POM filament not sticking to the build plate? In the creation of the process of printing my own bearings to reduce noise, minimize play/tolerances and size the bearings to the actual size of the application, I obtained a spool of Polyoxymethylene (POM) or also known as Acetal or Delrin. 



This polymer is a thermoplastic polymer that is frequently used in engineering precision parts that require high stiffness, low friction and dimensional stability. It has been chosen for these material properties to be used as bearing material for linear guide rails.

This image shows an example of the application of customized igus&reg; bearing that is as long as the housing part it is going to fit in:


Prints frequently get knocked over as it does not stick well.

How do I get POM filament to stick to the build plate?
Great material but very hard to print as it does not stick easy to the build plate as it has a low friction coefficient to grip onto the heated bed. Also, the material sets quite fast, once the filament leaves the nozzle, it soon hardens so you need to be careful with retraction and Z-hop (leaving small peaks that will be hit later by the nozzle knocking over your print). 

My experience with printing this material is based on printing with an Ultimaker 3 Extended (on glass) using a modified material profile (based on Nylon). It is printed at 240 °C (+5 °C for the first layer), no usage of the part cooling fan (if you do use cooling, the layers will not adhere well), a heated bed temperature of 80 °C, and a slow printing speed of 40 mm/s (20 mm/s for the first and second layer).

Ultimaker 3 Extended with printed POM bearing:



First thing I learned is to use quite large brim's (the image above shows a rather small one for this short bearing, for the longer bearings the brim size was more than doubled, e.g. 20 mm), brims enlarge the surface area so that there is more material that grabs hold of the heated bed. Also ensure to get it to stick long enough is heating the bed to 80 °C after smearing ABS juice (ABS dissolved in acetone) and spraying a PVA based spray over the dried ABS juice layer (3DLAC has been used, but other hairsprays or even gluesticks may work as well, as long as there is PVA in it). The temperature of 80 °C is chosen as this is the temperature where my PVA spray has the most tack/sticky-ness.

Other solutions like heating the bed up to 110 °C using 3DLAC or specifically designed sprays for higher temperature like e.g. Dimafix did not work well for me.

Note that complete infill may also give problems as filling out the whole surface area sometimes creates excess material that curls up, which is an easy target to be hit by the nozzle on the next layer. 

This image shows an example of using the printed customized igus® POM bearing that is as long as the mount height:



Collection of POM printed bearings:



Another application of POM bearings:



CoreXY hot end carriage