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Tuesday, October 30, 2012

Wood filament becoming brittle after a while

Wood filament now brittle, lost all its needed flexibility !

When I started printing this morning with my wood filament (~2-3 week old), all kinds of filament issues appeared, while I had almost none before. I soon realized that the filament now is much more fragile than one week ago.

First I though I had temperature and clogging issues, since I was testing my plugin for simulating wood grain.

Update: seller answer, see end of post.

But then, I cannot bend it more than 20° before it breaks. In fact, it breaks and stacks on itself in the filament feeder, just after the bolt in the small gap before it enters the bowden tube. I checked it had the usual longitudinal pressure. But I even broke it once pushing by hand into the bowden!

For some reason the physical properties of this filament changed. May be the temperature contrast made it suck some moisture or whatever (temperature in the room suddenly fell to about 15° at night, while it is 25° on daytime). Anyway, at the end of the day when I came back to print some more, and after I made sure that my nozzle was clean, and I just realized my wood filament is simply no more usable at all.

So what, shall I trust this filament?

For now, I heated it a bit,  sealed it in a bag with dessicant, and I will check later if I get better results. I also have another piece of filament that I broke accidentally sooner in the day that may be better.

Sadly, this is a real show stopper for me. I was to print some parts for business, and I cannot assume such a risk, especially given that this filament is permanently out of stock, hence I cannot buy some "fresh one" quickly.

In any case, I suggest you take much care of yours and keep it sealed. May be this filament deteriorates with time also, I just don't have a valid explanation here (has anyone a clue?)

Update: yes I should trust it - seller's tip!

You can "re-soft" it with a hairdryer (80-90°C), than you can bend it better. If broken you can weld the ends together. Please store the filament in an open! bag, not neccessary to dry the filament. Wood loves humidity.

I am not sure that it would fix the lost elasticity in the long term though (I did not try yet). At this stage I could add a pre-heater before the bolt in the feeder... No easy fix.

Anyhow, I gave it a try: I put all my wood filament in a big cardboard box together with a small air heater, until the filament was softer (and before it melts, obviously). This took 3-4 minutes.

This really improved printing for the day (temp was about 15-20°), even though the plastic seems to stay more brittle than before. What I did is double check my settings, and made absolutely sure I was not over extruding, else it failed the same way. This is a good practice anyway, but I like to be very slightly above than what's needed to make sure my layers are really welded to each other.

Happy bird again, though one layer did not stick fully to the next and it had to be glued !
I used one drop of cyanoacrylate on a piece of paper that I sled in between the two layers

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If you know me and you cannot tell exactly what my real job is, then you probably found the right Jeremie. Check for some pointers.

I am self-employed and I help start-ups, research centers, small companies with their needs related to computers, maths and mechatronics. If you have a project and know what "R&D" is, then you already caught my interest ;)