A few weeks ago I made a large spool to try and make some brittle 3d printer filament more usable.
Plastic filament becomes brittle with age. Recently a roll of pink filament was almost completely destroyed trying to use it. Now a roll of black PLA was found in the same state. A large spool was produced to test the theory that carefully warming and re-rolling the filament in a larger diameter coil may make it more usable. Coming off a large spool would lessen the amount of bending and flexing of the plastic during the printing process.
To get a large radius the print was broken into half then each half into quarters. Each section was printed individually. The outer most radius was made as large as would fit of print bed. I.E. one print occupies almost the entire print surface. The width of the spool (height of the print) was calculated so that it would hold 5lb of plastic.
Printing the spool in sections required creating seams to join together after printing. A zig zag teeth pattern was chosen so that parts would align accurately easily, and there would be more surface area along the seams to glue together.
There was only a small amount of orange plastic remaining. The amount of filament required was estimated before printing and seemed like there would be enough. By the last piece it was clear there was not enough. Transparent filament was joined to the end of the orange with a soldering iron. Transparent was chosen in the hope it would be less obvious. The joined filament didn’t feed into the printer smoothly, but some quick manual intervention allowed printing to continue without noticeable impact on the print.
The sections where cleaned up after printing. The brim was cut off and seams filed flat. The sections were joined by dissolving the joining surfaces lightly with acetone then pressing the sections together for 30 seconds. The sections where joined to form two halves of the spool, then the halves joined.
The model is 3mm thick. 3mm has been fine for previous spools but on the large version this was inadequate. It flexed more than desirable due to the larger size. The model needed to be changed, but two parts had already been produced by the time issue was discovered. Changing the size or with would lead to the parts no longer joining together correctly. Instead support veins where added to the cylinder section, and the sides. This helped stiffen the spool. The more flexible sections where spread around the final spool to minimise impact.
The spool came together well. Breaking the part into identical sections made it easy to assemble. Cleaning the sections and joining them using acetone has created a strong final item. The brittle filament was rolled onto the spool and it seems to unwinds well enough during printing.
A large spool is a good example of something that can be 3d printed but probably shouldn’t. There isn’t really anything about a spool that requires construction by 3d printing. It took over a day to print all the parts, and used at least $6.60 worth of plastic. Cleaning and gluing all the section took quite some time. There are probably better ways to make or source a spool. That said the model is available here.
