What is the best way to machine the counterbore for the disconnector? The length of the mag well and the fact that the counterbore starts on a curved surface poses a few challenges.
I have done it with a long series drill bit in the past by starting the counterbore at an exagerated angle to get past that curved face then straighten up the drill bit once the 7/32 hole is underway.
A slightly bigger drill bit or needle filing can also fix any misalignment when the drill bit wanders on the curved face.
Unless you made a specific tool for the job I cant think of many other ways to get at that one.
Thanks for the reply. I am thinking about trying a 7/32" counterbore bit with a 5/32" pilot and and collet chuck extension. If all of the pieces can be inserted in the magwell, just right, it may work and it would make the counterbore more or less controllable.
The Enco part numbers for the pieces I am probably going to get are:
368-1014 7/32 SHORT SER SS COUNTERBORE
368-3010 5/32 BODY 3/32 SHANK PILOT
891-7164 3/64-1/4" CAP DA300 COLLET CHUCK EXTENSION
240-3095 15/64" CAP. 300DA CNC COLLET
The collet chuck makes the setup a little pricey, but it is currently on sale and would have other applications.
glocklv1; I like your idea of using a piloted counter bore but I think you will find that the collet extension will be to large in diameter to allow you to get the proper angle.
Plus the counter bore will be cutting one edge at a time so feed and speed will be critical and theres an excellent chance that the counter bore will break because those little counter bores can not take any side load.
I suggest that what you do is take a piece of 1/2 stock about 4" long and center drill a hole that will allow you to solder a 7/32 end mill into it about 3/4 of an inch.
Before you solder the end mill turn down the outside diameter of your shank on the end that you are going to solder the end mill to about .350 of an inch for a length of about 1-1/2 inches.
Now there are 2 end mills sold in the 7/32" size one has a 1/4" shank and one is 3/8" you want the one that is 1/4".
Brownells sells a solder paste that can be used for this solder job.
Wrap a wet rag around the cutting end of the end mill coat the shank end of the end mill with solder and smear some solder paste in the hole you drilled into the homemade shank and make sure you hold the end mill in place while you are heating up the joint.
P.S. only apply heat to the outside of the homemade shank
A long time ago in a state far away... I drilled from the top then used a correct diameter carbide burr with a 1/8" shank to do the counterbore... insert the shank through the frame and then chuck it in a drill chuck.
I avoided this operation for almost a year because I thought it was going to be such a PITA. Finally, I just turned a little piece of drill rod to the correct diameter, cut a couple of notches in it, and hardened with a propane torch. Then I used Loctite red to glue it onto a drill bit that was the right size. Worked great, took all of 15 minutes, all of that worrying for nothing...
