simon

Has anyone come across a good way of keeping the UM2 nozzle clean. I'm only printing ABS. I don't actually mind the outside of the nozzle being black with burnt plastic, but I'm printing some white parts, the face against the glass is cosmetic. I'm really pleased with the quality and accuracy of the parts (they almost look like mouldings) but the face against the glass is slightly spoilt by 1 or 2 brown streaks. I'm not sure if this is contamination from brunt on plastic or slightly overheated filament caused by one of my settings. I'm printing at 250 C and 35mm/s. Bed is at 96C and seems to give nice parts with virtually no distortion. I was wondering if anyone had tried putting something around the nozzle that would stop stray strands of plastic from hitting the side of the nozzle and burning on. Even a really clean nozzle seems to turn black with burnt plastic after a few hours printing. I was wondering if wrapping a few layers of PTFE tape around it might help. It's good for 370C I think.

There must be now several hundred, maybe even a few thousand users out there. With the release of the UM2 this number is getting bigger all the time. I've been thinking for a while that it would be great to have a 'go to' section of the forum/website for both new and experienced where they could share their successful settings for different materials. I wouldn't want this to be just a forum posting, that over time becomes a multi page discussion or worse an unused and forgotten topic that works it's way down the popularity list, but an actual database that has a permanent location that only contains this information. The reason I think that this would be a benefit is....the forum is great for discussions and problem solving, but it's not a good way to store information that should be in a database. For this type of information the forum is clumsy and inefficient. It takes too long to find the information you need so the easy solution is to ask the question again rather than look trawl for it. The proof of this is the number of times the same questions come up over and over again about printing speeds, fan setting, infill speeds, material type etc. The other reason I think a database would be a good format is that we're all going though a learning curve. However because we didn't all start at the same time and can't dedicate the same amount of time to learning, there's and constant stream of people climbing that ladder of knowledge by starting at the bottom each time. Lastly, and for me, the most compelling reason is that rather than 100 people all doing the same test and getting similar results, those 100 people could be doing 100 different tests to expand the breadth and depth of understanding. I suspect at the moment a lot of plastic is being wasted because of duplicate independent testing. This activity would require someone with a knowledge of databases and statistics (and probably 3D printing). Sadly I don't have expertise with either. It could be organised in a number of ways. For example, after a print you could enter your various settings and then apply a rating (1 to 10) for quality. This way you could plot a graph of the results and successful values would start to form a 'normal' distribution for a quality result. You could chose a graph where appropriate for print speed vs quality or temperature vs print speed etc. Another alternative is to only publish successful results and qualify them as draft, normal or high resolution. There are many ways to do this, I don't know which would be best. A common qualitative scale would be required that users could rate their results against. So under extrusion, burning, warping, stringing etc. were all considered in the recording process. This could also help to expand the materials database. Presently there's plenty of information in the forum, easy to find or not as the case may be, about PLA and a bit about ABS. The database could provide information on nylon, PET, wood fill and so on. So, I know there are loads of variables (which is part of he problem anyway) but I would be very interested if any other members have had similar thoughts about this, have any ideas about what variables it would be good to record and compare, have already started this process, have any experience that could help make this happen or can think of a major problem with this that would make it none viable. I just feel at the moment there is a opportunity to pool our collective resources a build a really useful resource where the sum of the parts is greater than the whole, or however the saying goes. If we all contribute to the database, I think the results would be invaluable for everyone.

I have to agree with the last comment really. There are probably a hundred different manufacturers out there now, maybe more. There's no substitute for experience when it comes to getting successful prints. Not just experience of printing, but experience of designing too. It's possible to have a very finely tuned printer and have all the feeds and speeds worked out for the material you're using, but if the part isn't designed well or setup up properly for printing, you'll get a poor result, or a ball of spaghetti. However there are at least 2 compelling reasons to buy an Ultimaker. Firstly I believe Ultimaker is a very ethical and customer focused company who are passionate about what they are doing. If you have a problem, they will sort it out for you. Secondly there is a large (and rapidly growing) technical user community that you can tap into. In my brief exposure to this (I've used an Afinia for 12 months but I'm new to Ultimaker) I have benefitted hugely from their expertise. Normally within 30 mins, sometimes less, you'll have the answer you need from someone who's already done a dozen times what you're trying to do. They are incredibly patient and generously give up their time to help out where they can. Without that kind of support it really isn't worth investing in any 3D printing technology.

Actually you get the addition of 'contact ultimaker support' if it's below 5C, so it probably isn't that.

If your temp sensor is below 5 C you'll get that error. Try warming it for a few seconds with a hair dryer just to make sure it's above 5 degrees.

I had that with mine when I first had it. There was a bad connection on the heated bed. The thermocouple solder connection looked ok to the naked eye and in fact worked normally upto about 70 C but above that the connection broke down and became unstable. Re soldering the joint fixed the problem. I think there have been a few like that. It will probably test ok when it's cold, so check the connection with a magnifying glass.

I've just update my UM2, but the abort behavior was not a problem for me I.e. No retraction.

Can't see your images. You need to change the permissions in the gallery.

I've tried the bed at 110 but it did seem to cause horrible contraction issues in the bottom few layers. The first layer or two was ok but then, if printing a tube for example, the diameter would neck down, and then build back up again. No fan is ok as long as you have no bridging, but if you're extruding in thin air, for example filling in over sparse infill with a flat surface, a bit of fan is essential. A heated chamber in combination with getting your other settings right is probably the only way to do it really. I place mine in a metal cabinet . It's not sealed but it gets cosy in there. Above the heated platform it gets up to about 45C. Below it's about 25C. I've heard its important to make sure you don't cook you motors, but I've never heard of anyone actually doing it though. I prefer ABS because of its mechanical properties, but it does contract more than PLA. One of its key properties is it's glass transition temperature, which is somewhere around 100C for Ultimaker ABS (not exactly sure as I haven't done enough tests yet). By default it extrudes in the amorphous condition. The plastic molecules are all jumbled, and they take up more space (volume internally). If you hold plastic at a temperature above its glass transition temperature for too long the structure tends towards crystalline. Crystalline plastic has a lower volume than amorphous which it was you get higher levels of contraction. This is why on injection moulded products you can sometimes see the position of ribs on the out side of a product casing. It hasn't cooled quickly enough and at the point where the rib meets the casing the volume of plastic is higher and takes a little longer to cool down. This allows the plastic to transition towards crystalline. They are called sink marks and designers and injection moulders try very hard to prevent them. It's one of the key limitiming factors when injection moulding plastic. Amorphous contraction is about 2-3% for many plastics, but can be as high as 7-9% for crystalline. Crystalline also makes the plastic more brittle. Hope that helps explain some of the factors that you need to take into consideration :-)

Have you tried the default UM2 ABS settings. Bed 90 Fan 50 Printer head 260 Flow rate 107% Try print speed 30mm/s I printed a tall thin ABS part today with those settings. I did have a bit of delamination, but nothing like that. I'm still working on settings but something around those values may work better.

I'm pretty sure a Dremmel doesn't provide enough power for making a sand blaster from. I would guess you would need a minimum of 500 Watts. My Dremmel chokes all the time with a small cutting disk. If you really want to make something like that I'd use a mains powered drill. In my limited experience of particle blasting, there's a very fine line between producing a nice (ish) finish, and messing your part up. I think there are better ways to finish your part.

Yep, latest version of cura. Interesting that 13.10 does it correctly. Can I use 13.10 with the latest firmware. Are there any health warning with 13.10. And lastly can I use both versions side by side on the same computer (PC)?

Hi Daid, I have been trying to slice this part, but Cura doesn't support the overhang properly in this instance. Also the brim is starting from the projected edge of the part. Do you need to see the file or do you already know what is causing this? Or is it something I have done? Thanks Simon

Hi gr5, I figured out last night why the fans make such a difference. Wasn't really thinking about it at the time, it just came to me. If you're drawing out a strand of plastic in open air, the strand will tend to extend from the portion of plastic which offers the least resistance. If the entire strand is more of less the same temperature then the section of plastic which has the smallest cross section will be the weakest. It will keep on reducing in diameter until it snaps, which is what it was doing. However if you cool the plastic with a fan, the smaller cross section has a much greater surface area to volume ratio. It is governed by the square law. This means that the thinner part cools very much more quickly than the thicker part and starts to stiffen up more quickly than the thickest section. The result is the thinner cooler part of the strand is no longer the weakest, as it strengthens when it cools. Thus the thicker more voluminous section of the strand which is still hotter will start to thin out. In reality, this is a continuous process rather than having distinct stages, but I believe this explains why the fans allow plastic to extend evenly and bridge gaps.

Gr5, just wanted to let you know that sorted it for me. I actually used the default UM2 ABS material setting. Thanks for your help!

Thanks Nick, I will try that also. I do think that the underlying problem is the broken strand issue though. Although I'll try a thicker layer, I feel this is treating the symptom rather than find a cure. I might have to settle for that though.

Thanks gr5. Fan is the only thing I haven't tried. For ABS I was thinking no fan was the best option. There's no way in Cura I can just get it to automatically print the top layers slower is there, or do I have to use TweakAtZ and work out where it needs to slow down?

Thanks, that seems to work.

Hi all, I'm slowly coming up with solutions to printing with ABS but here's one thing I really can't solve. I've mentioned it before in other posts but its driving me crazy and I'm starting to think that the UM2 won't do this. Logically it doesn't seem right that I can't find the right combination of setting, but I've played around with print head temperatures, infill speed, flowrate etc. can can't get it right. The step Size is 0.1mm. This is just a simple 20 x 20 x 5mm box with 20% infill. It's obviously just a test print, but until I can get this right, there's no point in trying more complicated stuff, it's just a waste of plastic. It all prints fine until I get to the top layer which is dense infill. When printing the first layer of dense infill, the strands break before bridging the gap between one rib of sparse infill and the next, so it has nothing to anchor it down, The short broken strand then sticks up. As the head passes across the surface on the next layer it's like passing across a ploughed field. It eventually smooth's out to what you can see in the photo. I've tried temperatures from 230 -265 and the result is identical. If anyone can see what I'm doing wrong, or can tell me what setting to use, please let me know. I'm going to try 0.2mm steps as well. Annoying thing is that my Afinia can do this so easily (0.2mm steps). I believe the Ultimaker to be a more capable machine, but I'm really struggling.

Hi, does any one have a working version of Tweak at Z for the latest version of Cura. I managed to modify Bedtempatz so that is works but TweakAtZ is beyond me at the moment. I'm after version 3.0 which has bed temp control as well. https://github.com/D...TweakAtZ.3.0.py In the version I tried to modify, I just could get it to add anything to the gCode. Any help would be greatly appreciated.

Great, thanks I'll give that a go tomorrow

Ok, I've exported gCodes from Cura with and without this Plugin Activated and the file size is identical to the byte. So I guess it doesn't work. What a pity.

The bed temperature is normally set in the UM2 material setup controls. On the Plugin page there's a note that says. To use with Cura 13.11.2, add the middle line in between the two others: changeState = 0 currentSectionType = 'STARTOFFILE' (add this line) with open(filename, "w") as f: And change the following line: if getValue(line, 'G', None) == 1: To: if getValue(line, 'G', None) == 1 or getValue(line, 'G', None) == 0: I've looked at the gCode and can't see any of these instructions in the code that Cura has written. Presumably this is written for the UM1 or other printer. Does that mean it won't work with the UM2. If someone can quickly answer this it will save me some head scratching and plastic. Thanks in advance.

Actually ignore these questions. I was being lazy. Have managed to install it no problem. Just need to see if it works now.

Has anyone used the 'Bedtempatz' cura plug in with the latest version of Cura with a UM2. Does it work? If yes how do you install and use it? Thanks