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274444 | Christian Gagneraud <chgans@g...> | 2021‑08‑29 | Set of Mathieson plough iron (in metric sizes?) |
Hi Galoots, I recently bought a set of Mathieson plough irons. They are all in very good condition, marked from 1 to 8, all with the same stamp at the same location "ALEX. MATHIESON GLASGOW". This looks like an original set to me and by the look of it, they have been barely used. I'm thinking of making a nice box for them, to go with a Mathieson No 4 plough plane I'm restorating right now. The sizes puzzle me, it looks almost like a metric set, as I can't make any sense of the imperial sizes. Here are the figures: Number mm inch mm Error (%) 8 15.44 0.607 15 +6.6 7 13.05 0.509 13 +0.7 6 11.83 0.465 12 -2.0 5 9.78 0.385 10 -2.2 4 8.21 0.33 8 +1.7 3 7.04 0.277 7 +0.3 2 4.97 0.198 5 -0.2 1 4.00 0.158 4 +0.0 I can't make any sense of the imperial sizes (eg, numbers are not in 8th or a 16th of an inch), but the metric sizes almost match, except for #8 maybe. However this doesn't sound like a convenient set, the size progression is really odd: 4, 5, 7, 8, 10, 12, 13, 15+? The #8 is off by 3/16th of an inch And then if it's metric, why some random numbers instead of the size in mm. Hum... Anyone seen something like that? Will post photos soon. Chris. 1 AM, Monday here in locked down NZ. PS: I tried to measure the imperial sizes with a wood/brass stanley caliper (thank you galootaclaus), but had to resort to my digital caliper. |
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274445 | Claudio DeLorenzi <claudio@d...> | 2021‑08‑29 | Re: Set of Mathieson plough iron (in metric sizes?) |
I’ve never seen old plough plane irons in metric, which isn’t surprising, since all of mine are British made. I have a couple of harlequin sets (mismatched) and at least one complete set from a single maker. They typically range from about ⅛ to ⅝ but I have some ‘as found’ singles that were larger or smaller. None are exactly sized when using digital calipers or micrometers but I don’t know whether any were user modified for a special purpose. I had always thought (maybe) they were marked in some fractional system like Irwin or Jennings bits that are numbered by 16ths (a number 4 is 4/16, or ¼”, for example), but my #7 irons are about a half inch, so I can’t figure it out either. You raise an interesting point. I wonder how they arrived at the numbering system. There must be a reason. Does anyone know the history of this? Cheers from a sweltering Waterloo, no longer in lockdown mode Claudio On Sun, Aug 29, 2021 at 9:22 AM Christian Gagneraud |
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274447 | Kirk Eppler | 2021‑08‑29 | Re: Set of Mathieson plough iron (in metric sizes?) |
On Sun, Aug 29, 2021 at 6:22 AM Christian Gagneraud |
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274448 | Richard Wilson <yorkshireman@y...> | 2021‑08‑29 | Re: Set of Mathieson plough iron (in metric sizes?) |
I recollect seeing that Record, at least, provided plough irons especially sized for plywood. That beloved article, the Record 42 drawer bottom groovong plane, certainly had an alternate set of irons available for just this purpose. How much better to have an iron perfectly sized for 6mm ply than having to grind your own or fiddling with the wrong size groove. As for accuracy, we all know that in an era of stamped or sheared blades, they were never accurate to the degree we take for granted in our CNC made world. Richard who is currently discovering that a 43 works well when applied to vertical timber. > On 29 Aug 2021, at 14:21, Christian Gagneraud |
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274449 | Charlie Driggs | 2021‑08‑29 | Re: Set of Mathieson plough iron (in metric sizes?) |
Christian, Try multiplying the size number by the decimal for 16ths of an inch. I get decimals that correspond quite closely to the correct numbers in inches …. Charlie Driggs |
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274451 | Frank Filippone <bmwred735i@g...> | 2021‑08‑29 | Re: Set of Mathieson plough iron (in metric sizes?) |
When these plow planes were being used by makers ( 19th, 18th Cent), the size of the plow did not need to be very accurate. The inserted piece was (hand) planed to fit whatever size slot was cut.... Before the Industrial Revolution, the "ruler" used was as circumspect as the iron size. But then came the theory and practice of standards..... and availability of commercially made, standardized rulers. It is only in the late 19th and 20th/21st centuries that we cared, or could or would measure for absolute accuracy. Now we can measure to 3 decimal places for about $20. And we (hand) plane to fit. Progress. Frank Filippone BMWRed735i@g... |
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274456 | Thomas Conroy | 2021‑08‑30 | Re: Set of Mathieson plough iron (in metric sizes?) |
Chris wrote: I recently bought a set of Mathieson plough irons. They are all in very good condition, marked from 1 to 8, all with the same stamp at the same location "ALEX. MATHIESON GLASGOW". This looks like an original set to me and by the look of it, they have been barely used.... The sizes puzzle me, it looks almost like a metric set, as I can't make any sense of the imperial sizes. Here are the figures: Number mm inch mm Error (%) 8 15.44 0.607 15 +6.6 7 13.05 0.509 13 +0.7 6 11.83 0.465 12 -2.0 5 9.78 0.385 10 -2.2 4 8.21 0.33 8 +1.7 3 7.04 0.277 7 +0.3 2 4.97 0.198 5 -0.2 1 4.00 0.158 4 +0.0 I can't make any sense of the imperial sizes (eg, numbers are not in 8th or a 16th of an inch), but the metric sizes almost match, except for #8 maybe....The #8 is off by 3/16th of an inch And then if it's metric, why some random numbers instead of the size in mm. Hum... Anyone seen something like that? Hi, Chris, You are inhabiting the wrong mental universe. Get rid of all those little numbers; they are useless and meaningless in the world of the traditional woodworker. The first owner of those blades probably didn't have a measuring tool graduated finer than sixteenths, and may not have had one finer than eights. Wouldn't have known how to use one, or what to use it for. Why would you need one? You weren't making things from measured drawings that had to be precise to a thousandth of an inch or they wouldn't work. It wasn't until Henry Maudsley started scattering larval machinists like ragweed pollen (1820s or 1830s, call it) that anyone cared about tolerances of less than a sixteenth of an inch or so; and it wasn't until Laroy Starrett invented a machine for precision marking rules mechanically (1870s, IIRC*) that fine rules became affordable for the ordinary workman. They would work by divider and straightedge, not by numerical measurement and sight comparison with rulers. For decades I wanted a set of classic chisels graded by sixteenths up to two inches. Well, they don't exist. Oh, the old catalogues listed them, but they don't actually exist. You can get sixteenths up to about 7/16", with a precision of plus or minus1/32" if you are lucky. From 1/2" up to 1" or maybe 1-1/4" you can find them by eights with a tolerance of a sixteenth. Eventually I got a series of 2-1/2" butt chisels up to 1-1/2" by sixteenths, but I did it by regrinding about a third of them; and it was only possible because many of the great makers tapered their chisels back from the edge, sometimes by almost 1/8" over 6". By starting with firmer chisels worn down to short butt length, I sometimes got close to the dimension I wanted before I had to regrind. OK, your plough irons are a little irregular in change from one to the next (that is the proper number to look at if you insist on numbers, not the actual inches or milimeters). But not enough to be a real problem in use; if you just choose the one that is closest to what you want, you will never be as much as 1/16" away from the "ideal" measurement; apart from the big 7-to-8 gap, you won't be further off than about 1/32", roughly, if my numbers are right. Who would need better than that anyway? If you need precision, use dividers and you can go as close as you want, provided you don't try to cram an irrational universe into a rational straightjacket (rational and irrational in the correct mathematical sense, not in the vague half-assed common speech sense.) Tom Conroy Yes, I know that scattering machinist larvae like ragweed pollen is a mixed metaphor. It's vivid, though. Betcha you'll remember it.*I checked. Graduationg machines for steel machinists rules started with Darling, Brown and Sharpe around 1850, not with Starrett around 1870. Doesn't invalidate the basic point. Precision rules are machinists' tools, not woodworkers' tools. A woodworker never needs a measurement as small as 1/32"; hell, a six-inch wide board will shrink and swell more that that over the course of a year back where you have summers and winters. If you need a tighter fit, it is faster, easier, and actually more accurate to use divideres or direct comparison. |
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274457 | Christian Gagneraud <chgans@g...> | 2021‑08‑30 | Re: Set of Mathieson plough iron (in metric sizes?) |
On Mon, 30 Aug 2021 at 02:51, Kirk Eppler |
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274458 | Don Schwartz <dks@t...> | 2021‑08‑30 | Re: Set of Mathieson plough iron (in metric sizes?) |
This reminds me of the distinction between absolute and relative measure. What matters most in woodworking is not the absolute measure, but the fit, arguably also in metalwork. And ... if the shoe fits, wear it ( no matter the size )! Hurrah for common sense! Don On 2021-08-29 7:20 p.m., Thomas Conroy via groups.io wrote: > Chris wrote: > > > I recently bought a set of Mathieson plough irons. > They are all in very good condition, marked from 1 to 8, all with the > same stamp at the same location "ALEX. MATHIESON GLASGOW". > This looks like an original set to me and by the look of it, they have > been barely used.... > > The sizes puzzle me, it looks almost like a metric set, as I can't > make any sense of the imperial sizes. > > Here are the figures: > Number mm inch mm Error (%) > 8 15.44 0.607 15 +6.6 > 7 13.05 0.509 13 +0.7 > 6 11.83 0.465 12 -2.0 > 5 9.78 0.385 10 -2.2 > 4 8.21 0.33 8 +1.7 > 3 7.04 0.277 7 +0.3 > 2 4.97 0.198 5 -0.2 > 1 4.00 0.158 4 +0.0 > > I can't make any sense of the imperial sizes (eg, numbers are not in > 8th or a 16th of an inch), but the metric sizes almost match, except > for #8 maybe....The #8 is off by 3/16th of > an inch > And then if it's metric, why some random numbers instead of the size in mm. > > Hum... Anyone seen something like that? > > > > Hi, Chris, > You are inhabiting the wrong mental universe. Get rid of all those little numbers; they are useless and meaningless in the world of the traditional woodworker. The first owner of those blades probably didn't have a measuring tool graduated finer than sixteenths, and may not have had one finer than eights. Wouldn't have known how to use one, or what to use it for. Why would you need one? You weren't making things from measured drawings that had to be precise to a thousandth of an inch or they wouldn't work. It wasn't until Henry Maudsley started scattering larval machinists like ragweed pollen (1820s or 1830s, call it) that anyone cared about tolerances of less than a sixteenth of an inch or so; and it wasn't until Laroy Starrett invented a machine for precision marking rules mechanically (1870s, IIRC*) that fine rules became affordable for the ordinary workman. They would work by divider and straightedge, not by numerical measurement and sight comparison with rulers. > For decades I wanted a set of classic chisels graded by sixteenths up to two inches. Well, they don't exist. Oh, the old catalogues listed them, but they don't actually exist. You can get sixteenths up to about 7/16", with a precision of plus or minus1/32" if you are lucky. From 1/2" up to 1" or maybe 1-1/4" you can find them by eights with a tolerance of a sixteenth. Eventually I got a series of 2-1/2" butt chisels up to 1-1/2" by sixteenths, but I did it by regrinding about a third of them; and it was only possible because many of the great makers tapered their chisels back from the edge, sometimes by almost 1/8" over 6". By starting with firmer chisels worn down to short butt length, I sometimes got close to the dimension I wanted before I had to regrind. > OK, your plough irons are a little irregular in change from one to the next (that is the proper number to look at if you insist on numbers, not the actual inches or milimeters). But not enough to be a real problem in use; if you just choose the one that is closest to what you want, you will never be as much as 1/16" away from the "ideal" measurement; apart from the big 7-to-8 gap, you won't be further off than about 1/32", roughly, if my numbers are right. Who would need better than that anyway? If you need precision, use dividers and you can go as close as you want, provided you don't try to cram an irrational universe into a rational straightjacket (rational and irrational in the correct mathematical sense, not in the vague half-assed common speech sense.) > > Tom Conroy > Yes, I know that scattering machinist larvae like ragweed pollen is a mixed metaphor. It's vivid, though. Betcha you'll remember it.*I checked. Graduationg machines for steel machinists rules started with Darling, Brown and Sharpe around 1850, not with Starrett around 1870. Doesn't invalidate the basic point. Precision rules are machinists' tools, not woodworkers' tools. A woodworker never needs a measurement as small as 1/32"; hell, a six-inch wide board will shrink and swell more that that over the course of a year back where you have summers and winters. If you need a tighter fit, it is faster, easier, and actually more accurate to use divideres or direct comparison. > > > > > -- “What we are seeing is a decision by the government to get as many people infected as possible, as quickly as possible, while using rhetoric about caution as a way of putting the blame on the public for the consequences...” - Prof Robert West, health psychologist, University College, London "extremist individualism … an ideology that claims to be about freedom when really it means selfishness”. |
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274461 | Kirk Eppler | 2021‑08‑30 | Re: Set of Mathieson plough iron (in metric sizes?) |
On Sun, Aug 29, 2021 at 7:51 AM Kirk Eppler |
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274466 | Claudio DeLorenzi <claudio@d...> | 2021‑08‑31 | Re: Set of Mathieson plough iron (in metric sizes?) |
I vote for Kirk to be “Researcher in Residence for Assembled Galoots”, (yet another Galoot post with no pay, and sparse recognition). Cheers Claudio |
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274471 | Adam R. Maxwell | 2021‑08‑31 | Re: Set of Mathieson plough iron (in metric sizes?) |
> On Aug 29, 2021, at 22:35 , Christian Gagneraud |
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274473 | Don Schwartz <dks@t...> | 2021‑08‑31 | Re: Set of Mathieson plough iron (in metric sizes?) |
I believe that is correct. The same is true of my little Record plough. It pays to score the shoulder(s) of a rabbet or groove with a marking gauge or knife for a clean cut. Don On 2021-08-31 7:29 a.m., Adam R. Maxwell via groups.io wrote: > >> On Aug 29, 2021, at 22:35 , Christian Gagneraud |
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274475 | Kirk Eppler | 2021‑08‑31 | Re: Set of Mathieson plough iron (in metric sizes?) |
On Tue, Aug 31, 2021 at 6:29 AM Adam R. Maxwell |
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