More Progress with Forks

I was expecting to have to get the blowtorch out to help remove the twist from the blades, however, the torsional stiffness turned out to be quite low so no heat was needed.
 

Twist Removal

To minimise damage during the untwisting process I knocked up some tooling to hold and twist the blade.

Twist removal tools

The wooden blocks where used to clamp the blade in the vice, while the alloy plate with arm attached applied torsion.

The processed was surprisingly easy and was finished off with straightening out a lateral bend and a couple of passes through the profile forming tool

Having achieved a reasonable result for the basic blades I now took the plunge and attacked the original forks with there welded on blades.  These turned out to be surprisingly easy to remove.  To begin with I simple sawed off the old blades below the weld line. Then being able to see what was inside (bits of squashed tube join re-enforcing material), I made my way up towards the crown, cleaning away as much of the old blades as I could without damaging the crown. With hacksaw and chisel I split each blade vertically into two parts and then using my blow lamp applied heat.  With the blade starting to glow red I carefully hammered and chiseled the joint to separate the blade remains from the crown.  This turned out to be much easier than expected.

First fit of new blades

 With a bit of a clean up, trimming the blade ends and addition of 1/8" pins it is starting to look good.

Fork Crown Revealed

 How to form the blade ends?

This has been puzzling me for a while, should I make inserts or should I attempt to flatten the ends of the blades.
The worry with the later is how to ensure the finish is neat and professional looking.  With the old fork blades in my hand inspiration struck - why not section them and see if there are any clues.

Lo and behold question answered:

 The old fork blade has a neat rounded transition to the flat section.

Close examination showed a third layer of metal sandwiched between the two flattened sides of the blade.

In this photo the insert has been removed leaving a gap





Cutting the blade lengthwise revealed that the interleaved layer extended into the blade and was profiled to support the blade while the end was flattened.

The sectioning made it difficult to see exactly how the insert was profiled.







Fortunately I had two blade so could open up the other one more carefully to extract the insert, shown here

The material of the insert is much harder than the blade itself so with an appropriate outer forming tool the blade end can be flattened while the insert prevents unwanted squashing occurring