Grinding a small Internal Trapezoidal threading tool

[Wongster]

Hello folks,

May I know if anyone here has ground a small internal trapezoidal threading tool for a nut?  I need to make a Tr8x2 brass nut for an SLA 3D Printer I backed and received.  The nut that came with the printer is rather sloppy and those I bought from China are the same... Buying brand name nut is too costly for the cheapo printer.  So I am considering grinding my own tool, and at the same time, learn from doing it.

The tap drill should be 6.5mm.  Pitch of the lead screw is 2mm single start.  From the diagram I found online:

   

P = 2mm
H1 = 0.5P = 1mm
and the flat top = 0.366P = 0.732mm
Thread angle = 30 degree
(hope I get these correct)

I was trying to find pics online to sort of give me an idea how such a tool would look like before attempting to grind one myself.  I'm still a new hand in grinding HSS tool.  The last tool I ground was at least 4-5 years ago.  

Also, what size blank should I start with?

Best regards,
Wong