Thursday, December 17, 2009

Daisy 717 Repair Part 1

Nick sent me a big box of incredible airgun fun today. He's got some kind of secret gift for finding airgun stuff at yard sales, flea markets and gun shows that most of us can only dream about. In the box was a Daisy 717 target pistol. It was in several pieces. A quick reassembly and I found--as I had been forewarned--that the air valve was leaking like mad. Long time and extremely astute readers will note that Nick has already repaired the .22 cal version of this gun--the discontinued model 722. I thought I'd blog this anyway. I know, aways late to the party. Bear with me. The generic term 7XX is used to denote all the variants--the 717, 747 and the discontinued models 777 and 722.

Daisy 717. Age unknown.

If you've never handled a Daisy 7XX pistol, take a look at that ruler. It's about 14" long. Target guns can be almost cartoonish in size.

I began disassembly by removing the rear sight and setting it aside. Next, put the safety on by pushing it all the way to the right--or the ball bearing and spring will fly across the room. Ask me how I know this.

Then unscrew the grips.

Open the cocking lever,

and remove the three phillips head screws.

The left cover lifts right off.

The grip frame then pulls off and the compression tube comes off the front.

Wrap your hand around the left side of the safety and push it from right to left. The ball bearing and spring will pop out of the body of the safety button.

Give the cocking lever a quick close and the air valve and barrel assembly will "pop" out of the end of the compression tube from the pressure build up. If the pump seal is bad and it won't build pressure, just pull it straight out.

This o-ring seals the face of the valve to the inside of the compression tube so the compressed air goes into the valve instead of leaking around it.

Unscrew the pump lever pivot.

A curved washer is under the screw head.

Front sight lifts up. It's got a post that slides through a bushing for the cocking lever pivot. The post is threaded for the pivot screw removed above.

The steel cocking lever bushing. Note that is has a groove on the top end. The groove must sit at exactly 90 degrees to the tube when reinstalled. The bottom of the front sight has a corresponding notch that rests in this groove--this aligns the barrel to the compression tube.

Pulling the cocking lever forward removes the piston. There are two curved washers . One above and one under the cocking lever. The curved sides match the ID of the compression tube. They keep the lever centered at the pivot. The cylindrical bushing goes through it all.

Piston has an o-ring seal and a felt wiper. The felt (replaced with a foam ring on the new models) retains oil. It's only there to keep the seals wet with oil to prolong sealing and lifespan.

Fear not. The new foam ring Daisy now uses will retrofit perfectly.

Remembering Nick's previous experiment, I faced off the front of the piston using the Taig lathe. Removed several thousandths until the face was even and the high spots were gone.

High speed, a sharp knife, and light cuts.

LinkLapped the face with polishing compound on a granite plate. The spots in the center are low spots--small imperfections in the face of the casting.

Removed the valve with a 1/2" wrench.

Shoot. It's an early one. The valve seal is conical on the early guns.

The original on the left. A brand new 7XX valve is on the right. The white end seals are different shapes. The new seal is dome shaped. I don't know if the new seal is simply a drop-in replacement or if the seal needs to be turned down into a cone.

More to come...