Thank you to our advertisers!







Author Topic: would you thread the bottom of a bottle?  (Read 301 times))

Offline stalil

  • Shooter
  • *
  • Posts: 4
  • Real Name: Stavros
would you thread the bottom of a bottle?
« on: June 06, 2022, 12:31:25 PM »
Good evening gentlemen. I recently saw a modification on a 300bar, 400cc aluminum bottle which looks suspicious if not dangerous. Somebody drilled and threaded the flat bottom of an aluminum bottle, fitted on an airgun, in order to fit a fill nipple.
Do you think it is safe? Would you do such a mod?
Regards
SL

Offline rsterne

  • Member 2000+fps Club
  • Bob and Lloyd
  • GTA Senior Contributor
  • *****
  • Posts: 25654
  • GTA Forums Person of the Year 2017
  • Real Name: Bob
Re: would you thread the bottom of a bottle?
« Reply #1 on: June 06, 2022, 02:05:54 PM »
I guess it depends on the thickness of the bottom of the bottle, and how many threads of engagement you can get.... I do not know if drilling the bottom of the bottle weakens it or not....

Bob
  • Coalmont, BC, Canada
🇺🇦 Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦

Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).

Offline Madd Hatter

  • GTA Senior Contributor
  • ******
  • Posts: 4335
  • Real Name: Robert
Re: would you thread the bottom of a bottle?
« Reply #2 on: June 06, 2022, 02:36:15 PM »
Drilling a flat bottom I would think it would be okay but that's just a guess.
  • Juniper woods ranch   AZ
You can only be young once, but you can always be immature
Always follow your heart... but take your brains with you

I'm to old to die young

Men with knowledge but lack wisdom are like a blind man with a lantern

He, who will not reason, is a bigot; he who cannot, is a fool; and he, who dares not, is a slave. -- William Drummond, Scottish writer (1585 - 1649)

Offline Firewalker

  • GTA Senior Contributor
  • ******
  • Posts: 4177
  • Pray for Ukraine, save her from the Russian BEAST!
  • Real Name: David
Re: would you thread the bottom of a bottle?
« Reply #3 on: June 06, 2022, 04:43:13 PM »
Also, a small hole would pose less risk. Sounds interesting,  I may have to measure the base of my AEA bottle...  :o
  • USA, MN, Mille Lacs
"If I spend my hard eraned money on an airgun, especially a mid to high end airgun and it has any issues whatsoever, I'm boxing it up and sending it back where it came from. Nope, nope, nope... don't say you fixed it and send it back to me. I didn't buy a refurb and I don't want a refurb back.
Show me your customer service.. Take a new gun off the shelf and have your tech verify that it passes all the quality checks then send it to me. No sir... I don't want a discount or a store credit or a partial refund... I want exactly what I paid for and exactly what you said you were selling me. If you can't do that then stay out of my mailbox with your spam mail.
That's part of the problem with retail these days.. We, the consumer settles for whatever shovel full of stuff they feed us.
Shame on us for that."
-Bill

Offline Motorhead

  • Field Target Shooter .... Stand em up Shoot em down
  • GTA Senior Contributor
  • ******
  • Posts: 17035
  • 2019 Hall Of Fame Recipient
  • Real Name: Scott
Re: would you thread the bottom of a bottle?
« Reply #4 on: June 06, 2022, 05:25:05 PM »
Just recently did just that to a 500cc 3K aluminum bottle.  Fitted to an old school THEOBEN RAPID that had to have bottle removed to fill otherwise. ( what a PITA )
Found the bottom thickness once threaded 1/8-27 NPT has as many or more threads than the Foster fill fitting to be used.
« Last Edit: June 06, 2022, 05:30:50 PM by Motorhead »
  • Northern California ... Old Hangtown
** Home of MOTORHEADS AG Tuning Services **
      * PM me for further contact & tuning info.

       Sacramento Valley Field Target Club
#https://sites.google.com/site/sacvalleyairgunclub/

Offline Madd Hatter

  • GTA Senior Contributor
  • ******
  • Posts: 4335
  • Real Name: Robert
Re: would you thread the bottom of a bottle?
« Reply #5 on: June 06, 2022, 07:39:27 PM »
Just recently did just that to a 500cc 3K aluminum bottle.  Fitted to an old school THEOBEN RAPID that had to have bottle removed to fill otherwise. ( what a PITA )
Found the bottom thickness once threaded 1/8-27 NPT has as many or more threads than the Foster fill fitting to be used.
That's what I was thinking that the flat bottom would be thicker than a rounded bottom.
  • Juniper woods ranch   AZ
You can only be young once, but you can always be immature
Always follow your heart... but take your brains with you

I'm to old to die young

Men with knowledge but lack wisdom are like a blind man with a lantern

He, who will not reason, is a bigot; he who cannot, is a fool; and he, who dares not, is a slave. -- William Drummond, Scottish writer (1585 - 1649)

Offline stalil

  • Shooter
  • *
  • Posts: 4
  • Real Name: Stavros
Re: would you thread the bottom of a bottle?
« Reply #6 on: June 07, 2022, 12:35:49 PM »
without being a engineer, I have the sense that a flat bottom is not the ideal shape as a part of a pressurized vessel. Probably it is dictated by the manufacturing proccess. Therefore it is thicker or over engineered in order to offset the non ideal shape and keep everything as safe as possible. However I am not convinced that drilling it is a very safe approach. If I have made a mod which so far has not given any trouble is not a proof that it is a safe approach generally. Anyway, thank you gentlemen for your time.

Offline Motorhead

  • Field Target Shooter .... Stand em up Shoot em down
  • GTA Senior Contributor
  • ******
  • Posts: 17035
  • 2019 Hall Of Fame Recipient
  • Real Name: Scott
Re: would you thread the bottom of a bottle?
« Reply #7 on: June 07, 2022, 01:17:10 PM »
For what it's worth ... Allen Zasadny ( AZ ) whom is a Very well respected tuner for many many years now has been doing similar Filler to tank bottom modifications as far back as the 90's with Theobens and similar bottle guns.
Never read or seen an issue with those done in this manor ?
  • Northern California ... Old Hangtown
** Home of MOTORHEADS AG Tuning Services **
      * PM me for further contact & tuning info.

       Sacramento Valley Field Target Club
#https://sites.google.com/site/sacvalleyairgunclub/

Offline stalil

  • Shooter
  • *
  • Posts: 4
  • Real Name: Stavros
Re: would you thread the bottom of a bottle?
« Reply #8 on: June 07, 2022, 05:25:06 PM »
well, thanks Scott, however never seen these posts. If it has been tested often and by a respected  modder then it should be safe. I am just too cautious with hpa. If I knew it earlier it would have made things easier  for me in a couple of cases.

Offline Motorhead

  • Field Target Shooter .... Stand em up Shoot em down
  • GTA Senior Contributor
  • ******
  • Posts: 17035
  • 2019 Hall Of Fame Recipient
  • Real Name: Scott
Re: would you thread the bottom of a bottle?
« Reply #9 on: June 07, 2022, 05:50:42 PM »


  • Northern California ... Old Hangtown
** Home of MOTORHEADS AG Tuning Services **
      * PM me for further contact & tuning info.

       Sacramento Valley Field Target Club
#https://sites.google.com/site/sacvalleyairgunclub/

Offline Madd Hatter

  • GTA Senior Contributor
  • ******
  • Posts: 4335
  • Real Name: Robert
Re: would you thread the bottom of a bottle?
« Reply #10 on: June 07, 2022, 08:46:56 PM »
Man, that's one butiful rifle
  • Juniper woods ranch   AZ
You can only be young once, but you can always be immature
Always follow your heart... but take your brains with you

I'm to old to die young

Men with knowledge but lack wisdom are like a blind man with a lantern

He, who will not reason, is a bigot; he who cannot, is a fool; and he, who dares not, is a slave. -- William Drummond, Scottish writer (1585 - 1649)

Offline Motorhead

  • Field Target Shooter .... Stand em up Shoot em down
  • GTA Senior Contributor
  • ******
  • Posts: 17035
  • 2019 Hall Of Fame Recipient
  • Real Name: Scott
Re: would you thread the bottom of a bottle?
« Reply #11 on: June 08, 2022, 12:28:06 AM »
Man, that's one butiful rifle
All 3 are different rifles ... all 3 with AZ tank bottom fill fittings added.  Note last one has cover removed and the old school PARKER hydraulic to foster filler required shown is attached.
  • Northern California ... Old Hangtown
** Home of MOTORHEADS AG Tuning Services **
      * PM me for further contact & tuning info.

       Sacramento Valley Field Target Club
#https://sites.google.com/site/sacvalleyairgunclub/

Offline woogie_man

  • silence is golden,and not illegal
  • Expert
  • *****
  • Posts: 1775
Re: would you thread the bottom of a bottle?
« Reply #12 on: June 08, 2022, 06:13:20 AM »
My Theoben bottle that has the Allen Z fill port on it is just fine.  The hole that goes through the bottle is threaded, though there is also an aluminum nut inside the bottle that will pinch the fill adapter to the bottle.  There are no issues with this method, as it has been done many times for many years.
  • North Dakota

Offline CableStop

  • Marksman
  • ***
  • Posts: 362
  • yes
  • Real Name: Tom
Re: would you thread the bottom of a bottle?
« Reply #13 on: June 21, 2022, 07:18:01 PM »
My Theoben bottle that has the Allen Z fill port on it is just fine.  The hole that goes through the bottle is threaded, though there is also an aluminum nut inside the bottle that will pinch the fill adapter to the bottle.  There are no issues with this method, as it has been done many times for many years.

I like this strategy, you could even put a stainless steel washer and nut on the inside to spread the load more.  Only problem is it's hard to use tapered threads like NPT with a nut so teflon tape is probably not going to seal it, you'll need to have an o-ring somewhere. 
  • NH