PolyMax Polycarbonate 750g

Crazy good. Exceptional strength compared to PLA.

I’m printing a tiny piece mere mm's thick with a tiny vertical stem 2.5mm wide that has a small head on it (see image). This is printed in the orientation in the pic, so the stem is stacked layers with the head printed last. Layer adhesion being the weak point in 3D printing, this is the weakest possible orientation for stem strength.

With PLA and some very precise settings the printed piece is functional but prone to breaking if the head is knocked or tweaked.

Using PolyMax Polycarbonate I can put an unreasonable amount of pressure on the head, so much so its hurts, and it stays. Im sure I could break it off but that would be a scenario it will never face in reality.

So this piece is not only functional but reliable.

Some pieces have come loose for the bed during printing. I use UHU glue stick. Adding a little more glue than I might with PLA solves this easily. Being water soluble its perfect.

I started printing with no cooling, 270 C and a 0.42 width. My first piece was a larger object and these setting worked well.

I wanted as much layer adhesion as possible in the tiny part and kept these settings but I found that the printed line remained too gooey for too long. Surface finish was poor, bridging over supports was poor and the stem and head would simply remain too soft during printing and get dragged around with the print head movement.

So for tiny parts I ended up with the following settings.

Ender 3 Pro - 0.4 tip

Bed 95C no enclosure
Temp 255C
Width 0.38
Flow rate 97%
Speed 50 and 25mm sec
Cooling – Initial Fan speed 50% building to 100% when printing the stem.

Im am very happy with the result. The piece is printed very nicely, surface finish is good. Its has clean lines, is dimensionally accurate and again, very strong.

Printed a 200mm wide fan with recommended settings and spun it at 12,000 rpm. Still intact.

Easy printable at 250 degrees, bed 90-100. I could print it with excellent results at 50/30 (inner/outer walls speed), 60 infill, 20 first layer. On a glass bed or on Buildtak you will need glue to have it stick. I tried Miner Nano and it didn't work very well. Eventually used Magigloo PC and it worked perfectly, but it needs a very well levelled bed and optimal first layer distance (preferably you will need to use baby-stepping to find the right spot). If you have no drafts, and if the weather is not cold, you can get away without enclosure.
You do not need part cooling, but bridges can be problematic without it. I would suggest going at 60mm/s and 90% extrusion for the overhangs, or activate specific cooling options for the bridges/overhangs only.
No stringing with a direct drive and 1mm retraction, probably 0.5mm would be enough.
Very hard material as it is, but it can be annealed straight after the print (1h at 100 degrees) to render it even more structurally stable/tough - especially nice for parts that will be under mechanical stress.
Short of much more expensive materials, this is the one that resists the highest temperatures (100-105 before starting to soften up). Even better than ABS, so ideal for parts that are exposed to high temps (fan shrouds, or other parts that are close to heat radiating tools, etc.).

The material properties are great, a very good PC to print with. However in the last 200g there were at least 7 breaks in the filament (visible only once you got down to that level), which caused some real issues (a failed 18HR print!) Unfortunate otherwise I'd be considering the full 5 stars for this!