The auto-rewind spindles for PolyDryer boxes fit a variety of spools, but recessed hubs like this require a pair of washers to center the spindles:
They’re laser-cut, although you could print them easily enough:
The size for that particular spool:
- OD = 80 mm
- Flange side ID = 51 mm
- Nut side ID = 43
- Thickness = ¼ inch, near enough
Other spools required a 3 mm shim on the flange side to sit centered in the PolyDryer boxes. Those are basically identical what you see above, with a 72 mm OD matching the flange.
The PETG-CF filament arrived on cardboard spools, which are apparently the new hotness:
The 56 mm spool ID requires adapters on both sides, with the flange side getting a 4 mm shim:
That skootches the spool over against the 1 mm shim on the nut side:
It would be possible to modify the auto-rewind spindle diameters to suit, if you were a dab hand with Fusion360, but the variety of hubs around here tells me a set of cheap adapters & shims makes more sense.
You should not assume anything will fit the spools you have, no matter how much they resemble what you see above.
The OpenSCAD source code as a GitHub Gist:
| // Polymaker PolyDryer auto-rewind spool washers | |
| // Ed Nisley – KE4ZNU | |
| // 2025-05-20 | |
| include <BOSL2/std.scad> | |
| Layout = "Show"; // [Show,Build] | |
| /* [Hidden] */ | |
| HoleWindage = 0.2; | |
| Protrusion = 0.1; | |
| NumSides = 3*3*4; | |
| $fn=NumSides; | |
| ID = 0; | |
| OD = 1; | |
| LENGTH = 2; | |
| Gap = 5.0; // Build separation | |
| SpoolWidth = 20.0; // Show separation | |
| FlangeOD = 72.0; // auto-rewind spindle | |
| FlangeHubOD = 50.5 + 1.0; | |
| NutOD = 77.0; | |
| NutHubOD = 42.0 + 1.0; | |
| //———- | |
| // Define Shapes | |
| module EryOneCF(Side = "Flange") { | |
| SpoolID = 56.0 – 1.0; | |
| SpoolSideThick = 3.0; | |
| if (Side == "Flange") | |
| tube(4.0,od=FlangeOD,id=FlangeHubOD,anchor=BOTTOM) // flange side | |
| position(TOP) | |
| tube(SpoolSideThick,od=SpoolID,id=FlangeHubOD,anchor=BOTTOM); | |
| if (Side == "Nut") | |
| tube(1.0,od=NutOD,id=43.0,anchor=BOTTOM) // nut side | |
| position(TOP) | |
| tube(SpoolSideThick,od=SpoolID,id=NutHubOD,anchor=BOTTOM); | |
| } | |
| //———- | |
| // Build things | |
| if (Layout == "Show") { | |
| left(SpoolWidth/2) yrot(90) EryOneCF("Flange"); | |
| right(SpoolWidth/2) yrot(-90) EryOneCF("Nut"); | |
| } | |
| if (Layout == "Build") { | |
| left((FlangeOD + Gap)/2) EryOneCF("Flange"); | |
| right((NutOD + Gap)/2) EryOneCF("Nut"); | |
| } |
The Smell of Molten Projects in the Morning 
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