Stanley 720 chisels

I was recently given a set of 9 Stanley 720 chisels - ¼” to 1½” - see photo below.

Unfortunately when I was given them, the chisels were covered with well developed rust, which I removed using citric acid. They have cleaned up quite well but have some shallow pitting. They are now very sharp and a joy to own and use.

On removing the rust, I found on the back of the 1½” chisel a fracture or "split" - see photo. Despite the fracture the chisel seems very rigid but I have only been using it for paring.

I have no idea what would cause such a fracture. Is it because the chisel has been used as a lever? Is it metal fatigue of some sort?

Do any of our chisel aficionados have a view on what may have caused such a fracture in the metal of the 1½” chisel?

Many thanks

Therapy

What a beautiful gift.
I wonder if the Stanley 720 was built with a laminated blade.
That kind of cracking and in the place where it occurs, suggests to me that the blade is de-laminating in that place. The crack doesn't seem to go through to the front, so perhaps it will run longways.
If the blade is laminated and you aren't going to be belting the chisel or levering with it, then I think it will make little difference to the chisel's performance.
Cheers
SG

Yes, there is something seductive about old tools. Pity about the rust.

Scribbly's suggestion of a partial delamination sounds plausible, but I cannot find any information as to whether these chisels were laminated or not. What information I could dig up suggests they weren't. So perhaps it was just a flaw in the billet the chisel was stamped from, which snuck through inspection at the factory, but for some reason has 'popped' later down the track, but for what reason I have no idea - it doesn't LOOK like an abused tool. An opinion from a metallurgist would be your best bet, alright.

I too was given a set of long socket chisels quite a few years back (New Haven Edge Tool). They weren't rusty, but did have a few bad pits. Two had lost their handles & one of those (the 1 1/4") had been bashed on the top of the socket, which didn't do a lot for its apperance! However, they all cleaned up well, & I was able to grind & polish the damaged socket to the point where it in't noticeable. They are delightful to use - the way the socket is forged level with the back of the blade makes them perfect for paring.

They've given me great service & much pleasure over the years. I bless the bloke what gave 'em to me almost daily! :U

Scribbly Gum and IanW thank you for your responses.

The fracture or delamination is a weak point and so that the damage is not exacerbated, I will not allow the chisel to meet up with a mallet, no matter how nice the mallet might be.

Many thanks

Therapy

Hey Therapy, thats an aufully nice looking set of chisels,even with the fault. All consistent lengths. Did they look used much? Or at all!

OG

Old gunnie

Yes they are a nice set except for the rust damage and flaw on the largest.

They are all pretty well full-length and they don't look as though they have had much use. In fact a couple had never been sharpened.

As I mentioned they are a joy to own and use.

Regards


Therapy

If you google "Rose Antique Tools" and click the Stanley topic on the list to the left, you can download 1930s and 1950s Stanley catalogs. The 720 shows up in those of the 1950s, and the blade was not laminated.

Interesting to look at those old catalogs.

Admiral

Many thanks for the link.

I have downloaded the catalogue and yes, it is interesting to read about the wonderful tools of yesteryear, including my 720s.

Many thanks

Therapy

Is there any point in brazing the fracture to stabilise it?

Thanks,
Paul McGee