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PostPosted: Thu May 12, 2016 11:26 pm 
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Joined: Tue Oct 13, 2009 1:27 am
Posts: 2514
Location: Vancouver
Hey all. I'd hoped that Rick could do this for me, but he's going to need a lot of time to recover. And I've twice ordered the taps. Rick's shop has the first set somewhere and he's obviously in no condition (nor even the right country at the moment) to send them back to me. The smaller tap of the second-ordered set is lost in shipping, or at least hasn't gotten here after 2 months... The other, larger tap isn't a bottoming tap, so useless for this except to get the threads started. I ordered some 7075 aluminum bar stock from a metal shop in Israel (eBay - only shop with the dimensions I wanted) but it's still not here after two months and they've refunded me. Ordered more 7075 (at great cost for shipping) from a US seller, but today it turned out they've shipped 6061 and there's no way I can cut clean threads in that mushy stuff, need the 7075 for hand cut threads...

So all in all a comedy of errors, going on since last September. I'd REALLY like to get my 13ci Ninja bottle connected to my QB78D, which has a 45 degree angled Foster nipple. Is there anyone on here who can make a nice, clean job of cutting this adapter? Specifically I want a reversed dropped bottle adapter. I can supply the exact dimensions to someone willing to do it. Clearance ahead of the grip frame is a bit tight but there's room. I have the Foster QD fitting in hand, and bonded washer to put between threads and body. This is the layout:

Image

And this is roughly how it should be made:

Image

If you are set up for single point thread cutting then of course 6061 will be fine, provided the wall thickness is sufficient all around the big threaded hole. Around 1.125" should probably be enough, though 1.25" for insurance might be nicer. Any takers? I'm getting so darn eager to use this rifle for HFT... but with the current tube-only setup I get 7 or 8 shots with reasonable consistency at 19fpe. Let me know what you'd call a fair price and I'll see if it's manageable for me. I've already thrown a bunch of money at this with no results... dang it!


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PostPosted: Fri May 13, 2016 10:46 am 
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Joined: Sat Nov 03, 2007 4:19 pm
Posts: 8946
Location: Coalmont BC
1" thick 6061-T6 is plenty.... standard for tank blocks....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal;
Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!


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PostPosted: Fri May 13, 2016 10:57 am 
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Joined: Tue Oct 13, 2009 1:27 am
Posts: 2514
Location: Vancouver
Thanks for that Bob. Just didn't want to err on the weak side and regret it.


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PostPosted: Fri Jun 03, 2016 11:37 am 
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Joined: Tue Oct 13, 2009 1:27 am
Posts: 2514
Location: Vancouver
Okay, so my 7075 finally got here from an Israeli seller a few days ago, after more than 3 months in the mail., so i re-paid the seller her refunded money. Some 6061 did arrive... but was only 1/4" thick, and there's been a lot of messaging back and forth as the seller and eBay and I try to come to an agreement... which doesn't seem to be working out. Looks like he's convinced eBay that I'm a scammer and that he actually sent 1.25" thick stock. If this transaction fails after appeal I may just close my eBay account. While it's easy a lot of the time, a couple of crooks like this (themetalmerchant in this case, with whom I had one earlier transaction which went fine) are making it seem more trouble than it's worth.

Anyway, I shaped one of the blocks and bored the holes on my little TAIG lathe. Started the bottle thread with the tap, then decided to grind that down to convert it to a bottoming tap and proceeded to finish the thread. Bored the QD adapter hole, then took it to my old workmates at Toby Cycleworks where Tito enlarged that hole and tapped it in about a minute on his gigantic WWII vintage mill. Didn't want my money. Checked the large threads and found them to be fine.

Getting home I finished shaping to get the thing comfortable for handling then heated it to about coffee hot and sprayed with Rustoleum epoxy appliance paint then baked it once air dried for a couple of hours. Made a stainless steel band which is wrapped snug around the brass fill plug and bolted to the block, providing some protection against movement at the front end. Yesterday I made a steel bracket to hold the back end against the front grip frame, then once that held reasonably well made a kydex heat-formed cup pressed over that and the bottle for an exact fit, securing the bottle at the back. The kydex is hot glued then drilled and riveted to the 0.75" x 0.125" steel. This pulls the bottle firmly against a shaped ebony block which spaces it from the main cylinder.

Managed some testing up to 1,200psi for a few short strings and the bottle seals perfectly and is rock solid on the rifle. Unfortunately my 1.8K burst disc blew out, apparently defective as pressure shown on both my FX pump and the Ninja gauge was exactly 1,400psi at the time. But I'm going to get the regulator tested and adjusted soon and replace the burst disc. My testing before that then a bit without the bottle after the failure tells me that a setpoint of about 1,100psi would deliver my desired power level.

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PostPosted: Tue Jan 31, 2017 10:12 am 
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Joined: Sat Nov 05, 2016 10:52 am
Posts: 2690
Location: Caronport, Saskatchewan
Great work!

Sent from my LG-H812 using Tapatalk


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