Drilling flat-bottomed blind holes

josquin

josquin

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Reading John Y Cannuck's post about a disaster with unfilled sight base screw holes ("Nasty little horror story on drill and taps."), made me wonder how to drill a flat-bottomed hole, which would minimize the extra depth created by the angled tip of a regular drill bit.

I will be replacing the front ramp and sight on a Huskqvarna 640 wih one from NEGC, which will require drilling one 6-48 hole near the muzzle, which will have to be very shallow indeed. The pilot of a 6-48 counterbore won't do as it drills a clearance hole (.137 rather than .120) I guess I could just solder the ramp on with Hi-Force 44 but I'd like to have a screw in there.

:) Stuart
 
You drill the hole with a normal drill and then finish the hole with a flat bottom drill... you have to custom grind it... do this all in a drill press or mill where you can measure to the thou how deep you want to drill...

With the quality of the optics today I don't know why anyone bothers with front sights on high powered rifles...?
 
guntech said:
You drill the hole with a normal drill and then finish the hole with a flat bottom drill... you have to custom grind it... do this all in a drill press or mill where you can measure to the thou how deep you want to drill...
Click to expand...

Thanks, Dennis. I figured that might be the way to go, as there are no .120 end mills (!)

As to open sights, yes it will get a scope (probably a 1.5-5) but I like to have decent iron sights as well. They are traditional on an old rifle like this...
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and I like practicing with them. Plus they're still useful for shorter ranges should the scope "go south." (The white-line pad is going to be replaced as well.)

:) Stuart
 
And if you don't want to drill and tap, and don't want to solder, hard or soft, NECG offers a streamlined banded front sight unit. Put one of these on a Mannlicher Schoenauer I rebarrelled for a friend, and it is a very nice unit.
 
tiriaq said:
And if you don't want to drill and tap, and don't want to solder, hard or soft, NECG offers a streamlined banded front sight unit. Put one of these on a Mannlicher Schoenauer I rebarrelled for a friend, and it is a very nice unit.
Click to expand...

Funny you should mention that as I also have a sporterized 1903 M-S that will need a new banded front sight. But the NEGC ramp I want to put on the Husky is the one that allows height adjustment of the front sight since the rear sight is fixed.

:) Stuart
 
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