PT 1911 countersink slidestop radius DIY technique

Discussion in 'The 1911 Forum' started by Cuba, Apr 26, 2010.

  1. Cuba

    Cuba New Member

    Mar 10, 2010
    PT 1911 counter sink and radius slide stop pin end
    I started this thread to help the DIY type person that would like having this treatment done to their 1911 for what ever reasons you may have be it cosmetic or practicality.

    The major concern I had before countersinking my frame was the weakening of the frame, I did my home work and research concerning the countersinking of the frame which for some has been a legitimate point of contention.

    I've always thought that the protruding slide stop looked unfinished, but understood the purpose for it and after seeing some custom 1911's with the countersunk slide stop I though it gave it that finish look that I perceived was missing.

    I looked at the Nighthawk countersink profile, the Kimber profile, The Les Bear profile, Ed brown profile, the Valtro Jardin Custome profile and the Wilson profile though more profound I liked better for a couple reasons, one was that the countersink was wider which I felt spread the removal of metal in a more tapered manner which would weaken the frame less for instance if you file a V grove 2/32"deep on a piece of steel 5/32" and apply a fulcrum pressure it would probably break in half, but if you spread the 2/32" in a tapered manner it would bend but not break in two. Also making the countersinking 3/8" would make it easier to push the pin out, as well as to line up when assembling.

    I was concerned about the profile of the slide stop pin whether to leave it flat and slightly relieve the edge like the Nighthawk or round it off with a complete radius like Wilson's which is what is needed to easily assemble the slide but did not know exactly how to achieve the radius, when it came to me how an electric pencil sharpener worked and I figured a clever way to achieve this by using a hex head driver on the end of a drill covered with emery cloth (photo attached on post #1).I knew that the constant rotation of the emery cloth would create a perfect radius.

    I hope that this tutorial will helped some one that has wanted this treatment on their 1911.
    When enhancing your 1911 with a countersink slide stop pin most people find that producing a perfect radius on the pins end is very difficult, but I have found a technique that simplifies the process.

    You need to under stand that it is critical not to change the remaining diameter of the pin or frames shaft, also you don’t want to over heat the pin and change the tensile strength of the pin.

    First remove the slide from the frame and slip the stop pin through the hole on the frame, with a sharpie marker shade all the protruding section of the pin, if you have a black pistol use a silver color sharpie.

    Now take the pin out and on a grinding wheel start to grind the tip of the pin applying light pressure so as not to over heat the pin, as you start getting to the end of the marked portion check it with the frame, the idea hear is to leave the pin slightly longer then flush about 1/32” to 3/64” because you will need this extra material once you start to rough shape the radius on the grinding wheel, I would wrap a piece of masking tape about 1/8” below the end of the pin to assure that I don’t change any of the remaining diameter of the pin. Start rotating the pin around the grinding wheel in a continuous motion making sure not to grind where you’ve taped, when you have roughly radius the point of the pin you will end up with a slight point, which later on you will remove, that’s why you left the pin slightly longer to begin with.

    Third you will need a 7/32” or 3/16” hex head screw driver tip and a small piece ¾” x ¾”of plumber’s emery cloth. Install the 7/32” or 3/16” driver tip to a hand held drill and place the piece of emery cloth on top of the driver and hold it down with your rough slide stop pin and run the drill at a high rpm while pushing the stop pin down into the driver, it works like an electric pencil sharpener and will produce a perfect polished radius and while applying pressure and pushing the stop pin down, will remove the extra length that was left slightly longer and pointed.

    Now for cutting the countersink on the frame I installed a new cobalt 3/8" twist drill bit with a 118 degree profile tip on a hand held variable speed drill motor and centered it on top of the frame slide stop hole and drilled at a slow rpm keep the drill straight and only go as deep as the width of the bit 3/8” just enough to remove a minimal amount of material to create a dimple which turned out to be about 1/16" deep excluding the tip of the bit that will fall into the original cavity of the frame hole about 1/16" now the point of an 118 degree x 3/8” drill bit is 1/8” long, so you see if you have half of it falling into the cavity hole you are only removing 1/16” of tapered steel, to visually judge what 1/16” is just look at a 1/16” drill bit, it almost looks like a needle.

    Now I thought about a ball cutter but I knew I did not have a drill press needed to keep it dead center and that if I used it with a hand held variable speed drill there would be no way to keep it dead center, and I thought about a counter sinker but was afraid that the pointed guide spinning around the frame hole could make contact with the inside of the hole and increase the diameter of the hole and that’s something you absolutely do not want to do,

    So for me a new 3/8" bit would keep it dead center with out even touching the frame shaft.

    After I needed to smooth and polish the countersink area and what I used was a three inch piece of plumbers emery cloth which I rolled as tight as I could long ways and folded it in half and clamped the two ends onto my drills chuck and at a high rpm polished the inside of the dimple until it was perfect about 1 1/2 minutes make sure you plug the frame hole because you don’t want the emery cloth contouring to the frame hole and altering the diameter of the hole, what I used was a 13/64” drill bit and held it flush to the bottom of my dimple with my left hand while doing the polishing.

    One thing to remember if you have a black gun is to use some masking tape around the 3/8” dimple to prevent any swirl marks from the emery cloth mime is stainless and I was able to remove any swirl marks with a light rub of emery.

    Be aware that the 3/8” dimple will not have a 3/8” profound radius but more like a melted look since you’re doing everything by hand.

    I think that the 3/8” countersink even though it’s bigger you still have to work at it to push out the pin but it’s more practical for ease of take down. We tried using a 5/16” countersink on my sons SA mil spec and he uses the back of a pencil eraser for take down, I think any thing smaller than 3/8” you will be restricted to use a tool of some kind for take down
    Last edited: Apr 26, 2010
  2. JLA

    JLA Well-Known Member

    Feb 26, 2007
    Heart Of Texas
    Pretty cool man...
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