Anders Olsson

Strange topic maybe, but here is what I have noticed: I sometimes use the flow setting to tune the extrusion rate for varying filament diameter. It is quite convenient and works really well. However, tonight I had some really odd underextrusion problems. I am using slightly large Velleman ABS filament so I had the flow set to 97% to compensate for larger diameter (exactly 3 mm) I tried both changing nozzle and cutting away a part of the filament. But the filament was moving nicely through the bowden and everything else looked fine. I had been printing two hours and underextrusion just suddenly occurred in certain parts of the print. The problems occurred in narrow sections and small parts where the flow is decreased due to the print head changing direction often. I investigated it further and noticed how the flow almost stops in these sections if the flow setting is below 100%. It is obvious that it is the feeder motor more or less halts in these sections then. If I just increase from 99% to 100%, the problem will completely disappear though. I have not seen this before, but I don't think i have been using oversize filament for complex prints before. So I am not sure I have been printing complex structures with flow setting below 100% before.

Yes, a 3D-printed fan cap is an option of course. Nice design of that one by the way. You would need the hole for the nozzle to be at least 11 mm if you want to fit a 7 mm socket there to remove the nozzle without removing the fan cap by the way. I made some changes which means the heater blocks I have right now does not fit perfectly. Therefore I would need to get a new version manufactured and tested before releasing anything. That is probably not going to happen until earliest next week though because they are rebuilding the workshop I am using. My experience with sharing incomplete drawings or distributing non working components is rather bad so far (I am working partly with scientific instrument development) , that is why I rather keep things to myself right now. I know it is annoying for you but the situation quickly becomes chaotic once you have a few flawed versions in circulation. I could have kept the whole design process secret until it was finished of course, but I thought I rather announce it here when the prototype is working in case other people are working on the same topic. That way one could avoid several people working on this unaware of each other and I can get valuable input from people here.

Here is the dimensions of the original heater block compared to the one I am currently using: I thought I made the new block 1 mm thicker than the original one, but it turns out it was just 0.5 mm which means you can only save 0.25 mm by making it thinner. EDIT: You can save 0.5 mm of course. I would not go thinner than the original heater block for manufacturing reasons. As you can see the E3D nozzle is about the same diameter as the hole in the fan cap. (I added the fan cap in paint, but the hole is approximately 8 mm just as the maximum diameter of the nozzle key grip) This means you will run into problems if you shorten the nozzle more than 2 mm. I would prefer to have 1 mm clearance there to compensate for manufacturing tolerances. So unless you expand the hole in the fan cap you cant improve it that much with current nozzle. The threads can probably be a bit shorter and the hole for the nozzle a bit deeper, but the nozzle thread has 1 mm pitch, so I would not make it that much shorter. Then you need to cut those threads somehow and we came to the conclusion that you need 2 mm of space between the end of the tread and surface where the nozzle seats, for manufacturing reasons. It is of course likely that all of these parameters could be optimized a bit for large scale manufacturing. But that was not my main goal when I designed this one. I kind of did not want to push it too far since it might have consequences next time I want something done in the workshop :smile: You could also have a look at the available range of nozzles. There might be some other brand which has even smaller nozzles with shorter threads and smaller key grip which fits through the fan cap hole. In this case the most important factors for me was that I could easily buy nozzles and that they come in different diameters from about 0.3-0.7 mm, since I need this for my projects. I also tried to get away without modifying the printer in any other way, since it looked likely that it could be done that way. I did some testing with colorFabb Bronzefill and a 0.3 mm nozzle tonight by the way, mainly to test if the bronze particles would be compatible with the smaller nozzle. It worked perfectly fine. I was a bit surprised actually.

Based on my experiments I would probably keep the PTFE insulator as in the photo. PTFE has several very interesting properties. It has low friction and things does not stick to it easily, but even more interersting is that the coefficient of friction decreases with increased load (!) I think those properties is the key to why it is so difficult for any other material to compete with PTFE when it comes to handling molten PLA. The plug of molten PLA that forms when you have backpressure from the nozzle will not only be unable to stick to the PTFE, if you push harder the PTFE will actually become more slippery (!). (At least in general, I can not find any data for PTFE - molten PLA friction) You might get away with a short piece of Vespel like this and that might very well be a permanent solution. But as I said removing the PTFE completely might not improve things.

Well, the main space issue is the length of the threaded tube and the fact that you need some material above the nozzle to keep the thing together: (This is an old version, I did not have an updated assembly) The length of the nozzle only really determines the length of the heated zone. One could think of other designs where the sensor and heater are moved up, but that may complicate manufacturing quite a lot. You need to cut those M6x0.75 threads somehow. Easiest would be to simply shorten the threaded tube a millimeter or so, then there would be plenty of space with the latest design. I managed to redesign it a bit with another type of screw so that it does not stick out on the bottom of the heater block anymore. Now there is about one millimeter of space between the heater block and the fan cap. I don't know if that is considered enough, but it seems to work for me and I don't think I am getting much further on this without modifying other parts. If you wonder why switched sides on the heater and the sensor, I just made a mistake while drawing which I did not notice until it was manufactured :smile: Not that it really matters which side they are on though. I designed this to solve my own problems so the design goal was to be able to use unmodified standard components as far as possible. If it is manufactured in larger numbers there are all sorts of things one could do of course. I think the Ultimaker Original nozzle would fit too by the way. I don't have one to test with though and I am not sure the heater has enough power to keep it hot if the cooling fans are on.

Some results from tonights testing: There is quite some oozing if i pause a print. If I use the move material function and retract the filament more, like 25-30 mm, there is much less oozing, but at least for the blue PLA I could not completely prevent it. It feels like one could investigate other approaches than just playing with nozzle design and retraction to prevent this though.. I completed the extrusion test with the blue PLA at 210C (!) Destructive testing showed that bonding was good up to 7 mm3/s The 8 mm3/s and above could be separated from each other easily and for 9 and 10 the interlayer bonding was not good. This is still much better than it performed with the original nozzle long time ago. There might be other things that changed on my machine though. For example my teflon spacer is now glass filled and might have larger inner diameter now that last time i did the extrusion test.

Hi Jan :smile: 1. The idea with screw and the toothed washer is to fix the sensor and heater in an appropriate way, clamping them with the screw and using the toothed washer as a spring to even out the force. It seems to work okay, but I have done very little testing so far. This design also relaxes the demand on manufacturing precision compared to the previous design where the screw hole had to be perfectly centered between the sensor and heater holes. The screw hole is D-shaped and the idea behind this is that you can access the heater and sensor with a screwdriver and push them out in case they are stuck. I did not test if that works in reality though. (and in principle you would rarely need to remove them with an exchangeable nozzle) 2. Yes, my main goal is to be able to change nozzle without taking things apart. I would also like to be able to swap between nozzles of different sizes since some materials are difficult to print with 0.4 mm. Then I have some future plans for nozzles which will be easier to deal with of the design of the nozzle itself is as simple as possible. The sensor and the heater are leveled and the separation between them adjusted a bit to avoid conflict with the screw thread. I did not have time yet to do tests on oozing, retraction or printing temperature. It basically prints fine from what I can see right now, but that is all I can tell so far. The height of the heater block is the main concern. The limitation is the sensor/heater fixing screw. I removed the spacer now and then the screw just about touches the fan cap bottom when the heater block is as high as possible. It may be possible to redesign the heater block a bit to avoid this, or get a screw which has a lower head. It depends how much space is considered needed for adjusting the height on the dual extruder setup. I am printing glow in the dark PLA at 210C with fans at 100% and the screw touching the fan cap, and the temperature is stable. So it works even though not optimal, but the screw has to be fixed somehow I have a few 0.3 mm nozzles, but I did not test them yet.

I actually have a few of them made already, but I need to do some changes to the design, so I may end up using them for that purpose. The space is very limited as you probably know already, so even though I made the new heater block as tiny as possible I had to add a 1.5 mm spacer below the threaded tube just to fit things. I hope that some minor modifications may make it possible to fit it without spacers or machining of other parts, but I am not sure yet. I would also like to test if there are signs of heat transfer problem when the nozzle is extended like this. And I need to check if the heater block fits on the other side, for a future dual nozzle upgrade.

Here is one more photo I luckily have access to a really good workshop, so I just designed it and they managed to manufacture it for me. There is a toothed washer which distributes the force from the screw head onto the sensor and the heater. I don't know if this is a final solution, but it seems not worse than the original design at least. Regarding the teflon spacer I would like to get rid of that one to, but the spacer is much less of an issue for me than the fact that I can not easily change nozzle. So I tried to solve the most urgent problem first. :smile: I can provide more details tomorrow, really have to go to bed now, have to get up early.

Update 2015-04-12: - The heater block can be ordered here: http://www.3dsolex.com - Further information about ordering and installing the custom heater block can be found in this post: http://umforum.ultimaker.com/index.php?/topic/7689-custom-heater-block-to-fit-e3d-nozzle-on-ultimaker-2/?p=95991 - Some more things to keep in mind when installing the custom heater block: http://umforum.ultimaker.com/index.php?/topic/7689-custom-heater-block-to-fit-e3d-nozzle-on-ultimaker-2/?p=89581 Hi! I have printed some very abrasive home-made filament lately which eats my expensive UM2 nozzle a bit too quickly... :shock: Removing the nozzle also feels like an accident waiting to happen. I particularly dislike the fixing screw for the sensor and the heater. In fact, at one of my heater blocks the screw does not even fix the heater. The heater still stays there since it is pushed in by the cable, but I don't see that as good way of fixing it. So lately I have been putting some effort in finding a better design. I looked around for nozzles and the smallest suitable one I found was the E3D-V6. Based on the design of the original heater block I made a slightly stretched version with a modified way of fixing the heater and the sensor. Here is the result: :smile: Some of the dimensions were a bit off and I only just started testing it, but it looks fine so far and I think this could potentially be a way forward. At least for me it would be a major improvement if this works smoothly.

While looking for other stuff, I found flame resistant ABS filament here: http://filaments.ca/collections/flame-resistant/products/flame-resistant-abs-filament-1kg-spool

I bought some stuff from E3D a few weeks ago and among other things I added a roll of clear polycarbonate: http://e3d-online.com/Filament/Engineering-Plastics/Polycarbonate-Clear-300 It said printing temperature 280-310 C on the home page, so it is out of reach for the UM2, but I added it just in case I rebuild the printer to print at higher temperatures in the future. However, when it arrived it said printing temperature 250-280 C on the roll, so I immediately fed it into the UM2 for a test print The print came out perfectly fine, no signs of problems with bonding between layers or such. Several other projects passed by but today it was time for another try with the polycarbonate, a two hour print this time. And it prints absolutely beautifully, at least as good as ABS I would say! (that is a 42x1 mm thread on the outside) I am printing at 260 C with the buildplate at 105 C. Printing speed 40 mm/s, layer height 0.1 mm and for this particular print 50% infill. The platform is glued with a thick layer of "Tesa Easy Stick" There is not sign of problems at all so far. I cant even detect any smell or fumes, it is the least smelly plastic I printed so far I think. So I am starting to get curious now: Why isn't everyone printing this stuff? In my mind polycarbonate has way better properties engineering properties than other printable engineering plastics out there and it is not that expensive too. Or am I just lucky that my machine happens to tolerate polycarbonate better than an average UM2? EDIT: I tried some destructive testing of a more complex print and it shows signs of problems with bonding between layers. Solid prints, like top and bottom-layer, are super strong, really impressive. Thin walled structures including the infill pattern seems a bit problematic though I really need to modify my printer to print at higher temperatures because polycarbonate seems like the ultimate engineering plastic to me right now.

I had to take my car to the yearly inspection yesterday and while they had some things to complain about they did not notice that the sway bar is attached by a 3D-printed link on one side. :cool: It was covered in dust though, not shiny as in the photo, so it is not immediately obvious. I printed this strengthened sway bar link two months ago after having two original links failing in about one year. I added a few millimeters in all directions and printed it with 100% infill. At first, I considered this as a temporary fix and a suitable way to test the engineering properties of the Ultimaker ABS. Two months later it still appears to be fine though, so I might just leave it as it is for some sub-zero temperature testing the coming months :smile: For safety reasons, I would not replace critical parts of the car with printed parts. Less critical part though, like this one which was breaking all the time anyway, was highly useful to be able to "upgrade" with a printed version :smile:

At first, I thought it looked like a great deal, but after reading the details I could not figure out what I would use the new filaments for. I am confused as to why they select to develop so many new filaments with such similar specifications. The product range in the kickstarter project somehow does not fit either as engineering plastics or as plastics for printing art. I completely agree that Taulman should sell colored filaments. That kind of semi-transparent look of nylon is really not that appealing. Although color is theoretically unimportant for functionality, I feel it would be hard to sell printed nylon components looking like that, even if the material would be superior. 3D Prima has nylon available filaments in several colors by the way: http://www.3dprima.com/en/filaments-for-3d-printers/nylon-filament-3mm/ The only filament in the kickstarter project that would have been interesting for me was the tritan, because of it's high Tc and strength. It is a bit odd though that they go for a material which needs 270-280C when most people are sitting with teflon-insulated printers. Something with slightly lower Tc and strength printable at 260C would have been extremely interesting I think!

I have done quite a lot of prototyping an production of small series of components for the lab where I work. I only use ABS, here are some reasons why: - The maximum operating temperature of PLA is a bit low for engineering purposes. - PLA is a rare plastic outside the 3D-printing community. ABS is well known, which makes it easier to convince people that the printed components are just as good as injection molded things (I usually mention that LEGO is made form ABS) - The reliability of my printer has been much higher with ABS. I had lots of issues with random underextrusion with PLA while ABS simply never causes me any trouble. It might just be something with my printer though. - The shrinkage of ABS it a minor problem in my case, since I almost exclusively print small things (less than 100mm diameter and 40mm height). I also generally end up printing a prototype which I then measure carefully to adjust the dimensions for shrinkage in the final print. - I am experimenting with manufacturing custom filaments and ABS is much easier than PLA to extrude into a nice filament with a cheap extruder. If you intend to print large objects which will not be subjected to high temperatures, PLA is a good choice though. ABS it tricky when printing larger things. To get a good result you have to think about how shrinking will affect the component when designing it. What typically does not work with ABS is to print a large box with high walls, sharp corners and solid bottom. I don't use my printer for such things though since I consider 3D-printing not the preferred technique for manufacturing a box. But if you intend to print boxes, go for PLA :smile:

Download the latest Cura here: http://software.ultimaker.com The UM2 firmware comes with the Cura software. Then connect your UM2 to the computer with the provided USB-cable, start Cura and select the upgrade firmware option.

Strange. My UM2 has always been extremely reliable with ABS but not very reliable with PLA. A few things that I have sorted out so far: - Upgrade to 14.07 firmware. The the new priming cycle eliminate grinding issues at startup and the leveling fixes makes regular leveling unnecessary. This upgrade probably reduced the number of aborted prints from 30% to 5% for me. The improved priming also made it possible to reliably print slightly large diameter filament, like Velleman ABS, which are close to 3mm. Before 14.07 the grinding when priming caused enough damage to the filament to get it struck in the bowden. You still have to be careful though not to get plastic particles into the bowden when using 3.0 mm filament. Even a tiny particle can cause problems. - Check that the feeder motor is properly seated on the frame of the printer. In my case it was sitting on a nut that holds the chassis panels together. This moved the knurled wheel away from the spring loaded bearing, thereby decreasing the pressure on the filament and increasing the risk of grinding. Check this video, it shows how far the bearing should be pushed in when inserting a filament: - Make sure the teflon spacer is properly seated. I had issues with the diameter of the spacer being slightly large, which meant the spring could not push it all the way towards the nozzle. If this happens when you print ABS, you end up with half-molten ABS between the spacer and the nozzle. This increases friction dramatically. Here is a picture:

Interesting! As I said previously, I was planning to do further tests with metal spacers. Time has been limited though since I need my printer up and running for my business too. However, I tried another cooled metal spacer which looks like this: Suprisingly, it worked fine with PLA from start. Then I realized the reason why it worked was that the spacer was pushed up because the spring I used was to weak. This meant a thermal barrier of PLA had formed between the spacer and the nozzle, helping to keep my metal spacer cool. Not the kind of solution I was looking for :smile: With a stronger spring the thermal load on the spacer was too much and PLA was softening inside it. I was actually thinking of adding a stainless U-shaped heat break like the one in Kris post but that did not happen yet. The main problem I would say is that the fan is so tiny, which puts extreme requirements on heat sinks if you want to stay below the softening temprature of PLA. I can only imagine what the Ultimaker-team has been going through trying make it work with two heated nozzles...

I have done some experiments with various metal spacer designs lately. The conclusion so far is that with ABS more or less anything out of metal will work as long as is it kept reasonably cool. PLA is a completely different story. I kind of consider PLA as the root of all evil after seeing what it does inside the spacer :cry: It is not so much friction that is the problem, it is the fact that PLA softens into a rubber-like state at very low temperature. When the filament softens like 10 mm inside the spacer and you put it under pressure, the diameter of the rubbery part will increase. This forms a very efficient plug, which seals better the more pressure you apply. It gets particularly bad when feeding a hot filament shortly after retraction This can easily be simulated by feeding a piece of PLA through a 3.1 mm metal pipe, then heating the pipe until the PLA softens and feeding it with the output blocked. As long as the output is not blocked the PLA passes through even in it's rubbery state. When the output is blocked though, it forms a very strong plug which does not let go when the output is open again. Pulling the filament with the plug out backwards is easy though. The teflon spacer solves this problem by having a surface slippery enough to allow pushing the rubbery PLA-plug through the spacer. I have some ideas for a metal spacer workaround which I will be testing the coming days. It is not an easy thing to fix though, it might not even be possible to solve. Much easier would be to use the teflon spacer only for PLA and a metal spacer for other high temperature plastics. This solution is probably not accepted by the 3D-printing community though since people gotten used to being able to print both PLA and ABS with the same setup.

I used the fins from an old heatpipe-based PSU heatsink and put them on an aluminum pipe which happened to have the right dimensions.. I had a spring that could be cut down to fit where the old spring was. Here are two more photos: The last photo is taken after five hours of printing. I thought it would be full of ABS by then, but it was absolutely clean. There is no guide for the bowden tube to align it with the hole of the aluminum pipe and I think it draining most of the available heating power from the nozzle when running at 260C. But it worked fine with ABS. I will try to improve the design a bit today.

I was inspired by the attempts to make a metal spacer so I came up with this thing today: It has been printing for five hours now with like 1000 retracts and has been working perfectly so far. (printing ABS at 260C) I will take it apart tomorrow for some improvements and inspection.

I had plans to let a local workshop manufacture a UM2 heater block that would accept UM1 nozzles a few months ago. Other things became more urgent though, so that project is on hold. Here is a 3D-model of the original components that I made: The UM1 nozzle dimensions are approximate. As you can see, the heater block will have to be a bit larger to fit the UM1 nozzle. It may be a good idea to increased some of the dimensions to improve the thermal conductivity to the nozzle too. You will need to drill a larger hole in UM2 fan plate too, to fit the nozzle. When I was thinking about this last time, I was a bit concerned that the tube that holds the hotend might not like the stress when tightening the nozzle. I don't know if this is a real concern though.

I have been using the latest firmware for some time now and it works really well. The improved priming works perfect for both Ultimaker and Velleman ABS and I can use filament which is close to 3 mm now when the grinding when priming is gone. I am also quite happy with the leveling, however I have one more question regarding this. The calibration cycle uses 0.05 mm steps for both the coarse and the fine tuning. Is there some particular reason not to decrease the step size when fine tuning to lets say 0.02 mm ? I feel that the mechanics of the UM2 is precise enough to take advantage of a smaller step size, potentially improving the quality of the first layer even more. 0.05 mm step size really is a bit coarse when using a 0.1 mm paper and printing 0.2 mm initial layers. Personally I would prefer 0.04 mm (one full step) for coarse tuning and 0.01 mm (1/4 step) for fine tuning.

I recently cleaned my happy corner, so here it is: It does not get more clean or organized than that. My wife seems to have no problem with that luckily :smile:

Hi! As I am waiting and hoping that the issues with the UM2 dual extrusion kit will be solved soon I have been trying manual filament change when print is paused a few times. It works okay but is a bit complicated with the original extruder. I was just thinking, could an automated function for filament change in paused mode be added? (In case some one here with programming skills is out of ideas) That would make the UM2 more interesting I think and could be quite useful for me at least. It would be convenient if the loading cycle ended in a non grinding priming until interrupted by the user, so that the nozzle could be properly cleaned. After that, a proper retraction of the filament to avoid underextrusion/grinding when resuming the print. I don't know if this is too much to ask, but I think it would be an interesting feature. Even in the future, with dual extrusion potentially working, it would be interesting since it would allow for more than two types of plastic in one print.