eldrick

The atomic (aka cold-pull) method will Not remove all of the carbonized PLA that was created by heating it to 260C. Even if you do the cold-pull a dozen times until it comes out clean, the inside of the nozzle barrel will still be coated with high-friction black stuff. If you remove the nozzle (takes just a few minutes), soaking it in Acetone will Not remove the black stuff either, as it is not a solvent for PLA or for carbonized crud. Some may tell you to use a blowtorch to burn off the carbon, but don't do it - you'll oxidize the brass, and the surface oxides change its dimensions slightly and leave it less than smooth. The only non-destructive method I've found that will restore a nozzle to original condition once you overheat PLA in it or leave it sitting in the nozzle at temps over 170C without extruding, is to take a q-tip, discard 80% of the cotton so it fits snugly into the hole (while leaving a glob of cotton on the tip of it to fit the tapered bottom of the hole), and then use it to clean out the brass nozzle with metal polish until you see bare metal. I use Brasso.

First you create a Custom profile. Then you save it. Then you save it again, this time choosing the PLA profile (the choosing panel looks exactly like the initial profile selection, which is VERY confusing). Then you carefully Return and you can see your (permanent) changes to the PLA profile. The changes don't go away. It's a messy procedure that only a programmer could love or understand, but it can be done. Personally, I find it easier to simply set the temps to zero (if using Cura) and then ignore the profiles completely and set temps manually with Pronterface.

And here's the reply I got from 3DMakerWorld: "Sorry to know the difficulty you were experiencing. The specification of our 3mm filament is 2.9mm +/- 0.1mm, which is listed on our product page and matches many suppliers' spec. Since this is not a quality issue, we cannot provide a refund. You should check back with UM2 to see the diameter tolerance which the printer can handle."

I've designed the sport fencing products I manufacture and sell using Moment of Inspiration, and use TinkerCAD for simple stuff.

I just rec'd a spool of white PLA from 3Dmakerworld.com, a US supplier. While the PLA is extruded from 4043D PLA, and is the same Ivory color as I have been getting from ultimachine.com and protoparadigm.com, it is so thick that it won't run freely through my UM2 Bowden tube. The friction it creates leads to serious under-extrusion. This stuff measures 2.98mm, and while I suspect that they are trying to meet a 3mm spec, it won't work with any Bowden-tube feeder that is expecting 2.75-2.90mm filament. I've asked for a refund - we'll see what happens with that. Meanwhile, definitely Not recommended.

I would suggest that using the RepRap support and enabling temperature control is a viable alternative to using the ridiculously bad default Material settings on the UM2.

After getting my nozzle cleared of the black carbonized PLA that quickly builds up if you ever let PLA sit without extruding at temps over 190C, I still found tiny black flecks of something occurring randomly in my prints - particularly annoying since I've been printing a huge project in Ivory PLA. I finally pinned it down to rubber debris wearing off the belts, and then getting blown around by the fans and landing in the print. I noticed that the top of both motors at the rear of the UM2 were becoming covered in black particles of almost dust-sized stuff, and concluded that it had to be rubber from the belts wearing. After a thorough cleaning of the motor area and the rest of the build area, no more black dots in my printing. Has anyone else noticed this stuff, or are my belts too tight, or skewed and misaligned or something?

Remains to be seen. RPW declined to produce Ultimaker nozzles, as he is just too busy with J-head manufacture. I'm a lot happier with the .5mm nozzle than with the .4mm - .4mm is just too stinking slow, and too fussy about clogging. If my UM2 remains reliable (600+ print-hours so far according to the Advanced settings), I may keep it and the Zeni Kinetic. I certainly don't Need two printers, but it sure would be nice to have one available when the inspiration strikes while something else is running... Does anyone know what the increment is for one notch on the rear bed-leveling procedure? I'm curious how much I shaved off the flat on the .5 nozzle.

Well, that was easy. After going through the agony of obtaining a spare nozzle for my UM2 so I'd have a backup, I cleaned out my existing nozzle thoroughly, polished the inside shiny with Brasso and a q-tip, and drilled it out with a .5mm carbide drill bit with an 1/8" Shank = http://www.mcmaster.com/#2841A81. I used my inexpensive drill press at 3100rpm, held the nozzle by hand on top of a machinist's vise to keep it level but allow a bit of slop for self-centering, and slowly drilled it out from the inside. Since the inside of the nozzle is tapered before the actual orifice, the bit centered itself easily, and drilled a perfectly round hole (under 8X magnification), or close enough to perfect for me. I re-mounted the nozzle, and used 600/1500/2000 grit sandpaper successively along the back edge of the printbed (adjusting the height with the bed-leveling) to open up the flat on the tip a bit and polish it, and it's presently printing .8mm lines perfectly in .16mm layers. The tip looks flat and round, as does the hole, and it is printing smooth even lines. Printing is a Lot faster, as I can now use one external loop where I needed two before (or two instead of three), and the parts I manufacture will be structurally stronger because of fewer wider loops. The .51mm nozzle also moves about 60% more plastic, and with less back-pressure on the feeder I expect fewer skips at the same temperatures. Well worth the annoyance of procuring a spare .4mm nozzle, and an easy project - I could have done it easily with a hand drill or a Dremel if I didn't have a drill press.

As much as I like Cura, I usually wind up using Kisslicer, for features that don't exist in Cura. Kisslicer generates "standard" RepRap GCODE and does not use G10/G11 commands for retraction by default. My question is whether the Retraction settings on the UM2 control panel have any effect at all when used with GCODE from other slicers that don't use G10/G11? ========================================= Corrected: I found the Kisslicer setting that forces use of G10/G11. It's called Printer / Firmware / Mark path Start/Stop So am I correct in thinking that G10/G11 is what the UM2 machine Retraction settings modifies?

You can set the extruder and bed temperature for a UM2 in Cura by simply changing the Machine/Machine Settings/GCODE Flavor from UltiGcode to RepRap. The temperature settings will then appear in the Basic tab.

Cura lets you set the Printing temperature and Bed Temperature, and you can set them both to 0, which allows you to manually set the temperature in the UM2 and override the temperature set in Cura or for the material in the UM2. To make this work, you need to first change the Machine settings from UltiGCode to RepRap(Volumetric) - that gives you the temperature options in the Basic settings panel. [edit by gr5: not volumentric - but "reprap marlin"] [another edit by gr5: Okay - I'm told volumetric mode will work on UM2 if you also send M200 commands to indicate filament diameter - not sure how that works exactly]

Try running it through cloud.netfabb.com if possible, or download the free basic version of netfabb

That's mcmaster.com

If one was making changes to the fan behavior, IMHO it would be very useful to keep the fans running for a minute or two after a print ends, in order to keep PLA from baking in the nozzle during cool-down.

Probably - nylon absorbs a lot of moisture, and needs to be kept in a sealed storage container with a desiccant when not printing.

I got in on a GeckoTek buildplate for UM2, with magnetic attachment to a replacement heated aluminum plate. Should be interesting, as magnets don't tend to do well at high temps. https://www.kickstarter.com/projects/geckotek3d/geckotek-3d-printer-build-plate%20on%20kickstarter,%C2%A0 It will also be impossible to alternate the side used with the magnetic attachment, so I'll be really curious to see how well it actually works.

Thank you Sander. Unfortunately I just discovered that Ultimakers Sales department decided to send the nozzle to Portland Maine, instead of Portland Oregon. Their Sales or shipping departments appear to be populated by clueless incompetents.

I've sent a note to Reifsnyder Precision Works, asking them if they would consider offering nozzles for the UM2. They could supply various apertures, so .4mm would not be the only option. I'd expect a price of around US$25 and $7.75 shipping to Europe like their existing j-head nozzles. Perhaps competition will get some attention from Ultimaker management.

Not normally true. I have two UM glass plates on my UM2, and swap them between every print without re-leveling. I suppose if you were printing .06mm layers it could just possibly be an issue, but glass is pretty consistent in its thickness - if I mike the two pieces, they are well within the error tolerance for build-plate leveling, given that the UM2 jog-wheel seems to raise/lower the plate about .1mm at a time.

One at a time, aka sequential printing, is available in Slic3r, Kisslicer, and Simplify3D.

I use Tweak at Z regularly, and it is excellent - Thanks. I have only one feature request - make it available in a wrapper that allows one to use it with other slicers as a gcode post-processor program. As an example, I would love to be able to create gradual fan onset to keep PID values stable with gcode generated by Kisslicer, rather than Cura.

Same on mine. The screws appear to be some really soft material - like maybe cheese?

On small parts like that, printing PLA on a room-temperature bed with glue stick for adhesion generally works fine. This allows much faster cooling of part as it is printed. As to bed temps for larger pieces, I'd suggest starting at 65C for PLA, which helps with adhesion, then reduce to 55C after the first layer or two to allow the first layer to become firmer to resist warping caused by subsequent layers contracting.

And here is what a brass hotend nozzle, nearly identical to the UM2 nozzle, should cost: 18.38€ or US$ 24.99, with flat rate shipping of US$ 7.75 to Europe. That makes it almost exactly US$100 less costly than the ripoff UM pricing. https://www.hotends.com/index.php?route=product/product&manufacturer_id=11&product_id=52 Note that this is from Reifsnyder Precision Works, known for their high quality hotend parts.