Filing the blade to shape / size
I placed the blade in my vice and got out my angle grinder, but it quickly beame apparant that it was complete over kill and only filing was really needed. I started by filing off the T piece or ears (see pic 1) and then tried offering this into the pivot collar, but it was too wide, so i went back and filed a shoulder into each side of the blade (see pic 2) but still it would not slide in properly, so i then filed in a small rebate on the flat edge of the blade and this worked (see pic 3)
Anyone wishing to try this, i strongly reccomend taking your time and not rushing, its better to go slowly and file more off than needed, as you cant add it back on if you’ve taken too much off ! The final thing i had to do was file a small notch for the role pin to locate in. To do this i clamped the blank blade from the new flip fob and the HU57 together side by side in the vice and then took a triangular needle file and gently added a groove, this only took a few strokes. My HU57 was now a blade, although it did have a U section to the top of it, it wouldnt matter as it would be hidden inside the pivot collar. I then fitted the blade to the pivot collar and gently tapped in the roll pin using the watchmakers punch.