The handle is now mostly finished. It will be next weekend probably before I can continue working on it.
But here are two interesting pictures.
Here you see the handle clamped into the tailvice so I can reach most parts. A special carvers vice would be better, but I get along with this setup. An old scraper is jammed in the sawblade slot before clamping in the vice. On the bench the tools I use. A very coarse Bahco rasp, which works quickly but leaves a nasty surface. Then some rasps from Iwasaki. They work slower but leave a much better surface. Some round files for the tight spots and lots of sandpaper strips, cut from bandsander rolls. These are very tough, don't break so easilly like normal sandpaper. First I draw the outline of the contour on the flat side of the handle with a pencil. Then I use the rasps to round the handle up till these contourlines. It's important to make a nice smooth curve with the rasps. The sandpaper won't change it much anymore. After the rasps it's a matter of using the sandpaper in a sequence of grits. Making sure to remove all scratches and blemishes from the previous one. It's no sin to trace back on your steps when you find an ugly spot which needs more work with a coarser grit.
The sharp V-groove in the top and at the bottom of the handle can't be reached with sandpaper, so I use a sharp chisel to cut these.
The second picture shows the saw screws with split nuts. I made these on a metal lathe from brass. It's mostly standard turning. The head of the screw and the nuts are just slightly oversized 11mm with a very slight taper to the inward side. I hope this will help to get a good tight fit in the wood. The square part is hand filed. And the screw slot in the nuts is also handwork. First I cut with a hacksaw, then widen the slot with a narrow file.