Collapsing Stock for a Custom Crosman 1322 – Part 2

In my last post I detailed the design process for a collapsing stock for my custom Crosman 1322. Now that I had a design, it was time to start making!

The Exploded View

Just so we’re all clear on which part is which, an exploded view. The only part I didn’t make was the spring.

The Latch Body

I started with the latch body because it’s the most complicated part. Not only does it attach the stock to the rest of the pistol, but it also locks the stock so it doesn’t collapse when you don’t want it to. The features that plug into the back of the air pistol are round, and best done on the lathe. But the slot for the latch bar, and the holes, are better done on the vertical mill. We start with the lathe.

I started with 1.25″ diameter 6061 aluminum round stock. I used a chunk much larger than the part so that I would have something for the lathe chuck to grab onto. The extra length isn’t totally wasted, it will end up in my scrap bin and get used in some smaller project later.

Eventually I got the two smaller diameters worked into the part, and drilled the center hole. This hole is blind (it doesn’t go all the way through, and it’s where the hammer spring sits when the pistol is assembled. I didn’t stop to take pictures of each step as this isn’t really supposed to be a tutorial.

Once I had that done, I parted off the length I needed from the larger chunk. Then I gave the back a skim cut to pretty it up, and the lathe work was done. On to the mill!

Milling the Latch Body

At this point the part is still round. I held it in the mill vise and milled a flat across the largest part, establishing that as “top”.

While I was there, I drilled a clearance hole for the shaft of the latch button, then a larger, concentric hole partway through to capture the spring that would hold the latch locked. Lastly, I drilled and tapped the holes on the skinny end that will attach the whole contraption to the pistol.

I then flipped the part over, milled an equal flat on the opposite side to establish “bottom”. Then I milled a deep groove through the middle of the bottom, just a hair over 0.25″ wide, and halfway through to the top.

That slot will hold the latch bar.

A little time with a file knocked the edges off, and I had a part!

The Latch Bar

The latch bar is just a chunk of 1/4″ square aluminum with a hole drilled and tapped for 10-24 threads. The only thing I had to “machine” was the hole, the rest was done with a hacksaw and file.

The Latch Button

Back to the lathe for the latch button. It’s a really simple part, made from a bit of 1/4″ aluminum stock.

As usual, I cut the small diameter, threaded the end (with a die, this isn’t a high-precision fit), cleaned up the large diameter, and parted it off. Then I turned it around and cleaned up the end. Then I took a file and filed a bevel into the end to make it more comfortable to the touch.

A Brief Interlude to Design a Fixture

Sharp-eyed readers will note there are two rods, exactly alike. In particular, the spacing of the notches must match from one rod to the other. So ideally, I would cut them both at the same time. But how would I hold them? For that matter, even holding one round object is a bit of a challenge.

The mill has a limitation that makes the job harder, too. The rods are longer than the maximum distance the table can move. So I need to be able to move the rods in the vise without allowing them to rotate.

I decided to mount the bars on a long metal bar to machine them, so I could simply slide the whole bar in the vise to reach the far end. I would cut a pair of parallel V-grooves in the bar to hold the rods securely. A couple of blocks with corresponding V-grooves could be screwed down to the bar to hold the rods securely.

Building the Fixture

It isn’t obvious in the pictures, but the cutter I was using has a 90 degree point, so it naturally cuts a V groove. I bought it thinking it would be handy someday, and today was its day!

Since the bar is also longer than the mill’s table can travel, I had to do it in stages. First I cut one of the V’s as far as I could. Then I moved to the second V, and cut it as far as it would go. Naturally, for each V I had to take several cuts, each deeper than the first, until I got it as deep as I wanted.

Once I had both V’s to full depth, it was time to move the work far enough to the right to finish the grooves.

I made two hold-down clamps the same way, except they are short and I didn’t have to fool around with moving them in the vise.

Next, I drilled clearance holes for a 10-24 screw in the clamps, and threaded the bar 10-24. Then I could clamp the rods down solidly, and they wouldn’t move relative to one another.

Back to the Original Project

Once I had the rods mounted, it was a very simple matter to cut the notches.

And with that, all that’s left is the shoulder pad.

But that was an adventure in itself, and this post is getting pretty long. So we’ll wait until next week for that. But I’ll leave you with a teaser!