Needle modification and polishing


Needle-chuck Ninja
After I recently bought the Iwata Custom Micron SB, I noticed it had a different needle shape than airbrushes I already owned. The top area of the tip had a slightly wider angle than the tapered part of the tip. I wondered if that would be the reason why it sprays better than any of the other guns. So I modified the needle of my Infinity that was bent and twisted and didn't spray well anymore. I cut off the twisted part of the tip with a pair of scissors and started to polish. My polishing set-up can be seen here.

Testing proved that the Infinity sprayed better than it ever had done before that is probably the result of the tip modification and polishing. It was able to spray finer lines and the control while spraying dagger strokes significantly improved. Iwata's CM SB needle construction also works on other guns and it pays to polish...
Main problem I see with your set up it two spinning surfaces , Most the pros just use a cotton ball with polishing compound on it and the drill.
When you have the set up you are using heat can be an issue.
The set up you show is great for re shaping a bent or twisted needle But then you want to do the final polish like stated before.
A guy on another forum designed a jig for reshaping needles. So every needle is at the exact same angle of slope. He uses starts with a 300 grit stone and slowly moves up to a 10000 grit stone which in the end gives it a mirror finish.
But polishing needles can also go wrong so use caution when doing so.