Tuesday, January 27, 2009

Derrick's on a Trigger Frenzy! Part 1

Derrick here today. Some projects just beget other projects. While working on the wide-bladed brass trigger for the Crosman 2250 last week, I came up with a different trigger idea that I had to work out. As per my usual, I started working without a real plan--and as usual, it's got to have some match gun style.

First, I wanted some better pivot pins for this soon-to-be trigger. Found a piece of hardened 1/8" drill rod and marked off several intervals of 0.410". Might as well make a couple extra.

Used a carbide v-shaped bit to groove each 0.410" section. I didn't bother to cut all the way though. The hardened 1/8" drill rod is incredibly tough stuff. While that's just great for wear resistance and reduction of friction, it's lousy for cutting. I essentially "scored" the rod with the cutting tool. The drill rod then went into a vise and each section was snapped off. Was like breaking a glass rod. Not shown: I then turned on the grinder and ground each pin down to 0.393"---The final length needed for Crosman sized replacement pins.

The soon-to-be trigger blade: I wanted the face of the trigger grooved--just like in the movies! Mounted a piece of 1/2" wide brass in a Taig milling vise. Then bolted that to the horizontal milling attachment for the Taig lathe. (The Taig is all modular. It's pretty ingenious that way) It almost fell apart when I realized (incorrectly at the time) that I didn't have a small enough milling cutter. I ended up making the cut by using the tip of a center drill. My thought was that a center drill is so rigid, and this was soft brass, the tip wouldn't deflect. It worked. Two hours later, I realized there were 10+ suitable cutters in the Dremel kit. Sigh.

I cleaned the grooves up by hand with a needle file and set this aside.

I wanted the trigger blade to be rotational on it's long axis. A 2" long piece of 3/16" brass rod was chucked, faced, spotted and drilled through. I think I used a number 33 drill. The hole just allows clearance for a M3 x 0.5 bolt. I'll cut the brass to length a bit later.

Quack! It's a little aluminum duck! Cut away all the parts that don't look duckish.

Didn't show the first part of this plan: Took the world-renowned Crosman 22XX trigger, transferred the pivot and sear contact locations to this piece of scrap aluminum bar stock. Used a high precision fat tipped Sharpie. Color: Uh, green.

Excel Jeweler's saw. Think "micro coping saw" and you've got it. A great, inexpensive tool for fine precise cuts. Note: Fine precise cuts not shown here.

The Excel people are probably sending someone to repo my saw...

I'll knock it down closer to size on the grinder then go to it with a small file. I wanted some extra material here to work with. The big marker ensured it.

Does this help visualize my dream? The aluminum piece is the trigger pivot and sear contact. Call it a rocker arm.

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