This post is based upon advice and tips I received from Tim Barbieri, who is also working on a 3810, and we have been corresponding.
Even though you can put a straight edge on the metering surfaces and base of a main body, you can never tell if those surfaces are truly flat. If you can tell with a straight edge, then you ought to sent the main body to a machine shop to have it milled, like I did on my last one.
However this 763 met the straight edge test, even though the surfaces weren't really truly flat. So I followed Tim's advice, and got a friend who was in the glass business to cut me a piece of plate glass. He cut me a piece of 1/2" plate glass, to my spec of 3-3/4" wide so that it would fit the base of the body between the flanges with a little clearance. Here's the apparatus:

With this plate glass, I cut sheets of wet-dry sand paper and used double stick tape to hold them to the plate:

I started out with 220 grit, and you will find the high spots in a minute in wet sanding on a flat plate. I then switched to 150 grit to cut some meat then finished off with 220 grit. Back and forth for about an hour, I sure wasn't having fun. But the result came out pretty good:


Nice and flat and shiny.
Thanks Tim for the tips.
Now on to Main Body coloring.
Having fun now,
Even though you can put a straight edge on the metering surfaces and base of a main body, you can never tell if those surfaces are truly flat. If you can tell with a straight edge, then you ought to sent the main body to a machine shop to have it milled, like I did on my last one.
However this 763 met the straight edge test, even though the surfaces weren't really truly flat. So I followed Tim's advice, and got a friend who was in the glass business to cut me a piece of plate glass. He cut me a piece of 1/2" plate glass, to my spec of 3-3/4" wide so that it would fit the base of the body between the flanges with a little clearance. Here's the apparatus:
With this plate glass, I cut sheets of wet-dry sand paper and used double stick tape to hold them to the plate:
I started out with 220 grit, and you will find the high spots in a minute in wet sanding on a flat plate. I then switched to 150 grit to cut some meat then finished off with 220 grit. Back and forth for about an hour, I sure wasn't having fun. But the result came out pretty good:
Nice and flat and shiny.
Thanks Tim for the tips.
Now on to Main Body coloring.
Having fun now,