The Anonymous Widower

How to Make Dome-Headed Bolts

As I have said several times on this blog, the builder of my house was possibly named Jerry.  His worst piece of work was undoubtedly the staircase, which instead of using brass nuts and bolts, as probably specified by the architect used brass painted steel ones.

I have got part of the way, but to fix the staircase to the floor of the house, Jerry used Rawlbolts, which couldn’t easily be replaced, as they were set in concrete.  I got this far and you can see it looks a bit better but some are round one way and others the other.

In the end I decided I wanted some dome-headed bolts.  But just like the perfect woman doesn’t exist, the perfect bolt doesn’t either.  Although there are some good ones about.

So I had to make my own.  I started by purchasing some 10 mm. mild steel studding from Thomas Brothers at Archway. I used steel rather than brass, as this might give less trouble with dissimilar metals in contact causing corrosion and anyway Thomas Brothers don’t sell brass studding. They also were kind enough to cut the studding in half, so that I was less likely to poke someone’s eye out on the bus home.

I started by securing the studding in my Workmate.

Studding Secured in the Workmate

I then sawed off an appropriate length using a standard hacksaw, The stud was cut to be perhaps two centimetres longer than the steel bolt I wanted to replace.

The Cut Length of Studding

The problem with cutting any screw threads is that when you cut it, you damage the threads and nuts are difficlt to fit. You can mitigate the problem by putting a new blade in the hacksaw, but you really need one of these.

Hexagonal Screw-Cutting Die

It is a 10 mm. hexagonal scre-cutting die, that effectively cuts threads in round bars. Or in this case recuts damaged threads. 

My father had lots of these, although his were round and were held in a special wrench.  But because they are hexagonal, you can use them with a good ring spanner to cut the thread. I’m doing just that here, after first mounting the cut stud vertically in the Workmate.

Recutting the Threads

I actually turned the die from one end of the stud to the other to make sure that all damaged threads were repaired.  All I had to do then, was screw a dome-headed nut onto the pristine length of studding.

A Dome-Headed Bolt

They are now all installed in the staircase. 

The Bolts in Place

You can’t tell which ones are my fakes and which are the ones the builder put in the right way round.  Or was it the wrong way?

He didn’t put them in level either!

February 13, 2011 - Posted by AnonW | World | Building, Engineering, Jerry Builder, My House