Which nozzle do I need?  

RE:

The only constraint is you need a hardened nozzle. As to the choice of nozzle after that it depends on budget etc. Also be aware that the ObXidian nozzle come in two varieties, high flow and non-high flow. So make sure you pick the correct one when ordering. 

For PC-CF specifically you don't need a high-flow nozzle but it does need to be hardened.

Also you don't necessarily need to print the back cover in PC-CF. ASA, PC Blend or HT PLA will also work and don't require a hardened nozzle. If you do that the back cover won't match the color and shade of the front cover but you won't see it anyway. 

For what it's worth I have these nozzles:

• 0.4 ObXidian HF
• 0.6 ObXidian HF
• 0.4 Diamondback
• 0.6 Diamondback
• 0.8 Diamondback

As of now, unless I have a really massive PETG or PC that can benefit from a HF nozzle, I mostly just use the Diamondbacks

RE: Which nozzle do I need?

Thanks hyiger. It is confusing. The Core One came with a brass HF 0.4 nozzle. Why/when would I not want a HF steel hardened nozzle? Also, when would I want to use a 0.6mm or larger nozzle?

RE:

Posted by: @phil-16

Thanks hyiger. It is confusing. The Core One came with a brass HF 0.4 nozzle. Why/when would I not want a HF steel hardened nozzle? Also, when would I want to use a 0.6mm or larger nozzle?

I don't use brass nozzles anymore. For all filaments I use hardened nozzles. It keeps things simple.

You use the larger nozzles when you don't care so much for detail but want stronger parts with better layer adhesion or you also want faster print times. Also a 0.6mm is better for some types of filaments like wood or metal fill and foaming TPU filaments. 

For now, I would suggest getting a decent hardened non-highflow 0.4mm nozzle and use that as your "go to". Why the non-highflow? Because if it clogs (and it happens), it will be easier to unclog. Whichever nozzle you choose, be sure to read the manufacture's instructions on how to clean and unclog properly. 

Keep the brass one around if you are doing a large PLA/PETG prints and want to save some print time. 

Brass transfers heat the best - leading to fewer problems and slightly easier settings especially when striving for speed (which is usually a mistake).  Abrasive filaments destroy soft brass nozzles so when abrasives are used hardened nozzles are needed but they are not so forgiving.

An ObXidian nozzle will handle PCCF well 'though I usually use 0.6mm.

Larger nozzles offer potentially faster printing, sometimes stronger but with less precision.  Some coarser filament inclusions, eg., cork and woodfill are prone to clog regular nozzles so larger diameters are preferred.

The various high flow nozzles do slightly speed printing large parts where there is space to accelerate the print head to maximum speed but most of the time, on smaller or medium sized prints, the benefit is negligible.

Cheerio,