Enhancements to the Power Series I Stoning Fixture

For many years, I’ve owned one of Ron Power’s Series I stoning fixtures, and I’m amazed at the different jobs it will do and the high quality of the finished sears and triggers that can be produced on it. Before I owned it, I had to cobble something together for every stoning job. Usually, I would clamp a trigger between two 1-inch-square steel bars on a surface plate and let the tip of the trigger protrude a few thousandths.

More often than not, when I removed the trigger and installed it in the gun, it wasn’t right. Then I had to go back, Below left and do it over again, and it was virtually impossible to repeat the exact same setup the second time. Ron’s fixture and adapters have solved all that. Sometime when things get slow, usually after Christmas, I start dreaming up ways to build, modify, or improve a particular piece of equipment. That’s exactly how I came up with these modifications to the Power stoning fixture.

Building the Roller Assembly The first modification I came up with was building a roller assembly to replace the small steel roller. I first removed the elevator block and removed the section as shown in Figure 1. This is quite a hefty chunk of material to deal with. I located the roller-axis bolt and, using anew pilot drill, drilled the hole in the lathe using a four-jaw chuck. I Figure 1. took care to get the side of the elevator exactly 90 degrees to the drill.

I then drilled with a #3 drill for a 1/4-28 tap and enlarged the near side with a 1/4 drill for 3/8 inch. I then sawed both sides with a hacksaw and drilled a series of interlocking holes across the bottom, after which I sawed across the

bottom and cleaned up everything with a mill. If you "goof" and the hole is not perfectly square with the side of the elevator, you can take a small round file and elongate the 1/4-inch hole up and down slightly. Next, I used a number 43 drill to bore from the top down through the bolt hole and down in the side of the elevator so a 1/4-inch-long 4-40 Allen screw will go below the 1/4-inch bolt hole.

I tapped this hole and installed a 4-40 Allen screw in the bottom and one in the top, and adjusted the 1/4- 28 bolt until it was exactly 90 degrees with the side of the elevator. I cut the roller bolt slightly short so it wouldn’t drag on the side plate. The roller, shown in Figure 2, was made of a section of 3/4-inch heavy black iron pipe. I cut it to length, faced both sides, and bored it for the ball bearings.

The ball bearings (Figure 3) can be cheap ones, since they don’t Figure 3. have to bear a heavy load. (Mine cost $4.50 each.) I wanted a hollow roller assembly to avoid having a heavy rotating mass. I could have used a solid section of round stock and enlarged the center with a large drill and bored for the bearings. It’s important to ensure that when you spin the roller assembly, there is no run out on the OD.

I modified Ron’s hammer/sear adapter slightly in that I used a fineline metal-checkering tool and lightly scribed lines in the location that he uses for a reference point. I also drilled and tapped the edge of his trigger/ sear adapters for a 10-32 hole and pleted, I began to think how great it would be if the fixture could do the hammer-engagement surface also.

The stoning fixture will already square the hammer hooks and reduce the depth of the engagement surface, and you can put a mirror finish on the trigger/sear surface, but you still have a rough hammer-shelf surface. Building the Hammer-Stoning Adapter After the roller assembly was com- After much trial and error, I came up with a hammer-stoning adapter. The adapter, shown in Figure 4, is made of 2-inch heavy-duty angle iron and shaped as shown.

The adaptor is clamped to the side plate (Figure 5) and the location is spotted in the adapter for the 1/4-20 Allen bolt in the side plate that Ron uses to hold his hammer and sear adapters to the fixture. I drilled with a #7 drill and used a 1/4-20 tap for his original Allen bolt. To make sure of repeatability, the angle-iron adapter is bolted to the side plate and clamped tightly. I also drilled a 3/16-inch hole as shown through the original side plate and through the angle-iron adapter for a locator pin.

I chamfered a 3/16-inch pin slightly and used a center punch to put some "dimples" in the part that will be in the side plate. Then I drove it through the side plate and into and slightly through the angle-iron flange. Figure 2. Figure 4.

Figure 5. built a shoulder bolt (Figure 6) and screwed in the side of the adapter as needed. This is only needed when you are stoning a hammer surface, and allows very small incremental movements when you are trying to get the hammer surface adjusted so it will be parallel with the roller. The final modification I made was not to the fixture itself, but rather to the Brownells 6- x 1/2-inch stones (India, ceramic, and Arkansas) I use with the fixture. This modification is shown in Figure 7.

I cut one side to a 10-degree bevel so it will "reach in" to the back side of the hammer shelf. I use these stones only for hammer shelves so they stay sharp. If one should become dull you can sharpen it by holding it at a slight angle and raking it along the side of the diamond wheel. (The side of the wheel will cut just like the face.) Putting Everything to Work The original fixture still operates in the original manner and all of the original instructions still apply.

The only change is the hammer-honing fixture. To use it, mount the angle-iron hammer adapter as shown in Figure 5. Attach Ron’s adapter to hold the hammer with the hammer surface parallel to the elevator roller. The adapter is mounted on the face of the angle adapter (the side next to the roller). The most convenient method I’ve found is to place the fixture on my drill press table.

I can then adjust the height to a convenient level to work with. (The drill press table has to be perfectly level.) I make a cylinder out of a quarter sheet of white copy paper and place it close behind the elevator roller. I put a bench light over it and focus it inside the cylinder. This gives a nice soft defused light. Next, I rotate the hammer-hook Figure 6. surface until it seems to be parallel with the roller.

I use a binocular magnifier and look at the hammer surface and the roller and get them as close to parallel as possible. Then I take a level and put it Figure 7. on the roller and the hammer hook and elevate the roller assembly until the bubble indicates level. This will get you close. I always do the honing on the hammer surface before reducing the hammer-hook depth. This simplifies the process of getting the hammer surface parallel to the roller surface, since you have a much greater sighting plane to work with.

The next thing I do is coat the hammer surface with a black marking pen and lightly drag the modified India oil stone across it. Then I check to see where the black ink was removed. I then rotate the hammer and raise or lower the elevator until I’m getting 100-percent ink removal from the surface of the hammer. I then hone the surface until the heavy machining marks are removed, and follow up with a ceramic or Arkansas stone to bring the surface to a high shine— always keeping the original factory angle, of course.

I’ve found that many of Ron’s adapters work on oddball guns that he doesn’t build adapters for. You just have to match the hole in the hammer to one of the pins. If I can’t find anything that will work, I make my own using a section of 1/4- x 1-inch steel. In my part of the country, for example, the New England Handi Rifle with a heavy barrel is getting very popular due to its price and accuracy. I easily made my own adapter for it.

As a final piece of advice, be sure to make a drawing of every setup you use with this fixture. That will save you much time on the next job.