Getting to the point

[Lance Whitford]

I have been wondering about the logic behind the shape of needle tips. This all started when I had a go at making my own 0.18mm replacement needle for a Creos PS-771 by turning down a Chinese needle. After a bit of trial and error, I found I had to use a 0.5 mm needle as the starting point. The Chinese 0.2 and 0.3 needles projected way too far out of the nozzle. When I examined the Creos needle I was trying to replicate it was relatively blunt and had a two-part taper with a change of angle at the tip. This seemed counter intuitive, but clearly it works for current Microns as well. I remember my old Holbeins had needles with a very long graceful taper and mentally associate that with fine detail work. I came across a YouTube video of some guy having a rant about the blunt Iwata needle not working on his Olympos micron airbrush which kind of got me wondering about when the design philosophy changed and why.

 

[DaveG]

Ranting about it not working in his Olympos... hehehe, that is because it isn't for his Olympos!

The Holbein, and the Olympos are old school. They were creations of the thinking of the day... but, they never developed further. The Iwata is the next evolution, because they kept developing the brush(es).

A lot goes into converting liquid paint into finely atomized mist, and depositing it neatly upon a surface. There has to be a harmony between the needle protrusion from the nozzle, the angle of the area where paint is stripped from the needle, and the diameter of the laminar (straight) air flow emitted from the nozzle cap. Iwata needles don't tend to work in Olympos brushes not because of the nozzle, but because of the much larger opening in the Olympos nozzle cap.

 

[Lance Whitford]

I would imagine that we now have more science around how fluids and gases behave and probably the designers computer modelling of the spraying characteristics of various designs to help optimize the performance of these components for different use scenarios. One good thing with having thicker needle tips is that finer points are easier to bend so having slightly more beef at the business end will also make them a little more resilient to abuse – but not idiot proof based on experience