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!

Grip Stippling on the Diana Model 6M

I finally got around to making the grips on my Diana 6M a bit more comfortable. I had left them large so I could fit them to my hand but I never managed to get around to it until now.

I used a pencil to mark the grips where I felt material should be removed. I would fire a few shots and see how my hand was contacting the grips, the repeat the process.

Here was where there was an almost painful rubbing.

So I attacked them with a rasp, then a file and sandpaper.

Once roughly shaped, I remounted them on the pistol and shot a little more...

Getting to here with the left grip ok but the right needing a little more material removed.

Then I decided that Derrick can't have all the stippling fun so I attacked the grips with an awl.

It's insanely tedious.

At this point I wished I started by delineating the area to be stippled, so I did with a triangular file.

Getting there...

Pretty much done. Now often the stippled areas are left oil-less but I like how it looks and they are still pretty grippy.

It looks worse the closer you get...

Then the left grip...

After oiling I again decided that some delineation was warranted.

So I attacked it with a ball bur in the Foredom.

Oiled and rubbed with steel wool.

They don't look bad.

Remounted on the pistol...

It's far more comfortable to shoot now.

Resealing a Diana Model 10, Part 6

Just the stepped washer to do.

With the washer held against the rear piston seal I checked the gap with feeler gages. I showed .021" of gap. Going by my work on the Diana model 6, I want that gap to be .3mm, or .012". So I need to remove .009" off the face of the stepped washer. On the Diana model 6 I made a whole new stepped washer, which meant I could use the old Diana 6 washer for this purpose...

I chucked up the old washer and tried to face off .009...yikes! Totally hardened. Even with carbide I was having a very hard time removing material and getting a smooth face.

So I went out to my surface grinder and ground the face down.

A lovely smooth finish.
I replaced the stepped washer, checked the gap (it was right on) and screwed the end cap back on.

I ran a bunch of pellets through the chronograph, the last 10 shots with RWS 7.0 gr. Meisterkugeln gave me between 491 and 503 fps. That's about what it should be doing.

How accurate is it? Much more accurate than I am...time to practice.

Resealing a Diana Model 10, Part 4

I made a special tool to put the seals on the pistons.

The tool is two pieces. A plastic rod 1/2" in diameter, with a taper on the end and the other end turned to be a slip fit in a piece of brass tubing. The brass tubing is polished on the end for about 5/8" of an inch. It's about 8" long because that's what I had in my box of brass tubing. I could have used solid plastic rod and just bored a hole to mate with the pointed piece.

The assembled tool.

The tool was lightly lubed with thin oil, and I pushed the seal on, backwards from the direction it would be installed on the piston.

The seal was pushed past the plastic tapered piece, onto the brass tube.

I removed the plastic piece and pushed the seal against the edge of the tube.

I held the brass tube against the end of the piston button, making sure it lined up.

I pushed the piston seal off the tube and onto the piston, where it settled with a lovely and almost inaudible click. This was by far the easiest piston seal installation I have ever done, and I will likely use a tool like this every time I need to fit a seal to a piston. I did the same for the other piston recoil seal/bumper.

Almost done...

Resealing a Diana Model 10, Part 3

On I go...

The pistol action is held in the compressor.

I removed the end cap screw, then the end cap and the sleeve. The sleeve is for contact with the hand.

I used a depth micrometer to determine the gap between the rear seal and the end of the tube, .008". I also measured the distance from the end cap shim and the end of the cap, .422".

The pinion cap screws. I removed them.

I loaded the spring slightly with the compressor. As on the Diana model 6 I used my handy tool, a file tang.

With copper sheet to protect the cap I removed the right hand (looking from the top of the action) cap and pinion gear.

The cap and gear.

The rear piston rack in position.

Twisted up to clear the left hand pinion.

I slackened the compressor and the rear piston came out with the spring.

I pushed the front piston most of the way out with a .125 dameter brass rod through the transfer port. Then I was able to pull it out.

I think the front seal is bad.

The end cap shim and synthetic washer.

The synthetic washer was not in the best shape either.