jbeale

10 days after I received my UM2 via FedEx in the US, I got a bill from FedEx for a total of $38.34 for the import duty/tax/customs/other fees. Looks like about $7 of that was for the 3 extra rolls of filament I got with it.

I think this might work: pause the print and manually, using an extruder with a large nozzle, 1mm or more (less likely to clog on any dirt) inject the recycled plastic down in the infill area for strengthening. Or, I suppose this operation could be automatic using a 2nd head. That ought to improve part strength along the Z axis that can otherwise be low due to the layer bonding. You could even use mixed plastic colors (= mud color) since it would be infill and not visible on the outside, unless your main material is translucent.

Is this UM1 or UM2? What speed are you printing? Slower is often better, eg. surface smoothness at 20 mm/sec looks much better than 40 mm/sec on my UM2 printer, at 100 micron layer thickness. I also wonder if different versions of firmware may make a difference. I only just got my printer and have mostly used 0.1 or 0.14 mm layers, I have not tried 0.2 mm or larger.

Note: I tried printing two versions of an object nominally 100 x 10 x 2 mm (printed on edge, with the 100x2 mm face down) and the results (in PLA) were 99.74 x 10.19 x 1.86 and 99.72 x 10.16 x 1.89 mm so that is consistent with 0.2% shrinkage and 0.2mm slop, with some extra Z thickness for the inexact levelling on the first layer. It was this one: http://www.thingiverse.com/thing:382463 also available as https://www.youmagine.com/designs/10-cm-ruler I printed "5mm-ruler.stl" at 40 mm/s and "cm-ruler.stl" at 20 mm/sec. No surprise that the slower print had smoother surface texture, with less sign of mechanical resonances from head stop/start. larger images at http://umforum.ultimaker.com/index.php?/gallery/image/6977-ruler-compare/

Saying it is futile seems to me like we can say nothing about the final size, but are there not some approximate values, and some limits? Does PLA always shrink on cooling, or does it ever expand? I have read some people say ABS shrinks about half a percent, up to as much as 1% (due to thermal expansion coefficient of ~ 70 ppm/K), and PLA shrinks a variable amount but it is less than that. Is PLA part shrinkage ever more than a few percent? Let us say for designs around 10 cm in size (eg not something tiny like a single strand wisp of fiber). Correct me if I'm wrong and it is possible to get a solid part that is, for example 8 cm long, or 12 cm long, due to variable plastic effects, when it was designed to be 10 cm. If that were true, I don't think 3D printing would be possible; layers would not align well enough to adhere to each other. This link https://thingiverse-production.s3.amazonaws.com/assets/a7/3c/8f/7e/89/Zero_to_Hero_Rep2_Guide_DigiFabLab_2013-04-06.pdf says "For precision work, it is useful to keep in mind that PLA shrinks slightly. Shrinkage is about 0.2% (or one-fifth of one percent)." for what that's worth.

I see. If that is the case, it seems the calibration method described here http://blog.mcmelectronics.com/post/3D-printer-calibration#.U7QY30BCmdw is actually pointless...?

Thanks for your reply. It does seem to me, given that the firmware knows I am printing in PLA since I selected that in the menu, I should also be able to tell the printer that "this particular brand of PLA shrinks by 0.6% after printing". Or if all brands of PLA shrink about that amount, then the printer firmware should already compensate for it. Is there a reason why the printer should pretend that PLA doesn't shrink at all? Is there a problem with having a firmware calibration constant for this? If there was such a factor, I could print the same .gcode file in either PLA or ABS (after selecting the material in the printer menu of course) and have them both dimensionally correct.

I tried printing out the "Nickel Calibration Disc" from http://www.thingiverse.com/thing:84795 which is described in more detail here: http://blog.mcmelectronics.com/post/3D-printer-calibration I find my UM2 is printing too small by a factor of 0.994 in both X and Y axes (per my calibrated Mitutoyo calipers). It is at least consistent, I did two separate print runs some hours apart of this disc and the OD measurements were consistent between the two parts in both X and Y directions within 0.02 mm which I think is pretty good. (Measured OD was 37.87 mm, CAD file was 38.10 mm). On the Z axis, the parts were too thick by 0.27 to 0.30 mm but I assume that is a fixed offset, as I have set Initial Layer Thickness: 0.3 mm. So now I would like to enter this calibration coefficient into the machine so it can enlarge the X and Y outputs to the steppers by a factor of 1/0.994 and print closer to nominal dimensions, but is this done in Cura, or the machine firmware? I can't find any mention of it in the UM2 manual, or the LCD maintenance menu. The Cura user manual at https://www.ultimaker.com/spree/uploads/38/original/Cura_User-Manual_v1.0.pdf does not describe this kind of calibration constant.

"Printability rating of 0.0 from 0 users" does not seem useful. Why not hide that rating until there is an actual rating to display?

Here is another issue with YM: it crops the images. Look at this one: https://s3-eu-west-1.amazonaws.com/files.youmagine.com/uploads/image/file/46629/medium_Shield-20140508.png this is supposed to be a dimensioned drawing, but due to the YM crop, some dimensions are cut off the top and bottom, so the drawing is not useful. Thingiverse does this also on their in-frame view, but there you can just click "expand to fill screen" button, and see the full extent of the original image. If that option exists on YM, I am not aware of it.

I think for most people, 3D printing is already challenging enough without adding variable plastic quality. Just a few specks of the wrong kind of plastic (or non-plastic) can clog your head and ruin your print, and require a time-consuming cleaning process. There is a filament called Taulman T-Glase which is labelled "PETT" and is one of very few 3D printing materials to be approved for food contact. http://taulman3d.com/t-glase-features.html but I'm not sure if that is the same as "PET" (polyethylene terephthalate) http://en.wikipedia.org/wiki/Polyethylene_terephthalate. When I google for "PETT plastic" the only links are to that specific Taulman filament. Did they invent their own acronym?

If YouMagine eventually becomes very popular, there is going to be a problem with your URL links. Compare "youmagine.com/designs/fanduct-another-idea" with "thingiverse.com/thing:340161" On YouMagine, it looks like I have to choose a globally-unique name for each thing to avoid colliding with another page that might already exist. Thingiverse does that for me by assigning the number. WIth this system, eventually on YM people will have to avoid using common names for things and invent new words, and that hurts any search functions. I know a random 6-digit number is not very meaningful to a person, but at least it's a unique link which won't (necessarily) go stale if someone else wants to name their thing the same as I did, and it is also usually shorter than the title of an object, shorter is often a good thing in URLs.

One possibility is turning the fan OFF had the side effect of altering airflow around the tip and temperature sensor, and with the fan off, the temperature sensor is closer to the true tip temperature, and since it operates in a feedback loop, your true extrusion temperature is now lower. In other words, when the fan was on, it was cooling the head temperature sensor, so it was falsely reporting too low a temperature, so the actual extrusion temperature was somewhat above the setpoint and the too-hot plastic was causing issues. You could check this by turning the fan back ON and then just lowering the extrusion temperature 5 or 10 or 15 degrees, and see if that has the same effect.

Update: I just tried changing tip from 210 to 205 C, slowing print speed to 75% and turning off the heated bed completely after the first few mm (pausing print to add some white glue around the edges, to help adhesion). With this set of parameters, I would say my print quality is definitely improved. By the way, I think only the left-hand fan near the print head has any use. The right-hand fan, by the unused slot for an optional second print head, would only help that head, because the air doesn't really reach the other side. I notice some problem spots during the print (curled up edges on overhangs) and they are always on the right-hand side of a completely symmetrical model. The matching edge on the left-hand side is perfect. This points to the lack of airflow from that side. What I need is an alternative fan shroud that ducts the right-hand fan air over to where it is needed. I can see I'm not the first to have that idea: https://www.youmagine.com/designs/fanduct-another-idea http://umforum.ultimaker.com/index.php?/topic/5176-updated-um2-fan-mount/

As far as I know, the Makerbot and the Ultimaker are not very much different in the fundamental details. If you print the same material at the same temperatures at the same rate, I don't know why they would behave much differently. Could it be that you are printing different things or using different materials, or temperatures? I was getting a little bit better performance on overhangs with a MakerBot 1 than my new UM2 but there were some differences. For example the MB1 had a larger nozzle, and it was extruding more slowly in mm/s (because it could not reliably go faster), and I was using ABS then, and now I'm using PLA. With the higher extrusion and solidification temperatures of ABS, I guess it will cool and harden more quickly for a given ambient temperature, which might help overhang behavior. And in fact, according to this thread: http://forums.reprap.org/read.php?262,117402,120058 some people do report ABS works better for overhangs than PLA. The fans would probably cool more quickly if they weren't fighting the heated bed. One thing I've been thinking about is pausing the print after the first few layers are stuck, turning off the heated bed, and manually gluing the part down around the edges with PVA glue (regular white glue for paper). I tried stopping and manually gluing a tricky part last night and it did prevent parts from getting knocked off that were knocked off on the first attempt, I did not turn off the bed though but since the glue seemed to work, I will try that next. Of course, the white glue is not that strong and can be peeled off later, or I suppose dissolved in water.

@Conz: wow, you did a lot of work to try this out; thank you for your efforts on this project! Yes, splitting it in two and printing horizontally definitely gave the best profile. I tried printing with full support (and also 0.14 mm layers, because I was impatient) and it took a lot of work to clear out the support structure. The resulting profile was better than without support, but not nearly as good as your horizontal print. Also, it took a lot of work to separate out all the support structure. However after mounting it on a drill press and doing a lot of sandpaper work to smooth it down, then running it against the matching gear, it seems usable. A few more photos are here: http://umforum.ultimaker.com/index.php?/gallery/album/1043-worm-gear/ (These are all the same parts, even though the color looks quite different depending on the lighting.) And by the way, if anyone just wants a similar gear and doesn't want to print it, you can buy such things as replacement parts for a garage door opener, for example http://www.amazon.com/Chamberlain-Sears-Craftsman-Liftmaster-41A2817/dp/B00283W66I/ref=sr_1_15?ie=UTF8&qid=1404149719&sr=8-15&keywords=worm+gear+replacement

Here is a view of the other part of the gear, which came out well using the same settings, taking about 6 hours to print.

I just got my UM2, and am trying out things. I tried to print this worm screw and matching gear: http://www.thingiverse.com/thing:18544 The spiral thread forms a continuous unsupported overhanging edge, which does not print very cleanly for me. You can compare the below image of my actual print (left) and the Cura CAD rendering of the file at right. Is there any hope for tuning the printer for a better result on this print, or is this geometry just not suitable for this type of printer? (The person who designed it did not even have a printer, it was a CAD modelling excercise). The matching gear, by the way prints beautfully, but of course being printed flat it has almost no overhang. UM2 with Ultimaker blue PLA, 0.1mm layer, 100% infill, no support, 210 C head, 60 C plate, print speed 40 mm/sec adjusted to 90% speed, fans 100%. Ambient temperature 30 C. Print duration was about 3 1/2 hours.

Hi Steve, Thanks for your replies! My UM2 says it is version 14.06.2. With the power off, it is pretty easy to move the platform Z axis by hand. It will just barely stay up when lifted and I think it would fall down by itself if there was any weight on it, or with a slight vibration. The glass was bubble-wrapped and packed against the left side, and there was a folded piece of cardboard underneath the platform. ...and credit where credit is due; I didn't look carefully enough for the sample printout. I just found the small red geometric print, hiding under a flap in the bottom of the box. I edited my original post to add that info.

Maybe I'm just vain, but I like the Thingiverse "dashboard" feature that shows a graph of how many views, and downloads you've had each day across all of your models. Gives me a sense that I am doing something worth while :smile: (or is this feature already present in Youmagine and I just don't know how to access it?) Also, when you look at a CAD file, is there some reason you don't get to see a still image of the object while you wait for the 3D model to load? Looking at a 2D image tells you something about the model. Looking at a generic progress bar indicator does not, so it's more frustrating.

Thank you for that clarification, it makes sense. Probably many new users don't know that, so I think the UM2 User Manual should have a section with information like this. (Or does the UM2 automatically feed through several cm when you change the material type menu selection from ABS to PLA? I haven't tried doing that yet).

> "It is quite a hassle to switch back from abs to pla.." I did not realize it was a hassle; I am going to need to learn how to do this. Is there a description of what needs to be done, beyond using the menu to select "ABS" / "PLA" ? Is the hassle just working out the calibration curve of head temperature and fan speed vs. extrusion layer thickness and mm/s for each material, or is there something beyond that? Do I need to remove and disassemble the head to clean it each time when switching between materials? I did not see this mentioned in the user manual.

Good to know. I was just going from the label on the reel, which lists a large temperature range, in fact up to 260 C. I am wondering if my initial head clog was due to a higher melting-temp material left in the head to start with (perhaps ABS ?)

Regarding food, even if you have food-safe filament, most of the 3D prints I have seen have a bumpy or grooved surface texture due to the layer-by-layer print process. That means there are many cracks to trap food fragments and bacteria, so once it is in contact with food, it would be very difficult to clean it out completely. It might be a one-use-only thing, unless you can finish-seal it with some kind of paint or lacquer, but then that material would need to be food-safe.

I was very pleased to receive my new UM2 in the USA this morning, only 5 days after I ordered it direct from ultimaker.com. I thought it would take many weeks, in fact my confirmation email said up to 10 weeks. In the box was a printed version of the UM2 manual, which is also online here: https://www.ultimaker.com/spree/uploads/36/original/Ultimaker_2_User_Manual_V1.08.pdf Note 1: Look at the manual, page 13, in the description of parts figure labelled "Ultimaker 2 at a glance". There are two "12" callout circles, but no "15". The "12" circle on the left should read "15" (filament guide hole). Note 2: I see how the filment guide fits into the keyed slot in the case, and it is intended to rotate 90 degrees so the smaller end tab fits and locks into the small slot above. My black plastic filament guide will fully insert into the keyed slot, but it will not rotate up to meet the smaller slot using any reasonable amount of force. Note 3: On p.12, the manual states the accessory box contains "Test print done by this Ultimaker 2" but no such sample was included with my unit. I looked carefully. When I did my first test, I saw the printhead was already filled with a red material, different from any I ordered, so it had been tested in some manner, but the output never made it into the box. EDIT: Oops! Found it; the red print was hiding under a cardboard flap in the bottom. Note 4: I did my first test print using the blue coil of PLA provided, and set the menu option to "PLA" but did no other adjustment (temperature, etc). When attempting to print I got a very thin red line at first, from whatever was in the head before, and then nothing at all. At that point I aborted the first print attempt and tried another, with the same result. Then I went into the menu to manually heat the head to 248 C, then run some material. A large gloop of red, then purple, then blue came out. After that I was able to start a test print of the Ultimaker robot without further incident.