Cutting a Dovetail

[scottnc]

I have a project 336 Marlin nearing completion. It was a 30-30 re-barreled to 45 Colt using a round #2 taper Douglas barrel. I have ditched the barrel bands and need to cut the dovetails for the factory mag tube and fore end cap tenons. I have cut dovetails for flat top 1911's before but have never cut one on a tapered barrel. Assuming I set up with the mill head perpendicular to bore center - what do I use for zero (in Z) to establish the depth of the dovetail cut? Or, is the taper so slight (we're talking the minimum diameter of the cutter dovetail) as to be inconsequential? Thanks!!

[Der Gebirgsjager]

I used to get the barrel properly situated in the mill's vise, bring down the spindle so a small end mill just touched the surface of the barrel, and make a cross cut, then revisit the cross cut with a dovetail cutter. The depth was controlled by the depth gauge measurements on the machine itself as to how far to lower the spindle. If nervous, you can always finish it up with a triangular file.

DG

[M-Tecs]

Without knowing what sight you are mounting it's hard to tell. Some of the sight dovetails need to be cut perpendicular to the top of the barrel (not the bore) so the sight fits flush on the top of the barrel.

[scottnc]

M-Tecs - it is the tenons I need to cut on the underside of the barrel for the magazine tube and fore end cap.

[scottnc]

DG- In the past, with a flat top slide I would touch-off with an appropriate diameter end mill then make a series of cuts to -.010" or so of final depth, then make a pass with the dovetail cutter. The width of cut would then be adjusted a half thou at a time to fit. An open sight rear on a round barrel would usually require a flat of some sort that by default establishes a zero for the dovetail cut? Instead of setting up with the barrel bore parallel to the table (as I mentioned above) I'm now imagining indicating the barrel bottom to zero so the magazine tube will be parallel to the barrel taper once attached to the tenon? I suspect I am making more worry of this than necessary ;-)

[John Taylor]

Almost all the bottom dovetails are lined up with the bore. Fun part is knowing how deep to go. If you put the wood on with the nose cap you can scribe a line through the screw hole on the barrel for the center of the cut. Most Marlins are .060" to .070" deep. If you mess on the depth of the cut you should be able to find a blank tenon and drill and tap to get the screw holes in the right spot.

[scottnc]

Almost all the bottom dovetails are lined up with the bore. Fun part is knowing how deep to go. If you put the wood on with the nose cap you can scribe a line through the screw hole on the barrel for the center of the cut. Most Marlins are .060" to .070" deep. If you mess on the depth of the cut you should be able to find a blank tenon and drill and tap to get the screw holes in the right spot.

Good info, thanks!

[M-Tecs]

M-Tecs - it is the tenons I need to cut on the underside of the barrel for the magazine tube and fore end cap.

Thanks. It seems my reading skills are off today.