When were blocks changed?

[captainbob]

In Popeye's build of the Gothenburg a member posted pictures of blocks recovered from the wreck (see here) .  These blocks from 1745 have wooden pins.  When were blocks made with metal pins? 

 

Bob

Edited April 2, 2013 by Cap'n'Bob

[davyboy]

Hi Bob,good question.

 

I think that both types of pin were in use all of the time. Lees quotes wood pins (lignum vitae I would think) for small blocks and Iron or Brass pins for large blocks used in English ships. Marquardt quotes pins being made from Lignum Vitae,Cog-Wood (Laurus chloroxylon),Greenheart and Iron in his book 18th Century Rigs & Rigging which covers other countries as well as Britain. Neither of these books mention anything about dates of change from wood to metal.  

 

Hope this is of help to your question.

 

Dave

Edited April 2, 2013 by davyboy

[wefalck]

Are you guys talking of sheaves or really of the axles, i.e. the pins on which the sheaves run ? I have never heard that the axles were made from anything else, but metal. The friction of wood on wood would be rather to high and they would very quickly wear down without constant greasing.

 

I think there has never been a complete shift over from wood to metal as far as blocks for organic and man-made fibres is concerned. The sheaves of blocks for wire rigging to my knowledge have (almost) always been from cast iron. The wire rope would simply saw into wooden sheaves. Also, wire rope requires relatively large sheaves that would be quite expensive to make from wood.

 

wefalck

[captainbob]

Are you guys talking of sheaves or really of the axles, i.e. the pins on which the sheaves run ? I have never heard that the axles were made from anything else, but metal. The friction of wood on wood would be rather to high and they would very quickly wear down without constant greasing.

 

 

wefalck

 

I would tend to agree with you but it is obvious from the pictures the pins were made of wood.

 

http://modelshipworld.com/index.php?/topic/889-gothenborg-by-popeye-the-sailor-billings-1100-scale/page-8

 

Click and scroll down.

 

Bob

Edited April 4, 2013 by Cap'n'Bob

[rybakov]

I wouldn't doubt the use of lignum vitae, it is an extremely hard wood.

In the late seventies I had a piece of it in my hands and I couldn't find a tool able to score it.

As for friction I can tell you it was part of a propshaft bearing on a 10 000Hp bulk carrier, operating at 122RPM,

so you can figure out the resistance to wear.

In that capacity it was water cooled, but on the other hand it would get more friction in one minute than a block in one

hour, so I believe there would have been no problem

 

All the best

Zeh

[Kevin Kenny]

Does anyone know when sheaves were changed from Lignum vitae to brass? 

[wefalck]

Never ... well, I think brass or perhaps rather bronze or cast-iron came into use when wire runners came into use, for which even Lignum vitae was too soft. I believe expensive brass sheaves and ball-bearings came into use also on later 19th century yachts.

[Charles Green]

In addition to being hard as nails, lignum vitae contains oil that serves as a natural lubricant.  Oil content is a common property of tropical hardwoods.  It's what makes gluing those types of wood problematic unless they are wiped with acetone just prior to applying the glue.

[Kevin Kenny]

Its an interesting response as in the Swan practium a number of the sheaves a number of the blocks contain Bronze sheaves. 

[allanyed]

I had an old block from the early 20th century that is internally stropped and has a sheave that is LV, not brass.    Perhaps there were options/choices depending on the circumstance.

Allan

 

 

[grsjax]

2 hours ago, allanyed said:

an old block from the early 20th century that is internally stropped

Not trying to hijack the thread but I was just wondering when internally stropped blocks came into use.

[allanyed]

Wish we were a little closer to discuss face to face.  We're over in Wailea this week,  but checking in on MSW for the important stuff 😀   As to internally stropped blocks I need to look at my books when we get back home but I know they were common by the late 19th century so probably quite some time earlier.  I am sure there are members here with some contemporary based information.  I hope so, as I am curious about this as well!!  

Allan

[popeye2sea]

The ship I served in whilst in the Navy had fairleads for the signal halyards made from lignum vitae. 1985.

 

Regards,

[allanyed]

Henry, you bring up a great point, LV had a variety of uses.  The bearings for the propellor shaft where it went through the hull on all the ships I sailed in the 60's had LV sleave bearings.   I am sure that has changed, but it served us well for many decades well into the 20th century, perhaps longer.

Allan