Thursday, September 25, 2008

Cleaning Up a Crosman 66, Part 1

Well, I can't always work on lovely old vintage guns...The neighbor had a bunch of BB guns he had to sell for his daughter, so I bought several for $6.00 a pop. The Crosman 66 below had a few problems. The barrel shroud was missing the screws that hold it in place, the sight was missing and overall it was dirty. So I decided to take it apart and get it back into shape.

The Crosman 66

Notice the shroud is loose and rust freckled.

I used a square drive screwdriver to remove the three screws on the right side.

And one on the left.

I popped the cap off the pistol grip and unscrewed the buttstock.

The trigger assembly. This picture is important for reassembly. You can't really make it out but there are cobwebs in the trigger assembly.

The hammer assembly comes out when the tube is pulled and the trigger parts go all the pieces...

Punching out the pump pivot pin.

The pump arm removed. The pump seal was dirty.

The small rubber seal for the transfer port was removed.

The valve assembly was pushed out the front of the tube. The pump end was really dirty.

I chucked up one half in the lathe, locked the spindle and usncrewed the other half with a vise grip. The jaws were cushioned with a thick rubber band.

The valve, disassembled.
Everything in the gun is dirty. So I'll clean it all up and put it back together for the next post.

Tuesday, September 23, 2008

A Valve Stem Seal for the Crosman 167, Part 2

So, on to the valve.

The valve assembly was pushed out of the tube.

The valve assembly, disassembled.

I used a short dowel pin to press the valve stem out.

The disassembled valve.

Using the directions in Airgun Hobby Vol. 2, Number 3, on page 43, in an article titled "How To Make and Install Your Own Valve Seals" by Peter Ruut, I stamped out a 5/16" diameter disc from 1/8" thick 95 durometer urethane rubber sheet.

However I found that stamping the disc made the edge of the disc concave. This didn't seem ideal to me. I'm not sure why this happened, but will chalk it up to differences in material supply, ambient air temperature and possibly my use of an arbor press instead of a hammer...

So I turned down some 95 durometer rod to 5/16" diameter.

And drilled the hole for the stem.

I clamped a utility knife blade to the toolpost and cut the face off.

Then cut it to length. This worked well and gave a very smooth surface. I think I'll make a dedicated utility knife holder for the lathe.

The new seal on the right, old on the left.

I pressed the valve back together. Notice the bolt in the picture with the cutouts for the cocking pins.
I assembled the rifle and it held gas! Two days later and it's still holding fine, so I'm calling this repair good. I did replace the other o-rings as well, which certainly didn't hurt.

Monday, September 22, 2008

A Valve Stem Seal for the Crosman 167, Part 1

My Crosman 167 has a slow leak. If left for a few days the CO2 empties out, and the likely culprit is the valve stem seal. So I decided to take the valve apart and see if I could make a new valve stem seal. See here for the exploded view. Mine is the first variant with the simple trigger and no front barrel band. It should have an automatic safety, but that part is broken and I have yet to make a replacement.

The action removed from the stock.

The underside.

The valve screw 160-26 is removed.

The screw that holds the end cap is removed. This is where the automatic safety would be if mine weren't broken.

The setscrew that holds the bolt handle in the bolt is removed. My bolt handle is polished because the previous owner thought the bolt handle unscrewed from the bolt, thus marring it horrendously.

Removing the stud 160-10 which holds the action on the stock, and holds the valve spacer 160-7 in place.

The setscrew that holds the barrel in the receiver is removed, as is the barrel.

This reveals the screw 160-32, which also holds the 160-7 spacer in place, and attaches the receiver to the gas tube.

The receiver is removed from the tube. Left stud engages the cutout in the bolt on the left and the right stud (with square head) the cutout on the right. This allows the hammer to cock on closing. Opening the bolt pulls the hammer to the right where it is caught by the sear, and closing the bolt compresses the hammer spring.

The hammer assembly. The pins are a slip fit in the holes.

Spacer 160-7 with the stud and screw. It slides out of the tube when those two are removed.