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 Post subject: Re: 7mm Hayabusa Build
PostPosted: Sat Mar 14, 2015 3:21 pm 
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Location: Coalmont BC
The working load on the Bellevilles is specified as 675 lbs. at 0.009" compression.... I have five Bellevilles, and 1 turn on the Air Stripper is 0.050" (20 TPI) so that is 0.010" compression each.... 10/9 x 675 = 750 lbs.... It has nothing to do with the torque on the threads, we're talking pure force in lbs.... Those Bellevilles are rated at 1335 lbs. force maximum load at 0.018" compression each.... You can tighten the Air Stripper 1/2 turn by hand, it's not that difficult to get another 1/2 turn with a wrench, not that much torque required....

Threads have a huge clamping action for the amount of torque applied.... 1/2-20 NF threads in Aluminum have a recommended torque of 328 in.lb. (27 ft.lb.), which results in a clamping force of 3280 lbs.... so I am nowhere near the capability of the threads....

Bob

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 Post subject: Re: 7mm Hayabusa Build
PostPosted: Sat Mar 14, 2015 5:20 pm 
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rsterne wrote:
The working load on the Bellevilles is specified as 675 lbs. at 0.009" compression.... I have five Bellevilles, and 1 turn on the Air Stripper is 0.050" (20 TPI) so that is 0.010" compression each.... 10/9 x 675 = 750 lbs.... It has nothing to do with the torque on the threads, we're talking pure force in lbs.... Those Bellevilles are rated at 1335 lbs. force maximum load at 0.018" compression each.... You can tighten the Air Stripper 1/2 turn by hand, it's not that difficult to get another 1/2 turn with a wrench, not that much torque required....

Threads have a huge clamping action for the amount of torque applied.... 1/2-20 NF threads in Aluminum have a recommended torque of 328 in.lb. (27 ft.lb.), which results in a clamping force of 3280 lbs.... so I am nowhere near the capability of the threads....

Bob


Bob are those specs upon dry threads? Lubricated threads are slightly higher FYI.

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 Post subject: Re: 7mm Hayabusa Build
PostPosted: Sat Mar 14, 2015 5:29 pm 
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Location: Vancouver
There's the lubrication thing... but also, 1 turn onto the threads? Did I read that right? Putting a 750 pound load on 1 turn of the threads seems likely to cause distortion in that thread, especially if aluminum is involved. According to a couple of search results it seems the Hatsan stripper is some sort of aluminum alloy. Before jumping to the conclusion that the CF tube compressed, I'd want to examine that one stressed thread inside the stripper for any stretching. Seems a safer bet to shorten the CF tube or reduce the number of washers or somehow allow for at least 3 turns of the threads to be engaged fully before contact is made with the washers. Unless of course I misinterpreted the 1 turn thing and it's actually threaded on much more deeply than that.


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 Post subject: Re: 7mm Hayabusa Build
PostPosted: Sat Mar 14, 2015 5:42 pm 
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From Bobs pic believe that to be more threads. The one being its Adjustment amount.
API Idustrial Standards rule of thumb, 3 threads Carbon steel, 4 threads SS and Brass, 5 threads Alum. Grades of metal dont seem to play here, why :?: not sure never questioned the rule just followed it.

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 Post subject: Re: 7mm Hayabusa Build
PostPosted: Sat Mar 14, 2015 6:19 pm 
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The thread engagement is over 1/2".... I tightened the Air Stripper one turn after it contacted the Bellevilles.... There is a photo of the parts on the previous page, if this isn't clear enough....

The specs I quoted are for dry threads, and in fact I lubricated the threads with Honda Moly 60 so that they would turn easily.... but when you consider I am only at less than a quarter of the allowable torque, do you guys really think it matters if they are dry or lubed?.... The fact that the Bellevilles are not fully collapsed is proof that the load is well under 1335 lbs.....

I get the impression that many on this forum just want to criticize, which I find very strange when I go out of my way to share so much here.... It certainly makes me wonder why I bother.... Perhaps my English is just so poor I am difficult to understand.... :roll:

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
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Proud Member of the 2000+fps Club!


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 Post subject: Re: 7mm Hayabusa Build
PostPosted: Sat Mar 14, 2015 6:28 pm 
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Wasnt critiquing anything there Bob, it was just a question and just an added insight if you or those following did not know. But then maybe my English aint so good.... :lol: :lol:

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 Post subject: Re: 7mm Hayabusa Build
PostPosted: Sat Mar 14, 2015 6:32 pm 
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Yeah, I wasn't criticizing either. Plainly I misunderstood regarding thread engagement, must have missed something though I checked through the pictures a couple of times before posting that question.


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 Post subject: Re: 7mm Hayabusa Build
PostPosted: Sat Mar 14, 2015 6:33 pm 
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Sorry I snapped at you guys.... :oops:

Bob

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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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 Post subject: Re: 7mm Hayabusa Build
PostPosted: Sat Mar 14, 2015 6:40 pm 
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Hey Bob, no worries. You post this stuff in various places, spending a lot of time presenting the work you've done in a well thought out manner and explaining in great detail. A tremendous resource is the library of all your mods! Sometimes I just glitch out on how I interpret things, mis-reading what should be plain as day. Now that I think about it, of COURSE you meant 1 full turn after firm contact with the washer stack, as it only makes sense. I was just not being a focused reader and I can't blame you for taking that badly.


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 Post subject: Re: 7mm Hayabusa Build
PostPosted: Sat Mar 14, 2015 6:46 pm 
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Thats ok Bob, snow is disappearing and the rodents be out soon enough my way. Lots of reports in the Pincher Crk region of over whelming amounts waking up. Youll be outside to shoot soon enough....lmfao

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 Post subject: Re: 7mm Hayabusa Build
PostPosted: Mon Mar 16, 2015 9:29 pm 
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The mold arrived today for my 94 gr. Bob's Boattail bullets, with two cavities converted to HollowPoints....

Image

The Mold is available from Veral at LBT under # 284-94-BST.... and the HP conversion was done by Erik at HollowPoint Mold Services....

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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 Post subject: Re: 7mm Hayabusa Build
PostPosted: Mon Mar 16, 2015 10:16 pm 
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Might have missed it but solids are 94gr or the hollows?

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 Post subject: Re: 7mm Hayabusa Build
PostPosted: Mon Mar 16, 2015 10:28 pm 
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In theory the solids should have been 94 gr., but the only ones that have been cast so far were by a guy who had his mold made at 0.286" (which should add about 1.5 gr.) and they were 98+ gr.... so at the moment I don't have that answer for you.... The HP cavity should reduce the weight 5.6 - 6.0 gr.... so I'm going to guess 91 gr. and 97 gr....

Bob

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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!


Last edited by rsterne on Mon Mar 16, 2015 10:50 pm, edited 1 time in total.

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 Post subject: Re: 7mm Hayabusa Build
PostPosted: Mon Mar 16, 2015 10:40 pm 
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Cool spudz... :mrgreen:

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 Post subject: Re: 7mm Hayabusa Build
PostPosted: Tue Mar 17, 2015 9:18 pm 
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Joined: Sat Nov 03, 2007 4:19 pm
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Location: Coalmont BC
Cedric got one of the first three molds from Veral at LBT when we had him make the pattern for the 7mm BBT.... Here is his first shooting session at 75 and 205 yards....

https://www.youtube.com/watch?v=iMXrS5f ... prvoHuqE6w

Now more than ever I am looking forward to getting this build completed....

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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