donmilne

Thanks to Illuminarti for his extrusion rate test print - very intuitive and definitive. I wanted to try it out after installing IRobertl's feeder, and the results I got with it are quite counter-intuitive to me. This was ColorFabb 2.85mm Leaf Green, almost new reel. I've always understood that the slower the speed, the less stressed the extruder will be. Notice however that my results are quite crappy in the 3 to 4mm3/s band, then it gets better at higher speeds. Optimum seems to be around 7mm3/s. Below is the third of three test prints (sorry about picture quality) - all three showed a similar defect at low speed. The first print also showed minor underextrusion at 9mm3 and 10mm3, but that was much less severe on the two later prints (you have to hold it up to the light to make them very obvious). Can someone suggest why the printer will have problems at low speed, but not higher? p.s. I had a theory that the nozzle was too close to the bed and was being blocked for the early layers. So just before the third print I levelled the bed very carefully. I think it was well nigh perfect: e.g. the skirt was pefectly defined.

A "factory reset" to me means to discard my mods and return to factory settings, so no I did not do that. ISTR that I did check, on next power-up, that the adjustment was still in place: and I would expect that if the printer is showing me a value for a parameter in "Advanced settings" then that is the parameter it's going to use. I'll double check this however after the printer completes what it's doing now.

Weird thing. Today I wanted to give the printer a bigger test print, but I noticed it was printing 2mm above the glass. I did increase the motor current limit to the max allowed (yesterday at the same time I replaced the feeder). However it seems to do fine on a small test print immediately afterwards. Can changing one of those advanced settings cause it to lose the bed levelling calibration on the next power off?

Yes, well, hindsight is wonderful isn't it. I read the entire thread before starting and I'm pretty sure nobody said "btw, wear gloves". I felt I needed the strength of the 6mm screwdriver shaft to push down the spring, and another stubby screwdriver on the other side to stop the nut from being pushed out. I don't know how I could have done it with an allen key!

I'm just posting to thank the contributers to his thread, especially IRobertL for his design, and Sfriendri for his variant, which is the one I actually went for (I liked those spools guiding the filament in). No real problems, except that I stabbed myself in the hand with a Philips head screwdriver while trying to get that spring compressed on the yoke! There's probably some clever way to do it, but none that occurred to me. Ouch! I've no idea how to tune this for optimum working, I just backed off the pressure until it stopped skipping. Oh, and a lot of crap (old ground off bits of PLA) fell out of the stock feeder when I removed. That might explain the unpredictable underextrusion problems I've been having lately? The replacement looks like it'll be a lot easier to keep clean.

I just ordered some filament from ColorFabb (I wanted to try XT, got some PLA filaments while I was at it). To be honest they did make a mistake on my order (wrong color for one of the filaments), however they responded very quickly to my email about it. I see that the spools are perfect for the UM2 - very similar to UM's own, and no adapter needed.

I don't suppose it's a coincidence? E.g. when you heat it up it expands and when it cools again it will will find its lowest energy shape. Could that shape be a cylinder? After all when you deformed the original shape I assume that implies deformation stresses.

I noticed the same thing with Firefox on Windows - in fact I intended to ask a similar question. I'm glad to have it confirmed that it isn't caused by the latest Firefox 31.0 update which came shortly before I noticed this.

UM bank your money, don't supply the material, and don't respond to emails asking where it is. Other than that they're fine.

I meant that a single installation is locked to the PC you install it on, I didn't say that your license doesn't allow multiple installations - that's between you and the licensor. I would imagine however that it's a very finite limit. And I would point out that I've never had activation problems with Cura. Nuff said?

Seriously? I wouldn't have thought it was very interesting. Well ok, below is a sample of what I was doing. The software is calculating flame radiosity, i.e. how much heat arrives at certain points in the scene given a fire also somewhere in the scene. Jet and pool fires are handled, this example is a pool fire. The 3D aspect was peripheral, but it was considered important to understanding the calculation result (a previous effort by someone else - with no graphics - had proven impossible to understand). I'm sure it looks very crude, but bear in mind it was the mid 90s (it was written for Windows 95), but it was a full 3D scene, freely rotateable in real time, backface removal (BSP partitioning algorithm), color and texture mapping, even a little bit of anti-aliasing though that seems to be turned off here. All of this done in C - no graphics acceleration, no third party libraries. The scene had to be described rather than drawn, you could say a la OpenSCAD but it was dialog based, not scripted. I've been giving serious thought to digging out some of this old code and see if I can't come up with something that renders faster than OpenSCAD for simple scripted design work.

I mean a screw thread. Some of my projects involve metric threaded holes, nuts and bolts.

Any debate here (about dongles and activation) would be off-topic, so I'm happy to leave it alone with the explanation I gave earlier.

I bought Simplify3D just after getting my UM2 - I thought Cura's reputation for poor support structures would be more of a problem than it has turned out (now I try to avoid the need for support, or add something manually). The biggest problem was that it's locked to a single PC, hence not as flexible as say Cura. Even worse, every now and then the software would simply forget it had already been activated! (I suspect it had to do with me inserting a 3G USB wireless NIC whenever my ADSL landline was down, while disabling the internal ethernet NIC - thus changing the machine signature), and even worse it would then refuse to reactivate even after these hardware changes had been reversed: I had to email their tech support. Eventually they gave me a version that didn't need activation, so I can't complain about their tech support... but even so it left me wary about relying on it. I don't mind paying for software, in fact I kind of prefer it (I like the support rights it gives me)... but I hate dongled software in all its forms.

I'm a software engineer, and while I've written my own 3D graphical modelling programs back in the 90s I (ironically) have never needed to use anyone else's software before now. In general I hate all 3D CAD packages. I just don't get on with them at all- they all claim to be easy to use but aren't. They all face the fundamental problem of trying to do 3D manipulations with a 2D input interface. I get on much better with OpenSCAD, but of course my models look rather rustic compared with the rounded/bevelled edges and fillets and so on available in some of the better packages. Solidworks! Have you seen how much it costs? :shock: Can DSM do threads yet?

Hi George. Do you have a topic somewhere that expands on this?

Snap. When I was even more nooby than I am now, I too could only see two fans. The third one is the one you hear immediately you switch on the UM2. You can see it by looking at the printhead from the back side of the printer. It's central and a bit lower then the others. Incidentally, whenever I click one of your images to see a larger version I get "you do not have permission to view this image"... kinds of defeats the point of posting it! (I assume you've marked them as "private" or something like that in your gallery).

I was looking at the material settings today, I seem to recall seeing bed temperature as one of the material related parameters, along with an option to save your custom settings as a new preset. I have not tested this feature tho. Obviously the firmware version might be important.

Ok, I checked the filament, and sure enough it had been grinding. No nozzle blockage - when I cut off the bad part of the filament it extruded just fine. While I was there I noticed that the UM2 now has a "Flow%" parameter stored for the material. Do you know what that's about?

The layers view showed a solid top, so nothing wrong there. The printer didn't stop, it kept going through all the motions, printing on and with air, nothing at all coming out. I haven't yet looked for the gouge - I'm afraid I've just turned my back on it this last couple of days as these feeder failures and firmware bugs are beginning to be discouraging. Temperature was UM2 standard for PLA - not tuned. As to speed, I'm fairly sure it was faster that it was printing the bottom or the shell. I.e. where the base and shell was zzzzz,zzzzz,zzzzzz, the top was zop-zip-zop-zip, rather like when it was doing the honeycomb. I guess setting an explicit speed for infill is certainly something to try. The irony is that this widget I'm making is designed to reduce drag on the filament spool, reducing the risk of underextrusion. The mark I attempt (without the ears) was in place while this was printing. It works great! - visibly smoother.... but didn't prevent the problem.

A great resource, thank you!

Hi, thanks for replying. I'm not sure what you mean by "infill at the top" - it is supposed to have a solid top, with a 1.2mm thickness just like on the body. Are you saying that the top is considered infill rather than shell? You are exactly correct that the infill speed is set to 100mm/s with 40mm/s elsewhere. [Edit] No, I take that back. Infill speed is set to 0, it was travel speed which was set over 100mm/s (in fact 150mm/s). So I'm stumped: even if the top was considered infill it should have printed at the same speed. I have not yet used the "tweak at z" feature - I've just checked and none are listed as enabled. I don't really understand what the layers view is supposed to tell me - it has little or no mention in the Cura user manual. Maybe I should revert to the standard firmware before I try again.

Would that include his email system too? Because he hasn't replied to the email I sent yesterday. He seems like a good guy, eager to help - I hope they're back up and running soon.

One thing that occurred to me in the wee small hours last night is that setting speed limits in Cura is getting it backwards. What we should be setting is flow rate limits, i.e. if the extrusion "demand" increases per unit time then it should automatically drop the speed to avoid stressing the feeder.

Oh: Cura 14.6.1, IRobertl's bugfix firmware, which I have not updated since I've not seen a changelog for the latest official firmware.