alaris2

I'll second that. and probably a carbide bit is a good idea anyway. the work hardens very easily and then becomes impossible to drill - I found going slow was a really bad idea on some test pieces. I've ordered some carbide bits and a reamer too for good measure, I'll see what happens if I open the tube out by 0.1mm. meanwhile I now have a config 3 - E3D nozzle, E3D SS section, UM V1 heater block and heater, E3D cooler block. This is a totally V2-less solution for those wanting to go straight from V1 to V3. I've improved the fan design slightly and will post some pics shortly. I think I'll stick with the 'hanging' bowden solution since it seems to work better than expected. (I can even get the calipers in there or a marker pen to color the filament as it goes into the nozzle!)

another thread died of googlitis huh? a shame because this forum is so much better, but there are still a dedicated bunch of pros here Ian and with your enthusiasm we'll wind up making a totally new and better UM, which they'll never even know about cos they didn't read this forum

you're right to ask questions - and it's time for a hastily drawn cross-sectional sketch to explain! yes the bowden is floating above the nozzle in this config (config 2). in config 1, I used that metal collar piece and threaded the bowden into it, but when I broken the bowden it was too short so I borrowed an idea off a sketch you made - thanks for that! in config 1 I used the stainless steel threaded section. I believe this is crucial, but it had a 3mm ID which gave a lot of friction. manual extrusion was *very* hard. I switched to the UM v2 brass section in config 2 and it conducts heat up to the cold end faster than my little v3 fan can remove it - it wasn't designed for that. I could put a larger heat sink and fan on I suppose, but that increases the weight. I'd prefer to revert to the v3 SS piece - anyone have facilities to ream out stainless steel to 3.2mm for me? the reason for preferring this config is that after about an hour of printing, the top of the cold end block was getting close to 50C (ambient was 19C) which would have spelled disaster, except that I noticed PLA leaking between the v2 nozzle and threaded section (which I thought wasn't supposed to happen!!!) so I caused my own disaster by taking it to pieces to fix this and then promptly snapped the brass nozzle. ho hum. kisslicer tells me my current 'max speed' settings are : perimeter = 50mm/s infill = 70mm/s sparse infill = 100mm/s I haven't changed these settings in ages now so they're the same I used for v1 and v2 hotend testing. in summary, yes you're correct, you need an al. block for a cold end, with a heat sink and fan - no water cooling or lathe or other exotic tools. tho you will probably want a drill and tap/die set. BUT - I'm pretty sure you want that SS piece too. otherwise your printing time is limited by how fast you can remove the heat and heat prefers to travel up the brass tube not down to the nozzle.. the SS part is what attracted me to the E3D solution in the first place (since I have no hope of manufacturing that part myself)

Aha, thanks Joergen! taking it to pieces wasn't a problem but cleaning the PLA out from inside without scratching or damaging the internals was what was giving me trouble. I'll try some q-tips tonight!

I saw someone having problems with re-using a heater block with the new hotend but there was PLA on the threads. I also remembered reading an excellent article from Bertho about dissolving PLA with caustic soda. I think I remember someone suggesting to use this method to clean the parts prior to assembly. I just thought I should mention. don't try this. I forgot aluminum reacts big time with caustic soda and put the v2 hotend in the ultrasonic bath.. on the plus side, I have enough hydrogen now to power a fleet of fuel cell cars.. any safer ways to remove the PLA welcome (just heating it doesn't seem to work very well when it's stuck in nozzles and threads)

Success!!! I've been trying different configurations - here's an early version I tried, it's a hybrid between v2 hotend and the E3D metal hotend. It worked, but I broke my bowden by overthreading and the pressure required to extrude was astronomical. this was due to the ID of the stainless steel being 3mm instead of 3.2mm (as used by UM). So I switched to a slightly different configuration, with a floating bowden (since it's not long enough now to reach) similar to destroyer's setup. I removed the collar and switched to the brass UM threaded section for now. It means having to run the fan flat out to stop it overheating, but it works very nicely. complete success at max speed on first attempt (altho I did have to manually adjust the bed because I forgot to re-level it!). time for a bit more calibrating and tidying up.. I've already taken it up to 320C without trouble but I need to sort the fans out before trying nylon.

I confess I'm not sure either, but I think this thread will get really confused if we have so many hotend designs on it. no offence intended wakileh but do you think you could start a new thread on this one?

I can offer you all the assistance you need with k'slicer if you like. as far as I know, netfabb doesn't support retraction properly anyway so isn't the flavor du jour. whilst fully capable of making the mods myself, I have no bandwidth to do them right now until I have my new hotend sorted and I think some 'instructions for dummies' might be a really useful contribution to the community anyway. drop me a PM if you like and I can send you some screenshots. it's generally easiest to solve these problems visually. nik

it worked, but it could work much better. short story is that I asked for a 3mm version, but forgot the ID of the UM nozzle is actually 3.2mm. for thick filament there's a fair amount of friction therefore so I'll try and buy a reamer or something tomorrow and open up the holes to 3.2mm for a smoother print. I did get filament to come out, but it was a struggle by hand (didn't help my filament was 2.95mm tho)

this was next on my list of things to do actually - please do share more details. I've been wondering for a while what the purpose of the short belts is - direct drive seems a far better option. presumably the cost of the resiliert couplings is the only reason against it?

for the benefit of others - it's http://e3d-online.com/#/featured-products/4567186833 yes, they need to increase their presence on the web, but they are very new. you'll want the 3mm version of course (unless you want to experiment with 1.75mm filament) I'm hoping they'll start stocking other useful parts, nozzles, maybe even filament soon - it would be good to have a UK source of 3D printer parts. I'm about to test the full metal v3 hotend next. I waited all week for heat sink compound to arrive and now realize I need an M3 tap - but I can't wait any longer. I tested the UM v2 hotend most of the week, results were OK but nothing spectacular. it didn't pop the bowden or plug, but then neither did my v1 ever do that. so whilst it's not worse, it's not demonstrably better either. One thing I did notice - the v2 hotend seems to require more pressure to force the filament through? I've had to up the steps per E slightly to get decent prints and unfortunately I still get occasional variable print quality (as I did on the v1) which I was optimistically hoping would just fix itself. oh well. some photos in a few hours when I've done some prints with v3 for comparison.

destroyers solution is a slightly more elaborate version of what I had before going for the v3 metal hotend - it works quite well!

i tried 123d - it takes about 5 weeks to load and 5 minutes to crash. looks good until you try to use it in anger and find it does everything in a very 'autodesk' way. great if you're used to using those apps and have that mindset but not at all intuitive for real people to use :( alibre looked really good when i tried it this morning, but fails at one of the first hurdles - I can't load .stl, .obj. 3ds, in fact any of the files that I have. so i have to design everything from scratch again..

they were offering solidworks free to US students (which is no good since I'm not one) but that offer has now finished. not heard of alibre, it does look good however so i'll trial it. thanks Owen.

I too have noticed that the E setting isn't as useful as it might seem. in another thread I lamented the fact that I have to set it to >900 to avoid under extrusion and as speed increases, almost set it to 1040 to ensure a decent print. tests with the v2 hotend have so far shown i need slightly higher than usual numbers to achieve equivlaent quality prints - this basically means we are ramming filament into the hotend faster than it should be able to come out, yet not doing so always underextrudes. nobody has been able to explain why this is. (Daid did manage to very neatly explain why it shouldn't be, but this doesn't match my observations)

I've been exploring this same thread myself. freecad will be awesome in about 10 years time. but it's far from useful right now. lots of 'todo' and 'experimental don't use this yet' bits included. it does appear to identify and possibly correct damaged stl files (like netfabb) which might make it a suitable replacement for that at least. sculptris is good for organics probably, but can you easily make something like a box your projector might sit in? ie. a square with circles cut out of it etc. at precise locations? booleans usually fail in modelling packages and this has been the biggest limitation so far. hexagon (daz) is quite good, but booleans have issues. it is free tho. sketchup does the 'projector box' example quite well, but fails when it comes to curves and other non-box shapes, also a bit iffy on booleans and stl export. solidworks would be great. except it's too expensive to even consider.

layer height affects layer adhesion. for PLA and ABS you need to sqwish the layer into the previous layer to get adhesion which limits your max layer height. if the nozzle is 0.4mm, you might get away with 70% of that as max layer height (0.28mm) that's not far off the numbers tinsoldier and you yourself have already found. personally I use 0.24, 0.16 and 0.08 depending on the quality i'm after. i've run prints at 0.05 but it takes forever..

in all honesty, if you've used a Stratasys then this is worlds apart. this is a machine for engineers, not people who want trouble free awesome printing experiences. sorry UM but it's true at least for now.

before we all get excited, I'll remind us of Daid's words earlier today regarding maximum speed and actual speed and the telling phrase "a small model"..

I see a lot of people using solidworks - but isn't it ultra-expensive? do they have a free version available or something?

I hadn't spotted the arcol hotend - nice work but probably not suited for extruding nylon (which is where I'm taking this hotend) at 320C. the use of heater resistor is very common in the reprap community. I haven't worked out the wattage to see how it compares with the 40W heater cartridge but I note the heater block is smaller in all cases (to match the size of the resistor). that seems to suggest a limit to the maximum speed which would figure since repraps tend to run at slower speeds. having said that, the E3D boys mention 100mm/s which is nicely in UM territory, so maybe not? but their filament is usually 1.75mm, so maybe so.. at any rate, they've done calculations and tests with this hotend, so it's not total guesswork and their approach to design and test was not unlike Bertho's which was why I liked what i saw. I did look at ceramic and liked the idea, but the availability and machinability were issues - not all of us have the access to, or tools to work with exotic materials. the good thing about the stainless steel heat break is it doesn't conduct much heat (as snowygrouchs numbers show) so the heat from the heater block mostly goes to the nozzle. what little goes up is removed by the fan (which is a puny 0.09A 30mm type, it's not going to shift much air), so I *think* the increase in current draw is going to be minimal, certainly compared with the benefits - I'll find out for sure very soon! I should add, that in my costing above I include shipping and tax (ie. total price) to get the hotend to me in the UK. so it's 56 euro + about 18 tax and 29 shipping + paypal charges = £100 the E3D hotend is UK based and they include tax and shipping in the £50 price. they say they will ship anywhere at no more than the minimum shipping charge for that country (ie. no surcharge). today I constructed the v2 hotend and to UM's credit it went together very easily apart from the clips and bowden tube which were a bit fiddly. i did heat up the v1 hotend before removing the cartridge tho, after hearing someone had problems with the wires breaking off. no problems to report on my side tho. first print with the new hotend and.... yes it prints. OK but so did my v1. nothing dramatic to report I confess but I'll need to do some more scientific tests to show if it's 'better' in any way. if anyone has any requests for thingiverse items to print (not 50hr prints or yoda heads please then I'm happy to consider them and I'll post the results from the v2 and v3 heads here. I also constructed the E3D v3 head. I made one small mod to the unit as supplied by E3D - the reprap boys use a direct drive extruder, so I tapped the collar of the hotend with an M6 to fit my M6 threaded bowden tube (made that mod while it was being used with the v1 hotend and for those who haven't threaded their bowdens - I can highly recommend it). I'll take some photos in the next couple of days - I've just ordered some heatsink compound (might as well do this properly) to make sure heating and temperature readings are more accurate.

so UM took a long time getting the v2 hotend to us, and worse than that, we had no engagement with the community, no prior warning and there were lots of grumbles and complaints about popped bowden tubes etc. for months and months. then destroyer set up a very good thread as a wishlist for what we really wanted the hotend to do and I, for one, wanted to print with something a bit more exciting than PLA anyway. I have been watching an interesting thread develop in the reprap forum regarding an all metal hotend, and decided to talk to the inventors and persuade them to do a 3mm version that would be UM compatible (the original was 1.75mm). They did this and at exactly the same time UM promptly released the v2 hotend. several people have still been grumbling about the high cost of the v2 hotend, the fact it doesn't address all of the problems and the fact it doesn't come with heater or thermocouple (ie. can't be used as a 2nd extruder since you have to disassemble the first to reclaim some of the parts). I was disappointed to see the continued use of the PEEK part and no active cold side (I do like snowygrouch's solution - see viewtopic.php?f=6&t=1368) anyway, to cut a long story short, this is what's sitting on my workbench right now... top left is the v1 hotend, for comparison only. bottom left is the v2 hotend as supplied, cost approx. £100 from UM, right hand side is the UM compatible 'v3' hotend from E3D, cost £50. note they use a resistor for heating (which I'll replace with the superior UM heater cartridge to maintain the print speed). height is the same as the v2 hotend, heat break is stainless steel, top heat block is actually an active cold side and there's a 3mm polished hole down to the nozzle which is a 0.4mm in this case. Phut and I had an interesting discussion on printing with atypical materials - with an all metal hotend and active cooling, there's no reason why you can't print nylon, PC, perhaps even ptfe? at any rate, you're no longer limited by the hotend, but by the physical properties of the materials you wish to extrude. I'm about to put all this together and will then do some side by side comparisons of the 3 hotends if anyone's interested in photos or more details?

I've done that too, and I invented fluff and string but I have to say that's an awesome photo for marketing purposes - just needs a catchy slogan now

nice solution snowygrouch. I've been working on a similar 'cold end' myself and found the results to be excellent.

some more +1 for Bertho's extruder. it's an excellent piece of work. and Bertho's pic has a panda in it, everyone loves pandas. seriously, Bertho's mod is the only one that has survived the test of time on my UM. many other 'upgrades' started looking good but wore out or fell to pieces when subjected to the tests of time. PS. why is your octopus on fire?