the defaults in prints have been wall thickness, bottom top thickness, fill density, and support settings. Often I am just printing with the basic High Quality setting. The problem does not seem to be related to those particular settings, especially when you consider that after I cleaned the second clog out, it reclogged within seconds of starting the first print (which leads me to believe perhaps the hot-end did not get put back together again correctly in some subtle way) The printer flawlessly printed for 3-4 days, probably about 30 hours of printing, before the first clog. The only problem I had was an occasional first layer or perimiter not adhering; stopping the print and restarting it would always fix this.

Thank you for your quick responses. I did search for other threads but apparently I was too specific. In response to your questions, I am printing PLA (the silver that comes with the Ultimaker), using the default settings. The only things I am adjusting are options like support, top and bottom thickness, and wall thickness. The fan is coming on automatically as far as I can tell, but the problem isn't printing per-se: it's been printing wonderfully, doing long multi-hour prints, but now it has just started clogging -- so far twice in the last two days. As I mentioned, I found a plug-up in the white teflon part the first time. After reading your posts, I disassembled the hot end again. This time I could not manually retract the PLA; I had to remove the bowden tube and then found that the end of the filament had thickened a bit, making it too thick to retract. I have once again completely cleaned the entire filament path, and removed the tip and cleaned it out as best I can. However, I won't reassemble it just yet, pending further comments and suggestions. In particular, regarding: "6) Did you make sure that there are no gaps in the hotend when you assembled it", are there more specific instructions than given in the assembly instructions for ensuring there are no gaps? Are there specific things to be on the lookout for? I am wondering if the problem is in the interface between the white teflon part and the PEEK part. Here are a few photos of the hot-end, which may be helpful. https://www.dropbox.com/s/p3ws3vk8wftndzo/IMG_0426.JPG https://www.dropbox.com/s/zykcsz8ppn02mpz/IMG_0427.JPG https://www.dropbox.com/s/mw29zvvv14ujhg0/IMG_0428.JPG https://www.dropbox.com/s/a7zdhnwveq21re7/IMG_0430.JPG

I've only had my Ultimaker for a few days (albeit I have been using it a lot) and have already had two major clogs in the hot-end. The first I was able to fix by setting the temp to 250 and manually feeding. This got me back running for all of a day. The second one I haven't been able to fix at all. I've disassembled the hot end (twice!). The first time I found a clog in the teflon adapter. Removing this did not fix the problem. The second time I completely cleaned out the hot end -- set the temp to 250 and used a long 3mm bolt to scoop out everything I could. I also used the bolt to push through the residual plastic, and I think I got it all because I was seeing little puffs of burned plastic smoke come out of the nozzle. I reassembled and tested using the control panel, and it extruded fine, though it tended to curl up into little thread clumps instead of just dispensing vertically. I started a print. The outer boundary was thin and did not adhere. I stopped, readjusted the bed to make sure it was the right height, and started again. Same problem. I stopped, lowered the bed, and tried to extrude. Nothing. I tried manual extrusion. Nothing. It's 100% clogged again. At this point I am at a loss. I have a brand new machine which apparently has a V3 extruder. Thanks in advance for any help you can provide.

"I think it would be great (and probably easyish) to have the "bottom" layer optional." I'm a total noob, just been printing for a few days, but I already see a huge need for this. When printing objects you want to be hollow, you usually don't want the bottom layer, and the only way to do that and get a nice top is to hollow out the object by hand (which is a royal pain given how often meshlab crashes). What would be even more useful would be the abillity to have the bottom layer be a "lip" that extends in from the model edges by some programmable amount, to facilitate gluing of multipart models. And if you want to get really crazy, add the ability to put in N registration holes equally spaced radially from the center of the model at a specific inset from the edge of the model.