I Sorby English/Pig sticker mortise chisels

[mr edd]

Hi all
I acquired some I Sorby English mortise chisels with a Mr punch stamp above the name stamp, 1/4'', 3/8'' and 1/2'' all in poor condition, heavily rusted and lacking handles and resolved to try to get them to working condition again.

I de-rusted them, made some new handles using ash from a tree I acquired from a field near Saffron Walden which I have been painfully processing from riven hunks by hand to quarter sawn boards story for another day.........

However the back/face whatever you want to call the bit of the chisel on the opposing side to the bevel was badly pitted so started to try and remove some of the pitting on bench stones, then sand paper, and then in a moment total impatience I picked up a mill file started to draw file the back of the chisel to try and remove the very deep pitting.

I was expecting the file skid over the metal and not cut but to my surprise the file worked quickly and I managed to remove all of the pits and following a few minutes of work of the diamond stones I had a flat smooth chisel back with edges and an intact cross section.

ps my filing is not normally that accurate.

So question,

Is the steel normally that soft?

I did some trials in redwood, walnut and d fir and the edge did not seem to suffer.

Probably more an academic question than practical as for mortising uber sharp is not the be all, but just interested to see how others experience compares.

pss my grinder is buried under a mountain of tools atm so I used the file to re-establish the totally buggered primary bevel of the chisels as well before going to 300/1000etc.

The file much quicker than the water stone grinder

Evening all

Edd

 

[AndyT]

The bulk of the metal is a softer steel with a layer of hard crucible steel welded on to form the cutting edge. You can often see a difference in colour where the two steels meet. This gives a tough body and a hard, sharpenable edge. Smaller chisels were made of crucible steel throughout.

You can see the weld and two steels in this one.

 

[mr edd]

Hi Andy

Ah! that would explain the ease with which the bevel of the chisel filed, but to be honest the reverse flat back of the chisel filed quite easily too, on all 3 chisels but the file required more cleaning.

I would have thought the hardened laminated bit would have been much harder to file, but It was not????

Ta Muchley

Edd

 

[JohnPW]

A file should be harder than a chisel but softer than hardened untempered steel, you do the skid test to make sure you've hardened properly before tempering.

I think it's not common to use a file on blades (plane irons, chisels etc), I suppose there must be a reason, maybe because the file will wear out quickly.

Maybe your chisels are on the soft side, but they still should be harder and therefore more difficult to file than annealed soft high carbon steel or soft low carbon steel.

 

[mr edd]

I must check under better light to see If I can differentiate two different layers of steel.

Cheers

Edd

 

[mr edd]

Hi John PW

Normally the only time i involve a file with sharpening is jointing cabinet scaper's.

Thanks for your input, I suppose the odd thing was the reverse of the bevel side filed quite easily too.

I don't know, I just expected the metal to be a bit harder leading to the cutting edge.

Maybe I have a duff bunch of chisels?

The file still cuts ok tho, its a grobet mill file? and does not appear to be worse for wear for the abuse?

Cheers

Edd

 

[ED65]

I would have thought the hardened laminated bit would have been much harder to file, but It was not????

Indeed it should be, at least by modern standards of chisel hardness (near the tip, further back they are way softer). I have no idea what the norm was for your specific chisels but they might deliberately have been tempered softer so as to reduce the risk of chipping during deep mortising.

But it does sound like they're very soft. I've used a file (the same cheap machinist's file, from Aldi or Lidl) on numerous chisels and irons and only the unhardened steel on the opposite end from the bevel would be easily cut by it. Even on the cheapest blades the hardened steel near the tip can be scratched all right but I wouldn't consider them fileable.

If your chisels are all from the same source I wonder if there's a chance they were damaged in a fire, which would certainly account for the lack of handles and this does also make the steel particularly prone to heavy rusting. Not the only explanation for either thing of course but it's a possibility.

 

[mr edd]

Hi ED65

Fire damage is an interesting thought! not one I had considered.
They are a good length around 6'' + of blade so they should not be worn past the hardened steel but close to the tip on the flat side they still draw filed quite easily.

I will keep them as they look awesome and even if they are soft they are dead easy to put a new edge on!

Very interesting to hear all your thoughts tho.

Thanks

Edd

 

[Cheshirechappie]

I suspect that fire damage might have annealed the steel to point of being useless even in redwood.

The answer may lie in the relative hardness of files (usually hardened 'right out' and barely tempered at all, thus very hard but brittle), and the chisel, which is probably a bit softer than - say - Japanese laminated chisels. After all, you want a mortice chisel to cope not only with the impact of driving it, but the levering out of waste, which a Jap chisel might not like much. It may not need to be be much harder than a saw blade - and they can be filed easily enough!

 

[D_W]

Edd - you pretty much summed up the consequences of all of this when you said you chopped some mortises and the edge didn't seem to suffer.

The dandiest of chisels to use are the ones that are hard enough to work well and soft enough sharpen very easily.

It sounds unusual that you could file the hardened bit well, but you may have high quality files and the chisels may be a touch on the soft side. At any rate, the only thing that really matters at this point is the using of the chisels, and if that goes well, you're in good shape.

 

[MarkDennehy]

I think it's not common to use a file on blades (plane irons, chisels etc), I suppose there must be a reason, maybe because the file will wear out quickly.

Funnily enough, the most recent Maguire videos on sharpening mentioned that exact point - he claimed that "in the olden days" people using wooden planes with very thick laminated irons would use files to establish the primary bevel in the softer steel so the stones only had to be used on the harder steel in the cutting edge.

 

[mr edd]

Hi DW
Yep, they are working well!!!!!!!! and I am loving them as my first proper mortise chisels!
Am stuck at home this last week, having paid for £2500 of work to be done on my van Friday before last, some twit ran into the back of said van on the next Monday while I was parked outside a job about to pour a cuppa. Its a write off....yay.

So with lots of spare time while I wait for the insurance to come through (sometimes self employed sucks!!!!) I cut the mortises for four number 4 panelled doors today in Douglas fir using said chisels.

You would not want to pare with them now but I reckon they're still good for another good many more doors worth before needing a touch up on the stones.

I've got a whole bunch of chisels from lots of makers, Ashley Illes, LN and blue spruce to I. Sorby, Ward and Old and new Marples and love them all for different qualities but I was extremely satisfied with the ease I could file a new bevel and remove the heavy pitting from the back these latest ones. That kind of pitting near to the edge can be a deal breaker for me some older chisels.

Hi Mark Dennehy

I missed that one, thanks for pointing it out, writes a good article does Mr Maguire.

Cheers all

Edd