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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.
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 
wrote:
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 
wrote:

>
>
> 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?


I have a bunch of mismatched irons, and some are marked, and there is no
rhyme or reason to some that I can measure.  Here is a Samuel Newbould set
for example.  (Text only May thrash this)

1 0.158 5/32
2 0.199 3/16
0.283 9/32
4 0.322 5/16
5 0.406 3/8
8 0.661 5/8


On some of mine, it appears the cutting edge is wider than the body, and as
you shorten the blade thru use, it gets narrower.

Of my 38 stray irons, none is a perfect fraction using a digital caliper,
which is not terribly surprising.

Somewhere I saw a table of sizes by number, maybe a Marples catalog.  Will
add it later if I find it, but it did show a logical fractional inch
transition .  Here is a cat cut from 1938, just listing it as sizes in a set

https://archive.org/details/wm-marples-and-sons-1938/page/26/mode/1up


Kirk in Half Moon Bay, CA, about to walk the dogs to avoid the heat and
tourists.

-- 
Sent from my iPad, apologies for the Auto Correct errors. Kirk
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  wrote:
> 
> 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.
> 
> 
> 
> 
> 



-- 
Yorkshireman Galoot
in the most northerly county, farther north even than Yorkshire
IT #300
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
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...
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.
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  wrote:

>
> On Sun, Aug 29, 2021 at 6:22 AM Christian Gagneraud 
> wrote:
>
>>
>>
>> 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?
>
>
> I have a bunch of mismatched irons, and some are marked, and there is no
> rhyme or reason to some that I can measure.  Here is a Samuel Newbould set
> for example.  (Text only May thrash this)
>
> 1 0.158 5/32
> 2 0.199 3/16
>
> 0.283 9/32
> 4 0.322 5/16
> 5 0.406 3/8
> 8 0.661 5/8
>
>
Wow, #1, 2, 3 and 4 are a pretty good match! 5, almost, and 8 spot on!

Now why 5/32 and 9/32? a little bit smaller than 3/16 and 5/16? Are these
common thicknesses in the weirdysystemofunit world? :)
3/16 is a little bit smaller than 1/4, and so on...
The "almost matches" metric size was likely just a funny coincidence.


> On some of mine, it appears the cutting edge is wider than the body, and
> as you shorten the blade thru use, it gets narrower.
>

Definitely, same here.


> Of my 38 stray irons, none is a perfect fraction using a digital caliper,
> which is not terribly surprising.
>
> Somewhere I saw a table of sizes by number, maybe a Marples catalog.  Will
> add it later if I find it, but it did show a logical fractional inch
> transition .  Here is a cat cut from 1938, just listing it as sizes in a set
>
> https://archive.org/details/wm-marples-and-sons-1938/page/26/mode/1up
>

Interesting, from 1/8 to 9/16. They don't give the list tho :(

Looking at dado and plough iron list that came with the 55, it looks a bit
more organised.


Thanks,
Chris
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”.
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  wrote:

>
>
>
> Somewhere I saw a table of sizes by number, maybe a Marples catalog.  Will
> add it later if I find it, but it did show a logical fractional inch
> transition .  Here is a cat cut from 1938, just listing it as sizes in a set
>
>

Here is a listing here of what they should be

Plow plane irons are numbered #1 through #8 with sizes 1/8", 3/16", 1/4",
5/16", 3/8", 7/16", 1/2", and 5/8" respectively.

Stolen from
http://tinyshopww.blogspot.com/2017/03/fixing-and-fettling-wooden-plow-plough_28
.html#:~:text=Plow%20plane%20irons%20are%20numbered,and%205%2F8%22%20respectivel
y
.

He goes into similar detail about how none of them are close to the correct
size
-- 
Kirk Eppler, who made a wedge for an Ulmia glazier rebate plane yesterday
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
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  wrote:
> 
>> On some of mine, it appears the cutting edge is wider than the body, and
>> as you shorten the blade thru use, it gets narrower.
>> 
> 
> Definitely, same here.

Isn't this intentional? My understanding is that being tapered like this
keeps the plough iron from binding in the groove. It also keeps the arris
of the iron from wasting away the sides of the groove, which is a problem
I've had with Stanley versions: it's really easy to end up with a ragged
groove if you don't keep the handle perfectly vertical.

Adam
(who hasn't used a plough since last year, so could be all wrong)
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  wrote:
>>
>>> On some of mine, it appears the cutting edge is wider than the body, and
>>> as you shorten the blade thru use, it gets narrower.
>>>
>> Definitely, same here.
> Isn't this intentional? My understanding is that being tapered like this
> keeps the plough iron from binding in the groove. It also keeps the arris
> of the iron from wasting away the sides of the groove, which is a problem
> I've had with Stanley versions: it's really easy to end up with a ragged
> groove if you don't keep the handle perfectly vertical.
>
> Adam
> (who hasn't used a plough since last year, so could be all wrong)
>
>
>
> 
>
>

-- 
“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”.
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  wrote:

> On Aug 29, 2021, at 22:35 , Christian Gagneraud  wrote:
>
> On some of mine, it appears the cutting edge is wider than the body, and
> as you shorten the blade thru use, it gets narrower.
>
> Definitely, same here.
>
> Isn't this intentional? My understanding is that being tapered like this
> keeps the plough iron from binding in the groove. It also keeps the arris
> of the iron from wasting away the sides of the groove, which is a problem
> I've had with Stanley versions: it's really easy to end up with a ragged
> groove if you don't keep the handle perfectly vertical.
>

I assumed so, since almost all have some degree of taper, some more visible
than others.  Just never knew why.  I assumed it would reduce binding and
deflection of the blade, but not the ragged edge bit.
-- 
Kirk Eppler in Half Moon Bay, where nothing witty has happened, except many
hours of training for work things, which is far from witty.

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