Rochester Disassembly/Reassembly, Part 6

With the valve resealed I had to turn attention to the pump plunger.

Nasty.

A reader sent this trick of using snap ring pliers as a spanner.

Unscrewed easily.

Nut, leather pump cup and steel washer in the bottom of the cup.

You can see that a bit of the leather cup stuck to the brass…

A new Crosman pump cup will do the job and the height of the cup is similar.

Drilling.

Checking depth as I bore out the rubber cone.

Cutting off the cup.

Fits fine. I need to make another one with a slightly thinner bottom though as tightening down the nut causes the cup to expand a little too much. With the nut just snug it’s fine.

Temporarily reassembled for testing. I sealed the tube to the valve body with teflon plumbers tape. It’s been holding air for days now, which is a good thing. I’m going to use an o-ring and some teflon tape for the final seal.

A CO2 Tank Adapter for the Aeron Part 1

A few months ago, I ended up with a couple Aeron target guns. Didn't exactly mean to get two, but the second gun was purchased for a buddy on a whim--but the timing didn't work out for him and he wanted some other airguns. No problem, I've always got room for another match gun. Besides, my wife likes making metal silhouettes go CLANG with it.

This was one of Tom Gaylord's guns. He sent it with a small CO2 tank, and two different end caps. One allows filling from the tank (bulk-fill), the other allows use of standard 12 gram CO2 cartridges.

My grubby fingers are holding the bulk-fill cap. The 12 gram cap is installed on the gun.

Essentially, just swap caps then screw the tank to the cap to fill the gun.

Tank has a pin valve, bulk fill cap has a check valve.

The missing link. There's one small problem-- I don't have a way to fill the tank that fills the gun. I've been looking at all my various CO2 adapters and trying to come up with the simplest combination to make this work. If I start with a 20 oz paintball tank, attach a B&A bulk fill adapter, then a Crosman PB to Airsource adapter, I only need to make a double-threaded nipple to finish the connection. Yeah, only....

The small tank has M18 x 2mm threads (and needs an internal o-ring to seal on a stem) while the Air Source adapter requires M16 x 1.5mm threads.

Aluminum was ruled out by co-worker Rich who plays tournament paintball matches and has seen enough equipment failures to know what he's talking about. He was concerned that aluminum would suffer excessive thread wear over time if it was unscrewed under gas pressure. He was adamant about using either brass or steel. I didn't have a piece of 3/4" OD brass on hand so a piece of O-1 tool steel will have to do.

Faced the ends and turned one end down to 15.85mm...

and the other end to 17.8mm.

Threaded the skinny end to M16 x 1.5mm for the A/S adapter.



I didn't have a round 16mm thread-cutting die on hand . The hex die (it was essentially brand new) worked just fine. I'll have to cut a radius at the end of the 16mm thread to engage the internal o-ring in the female adapter.

The M18x2mm thread was harder to cut, as it's a big, coarse thread. Once started on the lathe for alignment, I quickly moved the die to a large handle and finished in the bench vise.

I'm a bit concerned about the M18 end. The end needs bored and an internal o-ring as well as a pin to depress the tank valve. I may have to grind some blank lathe tool bits before making any further headway.

I'll be back in a few days.

A Spare Magazine for an Aeron B96 Part-2 Final

Back to the Aeron magazine.

Bolted a couple 1-2-3 blocks together and placed the original mag against the soon-to-be. This arrangement kept things relatively square while I marked the angle across the corner. The angle appears to be for ease of insertion into the mag carrier on the gun. Not shown: milled and finished the angle.

I set up the original mag in the milling vise and used it to set up the quarter round cut. The depth of this cut indicates the mag in the carrier. I used a depth micrometer set against the lower fixed jaw on the vise to position the work in the same location.

Used a 4mm end mill then test fit the mag in the gun. It was a good fit in the carrier. A bit tighter than the original.

Not exactly an epiphany, but I've been thinking a lot about how to mark off the pellet hole spacing on the mag. It occurred to me that I could simply remove the barrel...
and just use a transfer punch to mark directly though the breech.

Put some layout fluid on the face of the mag, then slid it home.

Lucked out and had a punch that fit the breech like it was made for it.

Tap, cycle the carrier manually. Tap, cycle the carrier...

Testing: Drilled some aluminum with various sizes of bits then tested .177 cal wadcutters in the holes. No real surprises here, but I settled on a #16 bit for final size.

A pointed indicator is used to locate the center of the hole...

then it's replaced with a bit and through drilled.

Then back to the indicator for the next hole. Slow, but it worked.

Opened the holes up to #16 (0.1770").





Used a #15 bit in a pin vise to chamfer the breech side of the mag to allow the pellet skirt to seat flush.

A small groove cut with a 1/4" ball mill marks the side to load.

Front view. Test firing was surprisingly uneventful. The darn thing functions and the pellets go into a little tiny single hole on the target--??? I am utterly astonished that this even cycles--let alone works. Oh, the bottom mag is the new one. I'm absolute proof as to the old saying about blind pigs and acorns.

Rochester Disassembly, Part 5

With the valve apart it’s time to make some changes.

The internal valve body threads are 27 tpi, as best I can figure. I was hoping I’d have a tap to clean the threads out but it was an odd diameter…

So I used a pipe tap as a scraping tool, following the wall around to clean off all the schmutz.

The plug was cleaned up with a thread file.

Now it screws together easily.

Whatever the old seal is, it has to go.

I made an arbor to hold the plug on the lathe. A rubber washer protects the inlet valve seat.

Parting tool set up to make an o-ring groove.

Turning the groove.

Test fitting an o-ring

Doesn’t screw quite all the way on, but that will be addressed…

Cleaned up the face of the plug while I was at it.

Like new!

I needed to bore a recess for the o-ring in the valve body.

Just enough to get down to the thread root.

Seems to go together snugly.

The solder filled a groove at the end of the threads on the valve body. I turned away the solder until I just hit the brass.

Test fitting it to the tube. Aligned, the gap is too large, but I suspected the threads in the tube needed more cleaning.

You can see that the slot and the setscrew hole need to be aligned.

After cleaning out the tube threads a bit more the gap is acceptable and similar to the assembled versions…

I also made two seals for the inlet and exhaust valves. They may be too thick (.125”) although the old ones are so deformed it’s hard to tell how proud they should be. I’ll try them like this and modify as necessary.

Next up is the pump plunger, then figuring out how to keep the tube aligned and sealed to the valve body without resorting to solder. Then reassembly…