Anders Olsson

Did you inspect other components for wear yet? I am curious since I did not print that much with glow fill yet, but my custom made abrasive filament had effects on several components: - The nozzle was worn down by about 1mm in height and the diameter increased to about 0.7mm after similar printing times as you reported. - The inner diameter of the teflon insulator increased to about 3.5-3.6mm (which actually seem to have reduced retraction related problems) - The knurled wheel got a bit rounded and the ball bearing has a rough surface where the filament is moving. - There might be some wear of the bowden too. I did not measure the diameter yet but the problems with oversize filaments I had initially are gone after I printed the abrasive stuff.

I managed to ruin a UM2 nozzle in a very similar way when printing abrasive material. What I printed was something I would expect to be much more abrasive than glowfill though, so I am a bit surprised your nozzle look lite that after just 40 hours. When my nozzle was ruined, I put it in a drilling machine and turned it using a file until the flat surface was reasonably small again. You can get decent printing quality even if your nozzle diameter is like 0.7-0.8 mm, as long as the flat surface is not too large. You have to measure the true nozzle diameter and generate new files with that one in Cura though. By the way, I am working on a UM2 heater block with interchangeable nozzles for printing abrasive stuff: http://umforum.ultimaker.com/index.php?/topic/7689-custom-heater-block-to-fit-e3d-nozzle-on-ultimaker-2/ Things are taking more time than I expected though, so I can not provide this heater block yet.

Daid, would you mind having a quick look at this issue before next release? https://github.com/Ultimaker/Ultimaker2Marlin/issues/42 (Just try once to print the UM robot at 99% flow) I tried to read through the code to figure out what is going on, but I am simply not good enough on coding to get anywhere.. By the way, I managed to trigger the temperature sensor warning numerous times with the latest firmware. I first thought it was related to that I increased the maximum temperature to suit my polycarbonate experiments, combined with the larger mass of my custom heater block. But then I got these temperature sensor warnings at normal temperatures too, which I did not get with previous firmware and my custom heater block. It typically happens if you start "heat nozzle" or "move material" when the nozzle is cooling down. The heater responds too slow so you don't get the 20 degrees of temperature increase in 20 seconds that has to happen not to trigger the temp sensor warning. I solved this by reducing the temperature increase needed to 10 degrees. This was really needed when operating at higher temperatures (300C) with the custom heater block, where the temperature simply increases much slower.

DonMilne >> Yes, a flat FFKM-gasket would be better than an o-ring, but flat FFKM gaskets seems even more uncommon than o-rings. I think a thin O-ring would work, since it sits very close to the heat block which means the plastic stays reasonable soft there. 3Poro >> I used a glass filled teflon isolator. The only pure teflon isolator I had ended up too heavily modified for further use when I fitted the temperature sensor to it. As I mentioned, I suspect one of the parts is not perfectly flat and that is why it was leaking, I will have a look into that. Polycarbonate is quite tricky. I struggled to get reasonable layer adhesion but my destructive testing always ended up in things coming apart between the printed layers. On the other hand, I tested an ABS component in the same way and PC printed hot was obviously stronger. Printing hot and slow seems to help and PC prints quite nicely actually. Drying the filament in an oven at 120C for a few hours improves printing quality a lot too. I think there should be a combination of tricks that prints PC nicely in the UM2, but I have to keep testing to figure the parameters out. PC printing is on hold right now though, until I found out why it was leaking.

I have been printing Polycarbonate at 290-300C for about 6 hours now with the Vespel insulator. I had to stop since there was a strong smell of burnt plastic and I had to find out what was going on. It turns out there was a leak somewhere in the Vespel-area which soaked my heater block in polycarbonate :cry: The leak was most likely caused by one of the surfaces not being perfectly flat. I will investigate this further. When taking things apart I noticed that the teflon spacer seems to have survived the increased temperature: The slightly burnt surface on the teflon comes from numerous hour of printing before cut 2mm of the teflon spacer to fit the Vespel insulator. If anyone else ends up soaking the heater block in polycarbonate, I found out that burning it off with a micro torch works well (obviously has to be done outdoors, with sensor, heater and teflon spacer removed) Considering Vespel, I think I just found another alternative that looks interesting. It is commonly known as Kalrez, Isolast or Perlast and chemically called "perfluoroelastomer" or FFKM. It is used for o-rings and some grades have continous operating temperatures of up to 327C (!) I think an o-ring like that might be the ultimate thing to put between the teflon insulator and the heater block. It will serve both as a heat break and as a seal, reducing both thermal stress on the teflon and reducing the risk of leaks of molten plastic. These Kalrez o-rings seems to be as pricey as Vespel though, and I had difficulties finding an o-ring with suitable size.

I am almost exclusively printing ABS and here is what I recommend: - Fans has to be off . The only time I use fans for ABS is when I manually switch them on when printing tiny details in the end of the print. - The provided glue was not really good for anything in my opinion. I am using "Tesa Easy Stick"-glue now and it works really good for ABS (and almost too good with PLA) - The glue has to be applied when the buildplate is cold and the layer of glue should be rather thin. - Z-calibration (leveling of buildplate) has to be done so that the first layer really gets 100% infill. I prefer leveling a bit close to make sure there is enough plastic extruded to properly stick to the platform. - When printing large objects, I cover the front of the printer to reduce temperature gradients. Apart from that I use stock settings. I don't use brim or raft anymore (fans off and Tesa-glue made brim/raft unnecessary). By the way, make sure your UM2 has the latest firmware.There were several Z-calibration bugs sorted out this summer which used to make leveling unreliable/difficult.

I did some more testing of the Vespel insulator tonight. Initially it caused me quite some problems with PLA, but this was mainly related to the fact that my teflon spacer had 0.1 mm larger inner diameter than the Vespel insulator which caused major problems after retraction. After I drilled it to 3.3 mm it appears to be printing PLA fine. However, I still have a feeling that the Vespel causes some friction with PLA and that making it thinner would reduce friction. I managed to get a molten plug of ABS to stick inside the Vespel insulator too. (before I increased the inner diameter of it) I was worried that the ABS would bond to the Vespel since it was sitting there for quite some time at 260C before slowly cooling down. But the ABS-plug came out easily and did not show any signs of bonding to the Vespel. So apparently Vespel does not bond easily to ABS even though it chemically is a kind of polyimide.

I pricked up the Vespel spacer today, thanks again 3Poro! To get some idea of how it reduces the temperature of the remaining teflon spacer, I modified an old teflon spacer (not glass filled) to fit a temperature sensor. This teflon spacer was in bad condition already before I modified it, and making room for the temperature sensor did not improve it :???: So I don't know how realistic this test was, but hopefully it should give some idea about the improvement. I printed the Ultimaker robot in ABS at 260C, but I had to abort the print half way through because I was lazy to level the platform and the robot came loose. Anyway, the temperature had then stabilized at about 80C. Impressive so far, I have to say!! The current teflon spacer has suffered form previous experiments and has an inner diameter of 3.5mm , so I can not really conlude anything about retraction with this one (it worked, but showed potential for problems). Next test will be to fit another glass filled spacer with normal inner diameter and crank up the temperature to polycarbonate levels :grin:

Thank you CecilieVF, that was most of the information I was looking for! I would still like to know more about the type of plastic, like which of the common solvents it can handle, UV-resistance, aging and so on. But I guess Formlabs is not going to tell us exactly what kind of polymer they are using. About the supports, how much overhang (in degrees) can you print approximately before you need supports? Printing objects which are truly transparent is interesting in fact, I have to look more into this.

The #2 would work fine for me, I am happy to have that one if still available. :smile: I will PM more info.

Time for an update: I had to keep the printer running lately so I did not have time to modify the heater block more past days. Two of my heater blocks are back in the workshop for improvements (waiting there for them to finish rebuilding the workshop) and one heater block is hopefully traveling south right now :?: :smile: That leaves me with the one I am using right now left. I have reconsidered the sensor fixing a bit, I think i will make separate cuts from the top where you can access the sensor/heater to help pushing them out if stuck. I had some concerns about heat transfer if I cut to much material though, therefore I did some tests this evening. With temperature sensors mounted close to the heater and close to the nozzle, also reading the UM-sensor, I printed the extrusion test and concluded some things: - As long as the fans are kept off, you can extrude ABS at 255C at 10mm/s and the nozzle temperature is within two degrees of the temperature reading of the UM-sensor. - Switching the fans on at 100% at 255C makes the nozzle temperature drop to about 248C at low (normal) extrusion rates. - If you push with the extrusion test at 255C and fans at 100% the power of the heater is not enough to keep the temperature. You end up with about 249C at the UM-sensor and about 241C at the nozzle at 10mm3/s (I don't know why anyone would run the extrusion test with ABS and fans at 100% though, but it it a good way of testing the heater) I think this means I will cut some more metal to improve the design, because thermal transfer seems to be reasonable. Has anyone been running the extrusion test at ~255C with fans at 100% with the original nozzle by the way? It would be interesting to know if the heater keeps up with the thermal load with that one. (I could mount an original nozzle myself, but I have a lot of things to do right now)

Are you by any chance printing at flow rates below 100%? There seems to be a strange bug in Marlin that does similar things to my prints if I go below 100%: http://umforum.ultimaker.com/index.php?/topic/7764-underextrusion-when-flow-is-set-below-100/ If this is not the case I guess something is wrong with your teflon insulator (deformed/too small inner diameter). Or your filament is too large or damaged from grinding.

I haven't had any problems getting ABS to stick to the platform since I started using the "Tesa Easy Stick" glue. Using the fans is risky though, so I generally leave them off. When printing large objects I usually cover the front of the printer as an extra precaution, to minimize temperature gradients. The glue stick works well for that purpose too as you can see

I really like the Form 1+ concept, but I am missing crucial technical details about the printed material. Has anyone seen specifications of the type of plastic, the maximum operating temperature of printed objects and the strength compared to ABS or PLA? This is kind of necessary information if you want to print parts for engineering applications.

Does the temperature drop when the cooling fans start? In that case your heater block may be sitting too low, touching the fan cap

Those "external shield" and "nozzle retract" -solutions look quite well functioning I have to say, but somehow a bit bulky and complex for me to really like them. What I had in mind is: Did anyone ever consider a valve inside the nozzle? I am thinking of something with the same operating principle as the thing old diesel engines has inside the fuel injectors. Of course we are dealing with plastic which even if really hot is much more viscous than diesel. But if I calculated correctly we would have up to about 70-80 bars of pressure inside the UM2 nozzle (?). So using a few bars for opening a tiny valve seems reasonable. It would be a tiny thing and it would make nozzle cleaning more or less impossible though, so I guess Ultimaker would have to adopt the heater block with exchangeable nozzles.

That stuff is highly interesting! I wish I had the skills to find this kind of material. I have been spending quite some time looking for plastics but my google skills are apparently not good enough :sad: The Celazole Pbi appears to be exactly the kind of material you would like for the thermal insulator. The non-stick properties might even mean you can get away with the whole insulator made in this material even for printing PLA. As for the Vespel, I was reading a bit about it an it worries me a bit is that it basically is a polyimide, just as Kapton, and ABS is well known to stick very well to kapton. But maybe Vespel is different somehow (?). Anyway, I am seriously considering ordering a piece of Celazole Pbi now.. :smile:

I did some destructive testing on an ABS object which I had heated on the heated bed to 90C. While it still feels solid at 90C, it permanently deforms rather than flexing when you put some load on it. So I would not use Ultimaker ABS above 80C. I would love to have ABS that keeps it's mechanical properties above 100C but I doubt that you can buy such ABS as a printable filament (?) Polycarbonate is what I aim for when it comes to printing objects that can resist high temperatures.

I wanted to test the Ultimaker Original nozzle because it is rather large compared to other nozzles, probably among the largest M6-threaded nozzles there is on the market (?). So if the heater can keep up with that one there is possibly a whole range of M6-threaded nozzles from different manufacturers that would work with this heater block. The nozzles look a bit different inside, which might affect things like oozing, so it could be useful to have a range of designs to choose from to improve a future dual extruder upgrade for example. Initially, I designed the heater block for the Ultimaker Original nozzle, but I then changed my mind in favor of the E3D-nozzle, so was curious if the original plan would have worked too.

I tried with retraction off and it behaves exactly the same way, so it has to be something else. As I said, it happens when the flow is reduced because the head changing direction often. It then more or less stops the feeder instead of slowing it (of flow is less than 100%). I like the flow setting because it can be adjusted on the fly. That way you can optimize the flow for a particular filament first time you print with it and get a really nice result at first try.

I am happy to announce the brand new Ultimaker 2 Original :smile: :smile: Thank you Daniel at 3Dverkstan for the nozzle and other useful parts. To my surprise it worked quite well with the much larger Ultimaker Original nozzle. I tested heater by setting the fans at 100% and increasing the temperature to 260C. It managed to reach 260C and kept the temperature stable, but it was obvious that I was using most of the heating capacity then. There seems to be quite some interest in this design, so I will try to get a final version manufactured and tested. This will take a few weeks though, for various reasons.

I made a very simple test today to confirm this issue: What you see is how the extrusion is suddenly not working properly when flow rate is decreased from 100% to 99% The feeder motor more or less runs on/off, meaning the motor stops when the head is changing direction often and flow should be reduced. I will put this issue on github

Funny, I have been thinking a lot about designing some kind of valve like this lately. As you say, it seems like the only way of solving the oozing problem permanently. It might not be as difficult to design a valve like that as one think actually, the pressure it needs to handle is very slight after all. I wonder how Stratasys solves this problem by the way? Maybe one could sneak in and spy a bit at one of them at work.. :smile:

I have a number of things I would like to test with dual extrusion, but need it to be fairly reliable to be interesting to me. The ability to use two colors in the same object is interesting of course, but that is not the main thing I have in mind. More interesting is when you think of for example having transparent and non transparent plastic in one print. And much more interesting if you could use conductive and non conductive plastic. For practical uses you would prefer much lower electrical resistance than the plastics you can currently buy, but I think such plastic can be made with the right ingredients. Combine that with printed threads and printed springs and things starts to sound really interesting to me :smile:

I never remove the nozzle if it is blocked. Instead, heat the nozzle and push a wire from a wire brush inside the hole from below to clear it. Manually feed new filament through the nozzle. Repeat until the filament is flowing freely. If there is something that repeatedly blocks the nozzle and can not be pushed out, I usually use nylon filament (Taulman Bridge) . Push it through until there is nylon flowing through the nozzle. You will have to use the wire-brush wire to unblock it repeatedly. Then lower the temperature to 140C as you continue pushing filament through. It will stop flowing around 190C. When the temperature has been stable at 140C for a few minutes, gently pull the filament out. You will then get residual particles from inside the nozzle out. If your nozzle is severely contaminated you will have to repeat a few times. If you for some reason still can not clean the nozzle, I made a video of how to take the whole hotend apart: