nick-foley

PET filaments are a good choice - Madesolid PET+ and Colorfabb XT. Much stronger than PLA, but warp slightly more when printing and are more expensive. I'd only use them for smaller parts which need the strength. More or less indistinguishable from PLA in terms of print quality otherwise. In PLA's, printbl is excellent. The banana yellow has a print quality that is unparalleled in PLA. I'm not crazy about the color, but for producing ultra-high quality prototypes it is exceptional. Woodfill produces the nicest finished part quality I've ever seen, but until someone posts a thorough no-clogging 0.4mm nozzle print guide for it, I'm keeping it on the shelf since I don't have the time to deal with clogs.

Seeing the inside of the UM2 extruder for the first time - it looks very very printable. I bet you could even print the whole assembly in one piece, pausing the print to drop in the bearing... maybe even the spring. Probably best in something rigid though.

Yeah. I was looking at adding a pressure sensitive pad in line with the Bowden mount - sparkfun has several that look good - but don't really have the time to do that kind of tinkering these days. I like a pressure sensitive resistor better than a spring with measured travel, because the compression would make retraction more challenging, or at least less effective.

The problem with using only nozzle pressure ( ~ bowden pressure) as a proxy for flow rate is that it varies greatly with printing speed, printing temperature, and material selection. There is absolutely an improvement to be made by measuring nozzle pressure, but it isn't quite as simple of a setup as you describe.

No worries, done plenty of stuff dumber than that to my printer...

Yup ...that would explain the MAX TEMP errors. Going to need to swap out that resistor!

Just to be clear, you're not using the thermocouple PCB anymore, are you? Also, maybe take a picture of your Main PCB, particularly the R23 area? Also, have you checked the continuity of the wires running to your thermistor? With a multimeter, what is the resistance at the Main PCB end?

Hmm, not sure what's going on there. Maybe try a build of the firmware without any settings for the heated bed? Just to eliminate some potential causes of error?

No fan as silent as no fan at all! Also, having looked, I think there are significantly less than a billion fans that are the same size as the E3D fan... And even fewer - maybe none - with any indication that they might be quiter than the stock fan.

That's some extremely low gloss PLA you're using... what brand is it?

Clear are thermistor, Black are heater - they are much higher gauge.

Yeah, I think the ceramic (non cartridge) version is essential to getting most of the benefits from this hotend. The melt zone, amount of radiated heat, and total weight are all higher with the aluminum cartridge version... none of which are desirable features.

This happens to me all the time, and it has no relation to the "Fix Horrible - Type A" setting. It even happens on STLs with relatively low poly counts. Nothing shows up in X-ray or other modeling programs. Sometimes it adds a full layer, sometimes it adds a random portion of infill. Screenshot of problem: https://www.dropbox.com/s/00d4kr3cpx2hivv/Capture.JPG Link to STL: http://www.thingiverse.com/thing:208346

Just order a replacement from Mcmaster Carr. It will arrive in 2 days or less. Cost will be trivial relative to the time you've already spent stressing about it. There's a thread on here will all the part numbers.

I think the biggest contributing factor to this problem is the often-mentioned issue of Cura reversing print order each layer, so that if one layer ends on a small island, it also starts the next layer on that same small island. This can have a huge negative impact on print quality with some mode, as features get melted more than they should throughout the print.

Been doing some calibration pyramids... will post some pics soon. With the retraction-fixed firmware, a retraction speed of 35mm/s, a retraction distance of 4.5mm, and a travel speed of 230mm/s, I am getting absolutely flawless printing with no stringing at a variety of temperatures. "Cool Head Lift" feature works extremely well with this hotend as well, due to the low oozing.

Make sure you aren't overextruding, even slightly. That will kill any fine internal detail in a print.

Yeah, it's tough. I struggled with this for as long as I used the E3D. Others haven't had as bad of an experience. I could only use XT or ABS filament without clogging, because it's less sticky when molten. I ended up swapping out the E3D last week because I was tired of hearing that cooling fan and wanted to be able to print in PLA again. Put in the UBIS hotend, no more problems... Reaming out the aluminum heatsink to be a few tenths of a mm larger in ID might help, as well as making sure the stainless steel tube has a nice clean chamfer where the PLA enters. Cutting down your retraction distance to 1mm mostly solves the problem, but then your print quality may suffer, depending on the part.

I agree that contacting Printrbot to ask for more details is a good idea. After using this for a while, I can see a few minor ways to improve it, but it would be easier to make it happen with their team than to develop our own. (I just added my 3D model of the UBIS to my printhead thingiverse page, in case anyone wants to use it to design their own mount for it.)

Sounds like you're doing some great work. I'll reiterate what Illuminarti has said - I think a very critical component in perfecting print quality is accurately modeling the (nonlinear) relationship between intended extrusion and actual extrusion. I'm not exactly sure how to best quantify it... it seems like a multidimensional variable of viscosity per temperature per extrusion force per flow rate. Like a thermistor, however, it might just be best to pragmatically measure it and use the resulting intended vs. actual extrusion curve as a factor in move and extrude planning, even if that curve only approximates the full richness of the physical reality. I've also been thinking about trying to use bowden compression pressure as a proxy for nozzle pressure and flow rate (easier to measure, as you could put a force sensor in the bowden clamp at the extruder) and have the printer dynamically slowed to maintain expected bowden pressure.

Yeah, I think this is a more sustainable solution than constantly worrying about belt tension adjustments. With 303 tooth GT2 belts, no tensioners have been needed, even after 6 months of near constant use.

The direct drive mount I designed continues to work well: http://www.thingiverse.com/thing:208343 Having performed most of the upgrades described here myself, I would say that the biggest remaining problem for me is the Z-stage - the thing just flexes and gets knocked out of level way too easily. Doing a UM2 style Z stage would be cool.

Should just need to swap the temp setting from thermocouple to thermistor.

UM1 or UM2? Have you installed the https://groups.google.com/forum/#!topic/ultimaker/BNjPpoJpfrE That was what my UM1 did before I installed the patch. I've heard it now comes preinstalled with some things, but probably worth a shot.

I like moving the XY gantry better because: 1) XY repeatability is generally better than Z repeatability in my experience. 2) Some oozing is inevitable and it would be better if that didn't land on the print.