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