Inline filament Dryer with Polydryer

This is a inline filament dryer made out of simple thing. It dries and I am sure it can be improve, but not at this price.

The clothesline pulley is made out of metal and become hot and I pass the filament 3 turn around the pulley before exiting to print. So I believe that the Polydryer in combination with the hot pulley and the number of turn around the pulley is enough to remove sufficient humidity to print with ok result. 

This is a not a beta version, it is barely a proof of concept, but a working one ... maybe. Further investigation needs to be made and releasing it into the wild will ether prove the concept right or wrong.  

Test it on year old transparent TPU and It just print. Last time I used this TPU I had to dry it for 8 hours not to get a mess.  (See Photos)

Second test I did is with ASA. When wet, ASA cause terrible stringing and zit. Printed the shelf bracket and there is not one zit and no stringing at all. (See Photos)

During one print, The timer turned off the dryer and the ASA started stringing. Turn the dryer back on and stringing stop.

BOM:

1 x 200mm(8") clothesline pulley.

1 x 6mm(1/4") metal rod 85mm long.

3 x Printed parts

You will have to remove the rivet from the pulley that hold the clothesline mounting part.

Easy way to load is to put the filament in the hole of the pulley and turn the pulley the amount of turn you want.

Make a small hole in the pulley for easier loading. (See Photos)

I will add bowden pneumatic coupler to mine.

Removed the metal roller and bearing to help with airflow.

Update 2026-03-11

I recommend using this mod PolyDryer Air Exchanger 

I did the sponge test 1 hour at max temp, with and without the mod and there was a 5g difference with the mod and no vapour in the box. A 45% increase in efficacy is not negligible. I hot glue mine in place.

Also Added a funnel to redirect the air flow directly to the clothesline wheel.

Well is seem that with the air exchanger mod this contraption become obsolete in this design for regular filament. Like Dr. Igor said using the dryer while printing gives the same result. I will studies a way to improve on my finding.