Didn't know this... Delrin printing.

[airscapes]

https://gizmodorks.com/acetal-3d-printer-filament/

Looks like you need an active filament dryer, heated bed surface 130C made of wood or paper, heated enclosure and some luck.

[TommyDee]

Formaldehyde is a problem

[airscapes]

I am printing 645 for the first time right now. So far works nice with a skirt .05 from the model to help keep it from warping I would post some pics but the website seems to be broken