Measuring pressure
Scale
I use this scale US Solid Scale (model number USS-DBS86-5).
It is delicate enough to measure 0.1g which makes it good for IAF testing and can support 5kg of weight which is good for handling the weight of smaller pen displays.

Connecting the scale to a computer
Cable
This specific cable works to connect the serial port on the scale to a USB port on the PC
CableCreation USB to RS232 Adapter with PL2303 Chipset (amazon link)
Programmatically getting the pressure data to a PC
Tablet expert Kuuube, has provided some sample code to read the data from the scale into a PC using Python. See the GitHub project here: us_solid_scale_reader
Full setup
As of September 2025 my setup looks like this:
A foam block holds the pen and serves as an arm
An incision on the foam is used to securely hold the pen.
It does struggle with some pens that are thinner and "slip" a bit as pressure gets towards 400gf.
A metal ruler underneath the foam adds some stiffness
Masking tape secures the ruler to the foam
Weights on top of the foam are added and moved to adjust the pressure and to secure the arm

Videos
Seven Pens - Measuring Pen Pressure Response Curves - 2025/09/27
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