Inkyfingers,
Is that the standard BSP taps and dies you are using ?
I was thinking of using them as they are quite a fine thread, the 1/8th BSP is about 3/8" dia and has 28 TPI, and the 1/4 BSP is about 1/2" and has 19 TPI.I should have some of those sitting in a toolbox somewhere.
Is there an English version of this available? It's all Dutch to me...
I need to do a bit more reading!!