PrintPlace

Hi @Hpod, you may want to print breakaway support (same material support) with a Z clearance of 1 layer, but the resulting surface will still be rough (and the support will be hard to remove). If you'd like to achieve a bottom surface which is as smooth as the top surface in your pictures, you'll have to print with soluble support (such as PVA). Another possibility might be to design a cilinder (again, with a Z clearance of 1 layer) below the central hole to support it (i.e. designed support), changing your overhang to a bridge, but the surface will still be quite rough and the dimensions of the smaller holes won't be exact. Again, the best result would be to print this part with soluble support. Hope this helps.

Hi, a while ago, one of our UM2+ (UM2 upgraded with Extrusion Upgrade Kit) started printing visible layer lines (refer picture "BeforeMaintenance" in attachment). The cause of the issue was not printfile-related, as the same file printed perfectly on one of our other UM2+. The printer in question was scheduled for maintenance, so we immediately performed thorough maintenance, i.e. we replaced the trapezoidal nut (the thread was cracked slightly in one spot), we stabilized the Z stage (alignment of bearings for smooth manual movement of the print bed), we reinstalled the XY linear shafts (making sure the pulleys are correctly positioned and the timing belts are tightened, both the timing belts of the motor and the axles) and realigned the print head axes (using the alignment tool). We printed new tests and although the results are much better, they are still not ideal (refer picture "AfterMaintenance" in attachment). From our tests, the visible layer lines do not show up on the same height, but are rather printed randomly. We were wondering if someone from the UM team or the UM community would be able to help us get to the bottom of this. We were considering to replace the pulleys and timing belts, but at the same time they haven't been exposed to that much wear - far less than some of our other printers - so we wanted to post the question here first 🙂 Thanks!

It's been a while since we posted this issue / question, in the meanwhile we found the root cause and we wanted to post an update. First of all, @gr5, I really appreciated your throrough response and advice, this gave us a lot of material to work with. Throughout the last months we did some testing and eventually found the root cause of the issue. Somewhat expected, the underextrusion was indeed caused by a buildup of material inside the narrow passage within the nozzle. This concerned material residue - especially PLA and PETG - that got 'cooked' into the nozzle and is thus very hard to remove. Hot and cold pulls only remove superficial dirt, but it's very hard to use those to remove all the residue, so we had to resort to alternative methods to get everything thoroughly cleaned. The hypodermic worked well, but a 0,4mm drill worked even better, and now the print cores are printing again as if they were brand new!

We are a BE 3D Printing company operating a line of UM's - We have been active in the 3DP industry for about 10 years and have been working with UM's during (almost) the same amount of time. We keep our equipment in pristine condition, we perform periodic best practice maintenance and have been able to perform (most) of our troubleshooting and problem solving thanks to the information found within the UM community, the expertise of UM team members and our own experience. However, we've been experiencing one specific print core issue that we ourselves haven't been able to solve and neither have been able to find any information about, which is why we resorted to posting this question instead. The component in question is a standard AA 0.4 print core, which we only expose to standard, non-abrasive, high quality materials, i.e. PLA, PET(G) and ABS. I have always been told that the lifetime of a standard AA 0.4 under such usage behaviour approximates infinity (well, not infinity, of course, but a very, very, very long time). However, what we've been noticing in practice, is that the print behaviour of some print cores tend to change over time. I wouldn't call the change sudden, but I wouldn't call it gradual eather, sometimes it occurs over the period of, let's say, 5 decent builds, where the first one shows no issues and the fifth one clearly does. The issue itself manifests itself as wall delamination - We did some tests where we printed a (PET(G)) test part with the suspected defective print core (lifetime 41 days) and the output clearly shows wall delamination (We're only talking about X-Y outer wall delamination, not Z delamination - I manually seperated the outer walls a bit more to make it more apparent on the picture below): We then printed the same test part on exactly the same set-up, but with a working print core (lifetime 57d), and the output is printed perfectly: Both components beside one another, to make the difference very clear: Under the assumption that the manual build plate calibration was more or less identical between both test prints (this is something we made sure to be the case), this could suggest that the root cause is indeed to be found within the print core set-up, but then the question is, what could possibly cause the print core to behave accordingly? A heater sensor test shows positive results. It loads material without any problem, so there's no real need for any hot or cold pulls. The print core is designed in a fairly simple and straightforward fashion and we don't immediately see where things can go wrong within the set-up in such a way that it would result in wall delamination (except in those areas that are harder for us to test thoroughly, such as a malfunctioning of the board...?). This is also not the first time this happens, we noticed this behaviour a couple of times before, on other machines, with other print cores, that we eventually took out of order, but this is now becoming an apparent structural phenomenon. One can argue that it's faster to just buy a new print core. It might be, but this has always been about understanding what is actually happening (which is what drives most of us here, especially the veterans, I presume) 🙂 Looking forward to reading your input! 🙂 P.S. Now that I'm posting anyway - Big shout-out to gr5, your many contributions to this community have proven to be very valuable more than once. Keep on rocking!