<html><head><style type='text/css'>p { margin: 0; }</style></head><body><div style='font-family: arial,helvetica,sans-serif; font-size: 10pt; color: #000000'>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. <br><br>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.<br><br>That said, I look forward to learning more from this group and am very impressed with the work displayed.<br><br>Cheers,<br>Tom<br><br><hr id="zwchr"><div style="color:#000;font-weight:normal;font-style:normal;text-decoration:none;font-family:Helvetica,Arial,sans-serif;font-size:12pt;"><b>From: </b>"via Personal_Submersibles" <personal_submersibles@psubs.org><br><b>To: </b>"personal submersibles" <personal_submersibles@psubs.org><br><b>Sent: </b>Monday, March 23, 2015 11:31:27 AM<br><b>Subject: </b>Personal_Submersibles Digest, Vol 21, Issue 57<br><br>Send Personal_Submersibles mailing list submissions to<br> personal_submersibles@psubs.org<br><br>To subscribe or unsubscribe via the World Wide Web, visit<br> http://www.whoweb.com/mailman/listinfo.cgi/personal_submersibles<br>or, via email, send a message with subject or body 'help' to<br> personal_submersibles-request@psubs.org<br><br>You can reach the person managing the list at<br> personal_submersibles-owner@psubs.org<br><br>When replying, please edit your Subject line so it is more specific<br>than "Re: Contents of Personal_Submersibles digest..."<br><br><br>Today's Topics:<br><br> 1. Re: coarse vs fine thread<br> (Sean T Stevenson via Personal_Submersibles)<br> 2. Re: Specifications when ordering shell<br> (Andr? Eriksen via Personal_Submersibles)<br><br><br>----------------------------------------------------------------------<br><br>Message: 1<br>Date: Mon, 23 Mar 2015 08:04:52 -0600<br>From: Sean T Stevenson via Personal_Submersibles<br> <personal_submersibles@psubs.org><br>To: Personal Submersibles General Discussion<br> <personal_submersibles@psubs.org><br>Subject: Re: [PSUBS-MAILIST] coarse vs fine thread<br>Message-ID: <6cf7f2e3-1d12-44ce-abc7-d5caf7cf81a5@email.android.com><br>Content-Type: text/plain; charset="utf-8"<br><br>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.<br><br>Sean<br><br><br>On March 23, 2015 6:59:20 AM MDT, Alec Smyth via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<br>>Ah, I have pondered something related for ages. I have an aluminum bow<br>>dome<br>>retaining ring bolted to an aluminum seat. I used aluminum screws, to<br>>reduce galvanic pair issues. And then I broke off one of the screws by<br>>pure<br>>clumsiness. I will have to drill this out, as there's virtually no<br>>stub,<br>>and will probably end up with one screw larger than the rest if I need<br>>to<br>>re-tap. But my question is... would you guys recommend using aluminum<br>>screws in this scenario? I am not really concerned about their holding<br>>power, there's a large quantity of screws involved.<br>><br>>Best,<br>><br>>Alec<br>><br>>On Sun, Mar 22, 2015 at 3:09 PM, Adam Lawrence via<br>>Personal_Submersibles <<br>>personal_submersibles@psubs.org> wrote:<br>><br>>> Hi guys,<br>>><br>>> There really isn't an appreciable difference in performance between<br>>coarse<br>>> and fine threads. The more important questions are bolt/nut<br>>> material, thread engagement and torque.<br>>><br>>> The argument for sticking with coarse threads would be that you<br>>reduce the<br>>> chance for cross threading the wrong bolt during assembly, since<br>>coarse<br>>> threads are predominately used.<br>>><br>>> Adam<br>>> ------------------------------<br>>> *From:* Personal_Submersibles [mailto:<br>>> personal_submersibles-bounces@psubs.org] *On Behalf Of *Sean T<br>>Stevenson<br>>> via Personal_Submersibles<br>>> *Sent:* Sunday, March 22, 2015 1:13 PM<br>>> *To:* Personal Submersibles General Discussion<br>>> *Subject:* Re: [PSUBS-MAILIST] coarse vs fine thread<br>>><br>>> Helicoils are an option.<br>>><br>>> Sean<br>>><br>>><br>>> On March 22, 2015 11:58:31 AM MDT, Rick Patton via<br>>Personal_Submersibles <<br>>> personal_submersibles@psubs.org> wrote:<br>>>><br>>>> Hank<br>>>><br>>>> Fine is the only way to go as aluminum is a much softer metal than<br>>steel<br>>>> so it will strip much easier so the more metal you grab, the better,<br>>which<br>>>> fine threads will give you.<br>>>><br>>>> Rick<br>>>><br>>>> On Sun, Mar 22, 2015 at 5:55 AM, hank pronk via<br>>Personal_Submersibles <<br>>>> personal_submersibles@psubs.org> wrote:<br>>>><br>>>>> Help I need advice!<br>>>>> My new bow dome will be secured to the Al mating ring with straps. <br>>I am<br>>>>> laying out the bolt holes to be threaded in the AL ring. My<br>>question is,<br>>>>> should the bolts be fine or coarse thread? What holds better in AL<br>>? The<br>>>>> threads will be 3/8 by 1 in deep.<br>>>>> Thank you in advance.<br>>>>> Hank<br>>>>> _______________________________________________<br>>>>> Personal_Submersibles mailing list<br>>>>> Personal_Submersibles@psubs.org<br>>>>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles<br>>>>><br>>>><br>>>> ------------------------------<br>>>><br>>>> Personal_Submersibles mailing list<br>>>> Personal_Submersibles@psubs.org<br>>>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles<br>>>><br>>>><br>>> _______________________________________________<br>>> Personal_Submersibles mailing list<br>>> Personal_Submersibles@psubs.org<br>>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles<br>>><br>>><br>><br>><br>>------------------------------------------------------------------------<br>><br>>_______________________________________________<br>>Personal_Submersibles mailing list<br>>Personal_Submersibles@psubs.org<br>>http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles<br>-------------- next part --------------<br>An HTML attachment was scrubbed...<br>URL: <http://www.whoweb.com/pipermail/personal_submersibles/attachments/20150323/a6ace835/attachment-0001.html><br><br>------------------------------<br><br>Message: 2<br>Date: Mon, 23 Mar 2015 16:31:57 +0100<br>From: Andr? Eriksen via Personal_Submersibles<br> <personal_submersibles@psubs.org><br>To: Personal Submersibles General Discussion<br> <personal_submersibles@psubs.org><br>Subject: Re: [PSUBS-MAILIST] Specifications when ordering shell<br>Message-ID:<br> <CAMJapUYAXDcQwpr_qnr-TTUq+Hu=-jXUiKO6V-2JFk=vJAjFtw@mail.gmail.com><br>Content-Type: text/plain; charset="utf-8"<br><br>Thanks for the info guys! Made things abit clearer. The company I`ve talked<br>to is in Germany, and I live in Norway so I can`t go and measure the shell.<br><br>This is the tolerances they gave me on a OD1000x1500 shell:<br><br>OD +/- 2mm calculated out of >outside circumferential length and real wall<br>thickness<br>Ovality max 4 mm, measured at both ends<br>Straightness 1mm/m max. 3 mm<br>Length - 0 / + 5 mm<br><br>Is the ovality tolerance good enough?<br><br>Regards<br>Andr?<br><br>2015-03-23 14:54 GMT+01:00 James Frankland via Personal_Submersibles <<br>personal_submersibles@psubs.org>:<br><br>> Thanks for the clarification Steve.<br>> Regards<br>> James<br>><br>> On 23 March 2015 at 12:18, Stephen Fordyce via Personal_Submersibles <<br>> personal_submersibles@psubs.org> wrote:<br>><br>>> Hi guys,<br>>> The material certificate thing is all about quality control and<br>>> traceability of exactly what is the composition of the elements in<br>>> it. Ie. when the steel gets smelted and poured into a block (or whatever)<br>>> at the mill, that particular batch gets analysed for exact percentages<br>>> of all elements, and all parts poured from that batch are given the "heat<br>>> number" of the batch. Since the certificate is meant to trace back to the<br>>> original steel mill, it's often called a "Mill Certificate".<br>>><br>>> Each time the steel goes through a process (ie. rolling into sheet, the<br>>> sheet formed into pipe or endcaps) there is a chance the traceabilty to the<br>>> original analysed composition could be lost, if the material gets mixed up<br>>> - and there are varying levels of quality control that make sure of this,<br>>> and these are reflected in different types of material certificates.<br>>><br>>> The EN 3.1 cert is pretty high end (ie. good enough for the SS304/316<br>>> cryogenic liquid ethane pressure vessels I'm currently involved with at<br>>> work) and typical for most industrial applications at least. I've not come<br>>> across requirements for 3.2 (which is even more stringent), and we<br>>> frequently work with lesser requirements than 3.1.<br>>> Here's a good explanation of the difference:<br>>> http://www.classicfilters.com/blog/materialcertificates/<br>>><br>>> Tracing the material back to the mill is supposed to be important in case<br>>> there is a failure in another part in the same batch, so it can prevent<br>>> other failures. I've always thought the whole certificate/traceability<br>>> thing was just a PITA and that so long as you get steel or parts from<br>>> reputable suppliers who's QC practises you trust, then that's just as<br>>> effective. Especially when you're building a big system with hundreds of<br>>> welded parts.<br>>><br>>> Cheers,<br>>> Steve<br>>> (Among other things - mechanical engineer in Melbourne, Australia)<br>>><br>>> On Mon, Mar 23, 2015 at 10:55 PM, James Frankland via<br>>> Personal_Submersibles <personal_submersibles@psubs.org> wrote:<br>>><br>>>> Hi Andre,<br>>>><br>>>> I was in this position some years ago. Not knowing what to specify on<br>>>> the order.<br>>>><br>>>> I believe the EN number is a certificate of the material quality. Mine<br>>>> was done to EN10204.3.1.B but i never specified it. I just asked for the<br>>>> material type.<br>>>><br>>>> So just ask for your dimensions of shell, material, percentage of round,<br>>>> bevel, weld.<br>>>><br>>>><br>>>> Example.<br>>>><br>>>> Shell. P355 Steel. 10mm Thick.<br>>>><br>>>> OD 1000mm x 2000mm length.<br>>>> Shell to be within +\- 3mm on diameter.<br>>>> Welded seam.<br>>>> 35 degree external bevel with 2mm nose.<br>>>><br>>>><br>>>> Something like that should do it. They will send you a quote and should<br>>>> tell you what material grade it what code they will be working to.<br>>>><br>>>><br>>>> Make sure you specify clearly the tolerance of roundness you want and<br>>>> say your not paying for it if its not right. They will probably need to<br>>>> re-roll the cylinder.<br>>>><br>>>> Ideally go to the factory with a wooden template and measure the<br>>>> cylinder before you accept it.<br>>>><br>>>> Get the bevel put on, it will save you pain. But. don't bother with<br>>>> grit blasting, you need to paint it straight away after that or it will<br>>>> start to oxidise again. By the time you've finished your hull, it will be<br>>>> all rusty again. Grit blast when you've finished working on the hull.<br>>>><br>>>> Someone else may have some other suggestions. Comments.<br>>>><br>>>> Hope this helps.<br>>>><br>>>> Kind Regards<br>>>> James<br>>>><br>>>><br>>>><br>>>> On 21 March 2015 at 22:30, Andr? Eriksen <<br>>>> personal_submersibles@psubs.org> wrote:<br>>>><br>>>>> Hi,<br>>>>><br>>>>> I`m in the process of ordering the shell and tower for my submarine.<br>>>>> What specification should I ask for? (Europe)<br>>>>><br>>>>> I asked for EN10204 with 3.1 Sertificate (Not 100% sure of this, but<br>>>>> this is what I got when I ordered the endcaps from another company. 3.2<br>>>>> Sertificate was a bit too expensive)<br>>>>> Told them I had no special requirements for the plates and needed no<br>>>>> edge preperation.<br>>>>><br>>>>> *They replied*: "this is not the normal enquiry type, but we will not<br>>>>> ask any longer" (?)<br>>>>> And said the plates was going to be EN10028-3 with certificate 3.2.<br>>>>><br>>>>> I want to keep the cost down, but should I ask that they grit blast<br>>>>> the shell after rolling?<br>>>>> Also I didn`t ask for bevel on the edges. Again to keep cost down. But<br>>>>> maybe I should, to spare me the extra work?<br>>>>><br>>>>> May I ask what you tell your supplier when ordrering?<br>>>>><br>>>>><br>>>>> -Andr?<br>>>>><br>>>>> _______________________________________________<br>>>>> Personal_Submersibles mailing list<br>>>>> Personal_Submersibles@psubs.org<br>>>>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles<br>>>>><br>>>>><br>>>><br>>>> _______________________________________________<br>>>> Personal_Submersibles mailing list<br>>>> Personal_Submersibles@psubs.org<br>>>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles<br>>>><br>>>><br>>><br>>> _______________________________________________<br>>> Personal_Submersibles mailing list<br>>> Personal_Submersibles@psubs.org<br>>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles<br>>><br>>><br>><br>> _______________________________________________<br>> Personal_Submersibles mailing list<br>> Personal_Submersibles@psubs.org<br>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles<br>><br>><br><br><br>-- <br>Med Vennlig Hilsen / Regards<br>*Andr? Eriksen*<br>-------------- next part --------------<br>An HTML attachment was scrubbed...<br>URL: <http://www.whoweb.com/pipermail/personal_submersibles/attachments/20150323/983a24ab/attachment.html><br><br>------------------------------<br><br>Subject: Digest Footer<br><br>_______________________________________________<br>Personal_Submersibles mailing list<br>Personal_Submersibles@psubs.org<br>http://www.whoweb.com/mailman/listinfo.cgi/personal_submersibles<br><br><br>------------------------------<br><br>End of Personal_Submersibles Digest, Vol 21, Issue 57<br>*****************************************************<br></div><br></div></body></html>