Wednesday, December 22, 2010
Emergency Christmas Repair on a Crosman 38T
Tuesday, December 14, 2010
Jeffrey Corton’s Diana Seal Tool
As you can probably tell, I’m in the midst of Holiday craft selling insanity and haven’t had time to play with the Rochesters or any other airguns lately.
A while ago I received the following pictures from Jeffrey Corton showing his extremely simple (as in, "why didn't I think of that?"), no machining required version of the seal tool I made for the Diana pistol piston seals. Also scroll down to the bottom for a nice solution to the Crosman model 38 valve tool as well…
All pictures and text by Jeffrey Corton, thanks a bunch Jeff!
1. Parts: seal, electrical end cap (large end diameter slightly larger than piston crown), O-ring, 2" socket extension and socket (slightly wider than the electrical end cap).
2. Work seal over small end of cap.
3. Set end cap inside O-Ring. Press seal using extension/socket down to O-Ring. O-ring is simply present to prevent seal from sliding off the end cap.
4. Final position of seal and end cap.
5. Place end cap over piston crown.
6. Using extension and socket, press seal over end cap and onto piston. Picture has seal already installed and one set to go.
7. Seal pressed in place.
8. Remove extension/socket and end cap should be free.
9. Tada, mission complete.
As promised, a bonus for the Crosman Model 38 valve:
"Don't have a cool lathe like you, so I had to figure out another way to unscrew the Crosman 38T Valve. So: snap ring pliers. See attached pic. I just used the 90-degree attachment, didn't even attach the ends to the plier handles. Just set them in place and twisto-presto. Easy peasy lemon squeezy."
Thanks again Jeff!
Sunday, January 11, 2009
Fixing a Stripped Powerlet Screw Thread on the Crosman 38T

You can see the aluminum in the threads of the powerlet screw (#38C-045).

I carefully pried off the cup (#38-131).

You can see how the internal threads are stripped.

Lots of aluminum wrapped around the screw.

So I drilled out the hole to a letter "Q" drill.

And tapped it 3/8"-24 (fine thread)

I turned down a piece of steel to 3/8", drilled and tapped for the 1/4"-28 thread of the powerlet screw.

Then tapped it 3/8"-24

Threads...

I put a very shallow screw driver slot in the end.

And parted it off to length.

Looks good? I then deburred it all over.

I used red loctite to make sure it stayed in place and screwed it flush with the frame.

Inside the frame.

I pressed the cup back on.

Looking at this I wish I'd refinished the end of the screw...that the slot is so abused can only mean someone reefed down on it with some force, which is probably why the threads ended up stripping. Well, I'm the one who only buys used guns...so it's par for the course. You only need a tiny bit of force to seal and pierce the CO2 cartridge, which is why the manual (.pdf) says to use a coin, not a screwdriver to pierce the CO2 cartridge!

The repair seems to have worked well, although I'll check it nervously every time I charge the pistol. I am happy that I was able to resume plinking, this pistol is great for knocking over tin cans.