Desiccant core, made to measure for your spool

Measure the hole in the middle of your spool, how wide the spool is, and the smallest bead in your bag of silica gel. We cut a core that slides into that hole and hangs from its rim, with slots in the lid and the floor sized from your smallest bead and a margin for the way printed slots come out. It holds the beads inside the spool while the spool lies flat in its box. Prints standing up, no supports.

What you need before you start

What it will take

Spool centre hole: 25–90 mm
Spool width at the hole: 30–120 mm
Smallest bead of your silica gel: 1–6 mm
Nozzle size: 5 to choose from
Filament: 4 to choose from

As it comes

Silica gel it holds, roughly89 g

Core outside diameter53.0 mm

Core length73.2 mm

Filament, roughly43 g

Build plate: 130 mm as it comes, never more than 256 mm.

What you need to hand

A caliper for the hole in the middle of the spool.
The width of the spool, face to face, next to the hole.
The bead size printed on your bag of silica gel.
Your nozzle size and the filament you will print it in.

The part, drawn to your numbers

Cut through the middle — the core with its rim, and the lid, as they sit on the build plate

Drawn from the numbers in the form below, off the same geometry the file is cut from. It is not a photograph, and there is no photograph — every part that leaves here is a different size.

The spool

Measure the hole across its narrowest point, and the spool from face to face right next to the hole.

Spool centre hole

Across the hole in the middle of the spool, measured with a caliper at the narrowest point. Most 1 kg spools are somewhere between 50 and 58 mm, but measure yours.

Spool width at the hole

How deep the hole is: from one face of the spool to the other, measured at the hole. The core is cut so that its floor sits level with the far face.

The silica gel you bought

The packet gives a size range for the beads. We need the smaller number: the slots are sized from it, with a margin.

Smallest bead of your silica gel

The bead size on the packet is usually a range, such as 2–4 mm: give us the smaller number. The slots in the lid and the floor are sized from it.

The printer it will come off

These two are facts about your bench, and both have a right answer already filled in. The nozzle decides how narrow a slot stays open, which is why we ask.

Nozzle size

The nozzle you will print with. It does not change the model — it decides how narrow a slot your printer can keep open.

Filament

Sets the weight estimate and how much the lid can squeeze the core before the rim gives.

Finer adjustments

Clearance in the spool hole

How much narrower than the hole the core is printed, across the diameter. 1 mm slides in by hand on most spools.

Lid clearance

How much narrower than the core the plug on the lid is drawn, across the diameter. The lid sits on the rim by its own weight; the plug only keeps it centred.

More for the workshop

Remaining-filament gauge
A flat gauge that reads the grams and metres left on your spool, with a scale worked out from your spool.
What you need A ruler or calliper for an empty spool, a new one and its label, and your nozzle size.
Try your numbers
Spool hub adapter
A ring that makes a spool with a big centre hole sit on a thinner axle or holder, cut to the hole of your spool and the size of your axle.
What you need A calliper for the spool's centre hole and your axle, and the spool's width at the hole.
Try your numbers
Filament guide
A push-on clip with a guide ring, cut to your sheet or to a 2020 extrusion.
What you need A calliper for the sheet, or a 2020 extrusion, and your filament size.
Try your numbers