Its notOoh, a gas turbine engineer! That must be an interesting job
Also, you're right, I've been told a fair few times that surface finish will be a large issue for me. As far a laminar airflow, the DM7 bolt in itself provides quite a rough flow. There is an eddie behind where the air enters.
Also, as far as bolt materials go, Aluminium is the most cost effective material that has a low friction coefficient. That being said though, I could always lathe a bolt out of PTFE. If I remember my chemistry correctly, that has a friction coefficient around the 0.1 mark? (PTFE printing. I need to look that up.) Or CNC it. How much would it cost to borrow a CNC machine for a day I wonder? Or perhaps my university has one I can use... hummm...
Pete, that software looks amazing. How much does it cost?
PTFE would be a good material but I would suggest looking towards the HPPE (high performance polyethylene) spectrum of materials as they are made for this sort of application.
When it comes to Eddy currents and things like that im not that knowledgeable, I believe Robbo looked into with his ego prime (think thats what it was called) project so may be worth giving him a pm and asking politely if he could discuss
As far as NX goes im not sure how much it costs as I dont pay the licence the company I work for happens to own it (Siemens if u had not already guessed)
Cheers Pete.
(Pm me if u want more information about any of the CNC stuff and Im sure I can help you out somewhere.)