1 Topic by stemo159

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Topic: Method to Prevent Filament Unraveling From Spool w/ Pictures

Hey everyone, first time poster here. I am by no means an expert on polymer extrusion, but with this process in its infancy and having an engineering background, I felt obligated to contribute.

This method is simple and should address the issue of your filament unraveling from the spool without constant tension on the filament, as it did with me. This is tested with the MG94 ABS filament from Open Source Printing (OSP) and with the wooden spools they also sell on their website.

What you need:
- An Oven (such as the one in your kitchen)
- A spool (preferably one that doesn't melt/combust at low temperatures)
- Some method of temporarily keeping the filament from unraveling after you have wound it up on the spool (the filament holes in the spool work fine)
- The Glass Transition Temperature/Melting Temperature of your filament (Google Search: Glass Transition of [Material Name])

1. Set your oven temperature to around the glass transition temp of your material. For the MG94 ABS, this is around 105 Celsius, or 221 Farenheit. I set it to 230 Farenheit to be safe.

2. Place the wound up spool in the oven. I left mine in for 15 minutes, but that is probably overkill.

3. Take out and let cool down. I place mine in the freezer. When you release the tension, it should not unravel.

It's pretty simple. The concept is that when it reaches either the glass trans. or melting temp, the filament loses its material structure and allows it to adapt to its current shape; similar to how it leaves the extruder nozzle, but not completely liquid. I have not tested this much but it works for me with that material and temperature. I am not quite sure if it's the Glass Transition Temperature or the Melting Temperature, so some experimentation may be required with regards to that. Also, I didn't notice any real changes in filament diameter, but if that happens, you may be winding the filament too tight on the spool or setting the temperature too high/keeping it in the oven too long. Use the lowest temperature possible to achieve results.

If anyone else tries, post here with results along with material, temp, and any other relevant details. I hope this works for others and I apologize if this has been posted before.

Also, thanks to Tim for his hard work with the Filastruder. Great machine.

- Stemo

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2 Reply by elmoret

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Re: Method to Prevent Filament Unraveling From Spool w/ Pictures

Awesome, thanks for the tip! I've read it elsewhere, but not specific to the Filastruder. It is probably of most use here, since there's very little time for the filament to "relax". With industrial setups, it sits on a shelf in a hot warehouse for weeks, and has an opportunity to become de-stressed.

Filastruder - the robust, inexpensive filament extruder
E3Dv6 All Metal Hotend - the premier 3D printing hotend

3 Reply by insta

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Re: Method to Prevent Filament Unraveling From Spool w/ Pictures

I had a problem trying to dry a spool of ABS ... the polypropylene spool melted sad  So, word of warning I suppose...

4 Reply by bbriggsgeek

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Re: Method to Prevent Filament Unraveling From Spool w/ Pictures

I have used this method.  I set my oven at 200 and leave it in for about 30 min.  It does wonders.

5 Reply by ronsii

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Re: Method to Prevent Filament Unraveling From Spool w/ Pictures

insta wrote:

I had a problem trying to dry a spool of ABS ... the polypropylene spool melted sad  So, word of warning I suppose...

You might want to get a known accurate thermometer and check your oven as I am thinking it may be getting a little hotter than you set it for.

6 Reply by Tomek

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Re: Method to Prevent Filament Unraveling From Spool w/ Pictures

ronsii wrote:
insta wrote:

I had a problem trying to dry a spool of ABS ... the polypropylene spool melted sad  So, word of warning I suppose...

You might want to get a known accurate thermometer and check your oven as I am thinking it may be getting a little hotter than you set it for.

I had that problem when drying some taulman.

I think if I had covered the top and bottom in aluminum foil, more of the heat would be transferred by slower conduction and not radiation from the coils. Could be local heat is >> air temp of oven, while the oven is heating.

7 Reply by insta

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Re: Method to Prevent Filament Unraveling From Spool w/ Pictures

To be fair, I was drying it at 250F, and at no point did Ultimachine say their spools are oven-safe.

It also just softened and drooped, not full on "frozen pizza through the bars" melted.

8 Reply by bbriggsgeek

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Re: Method to Prevent Filament Unraveling From Spool w/ Pictures

i put mine on a cookie sheet because that happened to me too.  Just got a little deformed but still usable.