Will your spool fit the dryer?

1. Start with the job and measure your spool

Drying removes absorbed moisture; sealed storage limits exposure afterward. Feeding from a protected box is a third job. Stringing alone does not prove wet filament: use Prusa’s stringing and oozing checklist to check the profile, temperature, retraction, nozzle residue and hardware before shopping.

1. Measure the largest outside flange diameter in millimetres, then the overall outside width. Include protruding adapters or other parts that must stay attached.
2. Record the exact spool brand, material and revision. “1 kg spool” describes a product category and is not a dimensional standard.
3. Compare both dimensions with a documented per-spool limit. A chamber’s outside dimensions, spool count or filament diameter does not establish usable spool clearance.
4. Follow the device manual to confirm placement, free rotation and a clear outlet path before heating or printing. A dimensions screen cannot establish those conditions.

The spool passport keeps measurements, source notes, drying-cycle observations and storage notes in this browser. It is a notebook, not a moisture meter or a certificate of readiness.

3. Separate the recipe, the method and the spool heat limit

Use instructions for the exact filament product. A generic “PETG” or “nylon” label is not a drying recipe. Record the manufacturer’s temperature, duration and method together. Reaching the same setpoint does not show that a standalone dryer duplicates an oven’s airflow, heat distribution or drying time.

Check the physical spool separately. Prusa’s drying guidance describes revision-dependent spool preparation. A refill, adapter or different reusable spool may change the heat limit. A high-temperature reusable spool does not increase a dryer’s maximum temperature.

For example, Polymaker’s PolyMax PETG page gives 65°C for 6 hours if moisture has been absorbed. That does not establish the dimensions or heat limit of your spool, nor equivalent timing in each dryer. Do not transfer it to other PETG products.

Worked example: Bambu PETG HF on the original ABS spool

The PETG HF TDS v1.0 specifies a 200 × 67 mm ABS spool with 70°C heat resistance and a forced-air / blast drying oven recipe of 65°C for 8 hours. This is a manufacturer example, not a measurement of your spool.

• SpacePi SE: the 200 mm diameter exceeds its 190 mm limit, even though 67 mm is within the width limit and the dial reaches 65°C.
• Current S2: 200 × 67 mm is within the published 210 × 85 mm limits, and 65°C is within its settings. Rotation, clearance and equivalent drying time still need checking.
• Standard PolyDryer Box: the dimensions are within 205 × 78 mm, but the Box alone is storage only and cannot carry out the drying recipe.
• S4: its maximum reaches 65°C, but per-spool dimensions and the lower setting limit remain unknown in this evidence. Do not infer fit from “four spools.”

The TDS gives a separate X1 heatbed method with different settings (75–85°C, 12 hours). Do not substitute those settings for the forced-air recipe. Follow the document’s heat-distribution and heater-separation instructions; it does not authorize microwave or kitchen-oven drying.

Worked example: Bambu PA6-CF at 80°C

Bambu’s PA6-CF table calls for 80°C for 8–12 hours. No active dryer listed here reaches that requested temperature: SE stops at 65°C, S2 and S4 at 70°C. The Box has no heater. A longer cycle or a high-temperature spool is not evidence that a lower setpoint is equivalent.

4. Check print-through and feeder compatibility separately

An outlet and feed instructions can support printing from a dryer or box. They do not establish compatibility with your printer, an automatic feeder, flexible or abrasive material, adapters or the full tube route.

For an AMS setup, identify the exact model. Bambu’s AMS 2 Pro product and FAQ distinguishes printing and drying support and includes printer, accessory and firmware conditions. Do not apply those claims to the original AMS or AMS Lite. Follow the AMS 2 Pro drying-function guide for your configuration; its detailed firmware requirements were not retrieved in this desk review.

Run the environment planner to keep supported limits, known mismatches and unanswered checks visible. Save your own measurements and cycle observations in the spool passport. Neither tool measures moisture or guarantees compatibility, dryness or safe unattended operation.