I & H Sorby

[whiskywill]

I picked up a small I & H Sorby chisel at yesterday's boot sale. When I measured it I found it to be exactly 2mm wide. There was nothing to suggest that it had been narrowed down by a previous owner. I know that the brand eventually became swallowed up by Marples, but did it last long enough to make metric chisels?

 

[bugbear]

I picked up a small I & H Sorby chisel at yesterday's boot sale. When I measured it I found it to be exactly 2mm wide. There was nothing to suggest that it had been narrowed down by a previous owner. I know that the brand eventually became swallowed up by Marples, but did it last long enough to make metric chisels?

When you say "exactly", what accuracy/tolerance did you measure it to? It might just be a 5/64" chisel.

Or it might just be a "small" chisel, without a nominal size at all.

BugBear

 

[bugbear]

Here's a thread on narrow chisels.

teensy-chisel-t90347.html

BugBear

 

[D_W]

I picked up a small I & H Sorby chisel at yesterday's boot sale. When I measured it I found it to be exactly 2mm wide. There was nothing to suggest that it had been narrowed down by a previous owner. I know that the brand eventually became swallowed up by Marples, but did it last long enough to make metric chisels?

If it was ground or finished by hand, there's no telling what it was intended to be unless it was marked. A 2mm wide chisel could've been intended to be 1/10th of an inch.

 

[whiskywill]

When you say "exactly", what accuracy/tolerance did you measure it to? It might just be a 5/64" chisel.

You could be right. I used a digital vernier, which I believe to be pretty accurate. It measured 2.02mm or 0.08 inch. That is, indeed, very close to 5/64". Silly me. I had converted 1/16" and 3/32" but forgot the 64ths.

 

[bugbear]

When you say "exactly", what accuracy/tolerance did you measure it to? It might just be a 5/64" chisel.

You could be right. I used a digital vernier, which I believe to be pretty accurate. It measured 2.02mm or 0.08 inch. That is, indeed, very close to 5/64". Silly me. I had converted 1/16" and 3/32" but forgot the 64ths.

I suspect DW is right - it's just "small". Any closeness to a given round number
of units is probably a fluke.

BugBear

 

[D_W]

I've got two sets of wonderful plow irons - i don't remember the makes. I'll bet none of them land on what we expect they would - I think I may have checked one at one point in the past because I was looking to find something that would fit a certain size of plywood (of course, if those irons get some wear, they are narrower as they're shorter due to tapering three different ways).

I've never measured any of my older chisels, but I can't imagine that tools in the era before drop forging were often very close to perfect - at least not perfect in the sense of someone with a caliper. Quite a lot of the old ones are otherwise "perfect" to me.

 

[Cheshirechappie]

I rather agree with everybody else - I suspect it may originally have been sold as a 1/16" chisel, it being too small for a 1/8".

Bear in mind that woodworkers didn't have Vernier calipers or micrometers until very recently - and trees still don't! Older tools are often somewhat 'nominal' to size, many of them having been hand ground rather than machine ground. Given that lack of manufacturing precision, it's actually quite surprising how close to their nominal size most are.

I suspect that forging, hardening and hand grinding the very small ones was a more difficult task than the larger ones, which would hold their heat better for forging, lose it slower when heat treating, and be easier to hold for grinding. Thus, really teeny ones are probably even more 'nominal' than the more usually used ones.

 

[bugbear]

With the obvious exception of a mortise chisel, does the exact width of a chisel matter - as long as your 1/2" chisel is around half the width of your 1" chisel, you're happy, surely?

I can't see any practical problem with chisels being 10-15% away from their nominal width.

BugBear

 

[whiskywill]

With the obvious exception of a mortise chisel, does the exact width of a chisel matter - as long as your 1/2" chisel is around half the width of your 1" chisel, you're happy, surely?

I can't see any practical problem with chisels being 10-15% away from their nominal width.

BugBear

I don't see anybody in this thread complaining or saying that the exact width of a chisel matters. Why are you looking for the negative?