Chasing Titans – Upgrading the UMO+ to direct drive

After nearly five years of fun-tastic printing and extremely reliable service, I could feel that the time had come to upgrade the extruder of my trusty Ultimaker Original Plus. The extruder on this machine was always the one part that I was not 100% convinced about – after first assembling the kit in 2013, I had some trouble in getting the large nut holding the main gear to stay in place, with the result that once or twice the whole thing fell apart during a long print. I also always detested its location at the back of the machine, the clattering, tortured, noisy retractions, and the fact that I would frequently struggle to insert filament because it got caught on the rim of the bowden tube connector. However, after initial teething problems, I had made my peace with it – the nut stayed on, I got better at guessing the proper angle for inserting filament, and the printer was reliably producing very good quality prints, despite my sometimes punishing retraction settings.

However, this autumn I began to notice a different type of problem to emerge. I had experimented extensively with relatively abrasive metal filaments this summer, and as a result the delrin wheel pushing the filament into the extruder had become worn in places. While ordinary PLA and ABS were still extruding relatively reliably, printing flexible filament became nearly impossible. A bowden setup is not the best for this type of filament anyway, and so I began thinking about upgrading the extruder assembly to a direct drive setup. I had heard good things about the E3D Titan Aero as an upgrade for Ultimaker printers (the UMO+ has the same electronics board as the UM2), but I was not quite ready to change the hotend and fan assembly as well. Besides, my current hotend is still performing brilliantly, and as it is the UMO design is fully compatible with the exchangeable nozzles sold by E3D, should I wish to change the diameter I am extruding with at any point. If I am ever going to make that switch, it will be to a 3 or 5 colour mixing Diamond Hotend – but at this point my thinking is that I should really build a new printer to experiment with that setup.

Instead, I looked at just mounting the E3D Titan extruder directly on top of the printhead. There are a few interesting designs for doing this on Thingiverse, but none are for the UMO+ and its slightly chunkier printhead. I ended up remixing Nakwada’s UM2 design, by adding a chunkier baseplate with slots for the original wooden parts of the hotend and a hole for the cables to pass through. You can find the stl file of my modified design here, which I ended up printing in fluorescent blue ABS. Two problems I encountered were the printed part being slightly warped, and some of the holes being a bit snug, but neither mattered for the final assembly. I reassembled the extruder and hotend around it, taking care to insert the two long screws underneath the motor and extruder before screwing everything in place. The trickiest step was probably gauging the right length for and connecting the piece of bowden tube – I ended up also ‘funneling’ the bit going into the extruder a little, to facilitate filament insertion. When ordering the Titan make sure you order the mirrored version, as this will not interfere with your endstops on the UMO+, and you will only lose a minimal amount of build volume.  I also took the decision to order the matching pancake stepper motor at the same time to keep the weight of the assembly down. This needed to be re-wired with a JST ph4 terminal in order to fit into the UM main board. After scrutinising the schematic of the motor for ages, I eventually figured out that the colours of the cables matched the original extruder motor’s and paired them in the AABB (blue/red – black/green) configuration required, which so far has worked perfectly. I cannot overemphasize how useful it is to learn all about electrical crimping – see my tutorial on this to get started with it.

With everything back together I checked the E-steps setting on my machine. They were already at the recommended value, although I am not totally sure why. My former stepper motor had a stepping ratio of 1.8 (but was also geared) whereas the little pancake runs at 0.9. At 837 steps/mm, I am getting great results, so I’m not complaining, but I think I need to look into this a bit more to really understand. Thomas Sanladerer has made a great tutorial about this that might enlighten me a bit. Another setting that had to be adjusted can be found in Cura. Because of the much reduced filament path, retraction settings of between 0.5 and 2mm are the recommendation, versus my 3.3mm setting before the switch. I am getting very clean prints at around the 1mm mark, and will hopefully be able to reduce this even more as I become more familiar with the extruder – fewer retractions mean a cooler motor! I also modified my end gcode to not reverse the filament as much after finishing a print – 1mm should be enough to alleviate the pressure. Reversing it by the default 5mm got me into serious trouble as the still-molten filament was pulled right to the top of the bowden adaptor and solidified in a tapered lump, causing a blockage that meant I had to disassemble the whole extruder!

A few issues with the Titan I have run into so far were mostly related to the dreaded clicking/missing steps scenario discussed by many other users in the E3D forum. I am not quite ready to do the rather drastic modification suggested by one user, and for the moment reassembling the extruder really carefully to make sure the gears mesh absolutely perfectly and tightly seems to have done the trick. I am on my 3rd print currently without any problems, but am slightly worried about some of the ‘budget’ filament I own, as it is often 3mm rather than 2,85mm, and even the top notch Faberdashery filament I love to use (and is very precisely specced) seems like a tight fit. After printing the current batch of Christmas decorations, I am yearning to finally try some flexible filament and hopefully see amazingly clean results.

So what are my final thoughts on the Titan modification? It is too early for me to say whether I will love it or loathe it. My old extruder was definitely ready to be replaced, but I need to do some more testing before delivering a definitive verdict. I want to try as many different types of filament and really put the new boy through his paces.I think dealing with clogs could be a bit of a nightmare, but then I haven’t really had many of those over the years – maybe 2-3 per  year. It is clear that some of my processes will have to be modified, such as cleaning out filament from the hotend, and changing filament during a print. I will also have to revisit my spool holder – it might make more sense to have a mounted reel holder now to reduce stress on the filament.

Modifying the printer wasn’t as gruesome as I imagined, and so far everything is working well. I was more than a little surprised to see that the teflon connector in the hotend still looked like new – I had my spare one to hand, ready to replace it. I have been very careful in using my printer over the years, particularly taking care to not run it too hot, and it has clearly paid of.

I hope you enjoyed this account of my experiences  and would love to hear your thought on things you are planning to modify!

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