[PSUBS-MAILIST] Aluminum fine threads

hank pronk via Personal_Submersibles personal_submersibles at psubs.org
Mon Mar 23 21:23:59 EDT 2015


Tom,
Where are you from, good to hear from you.  Many machining questions arise.
Hank
--------------------------------------------
On Mon, 3/23/15, TOM WHENT via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Subject: Re: [PSUBS-MAILIST] Aluminum fine threads
 To: "personal submersibles" <personal_submersibles at psubs.org>, "personal submersibles-request" <personal_submersibles-request at psubs.org>
 Received: Monday, March 23, 2015, 8:22 PM
 
 #yiv2939091083 p
 {margin:0;}Hello! I am new to
 browsing this mailing list, right now as a matter of
 interest, not planning on building anything.. As a diver and
 also as a professional metal worker I am intrigued by the
 K-350 and also by the propane tank sub. 
 
 As a seasoned journeyman machinist I can say with confidence
 that it is course threads which are meant to be used in
 aluminum - primarily because of it's lower strength in
 shear and it's higher ductility which effects the
 cross-sectional strength of the thread at the pitch line. As
 a matter of practice in my trade fine threads are never used
 in aluminum due to the ease of stripping them.
 
 That said, I look forward to learning more from this group
 and am very impressed with the work displayed.
 
 Cheers,
 Tom
 
 From: "via
 Personal_Submersibles"
 <personal_submersibles at psubs.org>
 To: "personal submersibles"
 <personal_submersibles at psubs.org>
 Sent: Monday, March 23, 2015 11:31:27 AM
 Subject: Personal_Submersibles Digest, Vol 21, Issue
 57
 
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 Today's Topics:
 
    1. Re: coarse vs fine thread
       (Sean T Stevenson via
 Personal_Submersibles)
    2. Re: Specifications when ordering shell
       (Andr? Eriksen via
 Personal_Submersibles)
 
 
 ----------------------------------------------------------------------
 
 Message: 1
 Date: Mon, 23 Mar 2015 08:04:52 -0600
 From: Sean T Stevenson via Personal_Submersibles
         <personal_submersibles at psubs.org>
 To: Personal Submersibles General Discussion
         <personal_submersibles at psubs.org>
 Subject: Re: [PSUBS-MAILIST] coarse vs fine thread
 Message-ID:
 <6cf7f2e3-1d12-44ce-abc7-d5caf7cf81a5 at email.android.com>
 Content-Type: text/plain; charset="utf-8"
 
 Use 6061-T6 aluminum where possible. Hard anodize your
 aluminium parts, and protect them with zinc anodes. Use
 stainless fasteners coated in a corrosion inhibiting grease,
 and use stainless helicoil thread inserts in blind tapped
 holes.
 
 Sean
 
 
 On March 23, 2015 6:59:20 AM MDT, Alec Smyth via
 Personal_Submersibles
 <personal_submersibles at psubs.org> wrote:
 >Ah, I have pondered something related for ages. I have
 an aluminum bow
 >dome
 >retaining ring bolted to an aluminum seat. I used
 aluminum screws, to
 >reduce galvanic pair issues. And then I broke off one of
 the screws by
 >pure
 >clumsiness. I will have to drill this out, as
 there's virtually no
 >stub,
 >and will probably end up with one screw larger than the
 rest if I need
 >to
 >re-tap. But my question is... would you guys recommend
 using aluminum
 >screws in this scenario? I am not really concerned about
 their holding
 >power, there's a large quantity of screws involved.
 >
 >Best,
 >
 >Alec
 >
 >On Sun, Mar 22, 2015 at 3:09 PM, Adam Lawrence via
 >Personal_Submersibles <
 >personal_submersibles at psubs.org> wrote:
 >
 >>  Hi guys,
 >>
 >> There really isn't an appreciable difference in
 performance between
 >coarse
 >> and fine threads. The more important questions are
 bolt/nut
 >> material, thread engagement and torque.
 >>
 >> The argument for sticking with coarse threads would
 be that you
 >reduce the
 >> chance for cross threading the wrong bolt during
 assembly, since
 >coarse
 >> threads are predominately used.
 >>
 >> Adam
 >>  ------------------------------
 >> *From:* Personal_Submersibles [mailto:
 >> personal_submersibles-bounces at psubs.org] *On Behalf
 Of *Sean T
 >Stevenson
 >> via Personal_Submersibles
 >> *Sent:* Sunday, March 22, 2015 1:13 PM
 >> *To:* Personal Submersibles General Discussion
 >> *Subject:* Re: [PSUBS-MAILIST] coarse vs fine
 thread
 >>
 >>  Helicoils are an option.
 >>
 >> Sean
 >>
 >>
 >> On March 22, 2015 11:58:31 AM MDT, Rick Patton via
 >Personal_Submersibles <
 >> personal_submersibles at psubs.org> wrote:
 >>>
 >>>  Hank
 >>>
 >>> Fine is the only way to go as aluminum is a
 much softer metal than
 >steel
 >>> so it will strip much easier so the more metal
 you grab, the better,
 >which
 >>> fine threads will give you.
 >>>
 >>> Rick
 >>>
 >>> On Sun, Mar 22, 2015 at 5:55 AM, hank pronk
 via
 >Personal_Submersibles <
 >>> personal_submersibles at psubs.org> wrote:
 >>>
 >>>> Help I need advice!
 >>>> My new bow dome will be secured to the Al
 mating ring with straps. 
 >I am
 >>>> laying out the bolt holes to be threaded in
 the AL ring.  My
 >question is,
 >>>> should the bolts be fine or coarse thread?
 What holds better in AL
 >?  The
 >>>> threads will be 3/8 by 1 in deep.
 >>>> Thank you in advance.
 >>>> Hank
 >>>>
 _______________________________________________
 >>>> Personal_Submersibles mailing list
 >>>> Personal_Submersibles at psubs.org
 >>>>
 http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
 >>>>
 >>>
 >>> ------------------------------
 >>>
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 >>> Personal_Submersibles at psubs.org
 >>>
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 >>>
 >>>
 >> _______________________________________________
 >> Personal_Submersibles mailing list
 >> Personal_Submersibles at psubs.org
 >>
 http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
 >>
 >>
 >
 >
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 ------------------------------
 
 Message: 2
 Date: Mon, 23 Mar 2015 16:31:57 +0100
 From: Andr? Eriksen via Personal_Submersibles
         <personal_submersibles at psubs.org>
 To: Personal Submersibles General Discussion
         <personal_submersibles at psubs.org>
 Subject: Re: [PSUBS-MAILIST] Specifications when ordering
 shell
 Message-ID:
         <CAMJapUYAXDcQwpr_qnr-TTUq+Hu=-jXUiKO6V-2JFk=vJAjFtw at mail.gmail.com>
 Content-Type: text/plain; charset="utf-8"
 
 Thanks for the info guys! Made things abit clearer. The
 company I`ve talked
 to is in Germany, and I live in Norway so I can`t go and
 measure the shell.
 
 This is the tolerances they gave me on a OD1000x1500 shell:
 
 OD +/- 2mm calculated out of >outside circumferential
 length and real wall
 thickness
 Ovality max 4 mm, measured at both ends
 Straightness 1mm/m max. 3 mm
 Length - 0 / + 5 mm
 
 Is the ovality tolerance good enough?
 
 Regards
 Andr?
 
 2015-03-23 14:54 GMT+01:00 James Frankland via
 Personal_Submersibles <
 personal_submersibles at psubs.org>:
 
 > Thanks for the clarification Steve.
 > Regards
 > James
 >
 > On 23 March 2015 at 12:18, Stephen Fordyce via
 Personal_Submersibles <
 > personal_submersibles at psubs.org> wrote:
 >
 >> Hi guys,
 >> The material certificate thing is all about quality
 control and
 >> traceability of exactly what is the composition of
 the elements in
 >> it.  Ie. when the steel gets smelted and
 poured into a block (or whatever)
 >> at the mill, that particular batch gets analysed
 for exact percentages
 >> of all elements, and all parts poured from that
 batch are given the "heat
 >> number" of the batch.  Since the
 certificate is meant to trace back to the
 >> original steel mill, it's often called a
 "Mill Certificate".
 >>
 >> Each time the steel goes through a process (ie.
 rolling into sheet, the
 >> sheet formed into pipe or endcaps) there is a
 chance the traceabilty to the
 >> original analysed composition could be lost, if the
 material gets mixed up
 >> - and there are varying levels of quality control
 that make sure of this,
 >> and these are reflected in different types of
 material certificates.
 >>
 >> The EN 3.1 cert is pretty high end (ie. good enough
 for the SS304/316
 >> cryogenic liquid ethane pressure vessels I'm
 currently involved with at
 >> work) and typical for most industrial applications
 at least.  I've not come
 >> across requirements for 3.2 (which is even more
 stringent), and we
 >> frequently work with lesser requirements than 3.1.
 >> Here's a good explanation of the difference:
 >>
 http://www.classicfilters.com/blog/materialcertificates/
 >>
 >> Tracing the material back to the mill is supposed
 to be important in case
 >> there is a failure in another part in the same
 batch, so it can prevent
 >> other failures.  I've always thought the
 whole certificate/traceability
 >> thing was just a PITA and that so long as you get
 steel or parts from
 >> reputable suppliers who's QC practises you
 trust, then that's just as
 >> effective.  Especially when you're
 building a big system with hundreds of
 >> welded parts.
 >>
 >> Cheers,
 >> Steve
 >> (Among other things - mechanical engineer in
 Melbourne, Australia)
 >>
 >> On Mon, Mar 23, 2015 at 10:55 PM, James Frankland
 via
 >> Personal_Submersibles
 <personal_submersibles at psubs.org> wrote:
 >>
 >>> Hi Andre,
 >>>
 >>> I was in this position some years ago.
  Not knowing what to specify on
 >>> the order.
 >>>
 >>> I believe the EN number is a certificate of the
 material quality.  Mine
 >>> was done to EN10204.3.1.B but i never specified
 it.  I just asked for the
 >>> material type.
 >>>
 >>> So just ask for your dimensions of shell,
 material, percentage of round,
 >>> bevel, weld.
 >>>
 >>>
 >>> Example.
 >>>
 >>> Shell.  P355 Steel.  10mm Thick.
 >>>
 >>> OD 1000mm x 2000mm length.
 >>> Shell to be within +\- 3mm on diameter.
 >>> Welded seam.
 >>> 35 degree external bevel with 2mm nose.
 >>>
 >>>
 >>> Something like that should do it.  They
 will send you a quote and should
 >>> tell you what material grade it what code they
 will be working to.
 >>>
 >>>
 >>> Make sure you specify clearly the tolerance of
 roundness you want and
 >>> say your not paying for it if its not right.
  They will probably need to
 >>> re-roll the cylinder.
 >>>
 >>> Ideally go to the factory with a wooden
 template and measure the
 >>> cylinder before you accept it.
 >>>
 >>> Get the bevel put on, it will save you pain.
  But. don't bother with
 >>> grit blasting, you need to paint it straight
 away after that or it will
 >>> start to oxidise again.  By the time
 you've finished your hull, it will be
 >>> all rusty again.  Grit blast when
 you've finished working on the hull.
 >>>
 >>> Someone else may have some other suggestions.
  Comments.
 >>>
 >>> Hope this helps.
 >>>
 >>> Kind Regards
 >>> James
 >>>
 >>>
 >>>
 >>> On 21 March 2015 at 22:30, Andr? Eriksen <
 >>> personal_submersibles at psubs.org> wrote:
 >>>
 >>>> Hi,
 >>>>
 >>>> I`m in the process of ordering the shell
 and tower for my submarine.
 >>>> What specification should I ask for?
 (Europe)
 >>>>
 >>>>  I asked for EN10204 with 3.1
 Sertificate (Not 100% sure of this, but
 >>>> this is what I got when I ordered the
 endcaps from another company. 3.2
 >>>> Sertificate was a bit too expensive)
 >>>> Told them I had no special requirements for
 the plates and needed no
 >>>> edge preperation.
 >>>>
 >>>> *They replied*: "this is not the
 normal enquiry type, but we will not
 >>>> ask any longer" (?)
 >>>> And said the plates was going to be
 EN10028-3 with certificate 3.2.
 >>>>
 >>>> I want to keep the cost down, but should I
 ask that they grit blast
 >>>> the shell after rolling?
 >>>> Also I didn`t ask for bevel on the edges.
 Again to keep cost down. But
 >>>> maybe I should, to spare me the extra
 work?
 >>>>
 >>>> May I ask what you tell your supplier when
 ordrering?
 >>>>
 >>>>
 >>>> -Andr?
 >>>>
 >>>>
 _______________________________________________
 >>>> Personal_Submersibles mailing list
 >>>> Personal_Submersibles at psubs.org
 >>>>
 http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
 >>>>
 >>>>
 >>>
 >>>
 _______________________________________________
 >>> Personal_Submersibles mailing list
 >>> Personal_Submersibles at psubs.org
 >>>
 http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
 >>>
 >>>
 >>
 >> _______________________________________________
 >> Personal_Submersibles mailing list
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 >>
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 >>
 >>
 >
 > _______________________________________________
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 > Personal_Submersibles at psubs.org
 >
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 >
 >
 
 
 -- 
 Med Vennlig Hilsen / Regards
 *Andr? Eriksen*
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