Filament Splicer

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Filament Splicer

Postby pyronaught » Fri Apr 07, 2017 6:57 am

So I FINALLY got around to figuring out how to build one of these! It was harder than you would think it would be. The two issues here is that 1) heat has to only be applied at the two ends to be connected and nowhere else and 2) how to get rid of the excess plastic that mushrooms out when pushing the ends together. What finally worked is compressing the joint immediately after melting them together in a precisely aligned mold that has an exact 1.75mm channel in it that perfectly fits the filament and squeezes out the excess plastic into a thin set of wings that are easily trimmed away with an exacto knife. Note that this is a good use for Mic6 plate scraps if you ever made a mic6 plate, as the super smooth, flat surface is ideal for the molds parting surface.

The next step is to motorize the spool winding, as hand winding thousands of feet of filament from one spool to the other is time consuming and tedious.

splicer1.jpg


splicer2.jpg


splicer3.jpg
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Re: Filament Splicer

Postby jferguson » Fri Apr 07, 2017 2:25 pm

I'm reminded of a 1970s Braun Super-8 movie film splicer which ground mating chamfers on the two pieces of movie-film which were then glued together while clamped in position.
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Re: Filament Splicer

Postby pyronaught » Sat Apr 08, 2017 2:28 am

jferguson wrote:I'm reminded of a 1970s Braun Super-8 movie film splicer which ground mating chamfers on the two pieces of movie-film which were then glued together while clamped in position.


Ha, I used to splice super-8 film back in the 80s with a machine like that. There was a viewer screen built into it too so you could watch frame by frame as you scrolled the film by.
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Re: Filament Splicer

Postby pyronaught » Mon Apr 24, 2017 7:47 am

Interesting phenomenon: I had a bunch of partial Hatchbox orange PLA spools that I joined together into one full spool. This particular color seem especially sensitive to moisture and becomes very brittle once exposed. So brittle that the tiny bit of preload from being spooled is enough to crack it. So in transferring all those smaller rolls into one big one, the entire length of filament became exposed to the air momentarily. Well, two days after making the full roll it just started shedding pieces of broken filament as they started cracking. As each piece cracked, it allowed the filament behind it to unroll a bit, exposing it to more air, and then it would crack. This cracking and unrolling kept propagating into the roll until the entire thing just shed itself to pieces! I wish I took a picture because it was just bizarre looking. Luckily only that one brand of orange seems to do it, all my re-spooled grey and black rolls are holding up fine.
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Re: Filament Splicer

Postby sthone » Mon Apr 24, 2017 3:20 pm

They say you can put the spool in the oven at low temps (I forget the temp/time) to dry them out or I've heard of people using food dehydrators too and it will keep them from breaking like that.

I think the way you store it can make a difference but like you said some filament is just prone to moisture. All of my filaments are store in gasket sealed tubs with desiccant packs... I have an original roll of white Makergear filament that I bought with my printer 3 years ago that to this day has zero issues then I have several rolls of Prototype Supply that are like yours and will break right in the feed tube from the tension. While I've always heard good things about Hatchbox some brands are defiantly better than others.

Love the splicer though... I bought a bunch of parts to make one similar to yours I just need to find the time to get around to it.

How are you melting the ends together? I bought a heater cartridge and thermistor with the intentions of making a heated mold block like yours but am now wondering if that is overkill?
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Re: Filament Splicer

Postby pyronaught » Wed May 17, 2017 2:07 am

I just touch both ends to a soldering iron and then stick them together and quickly press them in the block. The block needs to be cold so that it solidifies quickly. The strands can be moved through the brass tubes and the ends will be pretty aligned so all you have to do is slide one piece while holding the soldering iron with the other hand. The joined filament is then pulled through the tube, so you will know if you messed up the joint right away rather than finding out when it jams in the exturder. I use the same brass tubes as entry and exist sleeves on my extruder to prevent erosion of the plastic.

On the filament getting brittle, it just seems to vary by filament type. Some colors don't do it, while others do. I try and use hatchbox or e-sun silver PLA for all my high volume printing, as the brittleness problem never seems to happen with that particular color. I've had rolls sitting around out in the open for a year and they don't get brittle. The Hatchbox orange PLA gets brittle in just a matter of a few days though.
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