Touche said:Fine if you have access to a grinding machine to make one from, what appears to be, an old cross head bit. For those of us that don't, a flat head screwdriver does the job nicely, for me this is the correct tool.
If you've done a good job of selecting the correct length spokes, the tip of the spoke will be about flush with the dome of the nipple when the wheel is correctly finished and spokes tensioned.
The 'pip' on the tool is hit by the end of the spoke and it lifts the screwdriver out of engagement. The end of the spoke is nicely 1mm below the dome of the nipple.
DON'T forget to get a 'Dishing tool' or make one from a piece of 3/4" plywood and a long bolt with a wing nut.
I will supply photos of my home made truing jig and dishing tool on request.