[Bell Historians] this week's obscure question

[David Bryant]

"Modern Metric coach bolts have a slightly larger head than their Imperial
counterparts. Imperial bolts are still available from specialist suppliers."

They're more expensive, though, and more difficult to get hold of!

"Perhaps the cheapest and easiest answer is to follow Taylor's practice of
recent years of using a standard bolt with a washer under the head. These
have the advantage that you have something to hold onto if you need to
remove the bolts. Coachbolts have a tendency to turn and angle
grinder/hacksaw are then required for their removal. "

I don't like doing this - the bolts invariable come loose, even with spring
washers. I find that coach bolts give far less trouble, and I've very rarely
had any probelm in removing them - if the worst comes to the worst, it is
simple enough to bang them into the timber with a hammer and cold-chisel,
then saw them off.

David