Joining Fibreglass Tubes

Fiberglass two brass threaded rings to each section, one male, one female with 'O ring seal? Or will the twisting affect any wiring connections inside ? Failing that an interrupted thread like a breech block on a field gun that locks up in a

10 or 8th of a turn ? but still separate parts fibre glassed to each section.

Just guessing as I don't like getting wet, safest place in ower house to hid anything is under the soap

-- Regards,

John Stevenson Nottingham, England.

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"Michael" wrote in message news:n%ixh.255710$ snipped-for-privacy@fe3.news.blueyonder.co.uk...

How about a spigotted joint with a groove in one part (like an O ring groove) then use a bicycle inner tube as an inflatable seal. Hydrostatic pressure is going to push your two bits together. You could use toggle fastenings to pull the two parts together before inflating the seal. In fact if you think you can make the parts accurate enough you might get away with toggle fastenings to compress an axial seal between the end of the male part and a matching step on the female.

Sorry for the misunderstanding, but it doesn't have to be water tight and there's no electrical connections to worry about as they're all dealt with within the sub.

I'll look into the ideas and report back,

Cheers,

Michael

In article , John Stevenson writes

Or a tapered thread, such as that used on oil drill pipe for swift connections?

David

In article , Michael writes

Completely off the top of my head - I have no experience of making things out of fibreglass - have you considered a taper joint? I was thinking of something like a Morse taper, or maybe a trifle steeper, maybe with a couple of retaining bolts* for peace of mind. I am assuming that each half of the hull will be watertight on its own, so the joint does not need to be watertight. However, you may take comfort from the fact that much laboratory glassware uses cone and socket joints (look for the trade name Quickfit) and this is perfectly liquid- and gas- tight if lubricated and prevented from coming apart under gravity or gas pressure. (I spent several year handling some pretty noxious substances relying on the integrity of such joints.)

Might be a bit more difficult to get a joint of the same precision using fibreglass, as I say I am not that familiar with its working. However, grinding the two parts together using some grinding paste would probably do most of the work. Would need to have circular symmetry of course.

Having just seen John's post since writing the above, you could adapt the cone idea by making it out of metal and moulding the mating parts to the fibreglass.

*Or some other means of holding the two parts together - even a couple of clips or catches.

David

Bulkheads/frames strong enough to clamp the sections together with a single

16mm or larger screw in the centre of one going to a threaded hole on the centre of the other. Use a pair of bevel gears to drive the screw from the outside using a chuck key.

Mark Rand RTFM

OK then just toggle fittings (as used on those "metal briefcase" toolboxes, for example). How strong or rigid does the joint need to be? That will determine how many you need, what size, and what the "socket" geometry needs to be (clearance, thickness, depth, etc).

Fine if the compartments are separate, I'd sort of assumed there was going to be a person inside. One hell of a project, by the way! All credit to Michael.

Rare-earth (eg neodymium) magnets may do the trick. Something like a bayonet approach, but with magnets and iron/steel sections instead of pins and slots, would probably be required to separate them (ie twist to move magnets away from opposing iron sections, then remove). You'd need a locating ring to stop it sliding off sideways and a pin to stop it rotating, but the rest of the construction wouldn't require nearly as much precision as a mechanical bayonet approach or huge thread.

Old hard drives are a cheap source of suitable magnets. One of the two magnets from an old 2.4GB hard drive I have to hand (the ones in newer, bigger, faster drives are stronger) lifts the 5kg telescope counterweight I had to hand and withstands reasonable efforts to shake said lump off, but slides off sideways without too much force. The ones from hard drives come on handy mounting plates.

I presume you've already thought of this, but whichever method you use, make sure the big bits all floats and have a bit of string tying them together too!

Tim

Tim Auton wrote: [snip]

Apparently I'm wrong about the ones in newer hard drives being stronger. The best ones are apparently those from really old 5 1/4" drives, but not ones which use stepper motors (which may not be easy to discern). They're all very strong though.

Tim

Halfords roof rack would save an awful lot o work...

Steve

Might get you blown up by a passing A10 tank buster though...

Mark Rand RTFM

So don't paint it orange...............

.

-- Regards,

John Stevenson Nottingham, England.

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