I've been a little worried about filing the torsion bars. It turned out to be more difficult than expected.
First I would strongly 
advise anyone who hasn't done this before to take the following two precautions before filing the fixed end: 
1 Seat the grub screws properly: If you have a sturdy vise, clamp the bar and swing arm in it securely by the bar. Now, loosen the grub screws slightly and apply a slight clockwise torque with your hand. See if the swing arm gives way a little. While still having the slight torque applied, tighten one grub screw and allow the swing arm to follow back until it finds a restful position. Tighten the grub screws as much as you dare. If the swing arm is not back in its original position now, you've managed to find a couple of degrees which it would have yielded under load! The idea with the process is to find the position where the grub screws are exactly perpendicular to the flat or slightly to the clockwise position of it. Any error to the other side is disastrous.
2 Torquing the swing arms to the true bottom of the thread: With the swing arm and torsion bar still in the steady grip of the vise, try to apply torque with your hand to the swing arm corresponding to full load plus a little extra for margin. Chances are that the thread you had already pulled tight will go yet a few degrees. Again disastrous if not found now!
On to the torsion bar filing: I didn't make a jig for the angles. Instead, I put the assembly horizontally in a vise with the axle end resting on the bench:
and with the angle correct, measuring from the top of the vise. 10mm from the top would produce the correct angle in my setup:
Here is the tricky part when doing this by hand. Try to find a horizontal reference that you can hold the file parallel to. In this case, the joint in the hull happened to be perfect!
Start with filing only a slight flat:
and install to check the angle:
After adjusting the 10 mm to 7, the angle came out perfect:
Now file the flat to its final depth. For the first three or four bars, use three to four iterations to arrive at the exact angle, two for the rest. One more take is necessary here:
That's more like it!
As perfect as I could possibly make it!
The sad thing about this part is that I was unaware of the precautions mentioned above and fell prey to both of them.
As a result, I had to file a bit more to get the proper angle back and now the flats are deeper than intended.
Yet another last thought that I've seen covered elsewhere too: Grub screws have a cup-shaped butt, designed to dig into steel and it sure does - both from the pressure of tightening the screw, but also from the tremendous torque exerted under load
You will want to either file the grub screws flat or better, replace them with ordinary Allen head screws with flat bottoms to take full advantage of the available thread depth. This way, the screws can't dig into the steel. It must be remembered that the forces are tremendous here and that the bars are in fact 5 or 5,5 mm in diameter and it takes quite a man to twist that!
A little too much is about right...
