M4 Ultra Headset Frame

The M4-Ultra headset is compatible with the OpenBCI M4 Ultracortex system. This new frame design does not require threaded inserts in each node, since the SLS nylon process is precise enough for functional threads. This design is also stronger and lighter than a headset printed using the FDM extrusion process. Octabolt electrode assemblies are not included with this frame. The "Print it yourself" electrode kit, as well as the OpenBCI device, can be purchased from the OpenBCI store.

The M4 Ultra headset is available in five sizes: The three standard sizes, and two intermediate between them (S, M-S, M, M-L, L).
In this listing choose:
"Extra Small" for "S"
"Small" for "M-S"
"Medium" for "M"
"Large" for "M-L"
"Extra Large" for "L"

More information about headset sizing.
The three standard sizes used by OpenBCI (S,M,L) correspond to these "virtual" head sizes:

Small head (standard minus 1cm offset)
48.9cm Circumference
17.4cm Long
13.5cm Wide
8.0cm High from circumference line

Standard average head:
55.2cm circumference
19.2cm long
14.4cm wide
9cm high from circumference line

Large head (standard plus 1cm offset)
61.5cm Circumference
21.4cm Long
17.5cm Wide
10.0cm High from circumference line

Actual size is very forgiving because the headset adjustment ranges overlap by 50%. So, if you have a perfectly average "M" size head the "S" headset would still fit when adjusted all the way out, and the "L" headset would fit when adjusted all the way in. Actual range is effectively greater, since the bolt has a range of 2.5cm and the spring has another 1cm. This excessive margin is to accomodate head shapes that deviate from the average. We do not state range limits for this reason.


More about 3D printed nylon:
At this thickness, the nylon is not as flexible, but it is very tough and strong. It has a higher detail and is less prone to cracking than extrusion-printed plastics. It has a matte finish and slightly grainy feel. Due to its porosity it may be useful to seal nylon with a laquer spray, or it can be ordered in dyed material. The pure white nylon can be refreshed using 200-grit sandpaper.

Questions? Email support@openbci.com