A friend of mine made me these super nice countersinks with a knurled aluminum shaft. To turn them into useful tools for manual work i designed and printed some hefts for them. For fun i did one in TPU, the other in ABS. Both work fine, but the TPU heft is much smoother and it’s slight flexibility gives a nice grip. The print quality of the TPU one is seriously much better, it was printed on the DuoCube, while the white one shows the Z wobble that my old machine acquired a few months back. I have to address that at some point in time, but hey, the machine is about 7 years old now and still pretty good for that.
Just a short post on the current state of compressed air cooling.
I am currently testing the Merlin extruder, i decided to name it in the same way as the hotend since the two belong together, which uses compressed air from an aquarium membrane pump (bubble pump). A medium size pump is sufficient for one hotend and one part cooler.
I made the mistake of ordering a larger pump than needed, which makes the printer unnecessarily loud due to to much air hissing out of the small gaps. On the up side, i might be able to push the Merlin hotend beyond 260°C with this. 🙂
This is something i wanted to do for a while. A handle, in this case a file heft, that is a mix of soft but tough material on the outside and hard plastic on the inside.
Like the bottle cap it’s ABS with TPU, but this time the ABS is the bulk of the piece. There are 2 perimeter shells of TPU around a 50% ABS hexagonal infill.
The heft weighs just 24 g, but is very stable with a smooth and grip friendly surface.
After some terrible experience with TPE i tried TPU. What a difference!
TPU prints super easy and gives you high quality surfaces and it is super tough.
Today my wife needed a new cap for an expensive cleaner, so i took 10 minutes to model one in C4D and printed it in TPU. The first print worked immediately, but i wanted to try something new. I set the TPU up together with ABS and printed the cap with ABS for the infill and TPU for the perimeter.
The result is very much worth the extra effort. The TPU gives a nice finishe and due to it’s elasticity it seals the bottle very nicely. The ABS gives the extra bit of stiffness so the cap does not deform so easily.
Next up is a file heft made up in the same way.
On the left printed @0.15mm Layer height with an 0.5mm nozzle on my DuoCore @210°C. On the right printed @0.2mm Layer height with an unknown nozzle @200°C on a friends i3. What is interesting are the differences in slicing, the left was sliced using S3D, the right one with Slic3r.
I was very positively surprised by the new GreenTec filament from Extrudr, that i ordered on a whim alongside a couple of kilos of my usual ABS.
Not only does it produce a nice matte finish, it prints without any hint of warp, the stability is excellent and it is a dream to postprocess with any kind of tool.
The only two drawbacks i found so far are that it sticks so strongly to the printplate (aluminum with 3Dlac @60°C) that damage to the part or printplate are a very real threat and the current price of €56 / Kg
I hope the price goes down over time, but even at the premium it might be worth it, especially considered that i don’t have to feel so bad about producing garbage prints since GreenTec decomposes neatly, different to PLA.
As it turned out, it was a lot earlier than expected that the silicone sleaves from this posting
Silicone Sleave for Merlin made the trouble worthwhile. Some peculiar behavior of Marlin lead to a thermal runaway for a couple of seconds at full power. The silicone, that is rated for 450°C deteriorated, but the extruder remains unharmed and even the hotend survived thanks to the new cooling.
For those interested, what happened was that while homing Z Marlin stopped working completely. Everything was frozen including menu and the PID for the hotend, which got stuck with the heater switched on. I haven’t found the reason for the behavior yet, but i’ll do the homing before the heating in the foreseeable future.
These two extruder bodies were printed in clone mode. The white one shows serious stribes that resemble Z wobble, but the blue one doesn’t. Since only X movement was different between the two it is either that, which i don’t believe due to the error existing on all sides, or it derives from the difference in the material. Interestingly the original setting was for the white material. If anything the blue one should show small signs of underextrusion since the filament diameter for that was smaller than for the white.
Interestingly the problem is uneven movement along z, not perpendicular to it.
On the RepRap forum the question came up how the Merlinb hotend is cooled when printing Polycarbonate @ 260°C
The design i currently use is rather simple, it focuses on cooling the lower part of the PEEK and guides the airflow as far around to the backside of the hotend as possible. Ultimately i would like to be able to press all air through a small gap at the lower end of the PEEK, but that is a tight fit given that the heater block needs to be insulated.
For testing purposes i bought a spool of the new Esun ePC polycarbonate from RepRapWorld. While not cheap it isn’t actually very expensive with €20 for 1/2 Kg. Given that the Merlin Hotend uses a PTFE inliner i was a bit sceptic if it would withstand the 255°C, but no problems turned up at all.
As can be seen in the images bridging does not seem to be optimal, there are even some holes in the top surfaces, something that did not happen with a simpler testprint before. Maybe a bit slower print speed (this one was done with 130 mm/s default in S3D) or maybe lower temperature will help. The stability is good, i destroyed an earlier print using a pair of pliers and i had to use quite a bit of force. Also noteable, the layer adherence was excellent, the part did not brake along layers at all.
Given the very good heat resitance (even better than ABS) i think i will find a lot of uses for machine parts, especially extruder parts since according to Esun the ePC material is not inflamable.
One thing to note, the ePC did not stick to glass when i used 3DLac, i had to print it with an ABS raft, easy enough with the DuoCube 🙂