2023-09-30

Last modified: 2023-09-30 18:53:26

Douzieme gauge

I took the "Tomorrow" list from yesterday into the garage and went through the items in order. It turned out I already had a version of FreeCAD on the garage computer that I had simply forgotten about. I updated it anyway. Must remember it is there and I can use it.

I didn't come up with a very effective way to clamp the parts to the table:

But it turned out to be adequate. I should really get some strap clamps for the milling machine.

Left shows the first type of spring I tried to make, middle shows a circlip tool, and right shows my take on copying the spring design from the circlip tool:

Pretty pleased with this so far. Next up is to start making the scale. The spring sometimes falls out, not sure what to do about that. Maybe I need to make another spring with longer "hooks" on the ends and hook them through the holes a bit better.

This thread has some more pictures and info about similar gauges: https://www.watchrepairtalk.com/topic/26974-i-know-this-is-some-measuring-tool-but-im-not-sure-what-scale-its-measuring/

And this page is a great resource for watchmaking tools: https://watchmaking.weebly.com/watchmakers-tools.html

I cut the scale material out of 1mm brass:

The cut went well, using the 2mm 1-flute end mill, with the same parameters that I previously used in aluminium.

But it is not big enough. I'm guessing the hand-filed jaw ended up too short, so the handles spring open wider than intended. But I think I have a better idea for how to do it:

1. drill the holes for the M1.6 screws in the handle
2. make the "washer piece" that will clamp the scale, with countersunk holes
3. take some photographs of the device open to different lengths
4. make the scale artwork in inkscape or similar, with slots for the screws, to allow adjustment
5. print it out and attach it, and check that it works correctly

And when that is done, I will have an idea of how the scale needs to relate to the rest of the device, and I can engrave and cut all in one setup.