Thursday, December 22, 2011

Fitting Echols Scope Mounts: Part 2

Scope Mount Blanks Along With Other Echols&Co. Parts

The next step in the process is to select a set of mount blanks in either 1" or 30mm.  We have our blanks made by Central Valley Machine of Logan, Utah  The blanks are made oversize in height and length and undersized in bore diameter to allow flexibility when fitting different scopes.

The front blank is machined to proper height and then is set up in the mill for boring.  The scope bore is bored to actual scope diameter plus .001-.002".  In the same set up, the ring radius (which was established when surface grinding) is bored into the base of the mount thus insuring that both the bore and the radius are in alignment with each other.
Boring The Ring Radius

The mount is then removed from the vise, deburred and set up for splitting the ring halves.
Ring Half Split

Next, the centerline of the mount is found and the screw holes and counterbores are machined.
Mount With Holes and Counterbores

The upper and lower mount halves are stamped with an F or R to denote front or rear and which scope the mounts were designed for (ex. Schmidt Bender=SB).

The rear mount is then machined concentric with the front.  The receiver is held between centers via mandrel and a holding fixture on the inspection plate.  A precision ground 1" bar is placed into the mounts and height and alignment are checked with a dial indicator.
Rear Mount .016" Higher Than Front

Rear Mount 0
Front Mount 0

Lapping is now a formality done mainly to remove machine marks.

Fitting mounts using this procedure ensures that the optic is held stress free and in alignment with the bore.  In most instances, the scope only has to be adjusted an inch or two from its optical center to zero the rifle when firing for the first time.

Excess material is now machined away from the mounts and cosmetic cuts are made (sides are angled and corners are given radiuses).  All surfaces are then hand polished to a 320 grit finish.

Finished Set of 30mm Mounts

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