Saturday, May 16, 2009

Making a Steel Breech for a Crosman 2240, Part 3

Almost done...

About to mill the slot for the bolt handle.

And milled.

This is a rather convoluted setup for milling the bolt catch. The breech is tilted on its side 30 degrees.

The slot cut.

A Crosman bolt (from their steel breech) fits perfectly.

Again, the rough finish.

Assembled on the 2240 to check for fit and function.

Now to do something about the finish.

An aluminum rod was turned up to be 7/8" diameter minus the thickness of some sandpaper. I used it to sand the radius smooth.

Looks much better.

I was going to lap the sides against sandpaper but then I remembered that I had a surface grinder! So I started to grind the sides.

I probably removed about 2-3 thousandths on each side.

Grinding the chamfer on the bottom.

Shiny, now I regret not making it from stainless...

A 220 grit Scotch-Brite Bristle Disc on my polisher.

I deburred and smoothed. You can see some sandpaper wrapped around a file just above the breech. I used it to smooth the breech cutout and the dovetail surfaces. I still see some faint milling marks but I'll live with those.

Another view. I tapped the two holes for the barrel setscrews.

I turned up an end plug.

And made a decorative series of grooves in the face.

I blued both with Oxpho Blue. I'm going to see if I can get it darker.

You can see reflections in the breech. Now I need to work on the bolt and bolt handle as well as figuring out what length barrel to use. But not bad for a first breech?

Friday, May 15, 2009

Making a Steel Breech for a Crosman 2240, Part 2

On I go. I coated the breech with layout dye and scribed hole locations as insurance against mistakes when counting turns of the hand cranks.

Picking up the bore centerline, steel pin was pressed into the bore.

Picking up the end. You can see the rough finish on the radius.

Spotting the transfer port.



The hole for the front hold down screw was drilled.

The rear screw hole drilled.

Slotting for the cocking pin.

I flipped the breech over and located the end again.

Drilling for one of the two barrel setscrews.

The other one drilled.

Milling out the loading port. Yes I managed to get a sliver of steel in my finger.

Counterboring for the front hold down screw.

Counterboring for the rear hold down screw.

Making progress!

Thursday, May 14, 2009

Making a Steel Breech for a Crosman 2240, Part 1

I picked up a Crosman 2240 air pistol a few months ago at a pawn shop. I decided it would benefit from a few modifications, the first of which is a steel breech. So here I go:

Some 1" Free machining steel was chucked true in the 4 jaw chuck.

I drilled down 2" with a long drill bit...

Then a slightly larger drill bit...then repeated until I was in about 4"

I reamed the hole 1/4"

Flipped the work and repeated the step drilling to the proper depth for the barrel.

And reamed to 7/16"

Unchucked my tube from the lathe and started milling.

One side done.

Flipped and the other side milled.

Flipped again...

Now my tube is a rectangle. Why didn't I just start with rectangular stock? Because I wanted to use free machining steel and I didn't have any square on hand.

Finding the edge.

Milling a step as preparation for the dovetail cut.

The other side step cut.

Milling the dovetail.

Almost looks like a breech.

The Taig won't handle a 7/8" diameter end mill, so I had to use my Barker horizontal mill. I aligned the work on the table.

And cut the radius groove. My Barker is pretty worn out so I got a terrible surface finish, the table was slewing back and forth during the cut as the rack feed must have about a 1/4" of backlash. The next breech, I'll line bore on one of the lathes, but for that I'll have to rig up a milling attachment and single point between centers bar.