1/4 bsw countersunk coach bolts
 

It seems any imperial coach bolts are hard to come by these days, anyone know where I could come by a dozen or so 1/4 bsw countersunk coach bolts, just over 1" long (or longer ). In the process of modifying some regular 1/4bsw coach bolts with a welder and the lathe but its a bit of a faff.

I converted some regular coach bolts by making a die from a piece of bar with a countersunk hole and a filed a square in the hole through the bar. I then heated the heads of the bolts and hit them with a hammer. The results were quite acceptable.