Milling a sight dovetail

[Long Ears]

A couple of years back Don Getz said when he uses his mill to cut dovetails he did it in two passes. At least that's what I understood. I'm getting ready to start practicing with my new mill. What I don't get is how would he be able to make two passes when the cutter is tapered? I have a 3/8 dovetail cutter maybe I should get a smaller cutter and cut one side at a time. Advice would be appreciated. Thanks, Bob

[David Rase]

You make the first pass with an end mill clearing out all the material except the dovetail recesses.  The second pass is made with the dovetail cutter.
David

[jerrywh]

 What Dave Race said.  Brownel has the cutters and the directions.

[Acer Saccharum]

Just don't try to mill dovetails on your drill press. 

[bama]

cut a slot with a 1/4" end mill to the depth of your sight base. Install the dove tail cutter and bottom the dovetail cutter to to bottom of your fresh cut slot. If you installed your dove tail cutter without moving the milling table along the axis of the barrel the dove tail should be lined up perfectly with the milled slot. proceed to cut the dove tail, work slowly use plenty of cutting fluid and all should be well with the world.
 

[T*O*F]

Just don't try to mill dovetails on your drill press.

I don't have a mill and have been cutting them on a drill press for years.  It just takes superior knowledge, care, and the right drill press.  Setup is critical and extreme care required when manually feeding the vise.  12L14 cuts like butter, but 4140 is a bit harder.  I started with carbide cutters, but switched to HSS, because the slightest overfeed will instantly shatter the carbide.

However, Acer's advice is well founded for the novice or person who doesn't have a firm background in the use of tools, as there is a steep learning curve which can result in disaster.

[FlintFan]

And don't forget to use cutting oil.  A small squirt on the cutter is all you need. 

[flehto]

When using a mill, shouldn't the top bbl line be parallel w/ the bottom of the slot if a swamped bbl is used? In others words...shouldn't the top flat be inducated ? W/ a straight bbl it's much more simple......Fred

[BJH]

I admit to using a mill to cut my dovetails. Except for front sights, I only pilot cut with a 1/4 inch straight end mill and side shift to enlarge the cut to slightly smaller than the top of the finished sight dovetail. Then finish with a safe edged triangular file. I always cut my dovetails undersized and file to finish fit. BJH

[BJH]

When I set up to mill a dovetail in a swamped barrel I simply use a good level on the top of the barrel to assure parallelism between the top of the barrel and the bottom of the dovetail slot. That is depending on the machine being set up level in the first place. This may sound scary, to allow the vise to clamp a tapered barrel I use one or two layers of shirt cardboard bent in a U on the smaller end of the barrel in the vise. The card board is compressible and nicely makes up the difference so the vise can clamp securely. I usually only take about .030 deep cut at a time with a end mill with this set up. Remember to take up the slack in the lead screw in the table and lock the table before cutting, to prevent cutter grab. BJH