I'm building a smaller version of the Rahn repeat-o-meter so I thought I'd show some progress pics. It's made from a slab of cast iron about 7/8" wide and is 8" overall in length.
For the hinge I cut two slits 30 thou wide 300 thou deep and 80 thou apart. The hinge itself is just a ground-down stanley blade which is clamped by four small grub screws with small ball bearings in the bottom of the hole pressing on the clamp. I set the gap between the body and the shoe using 5 thou shims and it gives 65 thou total swing on the shoe. The feet are HSS rounds set into holes using loctite then surface ground together. 3/8" diameter at the ends and a pair of 1/4" in the middle. There's no need for supporting bars because the tiny gap controls the swing of the shoe and the hinge is plenty strong enough to support it. If it does break, well, I'll just grind another stanley blade.
Here are the pics of progress so far.





This week I will slot the top bar for adjustment and fit the dial indicator then give it a test drive. I might make a handle or I might just leave it how it is since it's easy to store like that.
For the hinge I cut two slits 30 thou wide 300 thou deep and 80 thou apart. The hinge itself is just a ground-down stanley blade which is clamped by four small grub screws with small ball bearings in the bottom of the hole pressing on the clamp. I set the gap between the body and the shoe using 5 thou shims and it gives 65 thou total swing on the shoe. The feet are HSS rounds set into holes using loctite then surface ground together. 3/8" diameter at the ends and a pair of 1/4" in the middle. There's no need for supporting bars because the tiny gap controls the swing of the shoe and the hinge is plenty strong enough to support it. If it does break, well, I'll just grind another stanley blade.
Here are the pics of progress so far.
This week I will slot the top bar for adjustment and fit the dial indicator then give it a test drive. I might make a handle or I might just leave it how it is since it's easy to store like that.
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