TagMerlin

Some practical stuff

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.

Black: Hard TPU, White: ABS

New GreenTec Filament from Extrudr

GreenTec 02 GreenTec 01 Greentec 03

 

 

 

 

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.

biodegradable plastics

Thermal Runaway – Silicone cover to the rescue

Silicone Cover after Thermal Runaway

Silicone Cover after Thermal Runaway

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.

Esun ePC and the Duo Cube

ePC Benchy01 ePC Benchy02

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 🙂

Testing the Duo Cube – 50% Benchy

Duo Cube printing a 50% scale Benchy @ 0.02mm layer height

Duo Cube printing a 50% scale Benchy @ 0.02mm layer height and 0.2mm nozzle

Trying to print a 50% scale Benchy with a layer height of 0.02mm. A first test to print a M4 screw did work, the screw was functional and stable, showed that there might be a problem with bridges and steep overhangs at this scale. Als Top Layer don’t close easily.

This time i try it with a maxium speed of 40mm/s instead of 20.

 

Edit: As it turned out, overhangs and bridging don’t work at all. I have to invest a lot more time in determining a working setup for this,

Silicone Sleave for Merlin

After i did the cover that you can mold around the Merlin heater block, i wanted to make a sleave that can be put over the heater.

The mold comes in three parts, just drill up the holes to 3mm and assemble the parts with M3 screws to hold them tight. It is strongly recommended to use PTFE spray or other any other separating agent. The resulting sleave has a thickness of 1mm and can be easily ripped.

I recommend printing the mold in high quality to get a smooth surface, the silicone will show every small fault of the print.

MerlinSleave03 MerlinSleave05 MerlinSleave04Heatblock Sleave 03

Silicone cover for Merlin Hotend

Thomas Kramm from Hackerspace FFM created some nice Silicone sleaves for the Merlin hotend. Since he uses different heating elements than I, he uses shorter ones that I currently don’t have, I created an own version of this cover.

It protects against blisters 😉 and will reduce the amount of heat lost during print. With the cover the already printed parts will not be exposed to the heat as much as without and you can be a lot less discriminate with material cooling.

You can find the STL for the mold attached

I used silicone meant for tin molds, it holds up till 450°C and i think it will last quite a while at the <300°C it is used in this case.

I used Troll Factory Type 3 silicone

 

 

MerlinCover01 MerlinCover02 MerlinCover03 MerlinCover04 Heatblock Cover

Material Test: FPE Shore 40D Naturel

mat_FPE01First test print with FPE Naturel – Shore 40D
The brown border at the bottom is residue from printing Lay wood before. It turned out that this residue made the FPE stick nicely to the plate, later tests with pure FPE did not work as nicely.

Filament Diameter: 1.71 mm
Nozzle Diameter (Set): 0.2 mm
Nozzle Diameter (Used): 0.2 mm
Nozzle Temperature: 215
Bed Temperature: 100
Bed Surface: Aluminium with Water/Woodglue (3:1)
Layerheight: 0.2 mm
Infill: 100%
Perimeter Speed: 5 mm/s
Infill speed: 7,5 mm/s
Retract: 3 mm

Material Test: Laywood Cherry brown

mat_LayWood01Filament Diameter: 1.75 mm
Nozzle Diameter (Set): 0.2 mm
Nozzle Diameter (Used): 0.2 mm
Nozzle Temperature: 200
Bed Temperature: 50
Bed Surface: Aluminium with Water/Woodglue (3:1)
Layerheight: 0.2 mm
Infill: 100%
Perimeter speed: 30 mm/s
Infill speed: 60 mm/s
Retract: 3 mm

Material Test: Taulman Nylon 618

mat_Nylon618 01Filament Diameter: 1.78 mm
Nozzle Diameter (Set): 0.2 mm
Nozzle Diameter (Used): 0.2 mm
Nozzle Temperature: 245
Bed Temperature: 100
Bed Surface: Thermoplast (Warp)
Layerheight: 0.2 mm
Infill: 100%
Perimeter speed: 20 mm/s
Infill speed: 60 mm/s
Retract: 3 mm

I have a really hard time getting the Nylon to stick to anything. So far it only stuck on a piece of thermoplast i had laying around, but the plate gets damaged when printing and the Nylon isn’t sticking very good and warping as you can see on the image.
Later i got better results using gluestick (PVA glue) on Glas, for bigger prints this remains a problem though. I found that Whale Tufnol sticks extremely good, unfortunately so good that you can’t remove the part without damaging it.

 

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