The double iron blade

Or a cap iron screwed unto a blade.  I am not going to debate the merit or not of such an addition , simply point out some details I came across while cleaning a bunch of them.

 In the beginning, our planes had only one blade.  Usually tapered in thickness, being thicker at the cutting edge. Said cutting edge was a hardened piece of steel (tool steel) forged welded to a softer iron blade.  Similar to how axes are bited.

Everything worked fine, but the addition of the second blade (cap iron, chip breaker) around 1760 accomplished two things:

- It helped curled up the shavings faster near the cutting action, and
- It trapped water condensation between both blades.  A perfect recipe for rust to take hold.

I'm guessing they recognized that problem early on because for a while they were covering the back of the cap iron (chipbreaker) with some sort of blueish coating.

Take a look at the two chip breaker back.

The older Stanley one (second from left) has a blueish coating.

The newer one to its right does not anymore, they long stop doing that.

But that practice long preceded Stanley.  I do not know if it was the same process (coating) but you can often see remnants of it on older cap irons.

You can clearly see some sort of coating remnants peeling off  (abraded).

Whatever is left is still solidly attached.

So the question is:  Does it helped at all?

Debatable but here is what i often see.

Yesterday while re-conciliating my physical count with my data records, I came across an early Canadian plane, Dawson, from Montreal.  So even if I said I was done and had already cleaned up and put stuff away, you know, I just could not sleep if I did not stop the rust carnage's 

Dawson Montreal

1851-1874

And the poor blade stuck inside.  Its a small smoother.

Look pretty sad, but nothing that i cannot fix.

So put my tally sheet down, looked around and came up with a few more blades

In progress. Still shows brown spots after the wire wheel, 

back soaking after a quick sanding with 80 grit

Recognized the blade?

Evaporust, brushed, wire wheel, spot sanded, rust eraser then wiped and buffed with Autosol

The blade may be practically worn out, but there is still cutting steel at the end and plenty of good metal to raise a good edge.

Talking of worn out blade, that one is definitively pass its best before due date.

So why bother?

Because it is part of the tool history.

All I am after is to stop further rust damages.

Pic in progress

Done.  Also addressed some damages to the edges

I came across lots of damaged top edge, from using a metal hammer harder than the softer iron blade.
That would be just about any decent hammer BTW.  A Brass hammer head  would deform before it deformed the soft iron.  These must be addressed to stop the damages and to render the blade safer to be hit later on.

I often see also lateral damages to the blade, from hitting the sides to adjust lateral.  Which is why Stanley invented the lateral adjuster later on :-)

This one has damages to both top and sides, but it is the cap iron, not the blade!!! 

Here is an interesting details I came across in this short marathon.
How the cap iron is fastened to the blade.

Notice how the screw shrunk.

Interestingly, the bolt diameter and thread sizes seems to have remains

 pretty well the same all along and not just Stanley.

Which just add to the confusion, which belongs to which?  

Hint the bolt should go all the way thru cap iron and be flushed on the nut side.

These last two have the same threads but not cut the same.

Take a look at the base

The screw length changes along the way it was attached.  I have no idea which methods came first in what order, but we all know it finished with the shorter screw to attach a thin steel cap iron to a thin steel cutter.

In no particular historical order

This one, rarely come across this one,  use a separate nut and screw

The nut is filed to slide between the slots of the blade.

Attached

This one is yet different

No more loose nut to loose.  

The nut is solidly embedded into the cap iron

The one most often seen, mostly British tools

The brass dome nut is also embedded solidly 

This is a new one on me.

That is from my Dawson blade

The nut is not attached, but is machined from a thicker stock

Pretty solid, probably the most secured

And of course the Stanley design we are all familiar with.

The top horizontal slot is to engage the depth of cut adjuster.

This design forced Stanley to move the hole location on the blade slot from the top to the bottom.

This design also introduced a small irritation factor with today's unwary woodworkers.
Because we rely on that slot located at the top of the chip breaker to adjust our cutter in and out... Guess what?

It had to be adjustable to compensate for the inevitable wear and tear on the blade which will be sharpened umpteen time in its life.  That's the reason for the slot in the blade.  Problem is, they are a lot of Stanley clones out there but no one ever seems to came up with a standard location ...

Notice anything different??

If you do, that is the reason why it gives you headaches when you attempt to swap blades :-)

And if you thought that the two outer ones were the same...

NO, not even close. Both now on right.

From L-R Stanley's regular bench planes iron (first 3), 

Stanley No 113 compass plane blade, and a transitional plane blade.

In these pics I lined them up by the cap iron edge, not the cutting edge.  The three regular Stanley are various vintages and the hole location changed a bit, but not enough to cause much trouble.
The Compass plane No 113 however will have a hard time to give you any cutter exposed to cut if someone swapped the cap iron or the whole blade assembly with a regular one.  That is because of the flex sole, the frog surface is longer than on regular planes.  Buyer beware.  Oh and also the lever cap is slightly different, longer. Also sometimes swapped on unsuspecting would be buyer.  Finding original spare parts?   You will have better luck lining up to get your bucket of prop wash filled :-)

Similarly, in a transitional plane, the yoke adjuster sit higher on the frog, so the slot location is yet a bit higher.  because the small frog sit on top of a 2-1/2 in thick chunk of wood.

And to add to the fun, others would be Stanley clones used all kind of slight variations in slot location, more pronounced than the slight variation shown.  Oh and they varies location thru the years.  Ever noticed why most modern blades maker have a disclaimer on their Stanley replacement blades? May not fit all models produced thru the years etc

Moral of this story, to keep your sanity and let the plane works as intended, if you want to swap blade, you may want to re-use the original cap iron, just saying.

And since I had the Evaporust bath set up again, I may as well ...

This is what I ended up with and it is all Dawson's fault :-)

And then I drank a Coke to dissolve all the rust I have no doubt ingested.

Like my Dad, I am a Coke man, we both flunked the Pepsi challenge :-)

Dad was so pissed when they tried to changed his Coke.  It taste like $@^# Pepsi!!

Bob, all rusted out from de-rusting umpteen tools saving them from a slow but inexorable death.
You know, they used to say, You are dust you will return to dust when you die.  Well with today's micro plastics being everywhere, soon it will be: You are plastic you will be recycled when you die :-)

Why did the screw hole location changed on Stanley type irons?

Part 2 of my answer to Ralph of the Accidental woodworker 

You know the "hole" the one that used to be located near the top of the iron

Pretty well all used up Adam & Co blade showing typical hole at the top

Found inside an American Arrowmammett work plane

That hole was first introduced to facilitate removing and installing the new fangled cap iron making the blade a double iron. Such double iron first appears around 1760. That long slot is required in order to re-adjust the cap iron as the blade get used up by repeated sharpenings.

At first the cap iron was secured by a captive nut welded to the main blade

AARON HILDICK

DIAMIC

WARRANTED

CAST STEEL

Typical British blade arrangements. Found on a British C NURSE plane starting in 1840. 181-183 Walworth Rd address making it between 1909-1937

Then around 1892 it moved to the bottom, first introduced by Stanley.... and for good reasons...

But as you can see above,  well after Stanley moved the hole location down in 1892, the traditional hole on top remained for a while. That was a patented feature from Stanley so no one else could do that without paying them royalties.
Yet many sources stated that the hole on the top indicated a blade made prior to 1895 (or 2), that would be not quite true, but some sort of indicator.

But why did Stanley made the move?

Because starting with the TYPE 5 1885-88 a new feature appears on the Bailey design, the Lateral lever.

Then at TYPE 6A 1891-92, the new feature was the relocation of the hole at the bottom of the blade near the cutting edge.

The raised lip at the end of the original lateral lever was soon replaced by a small disk, its job is to engage the slot on the blade and allow side movement (lateral) by skewing the blade left and right.
The problem that was soon discovered was, as the blade is used up by repeated sharpening, the big hole on top falls in the spot were the lateral lever engage the slot, negating its proper usage.

Solution? Move the hole at the bottom and problem solved.
You can now used that blade to its last inch of its life...

Of course that problem only appears on planes with the Stanley type lateral lever, other design do not need that "fix", that and the feature was patented, so no one else could claim it.

So how did Stanley explained that newly introduced feature?
If you were to believe their tool propaganda in the literature, they claimed it was for ease of installing/removing the blade from the cap iron.

QUOTE " The improved form of this plane iron renders it unnecessary to detach the cap iron from the blade, at any time, as the connecting screw will  slide back to the extreme end of the slot in the plane iron, without the danger of falling out. The screw may then be tightened, by a turn with thumb and finger, and the cap iron will serve as a convenient handle, or rest, in whetting the cutting edge of the plane iron." UNQUOTE

Hum and how does that work in practice? Never found that to be a problem or hindrance or even a plus, to have to hole located on top or bottom while sharpening, and I always separate both.

As far as the argument that you can slide the sharp edge without rubbing it along most of the blade while re-installing, that too was never a problem in my book. Regardless of how and were you re-install the blade on the iron, you have to be careful to protect that sharp edge anyway...

Original Patent by Edmund Schade assigned to Stanley

No 473,087 Apr 19 1892. 

Ŀook carefully the dotted top hole location were it would had fallen 

if not relocated.

In the original Stanley's patent the following claims were made:
My invention relates to improvements in plane iron's; and the objects of my improvement are to facilitate the manufacture of the plane iron, to improve its quality when made, and to make the iron capable of being worn down farther than the old style of iron used in conjunction with certain planes...

We also have annectorial evidence from court testimony of Stanley employees during a patent infringement case against the Ohio Tool company (to be later purchased by Stanley) .

The OHIO Tool Company, one of Stanley competitor who produced almost identical copies of Stanley Bailey design, had of course the same problem with theirs. Their solution was to make the hole at the bottom but made it shaped like an hexagon instead of circular, in a bid to avoid patent infringements.

OHIO clever improvement upon Stanley :-)

Too obvious of course so Stanley took them to court... and lost.

On May 16 1902, the judge citing that QUOTE " Schade device may be an improvement upon the previous devices, but it is only so in degree. The problem is so simple and may be solved in so many different ways that invention cannot be predicated by its solution in one particular way. The court is unable to resist the conclusion that Schade's achievement was only what might be expected from a clever mechanic, and that no new results, such as contemplated by the patent law, was attained thereby. The bill is dismissed" UNQUOTE.


Stanley would appealed the case on Oct 3 1903, and the ruling was upheld and Stanley ordered to pay the court cost of Ohio Tool Co.
Judging by the amount of time and money Stanley spend fighting Ohio, it would appears almost vindictive...

And what about the claims about the quality improvements of the irons by relocating the hole at the bottom ??

QUOTE "By making the circular enlargement at the end of the slot, which is nearest the cutting edge, I am enabled to make the plane irons by pressing them out from sheet steel, and to harden and temper them to a point, so that fewer irons are lost in hardening and tempering, and are less liable to become cracked or broken at said point after they are put to use. This is because there are no angular notches at the lower end of the slot from which a crack will start." UNQUOTE

Well, I have never ran into a blade with its hole on top cracking in use, mind you all the ones I ever saw had a rounded end to the slot, not a square end...
Although, if you were to press them from sheet steel versus hand forging them, perhaps it would have been a different story??

And then we have Stanley manufactured blades in the early 20th century with the hole still on top for their Siegley copies, such as found by Ralph. Humm so much for their claims of better blades quality with the hole at the bottom...
In manufacture, they simply reverse the blade at punch time.

So there you have it, the reasons the hole moved was to enable the blade being used up to the last inch of its life on a Bailey type lateral lever plane AND ease the manufacture of cheaper blades by stamping them prior to hardening.
Clever perhaps, but no where near the claimed reasons in their tool propaganda literature...

And that is what history has recorded about it

Bob, the tool detective