Two steps forward...

Two steps forward...

Joined: October 3rd, 2010, 3:22 pm

January 11th, 2011, 1:39 am #1

one step back.

Well, in my amazing cough prowess as an uh ahem "expert" machinist, with one fell plunge of the quill on my El Cheapo Taiwanese Bridgeport clone mill, I afforded myself the opportunity to refine, redesign, and remake the breech on the PCP project.

I found that the aluminum pedestal in the auto loader was garfing up the pellets as well as causing excessive friction. I made an insert to hold the cylinder out of Delrin. The tolerances are much better this time around so in the end the extra work will pay off. There's still quite a bit of work left to do on the breech.

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Oh, and the reason there is a 1/2" piece bolted to the back of the breech? I had a moment of subconscious spontaneous creative brilliance that bored the barrel hole a 1/2" too deep. A long breech will look cool on this rifle anyway. DOH!

My hat's off to those in Crosman land and beyond that can take a block of metal, clamp it in a mill vise, and with a hand mill create a work of art. It's so much harder than it looks.

But all this practice is teaching me a great deal about machining. The next project will be that much nicer. Phil, I'm watchin' that big bore pumper. Ya got me thinkin'...
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Joined: November 19th, 2004, 4:39 am

January 11th, 2011, 3:38 am #2

Can't wait to see the working proto
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Joined: April 1st, 2009, 3:18 am

January 11th, 2011, 3:38 am #3

one step back.

Well, in my amazing cough prowess as an uh ahem "expert" machinist, with one fell plunge of the quill on my El Cheapo Taiwanese Bridgeport clone mill, I afforded myself the opportunity to refine, redesign, and remake the breech on the PCP project.

I found that the aluminum pedestal in the auto loader was garfing up the pellets as well as causing excessive friction. I made an insert to hold the cylinder out of Delrin. The tolerances are much better this time around so in the end the extra work will pay off. There's still quite a bit of work left to do on the breech.

[/IMG]

Oh, and the reason there is a 1/2" piece bolted to the back of the breech? I had a moment of subconscious spontaneous creative brilliance that bored the barrel hole a 1/2" too deep. A long breech will look cool on this rifle anyway. DOH!

My hat's off to those in Crosman land and beyond that can take a block of metal, clamp it in a mill vise, and with a hand mill create a work of art. It's so much harder than it looks.

But all this practice is teaching me a great deal about machining. The next project will be that much nicer. Phil, I'm watchin' that big bore pumper. Ya got me thinkin'...
it is! Just tell people the bolted rear is for access purposes (smile) - no one well tell the difference. Does look good. I would love to have even a "cheap" mill and lathe. Improvising is what I have to do, like using a 1/2" drill as a lathe! Pretty funny, I know. It works! My watch making fine hand movements have allowed me to be pretty prcise - enough to do what I need to do on the valve stuff. Take your time and I'm more than certain your PCP project will turn out to be awsome! Make us envious!

My big bore pumper is in the plans still. Still waiting for all the materials to arrive that was ordered, i.e. 12 inches of 1" 4130 rod stock, 36" of 4130 tube, QB78 rifle that will get gutted for parts (cheaper to buy the entire rifle). Got my 5/8" 9mm barrel in 17.5" unchambered from Numrich. An idea spawned from when another forum member raised the question of whether or not a 1377 can be shortened... Did it once, and then I had an epiphany on making a single stroke 1377 that is shortened. So, guess there are two guns in the works now!

"Well, I thought it was a rabbit but it turned out to be Bear Grylls in a rabbit hide."

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Joined: October 3rd, 2010, 3:22 pm

January 11th, 2011, 4:08 pm #4

I'd imagine you building a 30mm single stroke concrete busting cannon! ;^) I hope you get one.

I did a 1/4" dia counterbore from the rear of the 1/2" piece to capture the breech end of the cylinder spindle spring. Turned into a happy mistake after all.
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