Wednesday, August 17, 2011

TF79 Upgrades--Part 6 Baseplate

The adjustable buttplate has to be attached to something solid on the rifle butt--in this case, that's the baseplate.

Skipped a few semi-important steps here. Here's the gist of what happened: This will be fitted to match the contours of the rifle butt but I also need to mill a slot in the plate for vertical adjustment. I can't hold the plate in the milling vise once it's shaped to fit the stock, so the slot has to be cut first.
The aluminum plate is virtually the exact same width as the butt of the rifle. That means I've got no room for error in the mounting holes. I started with the rifle's old rubber buttpad. Set it on the aluminum and spotted the mounting holes through it. Then measured the holes in the rifle butt using a caliper to pick up hole centers. Back to the aluminum to verify--and correct--the hole locations slightly. Keeping the holes on the same line did the trick.

After the layout, I center-punched the marks and through drilled.

Then countersunk.

Holes lined up exactly.

The mounting side-to-side is correct.

A bit of dykem and I scribed a fine center line. The hash marks are the end points for the slot. Not a critical length.

Mounted up the milling attachment in the Taig. Used a pointed 3/8" indicator to first set the height then verify that the workpiece was level. When the crosslide is advanced and the point doesn't stray from the scribed line, it's good.

A 1/4" center-cutting endmill was mounted without disturbing the setup.

Started with a light pass.

Used quite a bit of cutting fluid to keep the aluminum from adhering to the cutter.

Followed with repeatedly deeper cuts.

Until it broke through.

Bolted this to the rifle stock and scribed the outline.

I'll cheat a bit and cut the corners off with a hacksaw.

Then go to the sander.

Remember to angle the toe.

It's about 90%+ fitted. Since I'm going to refinish the stock, this is as far as I'll go with the baseplate for now.

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