7.13) Item 8, Body Fabrication

Right, that's the bulk of the parts complete, but the hardest part is just coming. The Body Fabrication. What we're looking for at the end of this is:-

For this fabrication we need 8 off Item 16,

two off item 17, and four of Item 18 (Pivot Block) shown below:-

You also need one Horizon Mirror Support (Item 19)

Two Shade Stops (Item 58) are required too,

.

The last piece for the body fabrication is a heck of a lot of work. The frame (Item 15). This item is so complex it takes quite a few drawings to detail it properly

Before starting on it, I would suggest that you download the CAD drawing from section 9. Then use CAD to plot out the profile at 1:1 on sticky backed paper. Attach this to the brass and use it as a guide for the less important parts of the frame.

Now for the drawings of the frame.

Drawing 2:-

Drawing 3

Drawing 4

The following notes apply:-

Cut the gear teeth at the bottom of the arc with the gear cutter shown in section 8.

The gear teeth MUST be cut on the rotary table at exactly 0.5 degrees apart. Ensure that you turn the table the same way all the time and take up backlash in the mechanism in the same way before each tooth. The entire accuracy of the sextant depends this operation.

Cut the scale graduations with the engraving cutter in section 8.

A majority of the cutouts are decorative and can be dispensed with if you want to. The central 6mm hole in the R31 cutouts is solely intended as a locator for milling out the cutout.

Right, now is the time to solder the bits together.

The notes to the above fabrication drawing are:-