Dovetail Forming Chisel
Instructions:
#Tool-Dovetail tempered steel dovetail forming chisel.
Figure 1.
Figure 1. Cut a narrow slot for the sight or barrel lug.
A front sight slot must be the full depth of the sight base, to allow the lower
edge of the blade to touch the barrel. File away the raised ears for a front sight.
A rear sight slot should be 0.030" to 0.040" deep, to a maximum of .062"
(1/16") deep. A shallow slot will more easily form a raised dovetail. The initial
slot must be narrow enough to allow the 60 degree angled edges of the sight overhang
the slot. The undercut will be formed, and edges raised, by the dovetail chisel.
The undersize slot may be cut with a milling machine, or adjoining hacksaw slots
smoothed with a file. Used for sights and underlugs, practice this technique on
hidden underlugs first. Set key lugs full depth to place the key flush with the
barrel's bottom.
Figure 2.
Figure 2. Place the dovetail chisel in the undersize slot. It is
very important for the foot of the chisel to sit flat on the bottom of the undersize
slot. If the chisel is struck as shown, with the foot tipped upward, it will leave
a small step in the corner, that must be removed with a three corner fi le with
one safe-edge. Carefully inspect the chisel angle, before you begin striking the
rear edge to form raised moldings above the undercut edges.
Figure 3.
Figure 3. Depending on the depth of your slot, one or two brass
shims may be needed to level your chisel. Two thicknesses of brass shims are provided.
Figure 4.
Figure 4. Place the thin, thick, or both brass shims below the
base of the chisel, until the chisel foot sits flat, or is tipped downward slightly.
If you do not have the chisel oriented properly it will leave a small step in the
corner of the dovetail. If no shims are used in a shallow notch, the undercut slot
may tip upward. Raise the dovetail, forming a molding, with repeated hammer strikes
to the rear edge of the chisel.
Figure 5.
Figure 5. Place the chisel edge at a corner of the undersize slot.
Hold one hand on the chisel arch, to brace it. Strike the angled flat at the rear
of the chisel. Several light blows will lift an edge more easily than a single heavy
blow. Rice, Colerain, Getz, Goodoien and other barrels made of 12L14 steel work
easily. Green Mountain barrels are slightly harder 1137 steel. Douglas, or Spanish,
Italian or other imported barrels are often drawn steel, work hardened, very difficult
to form, not recommended for use with this tool.
Figure 6.
Figure 6. Once the first edge is raised, repeat on the opposite
side. The chisel has high relief to clear the first raised edge, to prevent any
damage.
The slot above is shown with lifted dovetail edges formed to create moldings on
either side of the sight. If you did not have the dovetail chisel nose flat against
the bottom of the slot, you may find a small step inside the corner of the dovetail.
If this occurs, it must be removed with a safe-edge triangular file, before fitting
the sight. Use Swiss pattern needle files to shape the raised ears into attractive
moldings.
Figure 7.
Figure 7. Debur the sight base. Remove any casting gates with a
file. By convention, install the sight from the lock panel side, right to left.
Gently tap it in place with a brass or hardwood drift punch to prevent marring the
sight or barrel fl ats. To remove the sight, drift it the opposite direction, from
left to right.
Figure 8.
Figure 8. Installed on an octagon barrel, in a raised dovetail,
the sight base is wider than the dovetail, to extend past the side edges of the
dovetail slot. When zero'd, strike a center-mark across the front joint.
Made of hardened steel for long life, use a whetstone to hand sharpen the edge at
a 60 degree angle.