[PSUBS-MAILIST] coarse vs fine thread

[Sean T Stevenson via Personal_Submersibles]

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
>>>> _______________________________________________
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>>>> Personal_Submersibles at psubs.org
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>>>>
>>>
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>
>
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