Splicing Filament

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pyronaught
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Splicing Filament

Post by pyronaught » Tue Sep 01, 2015 10:58 pm

Anyone ever tried to splice the end of one spool to the beginning of the next in order to save a print? I don't mean using one of those commercial splicers, but hacking it. I've got a 20 hour print that looks like the spool might not make it till the end. I've practiced a few splices using a soldering iron to melt the two ends and squish them together, then sanding the joint flat after it solidifies. The joint holds up pretty well to tension but not severe bending. Seems like it should work though. Worst case it jams or breaks, but then the print is screwed anyway so might as well try it. Unless there is a way to pause a print and change out filament the normal way and still be able to resume where it left off. That would be the reasonable way to do it, but I've never used that pause feature and don't trust it.
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Jules
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Re: Splicing Filament

Post by Jules » Tue Sep 01, 2015 11:30 pm

Just did it this afternoon as a matter of fact - very low tech. It involved cutting the expiring filament near the spool (flat edge, not tapered), letting the remainder in the clear tube scoot it's way on in until there are about 6 inches left above the filament drive. Take the clear tube off the cut piece of filament, the machine can handle feeding a few inches in without the guide tube. Feed the new (flat, not tapered) filament end through the clear tube and out. Watch for the tail end of the original spool to disappear into the filament drive, then stand there and feed in the new cut end with moderate pressure until it catches. Put the new spool on the holder and disaster is averted.

Doesn't even skip a beat, and you don't have to wait until the original spool is completely expired before you do it. (On a 20 hour print, why risk it?) :D

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jdacal
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Re: Splicing Filament

Post by jdacal » Tue Sep 01, 2015 11:47 pm

That only worked one time for me and it must have been a freak occurrance. Problem is as soon as the old filament gets past the teeth of the gear it stops there. Theres no guarantee that the new filament will match up evenly with the now stuck filament and push it in the rest of the way. Most likely it will glance off it and go off to the side. Assuming I'm reading right the method you described.
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jsc
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Re: Splicing Filament

Post by jsc » Tue Sep 01, 2015 11:48 pm

I have managed to get a good splice with my splicing pliers: viewtopic.php?f=2&t=2598

They are mainly helpful in getting the ends aligned. My procedure is to get the ends to line up, melt the end with a flame, then mush them together until set. The bead crimping pliers can then be used to crush the joint into round. I bought the electrical wire strippers Jules mentioned but found them unsuitable.

I’ve been playing around recently with aluminum shims rolled into a tube cut from aluminum cans to see if I can form the weld without the bead, but I cannot get the filament to melt even with prolonged application of heat.

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Jules
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Re: Splicing Filament

Post by Jules » Wed Sep 02, 2015 12:08 am

Most likely it will glance off it and go off to the side. Assuming I'm reading right the method you described.
Well, i've only done it a few times - maybe i've been lucky too. I never had a problem with it side-shooting when i cut both ends flat and kept an even pressure on it while feeding it in. (Might do a few more experiments as soon as the current print finishes up, just for kicks.)
I bought the electrical wire strippers Jules mentioned but found them unsuitable.
Yeah, those didn't work for me either - i didn't realize until i got them that they had a sharp edge inside. (I need to go delete that suggestion.) The bead crimpers did a much better job reshaping, even if it took a bit of fiddling.

Pyro, did you read through Jin's experiments on the splicing? He's the farthest along with it - it's definitely workable. And you can melt the ends of the filament against the hot nozzle to join them, just leave yourself lots of time for reshaping before letting it feed in.

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pyronaught
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Re: Splicing Filament

Post by pyronaught » Wed Sep 02, 2015 12:14 am

Jules wrote:Just did it this afternoon as a matter of fact - very low tech. It involved cutting the expiring filament near the spool (flat edge, not tapered), letting the remainder in the clear tube scoot it's way on in until there are about 6 inches left above the filament drive. Take the clear tube off the cut piece of filament, the machine can handle feeding a few inches in without the guide tube. Feed the new (flat, not tapered) filament end through the clear tube and out. Watch for the tail end of the original spool to disappear into the filament drive, then stand there and feed in the new cut end with moderate pressure until it catches. Put the new spool on the holder and disaster is averted.

Doesn't even skip a beat, and you don't have to wait until the original spool is completely expired before you do it. (On a 20 hour print, why risk it?) :D
I would not want to chance that, even when running in new filament the normal way I get a jam one time out of three and the gear chews a divot in the filament, forcing me to have to reverse the drive to get it back out and try again. I would have better odds of avoiding a failed print with the splice I think.
Experience is what you get when you didn't get what you wanted.

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Jules
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Re: Splicing Filament

Post by Jules » Wed Sep 02, 2015 12:36 am

Nope, just did it again and had absolutely no problem - did not skip a step, and it's rocking along. I did fail to mention the first time though, that it helps to straighten out the end that you are feeding in so that there is not as much curve in it, you want to push it straight down into the filament drive, and you should have several inches extending out of the clear tube so you can get a good grip on it to feed it in. As soon as the end disappears into the filament drive, you follow it in with the replacement. You will have to follow the print head around for about half a minute or so with your hand, pushing down slightly, until the old filament clears the teeth and the new one feeds in. But that makes the fourth time i've done it that way and it's worked perfectly so far.

Maybe the key is that both the disappearing end, and the end that you feed in, both need to be perfectly flat. I actually have to turn my sprue cutters around so that the correct edge winds up flat when i trim the filaments to prep them for the feed.

I'm tempted to play with some color changes in a little while when this one finishes - obviously it won't be an accurate way to place a color change, but i want to see if varying the filaments can be done as easily. If it works, i'll write it up with photos. It's hard to describe what you're doing without pics sometimes.

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Jules
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Re: Splicing Filament

Post by Jules » Wed Sep 02, 2015 12:46 am

pyronaught wrote: I would not want to chance that, even when running in new filament the normal way I get a jam one time out of three and the gear chews a divot in the filament, forcing me to have to reverse the drive to get it back out and try again. I would have better odds of avoiding a failed print with the splice I think.
What are you printing? (Cause my method would probably not work too well on something like PETG. Too springy.)

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jdacal
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Re: Splicing Filament

Post by jdacal » Wed Sep 02, 2015 1:13 am

Jules wrote:
Most likely it will glance off it and go off to the side. Assuming I'm reading right the method you described.
Well, i've only done it a few times - maybe i've been lucky too. I never had a problem with it side-shooting when i cut both ends flat and kept an even pressure on it while feeding it in. (Might do a few more experiments as soon as the current print finishes up, just for kicks.)

I know I didn't try cutting it flat. That would be great if it would work consistently, will try it again next time I under estimate my filament. What's there to lose? ;)
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pyronaught
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Re: Splicing Filament

Post by pyronaught » Wed Sep 02, 2015 1:14 am

I'm printing ABS. I've got the splice done and put the new roll on. The easiest way I found was to hold one end in each hand and touch them both to a hot soldering iron at the same time, then smoosh them together real fast and hold until solid. The hard part is getting them exactly end to end, especially with vision as bad as mine is up close. The excess that mushrooms out was clipped and then sanded flat. It looks pretty good in the image below, as long as it doesn't break. Not sure if it will ever make it to the extruder, now it is looking like the print might finish without reaching the splice. Better safe than sorry though. I wish I marked a line where the splice was so I could know when it is about to go through. It is pretty much invisible now.
splice.jpg
splice.jpg (401.05 KiB) Viewed 12134 times
Last edited by pyronaught on Wed Sep 02, 2015 1:19 am, edited 1 time in total.
Experience is what you get when you didn't get what you wanted.

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