sheaves for block-and-tackle
Richard Smith
Block and tackle - new or second-hand - not readily available - at
least not outside millionaire price pretty stuff for yachting.
Looks might have to go self-sufficient.
Thinking of 3-sheave blocks so rig 3-by-3 tackle system, with 12mm
(1/2inch) fibre rope.
Bit stumped for good achievable design to make sheaves.
Welded sheet metal? Maybe answer isn't metal? Any ideas?
Rest of block - can plasma-cut plate and weld up structural frame of
block - can see my way through that.
Richard Smith
Stuart Wheaton
> Hi again everyone
>
> Block and tackle - new or second-hand - not readily available - at
> least not outside millionaire price pretty stuff for yachting.
>
> Looks might have to go self-sufficient.
>
> Thinking of 3-sheave blocks so rig 3-by-3 tackle system, with 12mm
> (1/2inch) fibre rope.
>
> Bit stumped for good achievable design to make sheaves.
Buy them?
Pretty reasonable compared to the time and materials you'd consume to
make them...
Gunner Asch
wrote:
>Hi again everyone
>
>Block and tackle - new or second-hand - not readily available - at
>least not outside millionaire price pretty stuff for yachting.
>
>Looks might have to go self-sufficient.
>
>Thinking of 3-sheave blocks so rig 3-by-3 tackle system, with 12mm
>(1/2inch) fibre rope.
>
>Bit stumped for good achievable design to make sheaves.
Delrin makes good pulleys. I have a quantity you can have if you give me
an idea of what size you need.
So does aluminum. But only for rope.
Gunner
>
>Welded sheet metal? Maybe answer isn't metal? Any ideas?
>
>Rest of block - can plasma-cut plate and weld up structural frame of
>block - can see my way through that.
>
>Richard Smith
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I think our dog is a Democrat, as he is always looking for a handout"
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Heh, heh, I'm pretty sure my dog is a liberal - he has no balls.
Keyton
Bruce In Bangkok
wrote:
>Hi again everyone
Normally the cheek pieces are made from, or partially made from,
metal. Even the wooden blocks use steel straps to connect the axle to
the hook, so sheet metal will work perfectly well.
One of the reasons for higher price marine blocks is that the better
ones use a frictionless bearing of some sort between the sheave and
the axle. Roller or ball bearings.
There is a site http://www.conradblocks.com/ that while it doesn't go
into detail does show some pictures of wooden blocks that give you an
idea of how they are constructed with the steel strapped wooden cheek
pieces. If you click on the title "Servicing a Conrad Block" it leads
to a page that shows line drawings of the construction of the block.
Cheers,
Bruce
(bruceinbangkokatgmaildotcom)
Richard Smith
> On 04 Dec 2009 10:55:56 +0000, Richard Smith <r0d...@weldsmith4.co.uk>
> wrote:
>
> >Hi again everyone
> >
> >Block and tackle - new or second-hand - not readily available - at
> >least not outside millionaire price pretty stuff for yachting.
> >
> >Looks might have to go self-sufficient.
> >
> >Thinking of 3-sheave blocks so rig 3-by-3 tackle system, with 12mm
> >(1/2inch) fibre rope.
> >
> >Bit stumped for good achievable design to make sheaves.
>
> Delrin makes good pulleys. I have a quantity you can have if you give me
> an idea of what size you need.
> So does aluminum. But only for rope.
>
> Gunner
>
> ...
Gunner - I'm in the UK - and I don't want to be funny or anything, but
you have to be from the USA. So postage would be a problem. I'll
enquire at work though - there might be offcuts of the stuff. I've
looked on-line (Wikipedia et. al.) and find "Delrin" is one and the
same as Acetal I've heard mentioned for sheaves - so seems the stuff
is popular the world over for the application. Richard S.
Gunner Asch
wrote:
Indeed. Delrin is the material most often used for climbers (pulley
wheels) blocks and sail boat riggings, Nylon used to be popular..but its
sag factor would over time become a problem..as was its inability to
deal with UV from the sun.
And yes..Im in California..in the USA...so we are definately a half a
planet apart. <G>
You more than likely can find delrin scraps closer to you, but if you
cannot..email or message me and we shall see what we can do.
Ive got a small but decent collection of it. As well as HDDP etc etc
Gunner
"First Law of Leftist Debate
The more you present a leftist with factual evidence
that is counter to his preconceived world view and the
more difficult it becomes for him to refute it without
losing face the chance of him calling you a racist, bigot,
homophobe approaches infinity.
This is despite the thread you are in having not mentioned
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the subject." Grey Ghost
Bruce In Bangkok
wrote:
There is nothing wrong with using metal for the sheaves. The reason
for using plastics in the boat stuff is usually they do not have any
form of separate bearing and the plastic sheave runs directly on the
stationary pin.
I know that the U.K. destroyed a lot of their fishing boats but aren't
there any supply houses that still supply the industry (if there is
any industry left, that is)? Unless you just "want to do it" buying
ready made may well be cheaper the making.
Cheers,
Bruce
(bruceinbangkokatgmaildotcom)
Steve B
"Bruce In Bangkok" <decypher...@sig.line> wrote in message
news:k9rph55saki9gccic...@4ax.com...
Some of the old rigging is very interesting. Some used blocks of a black
material drilled with holes, then ground into a groove for the ropes to pass
through. No rolling sheave at all. And the ones that actually do have
sheaves have a lot of character, and look cool hanging around. They usually
have a mf'r plate on the side identifying them. I don't think I'd actually
lift anything with one, though.
Anyone know what the name of that black material is? I know, but can't
think of it.
Steve
Bruce In Bangkok
Called "dead-eyes", at least on the Western side of the water :-)
Usually used where rigging was set up with lashings rather then
rigging screws (to use East Side nomenclature).
> No rolling sheave at all. And the ones that actually do have
>sheaves have a lot of character, and look cool hanging around. They usually
>have a mf'r plate on the side identifying them. I don't think I'd actually
>lift anything with one, though.
>Anyone know what the name of that black material is? I know, but can't
>think of it.
>
>Steve
I'm not sure what you mean by "black material" but if they were
authentic dead-eyes (actually used for rigging) they were likely
Lignum Vitae.
Cheers,
Bruce
(bruceinbangkokatgmaildotcom)
Steve B
"Bruce In Bangkok" <decypher...@sig.line> wrote in message
I told you I knew it, but couldn't think of it. That's it. What is it made
of? Looks like the original Delrin.
Steve
Bruce In Bangkok
<desert...@dishmail.net> wrote:
Lignum Vitae is a wood, a very heavy and hard wood. Used for all kinds
of things. British Bobby's truncheon; belaying pins (on USS
Constitution); ships propeller shaft bearings; made one for a U.S.
flagged tug in Vietnam in about 1966; can be used as medicine - a tea
made from the bark is reported to have contraceptive qualities.
Basically it a very hard, dense, oily, wood that has self lubricating
properties.
Cheers,
Bruce
(bruceinbangkokatgmaildotcom)
Richard Smith
>
> And yes..Im in California..in the USA...so we are definately a half a
> planet apart. <G>
>
> You more than likely can find delrin scraps closer to you, but if you
> cannot..email or message me and we shall see what we can do.
>
> Ive got a small but decent collection of it. As well as HDDP etc etc
>
> Gunner
Thanks for offer Gunner - appreciate the thought -- Richard S