Saw Steel: Does it have to be spring steel to be any good?

[Matthew Hutchinson477]

This weekend I found a 16" R Waldo tenon saw with a brass back for $5. Hardly any information on the maker that I can find on the net but it says "Sheffield" on the spine so I figured it must be a decent saw. Unfortunately it might actually only be worth $5 because the brass spine is bent and the saw plate itself might be no good. As for the former I think I can figure out a way to straighten that but the saw plate I'm concerned about. If I bend the plate it won't spring back to (somewhat) straight--it holds the bend. I can bend it the other way to get it back to what it was but I wonder if the fact that the plate holds a bend means that it isn't good steel. I assume it either isn't spring steel to begin with or it is spring steel that has been ruined somehow.

Any of you experts see many old saws not made out of spring steel? Any chance this one is still worth the effort? Enlighten me, on saw steels, oh great Saw Swamis of the Creek.

[Patrick Chase]

This weekend I found a 16" R Waldo tenon saw with a brass back for $5. Hardly any information on the maker that I can find on the net but it says "Sheffield" on the spine so I figured it must be a decent saw. Unfortunately it might actually only be worth $5 because the brass spine is bent and the saw plate itself might be no good. As for the former I think I can figure out a way to straighten that but the saw plate I'm concerned about. If I bend the plate it won't spring back to (somewhat) straight--it holds the bend. I can bend it the other way to get it back to what it was but I wonder if the fact that the plate holds a bend means that it isn't good steel. I assume it either isn't spring steel to begin with or it is spring steel that has been ruined somehow.

Any of you experts see many old saws not made out of spring steel? Any chance this one is still worth the effort? Enlighten me, on saw steels, oh great Saw Swamis of the Creek.

From a functional point of view, you need a steel that's around Rc50 to stay sharp. You also need the plate to be thin for obvious reasons. Hardness in steels correlates almost perfectly to yield strength (the stress at which it permanently deforms), and thin plates are inherently more springy than thick ones, so a plate that meets both requirements in inherently springy.

While it doesn't matter one bit whether a saw is made out of something called "spring steel" (an ill-defined term BTW), a sawplate that isn't springy is either too thick to cut efficiently or too soft to cut for very long.

[Rick Whitehead]

The book "Hand-saw Makers of Britain" by Erwin Schaffer and Don McConnell has a listing for a Robert Waldo, in Sheffield, c. 1850.Unfortunately, that's all the information they have for him, except they mention a saw by him having truncated cone saw screws. Does yours have them too?
George Wilson, formerly of this forum, gave some directions on how to straighten a back saw blade in some of his posts. If you do a search for his name, you may be able to find those posts.
However, since the saw is so old, and not in usable condition, that I wouldn't try to use it. I'd sell it, and use the proceeds to buy a more modern saw in better condition.
Rick

[Stanley Covington]

While it doesn't matter one bit whether a saw is made out of something called "spring steel" (an ill-defined term BTW), a sawplate that isn't springy is either too thick to cut efficiently or too soft to cut for very long.

Amen. The term "spring steel" was used so loosely that it no longer has meaning when talking about saws. I don't think the term is used for modern saws. Pete Taran could probably enlighten us since he used to make excellent saws.

[John K Jordan]

... you need a steel that's around Rc50 to stay sharp.

How do you test the Rockwell hardness on a saw blade?

A place I used to work had a tester but I understood it was not useful for thin steel.

[Larry Frank]

There are hardness tests for thin steel which use lower loads. This is very common for sheet steels.

[John K Jordan]

There are hardness tests for thin steel which use lower loads. This is very common for sheet steels.

Is there a way to do that inexpensively at home? I typically test hardness with a file but I haven't tried that on a saw tooth.

[steven c newman]

Roh-kay...Raggie...here goes..

Terms like London Refined Spring Steel...Sheffield Spring Steel and the like were marketing HYPE.....

Backsaw plates, being thinner than normal saw plates, were given a spine. otherwise, the thin plate would be flopping around in use.

IF someone bent the spine on the backsaw....the spine needs to be removed from the plate first, straightened out. When installed back on the saw plate, only go 1/2 onto the plate, checking how the plate straightens out due to the fixed spine. Helps to have the plate in a saw vise when doing the install of the back.


Spine needs to go on straight with the top edge of the saw plate. this prevent "wrinkles" in the plate. While the plate is out of the spine, clean it up, shine it up, so it can be ready to go.

[Roger Nair]

Here is a story, that may be historically correct or perhaps myth. Part of the market force of the early 18th century was to produce uniform steel for the instruments of the British Empire, particularly uniform springs for naval chronometers, which may be the high tech challenge of the time. To say something is spring steel is to say the steel is of a highly consistent quality and to say Extra Refined London Spring Steel as Disston did is just a way to flog the goods by icing the cake.

[Matthew Hutchinson477]

From a functional point of view, you need a steel that's around Rc50 to stay sharp. You also need the plate to be thin for obvious reasons. Hardness in steels correlates almost perfectly to yield strength (the stress at which it permanently deforms), and thin plates are inherently more springy than thick ones, so a plate that meets both requirements in inherently springy.

While it doesn't matter one bit whether a saw is made out of something called "spring steel" (an ill-defined term BTW), a sawplate that isn't springy is either too thick to cut efficiently or too soft to cut for very long.

I clamped the saw plate in my vise and took a triangular file to the teeth this morning. Though this is entirely subjective, it doesn't feel any softer than the old Disston's I've sharpened. I realize this "test" may be worthless but it's all I can think to do.

One thing of note is that when I bent the saw plate in an attempt to evaluate it, it bent in the middle and nowhere else. Possibly a weak spot in the steel? Another odd potential sign is that the teeth are worn waaaay down in the middle of the plate but teeth at the toe and heel are not nearly as worn. My guess was that a previous idiot, uh I mean user, did what a lot of folks do and just didn't use the full length of the saw. The way the teeth are worn, though, makes it look like someone tried to use this thing to cut metal or something.
IMG_5229.jpg
IMG_5229.jpg
IMG_5229.jpg

The toe:
IMG_5230.jpg

The middle:
IMG_5231.jpg

[Patrick Chase]

One thing of note is that when I bent the saw plate in an attempt to evaluate it, it bent in the middle and nowhere else. Possibly a weak spot in the steel?

It had probably been bent there before and straightened, which would indeed create such a weak spot. Steel isn't as bad as some other metals in that respect, but it does "remember" where it's been bent.

[Matthew Hutchinson477]

If it is the case that the steel is soft, could I effectively re-harden it using the classic DIY method of heating it up and quenching it in water or oil?

[Matthew Hutchinson477]

Is there a way to do that inexpensively at home? I typically test hardness with a file but I haven't tried that on a saw tooth.

Well there are the hardness-testing files you can buy like these:

https://www.mscdirect.com/browse/tn/...navid=12108118

But they still aren't cheap at $130 for a set. I have yet to find an inexpensive way to test hardness. The best I've come up with is to use the same file and compare the steel in question to something I either know, or at least know enough to be sure it is hard enough to work.

[Matthew Hutchinson477]

The book "Hand-saw Makers of Britain" by Erwin Schaffer and Don McConnell has a listing for a Robert Waldo, in Sheffield, c. 1850.Unfortunately, that's all the information they have for him, except they mention a saw by him having truncated cone saw screws. Does yours have them too?
Rick

Nope, this one just has the standard-of-the-day split nuts, or should I say nut because it is missing two of the three.

[Pete Taran]

A lot of confusing and not quite accurate stuff in this thread. The straight facts:

London Spring Steel was not marketing hype. It was, in fact, steel that was made in England, mostly Sheffield. Before Henry Disston figured out a way to make cast steel in volume in 1855, all steel that could be used for cutting, saws included, was made in England. That is not to say that there wasn't some backwoods tool maker that took a piece of wrought iron, sealed it in an iron box with some toe nail clippings and saw dust and burned it in the fire for days to get the carbon in the box to migrate into the steel. That did happen, but the result was highly variable. The folks in Sheffield had it down pat, and so all the steel in those early days was made in England.

So it went until Disston figured out how to make crucible steel in volume in 1855. He patented it, produced it, and even successfully lobbied Congress to impose a tariff on tool steel coming into the country (what's old is new again) to allow domestic production to flourish. It did. At that point, Disston continued using the name "London Spring Steel" as that was what the discerning customer was used to at the time. Just as McDonalds today would not change the name of their Big Mac sandwich to Jimmy's Funk Burger if the company sold, so too did Disston realize the importance to keep the name of London Spring Steel associated with the Highest Quality Saws he made. The other saws like the #7 and other did not sport this name, and were also the stuff he made, just without the distinction.

Spring Steel today still means something, it is not marketing hype. Spring Steel is steel which is hardened, and nominally used to make, among other things, springs. It is typically regular carbon steel with between .75 and 1% carbon added, and then tempered. Can you anneal spring steel and reharden it? No, not really. The steel is so thin that the act of heating it up in atmosphere and then quenching and drawing it would burn most all the carbon out of it which is what makes it useful for holding and edge in the first place. Spring steel is not expensive or hard to find. I have 100s of pounds of it in my basement. I would never consider reworking a blade that is kinked, I would just drive the old blade off the back, cut a new one and reassemble.

Finally, there are many different kinds of scales involved in steel hardness testing. The two major ones are the Superficial and the Normal Scale. The most common type of tester was made by Wilson. They made stand alone units that just measured on the normal scales (includes A, B and C which is the one most people recognize). They also made a unit that just tested the superficial scales among which are the 15N, 30N and 45N scales. They also made a unit called a Twin Tester which allowed testing of both scales in one machine. That is the unit I have. The deal is that with thin pieces of steel, the diamond indenter can actually poke through the sample which distorts the reading. That is why those scales use a reduced weight to drive the indenter only "superficially" into the sample, hence the name. The 15N, 30N and 45N represents the kilograms of force needed for the test. The Rockwell C test uses a full 150 kilograms of force. There are conversions to translate superficial readings into normal readings if needed.

Hope this helps. I've attached a picture testing the hardness of a pure lead ingot. In this case, I used a 10mm steel ball and didn't use the scale at all as the hardness is calculated from the diameter of the resulting depression and the force applied. It is a very handy tool for many uses.

testinprogress.jpg