Steel in 1840 would have been blister steel, made by cementation of Swedish oregrounds iron bars. It might have been crucible steel, made by melting and casting blister steel. These are materials that are no longer produced. The last blister steel was made in about 1950. The production of steel was revolutionised in the 1860s, by the development of new methods of producing it by Bessemer, Siemens, and others. However, blister and crucible steel continued to be made. This means that data on blister or crucible steel from the 1890s or early 20th century would probably be valid for earlier periods, as the developments made in the 19th century did not radically change the process.
I would nevertheless question whether the bolts are in fact steel at all. My guess is that they would have been of wrought iron, but (like Chris Evans) this is not quite my period.
My guess is that modern steel bolts of the dimensions of the original would be at least as serviceable, but I am speaking beyond my expertise and that view should not be relied upon. In some senses, it is a question of how authentic the repair is to be. If this is a heritage (rather than a commercial) enterprise, it might be worth investigating what the original bolts are made of and seeking to match that, in wrought iron (of which there is at least one supplier - using recycled material) or a modern carbon steel of similar composition to the original.
I am not sure whether this helps. I am posting this to the whole list (as well as the original enquirer), because others may differ from my views or be able to throw more light on the subject.
Peter King
49, Stourbridge Road,
Hagley
Stourbridge
West Midlands
DY9 0QS
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01562-720368
-----Original Message-----
From: Arch-Metals Group [mailto:[log in to unmask]] On Behalf Of Chris Evans
Sent: 22 February 2013 09:13
To: [log in to unmask]
Subject: Caribbean sugar mill and Sheffield steel
I'm passing on an enquiry I've received from George Croome of the River Antoine estate in Grenada concerning the properties of steel made in Sheffield in the 1840s. I'm not competent to comment, but perhaps someone on the list may be able to assist. If so, please contact Mr Croome directly at [log in to unmask]
"In Grenada, my company operates a small rum distillery, using sugar cane juice grown on the estate, which is crushed in a 3-roll mill made by George Fletcher & Co. of Derby in the 1840's. The mill is still driven by the original water wheel - the only working water wheel in the Caribbean....
The mill has eight horizontal through-bolts which take the thrust from the two bottom rolls and are adjusted as the rolls & bearings wear....
After 170 years of daily operation, the bolts have started to elongate and break. Fletchers (who are still in existence as Fives Fetcher) are very good, but they tell me that the warranty has expired !
I need to replicate the bolts, using modern steel, and I have been trying to 'reverse-engineer'. For that, I need an estimation of the original load-carrying capacity of the bolts. I have engineering data books showing steel properties, going back as far as 1890, but I know that there were huge improvements in steel-making in the 50 years before that time, so the 1890 figures might not be representative . Fives Fletcher are looking back in their archives to try to calculate the theoretical total tensile load on the eight bolts as a component of the thrust from the rolls.
I am hoping that we could use a continuous threadbar rolled from 50,000 psi yield steel perhaps 1.2 inch OD to replace each bolt, as such threadbar is readily available.
My question therefore is, can you give me your opinion (i.e. hazard a guess !) at what type of steel would have been used to make these bolts in 1840, and what allowable stresses might have been assumed by the original engineer."
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