T. J. Gardner Plough Plane Irons

[Plumberpete]

Sorry, I can't help myself at the moment - I've got a week off work and nowhere to go!

I picked up these T. J. Gardner plough plane irons on a well known auction site recently (well 7 of them - I already had the No. 1) and I've noticed something a bit strange about them. They all seem to show the folding process in the steel and I wondered what had happened.

Were they;
a) always like this - T. J. Gardner had their own foundry and engineering works for a short period (Simplex [Bristol] Ltd. 1918 - 1922) - were they trying to replicate the Sheffield edge tool makers and these were their early attempts?

b) corro-dipped or electrolytically de-rusted to excess?

c) reduced to this by the rusting process, which was only exposed once the rust was removed?

Any ideas anyone?

Sorry about the poor photography, I've only got an iPhone to take photos with.

 

[AndyT]

Well Pete, you do come up with some good questions!
I have no idea, but if your No 1 looks the same as the separately bought larger sizes, that would seem to make theories b and c less likely.

I've been and checked, but I don't have any Gardner plough irons, nor any by anyone else showing that sort of stripy steel effect.

PS - I've heard that someone is bringing out a book soon about Bristol Plane Makers - I hope it has answers to all these questions! :wink:

 

[Plumberpete]

Hi Andy,

The No.1 iron doesn't have this effect, but that may have been made at a later date or by someone else.

I also have another plough plane iron stamped T. J. Gardner Bristol that also doesn't have this effect, so they were probably made over a long period and possibly by one or more of the Sheffield makers.

I was hoping someone could help me with these questions so that I could then write the book!

 

[Cheshirechappie]

I have some plough irons which, after reading this post, I've had a closer look at. They show very similar markings. I think I may have a reason, too.

Look carefully at a sideways-on view, and you can see that the irons are laminated - a thin layer of high-carbon cast steel forge welded to a softer backing material. It's the softer backing that carries the 'fold' marks. I think that may be because the backing is wrought iron.

Wrought iron was made by 'puddling' pig iron in a reverbatory furnace. The furnace was charged with cast-iron 'pigs', small ingots cast out of the iron run from a blast furnace. That iron tends to have a very high carbon content - something like 4 or 5% - making it brittle and unsuitable for any use requiring a degree of flexibility or malleability. Removing the carbon (leaving about 0.05 - 0.1%) gives a metal that blacksmiths can shape and weld, which they can't do with cast iron. The 'pigs' melt in the reverbatory furnace, then the mass of molten iron is stirred ('puddled') until the carbon burns out of it. As the carbon content reduces, the melting point of the remaining, purer, iron goes up, to a point just above the temperature the furnace works at. The puddled mass thus becomes 'pasty', and can be divided into lumps and removed from the furnace, to be worked under hammers. The iron retains other impurities, but these tend to gather together, and when the iron is worked under the hammer, they become drawn into strings or laminations (some are ejected as scale during hammering). The result is a material with 'layers', which show up after the wrought iron is forged, cooled and subsequently cut to shape.

Mild steel - iron with a carbon content of 0.1 - about 0.3% - didn't come about until Mr Bessemer invented his converter in the 1860's, and rapidly replaced wrought iron for most engineering purposes, being of slightly higher tensile strength and much more homogenous. It was thus a far more reliable material for boiler plates, structural sections, machined parts and so on. However, wrought iron continued to be available (the last was made in the 1960s, I think - by Walmsleys of Bury), for applications that didn't really need the strength of mild steel. As it's a far easier material to forge weld than mild steel, blacksmiths still favoured it for their work. Consequently, it's entirely possible that plough irons continued to be made by laminating cast steel to wrought iron well into the 20th century - until the cost of tool steel reduced sufficiently to make solid cast steel plough irons more economical than laminated ones.

Might be wrong, though. Anybody got a better idea?

 

[Plumberpete]

Hi Cheshirechappie,

Your post makes perfect sense. One question though; Why is this apparent in some plane irons but not others? Is it usually polished out?

 

[Cheshirechappie]

Sorry Pete - I edited my post to put the extra paragraph in about mild steel.

I know that the pressures of production during WW1 pushed the development and installation of electrical furnaces for specialist steelmaking in Sheffield. I suspect (can't prove it) that post WW1 this brought the cost of tool steels down to the point where making edge tools from the solid steel became more economical than laminating. So any post-war irons wouldn't show the 'lines' in the backing material, because there isn't any!

 

[AndyT]

Now that does make sense, thanks CC.

I've been and looked again at the mismatched assortment of plough plane irons in my workshop. About half appear to be all cast steel but the others have a visible boundary. They presumably have mild steel for the body. It makes sense, when such a large proportion of the whole is not for cutting and indeed, needs to have a notch filed in it to fit to the skate.
Some pictures:

This shows the steel tip. Behind it, the metal is soft enough for an owner to have marked his name

Side view

Maker's mark

This one has a very clear boundary

 

[bugbear]

Mild steel - iron with a carbon content of 0.1 - about 0.3% - didn't come about until Mr Bessemer invented his converter in the 1860's, and rapidly replaced wrought iron for most engineering purposes, being of slightly higher tensile strength and much more homogenous. It was thus a far more reliable material for boiler plates, structural sections, machined parts and so on. However, wrought iron continued to be available (the last was made in the 1960s, I think - by Walmsleys of Bury), for applications that didn't really need the strength of mild steel. As it's a far easier material to forge weld than mild steel, blacksmiths still favoured it for their work. Consequently, it's entirely possible that plough irons continued to be made by laminating cast steel to wrought iron well into the 20th century - until the cost of tool steel reduced sufficiently to make solid cast steel plough irons more economical than laminated ones.

Might be wrong, though. Anybody got a better idea?

I think you're essentially right, but I'll add that laminated tools of mild steel and HC steel were definitely made; - best known are probably plane blades by Record and Stanley.

So the transition wasn't directly from "wrought iron + laminated" to "solid cast steel".

BugBear

 

[matthewwh]

This is a knife made by one of our customers, the blade is laminated using our wrought iron, the core layer is silver steel.

The blade has been etched in ferric chloride to bring out the pattern of the natural impurities in the iron. Silver steel, despite the name, etches black thanks to its low nickel content, it is chemically very similar to the crucible steel that your plane irons will be edged with.

With the widespread adoption of the Bessemer process (after it was eventually perfected by Robert Mushet who was later paid a royalty by Bessemer) the volume of edge steel produced rocketed and the price plummeted. Hence it therefore became cheaper to make the whole thing out of cast steel than hammer crucible and wrought together.

Cast steel eventually took over completely and Huntsman's crucible process died out. The words 'cast steel' gradually disappeared from tools because all steel was cast - and still is!

 

[Plumberpete]

Hi all,

Thanks for your replies. I've not had a chance to get on here for a couple of days as my partner Tash went into labour Wednesday evening and gave birth to our son Joseph (Well, Joe really - named after the late, great Joe Strummer) at 4am, Thursday morning.

It might be lack of sleep but I'm still a little confused as to why these plane irons are so different to all others that were produced during the same period.

With this thread I suppose what I was getting at is this;

T. J. Gardner were in business from 1880 to 1922. Would the process used for making these plough plane irons (wrought iron puddling) still be in common use by the foundries in Sheffield or Birmingham at this time, or is it possible that T. J. Gardner themselves made these in Bristol using a rudimentary technique that was no longer used by the leading manufacturers?

 

[matthewwh]

First of all, huge congratulations on your wonderful news Pete, enjoy every second - you have the rest of your life to ponder plough plane irons.

It is a replacement technology, so the ones you have would probably have been from very early on in their history. Kinda like an apple computer with a floppy drive.