Saw Blades And HSS References

I'm wondering if someone can disprove or absolutely confirm that saw blades do not consist of HSS.
The term Bimetal or bi-metal doesn't absolutely mean that a blade consists
partly of HSS, or that a blade could.
Typically, all saw blades are bimetal, since the blade backing section is somewhat mild steel, and the tooth section is high carbon steel continuously welded along the length of the blade (including hole saws).
Envision a coping saw blade (tooth section) welded to a steel backing section that makes up the overall width of the blade, such as a hacksaw, bandsaw or hole saw blade. When the paint is removed from some new saw blades, this is evident.
The little knowlege that I'm certain of concerning HSS is that; 1. it doesn't bend (or flex repeatedly) 2. it can't be filed with an ordinary file
When I see references to HSS saw blades, it sounds like a crock to me, although these references are common.
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What type of saw blade are you referring to? I'm assuming band saw, hacksaw, sawzall, hole saw, etc?

Are you telling us, or asking?
I've only ever seen "bi-metal" referring to HSS teeth welded to a more flexible/less hard backing.

No. You can get HCS (high-carbon steel) blades, bi-metal blades and solid HSS blades (power hacksaw blades are commonly available as either bi-metal or solid HSS).

HSS is not simply high-carbon steel. There is a rather strict technical definition of what HSS is composed, and HSS is not simply high-carbon steel. Google is your friend.

Can you provide specific examples? Perhaps we can take a look and advise you...
Regards,
Robin
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The quoted text didn't get marked as quoted GD Microsoftshit products
Robin's remarks are ***
wrote:

*** What type of saw blade are you referring to? I'm assuming band saw, hacksaw, sawzall, hole saw, etc?
There have been countless references to all types of HSS saw blades here in RCM.

*** Are you telling us, or asking?
I'm saying this as a deterrent to the too-common usage of HSS in blades.
*** I've only ever seen "bi-metal" referring to HSS teeth welded to a more flexible/less hard backing.
Are you referring to individual HSS teeth welded to steel, such as a circular saw blade? (commonly misrepresented as a skilsaw)
Circular saw blades that have carbide teeth brazed to a mild steel disk, are common, but I'm unaware of other common saw blades with individual brazed teeth.
Are you saying HSS bends? As in HSS bandsaw blade? HSS hole saw blade formed into a circle? I disagree.
If you're the same Robin that's been partcipating in RCM discussions for years (haven't seen you here for a while), I can't believe that you haven't seen a broken HSS cutting tool, such as a HSS cutoff/parting tool.
Generally, broken cutoff/parting tools happen when they are improperly supported or improperly loaded (side pressure), snap.. as in not flexible.

*** No. You can get HCS (high-carbon steel) blades, bi-metal blades and solid HSS blades (power hacksaw blades are commonly available as either bi-metal or solid HSS).
I'd like to see an example of a solid HSS saw blade. The only ones I'm aware of are slitting blades (small like a Dremel saw, or larger like a slitting blade typically for use on a mill). And when they are flexed, they snap, which is my primary point.

*** HSS is not simply high-carbon steel. There is a rather strict technical definition of what HSS is composed, and HSS is not simply high-carbon steel. Google is your friend.
I'm aware that HSS is not HCS, I tried to make that distinction by typing out high carbon steel when I was referring to high carbon steel, I thought that was obvious.

*** Can you provide specific examples? Perhaps we can take a look and advise you...
*** Regards,
*** Robin
A specific example woud be a slitting saw. Properly supported and properly loaded in the direction of a cut, they perform fantasticlly. However when flexed, they snap.
A HSS bandsaw would not flex. It couldn't be formed into a circle for welding without breaking the HSS "tooth section". The same goes for hole saw fabrication.
A HSS hacksaw blade would snap if not supported or used very cautiously, loaded as lightly as a jewelers saw blade, essentially.
Summation: HSS does not bend. Thin cross-sections of HSS will snap.
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<snip>

I have two boxes of Sandvik HSS power hacksaw blades here, HSS through and through, but they're quite thick and they're not expected to flex in service. However, they do flex somewhat -- I don't know how much because I've never broken one. But they are a bit bendy.
It may be they're tempered differently for use as a sawblade than they are for a lathe cutting tool.
-- Ed Huntress
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Thanks, Ed. I was interested in what you're perspective would be. I saw a Starrett Redline 18" power hacksaw blade advertised as HSS (though not specifically stated as solid HSS), about $22 each US, at Ace Hardware's online store.
Power hacksaw blade duty is a long way from a flexing bandsaw blade, and Starrett makes the claim that their Redline bandsaw blades are also HSS.
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STOP saying "does not bend" - it is fully and completely wrong.
Get an indicator and a lever of some type and watch. Even carbide will bend to some degree without shattering. Otherwise, your cutting tools would shatter as soon as they touched the work. And that's ENTIRELY enough about that.
Take a look at http://www.starrett.com/pages/934_bi_metal_unique_saw_technology.cfm
The HSS strip is welded onto the flexible backing, and then the teeth are ground into the blade. The grind SEEMS to finish past the weld boundary, meaning there are individual HSS teeth created. The grind likely occurs before the coil is wound up again, thus, the HSS strip is never coiled while hard.
If you really want a good answer, call Starrett's band saw blade facility at 336-789-5141 and ask for "someone in technical". Don't make accusations and don't patronize these people - all they do is make really good band saw blades!
ULTIMATELY you believe all these manufacturers are basically lying. Well, run a good quality hole saw at HSS surface speed and see if it melts. Simple. No magic. Absolute answer. NO NEED to post one more reply until you've done this or similar.
Regards,
Robin
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Until I complete my new assignment Robin, I only have this to clarify "does not bend" = not easily bent.. in an arc.. roughly estimating the diameter of a bandsaw wheel (or radius for you physicists out there).
But also, When the discussion refers to bandsaw blades numerous times, what is so difficult about understanding "bend"?
When you've experienced HSS snapping, were you attempting to do something to it other than bending? Flexing? Twisting? Just aggravating it maybe?
The method of bandsaw/holesaw and straight saw blade fabrication I referred to earlier was the Traditional weld or laser bonding process, as I had described.. adding a hard cutting material to the edge of a softer, flexible backbone.
You have partially answered some of my question, but then based it upon your own assumptions..
The HSS strip is welded onto the flexible backing, and then the teeth are ground into the blade.
Or the teeth are milled.
Your words: SEEMS to, followed by likely occurs
OK, I shall not be patronizing because you said not to.
The Starrett page doesn't state that the "new" technology (at that time, see article 2005 issue of Modern Metals) Bi-Metal Unique product blade material is available in coil (roll was the wrong word) stock, only that straight blades and portable band saw blades are available.
So what level of real production performance are you seeing with this Bi-Metal Unique product?
Seems odd to exclude coil (not roll) stock. Maybe the stuff can't be welded with a common blade welder.
When I looked for coil stock of the HSS with 8% Cobalt Bi-metal Unique, it only showed portable bandsaw coil stock for the Flex-Back product, not the Bi-Metal Unique product.
But then a footnote states.. bi-metal unique and M42 blades also available 100 per box (if they didn't mean 100' per box).
It's all highly confusing, good thing that they list phone numbers though.
What I've said is I think HSS bandsaw blades were created in a marketing department or firm (based on my experiences that HSS does not bend (which means not easily bent.. in an arc.. roughly estimating the diameter of a bandsaw wheel).
The reason crapVista Windowshit products Mail isn't quoting the couple of random messages is because the posters are commenting thru TheGoogGroups, it appears.
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While there are many points in your message to which I would love to respond, I have only one request:
State your question in one sentence.
Regards,
Robin
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My question has already been addressed, Robin
Warmest Regards
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I guess I can disprove it, Bill.
I have hack saw blades that are solid HSS. I have hack saw blades that are bi-metal - HSS edge with alloy or carbon steel back. And I have hack saw blades that are solid carbon steel.
I have band saw blades that are bi-metal. I have band saw blades that are solid carbon steel - same steel from teeth to back. I don't happen to have any solid HSS band saw blades, but they are made.
I have circular saws that are solid HSS. I have circular saws that are solid carbon or alloy steel. I don't recall seeing any bi-metal circular saws, but that doesn't mean they don't exist.
There are bi-metal hole saws, and solid carbon or alloy steel hole saws.
Coping saws, hand saws and other human-powered woodworking saws are typically carbon steel, but who knows what might be available?
You are correct that The term Bimetal or bi-metal doesn't absolutely mean that a blade consists partly of HSS, or that a blade could. But if you check those that are available, you'll find that that is exactly what they are.
All saw blades are not bi-metal. As I've listed, some are, but others are solid HSS or solid carbon or alloy steel.
Your knowledge concerning HSS is a bit off too, I'm afraid. It can flex, and it can be filed. Not in the fully hardened state, maybe, and not as well as some other steels, maybe, but it can.
John Martin
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Thanks for your input, John. I have seen blade manufacturers state that their blades are HSS, and often label them as HSS, but I'm not aware that any version of HSS is soft enough to flex.
Because a package states that a blade is HSS isn't convincing to me.
A commonly available HSS in it's annealed state is the shank section of HSS twist drills. In the annealed state HSS doesn't make a good cutting tool for metalworking. I'm fairly certain that the annealed shank of a drill or reamer wouldn't bend before breaking, such as a Cleveland or other quality genuine HSS drill, not HFeuroasia-somewhere cheese steel.
I wonder how many HSMs have found a way to bend or reshape a HSS drill or reamer shank.
I would suggest that solid HSS hacksaw blades would not flex before snapping.
A solid HSS hacksaw blade would have the brittle characteristics of a HSS cutoff/parting blade/tool, with the extra fragility of having tooth gullets ground into the edge. Or why wouldn't it?
I can't recall ever hearing of a problem where a cutoff/parting tool became bent.. they either snap (or chip) or they don't.
You might be implying that a 100+ inch length (of thin cross-section or any other shape) of solid HSS could be formed into a circle to form a bandsaw blade, then tensioned and run continuously in a loop, while applying pressure to the blade edge.
I just wonder how you accept that this is logical, that's all.
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-
My brother-in-law manufactures band saw, hack saw and hole saw blades. When the catalog says a blade is HSS, the package says it is HSS, and it says on the blade that it is HSS, I tend to believe that it is HSS. Maybe I'm too trusting, though.
Their Redstripe hack saw blades are solid HSS. They do flex, but not as much as their bi-metal or carbon steel blades - which is why they recommend them where the work is firmly held and the blade is not subject to much twisting. They will snap if flexed too much.
They do not currently list a solid HSS band saw blade. They had one in their 1985 catalog, which I have in front of me, but do not offer it today. It was a thin blade - .020" or .025" against the .035" of their typical bi-metal blades.
Now, this next part is just my own guess, because I don't in any way speak for them. I believe that the solid HSS band saw blades were, like the solid HSS hack saw blades, more subject to breakage from twisting and flexing than the bi-metal blades. The bi-metal blades were more subject to stripping teeth, although welding technology has improved. But again, that's all just my guess.
Take almost any carbon steel hack saw blade. Bend it double, and roll the bend around a bit. Listen carefully while you do it, and you just may hear the cracking sounds as the blade cracks at the gullets. Without cracking completely across. How can it do that? Since it's solid carbon steel, shouldn't the entire blade by your logic have the brittle characteristics that the tooth edge does?
Shouldn't it be impossible to make a spring from the very same material you make a brittle cutting blade from? But you can do that, can't you? So, maybe it's similarly possible to heat treat HSS to get a wide range of characteristics, just as you can with the high carbon steel.
I accept that it is logical because it is, to me, just that. Logical. Not sure what it might take to convince you, though.
John Martin
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I was following you right along John, until you brought up the high carbon steel hypothesis.
*** Since it's solid carbon steel, shouldn't the entire blade by your logic have the brittle characteristics that the tooth edge does?
High carbon steel is easily annealed, but HSS not so much. As I said earlier, the saw blade backing (backbone?) material is generally a milder steel. It could be similar to steel banding material. It flexes very easily and doesn't work harden.
Springs should not, and aren't usually made from brittle materials, because they wouldn't serve their purpose. Generally, when a spring is bent by hand for example, it bends (until the radius becomes too small, such as around the corner/edge of a vise jaw).
We seem to be approaching the area of modulus of elasticity, which isn't at all what I was referring to, as far as HSS being suitable (or even possible) for use as a flexible blade material, such as a bandsaw blade.
I'm no metallurgist, but if HSS has a MoE, I'd guess that it wouldn't even resemble mild steel, and I'm guessing that it would be significantly different than high carbon steel and/or spring steel.
I remember using some hacksaw blades decades ago, that would snap completely thru their width, and I believe they were high carbon steel entirely, with very little or no annealing of the blade back material, so it was as brittle (or nearly as brittle) as the tooth area. I suspect that these may have been the cheapest blades available at that time, and I haven't encountered any hacksaw blades made like that, since then.
Modern, commonly available, general use hacksaw blades are typically a softer/mild steel back material with a hardened tooth area (generally a welded section added to the mild steel back material by continuous welding). But it's highly unlikely that the hard tooth section is actually HSS, as HSS does not bend.
To offer an answer to the question "wouldn't/can't the cracking be heard as the blade is bent".. well yes, and that's because the tooth area is a strip of high carbon steel mated to a flexible back material, but the tooth strip/area is not likely to be HSS, because solid HSS doesn't bend.
So what good would a bandsaw blade be, if all the teeth cracked at the tooth gullets?
I don't know if HSS can be combined with high carbon steel to create a HSS alloy, but if it can, my swag would be that the percentage amount of HSS would be small.
I strongly suspect that the concept of HSS bandsaw blades (or any other flexible HSS blade) was created in a marketing department or firm.
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Wild_Bill wrote:
Never considered the subject???

Springs (old days) = AISI 1050R to 1090, and can be tempered from tough(30-45Rc) to brittle (45-60Rc). Leaf springs are often in the 45 to 50 range). Yield and tensile are essentially the same as quenched.

I'll have to check my ASM lit, (I just have the HT lit at home), for materials commonly used for hack/band saw blades.

(snip)
You'd be right, different melt point, molecule (face/cubic centered), different structure, etc. etc. It would be near impossible to join by fusion weld.

Probably right, the Bi-metal is more likely done using one of the "S" or "H" type tool steels.
Matt
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Thanks Matt, I'm interested in any further info you can offer.
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Wild_Bill wrote:

Well Wild_Bill;
I went searching for what in the HS steels could be welded successfully to a med/high carbon backing. It looks like maybe all of the "M" HSS grades could be joined without screwing up the carbides in the HSS part and work OK.
None of the HS steels "like" to be normalized so there has to be some provision for retarding the cooling after weld.
"T" series HSS austenitise at 2300 - 2375 (T9 and T15 a bit lower), "M" series will go at ranges from 2150 - 2275. So either would have to be hardened first, then tempered, then some provision for annealing everything below the tooth edges would have to be made for a weld to be made.
Not all the processes could be done quickly, heating and quench would occur in a furnace, then temper, then if the HSS section was in a coil it would need to go back up to over 1400 but less than 1600 to be joined with the backing. After welding (quickly, while everything is straight) induction units could raise the temp to 1600 with the teeth in some heat sink medium. Then the slow part... For a full anneal the temp drop cannot exceed 40 degrees per hour, for a quick "partial" anneal up to 200 is possible. I don't see how it could be "hot" coiled into a furnace for the anneal (remember the teeth have to stay under 1600).
I couldn't work a solution for welding both parts annealed then do the hardening, quench and draw, and then anneal again (the HSS part).
I also first thought after you posted that it probably was one of the "H" (hot work tool steels) but it appears only the "T" and "M" types would have any abrasion advantage over plain old AISI 1060 blades with induction hardened teeth.
I liked the "M" series because the are less brittle than the "T" and have almost as much abrasion resistance (much cheaper too)..
Matt
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Fantastic, thanks again Matt.
It is extremely unlikely that I would've ever found out that much, or as concise information on my own.
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On Mon, 1 Dec 2008 05:47:04 -0500, "Wild_Bill"

The modulus of elasticity of all those alloys, in fact all steels, falls in a very narrow range. But that has little to do with this discussion.

You need to clarify what you mean by "bend." Clearly HSS can bend without breaking, just like any metal, as long as its ultimate tensile strength is not exceeded. What's different about fully hard HSS, compared to materials you might consider "springier" (using that term very loosely), is that the difference between its yield and ultimate tensile is very small. In other words, there's not much difference between how much it can bend and spring back and the point where it will break, i.e., it's brittle.
The difference between carbon steel hacksaw blades vs. HSS bimetal blades when cutting difficult materials (SS, alloy steels) is remarkable. Get yourself a carbon blade from a good manufacturer and a Lenox (sorry, John <g>) bimetal blade and try cutting an allen wrench in half. I doubt you'll make much of a dent with the carbon blade. The bimetal blade will be a bit worse for the wear, but it will cut the wrench.
The edge on good bimetal hole saws is clearly HSS -- otherwise the speed required to run a 3" hole saw in steel without instantly dulling the teeth would be abysmally slow. If you've ever tried using a carbon steel twist drill in steel, you'll know what I mean.

There'd be no good reason to weld a carbon steel edge to a carbon steel back. If the goal is a hard edge and softer back, then differential hardening/tempering of the blade will accomplish that, and is exactly what's done for carbon steel bandsaw blades.

As long as the teeth stay attached to the back, I don't see that the cracks would be a problem.
--
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Thanks Ned, but I can't help but see some holes in your remarks.
I was trying to steer away from the modulus characteristics because they aren't relevent, but you're right, that all steels fall within a small range, I forgot while I was thinking too hard about flexibility.
HSS can be annealed, but then it doesn't cut steel. The shank of a HSS drill or reamer can be filed, but it's not a grade/level of hardness that would make a good cutting tool for metalworking. Full hard HSS cuts most steels very well, annealed does not.
Full hard HSS doesn't flex, it snaps.
Several times when I referred to a saw blade bending, I was talking about traveling around bandsaw wheels, bending (and then straightening) repeatedly.
I find it real dificult to read that you would suggest that it doesn't matter if the tooth gullets in a saw blade were cracked. Yer yankin a chain, but it's not mine. Good Grief. With cracked gullets, I wouldn't expect anything less than a fairly sudden blade failure, especially on a commercial horizontal bandsaw.
There are saw blades where all the teeth are interrupted, they're carbide-toothed blades.
Bi-metal, in reference to most (if not all) saw blades really means nothing more than a hard alloy strip for cutting is mated to a softer, more flexible (and probably cheaper) material that makes up the majority of the width of the blade.
The hard cutting strip (I referred to earlier as a coping saw blade) section of a bi-metal saw blade is fused with a softer, more flexible backbone on quality saw blades. I've seen the illustrations in literature within the last few years, but can't locate them now.
I've also seen the mating line between the hard cutting strip and the softer backbone of quality holesaws and hacksaw blades (which was not the HAZ transition between induction hardening and the annealed softer backbone of cheaper blades).
The cutting strip of quality saw blades is a hard alloy, but it's not going to be full hard HSS (the type of HSS that cuts steels) because HSS doesn't bend around bandsaw wheels, nor would it be formed into circles from flat blade stock to fabricate hole saws.
Ed mentioned HSS power hacksaw blades, but Starrett and some others keep attaching HSS to their bandsaw blade features. There have been many references to HSS saw blades here in RCM that probably aren't based upon anything other than the packaging markings. I believe it's crap, just marketing.
I did just look thru the Lenox online bandsaw material, and didn't find any mention of HSS in bandsaw blades, but I might've missed it. http://www.lenoxtools.com/enUS/Products/BI-METAL.html
I don't think I have implied that a carbon steel cutting strip would be mated with a carbon steel backbone, as you say there would be no reason for it. I've maintained that the backbone of the blade will be a softer steel, more flexible than the harder alloy used for the cutting edge, but not a HSS cutting edge (because full hard HSS doesn't bend).
I don't own a hardness tester, but if I were to choose, I think a high carbon steel drill would drill steel better than the annealed shank of a HSS drill or reamer (properly fluted and sharpened equally). The reason for my choice would be that the high carbon drill would resist filing better than the annealed shank of a HSS drill or reamer.
I understand that you were using the hex/allen wrench for an example, but for cutting those, a hacksaw wouldn't be a choice, only an abrasive disk.
It's a bit confusing when you agree that HSS is brittle, then go on to say that the cutting edge of a bi-metal holesaw is clearly HSS. Did it not occur to you that the brittle HSS would snap before being formed into a circle.
My smallest Millers Falls holesaw is 7/16" and then I have some Lenox in between, and the big 3" new ones are Starrett, not marked HSS, not marked bi-metal, but the label reads High Speed Welded Edge. Starrett Safe-Flex Hole Saw Variable Pitch. There is a distinctly visible seam about 1/16" behind the deeper gullets, all the way around the saw. At the rear edge of the blade there is a wider welded area (looks more like TIG) to join the circular top arbor plate to the blade. A similar looking narrower weld joins the ends of the blade to form the circle.
I don't believe this Starrett holesaw is anywhere near the quality of a commercial shop grade metal cutter, though.. just an example.
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On Mon, 1 Dec 2008 14:04:57 -0500, "Wild_Bill"

As I said before, you need to be more specific about these terms. If by "flex" you mean, "deflects then springs back to its original shape," then HSS does indeed flex. More, in fact, than a softer carbon steel.
If "flex" means, "permanently deforms before it breaks," then yes, HSS doesn't flex much. But the first definition fits better with the everyday sense of flex.

That's exactly where I'm coming from. If blades with independent teeth work, why does it matter whether they were applied that way, or were separated by cracking in use?

That's your thesis. No one else has agreed yet.

We haven't determined whether or not the HSS steel on the edge of a bandsaw blade will bend to the radius of the wheel without fracturing. The calculation is not difficult -- give it a shot.
As for hole saws, I agree that hardened HSS will not bend to the small radii required. Presumably the edge is formed before heat treat.

Again, define your terms (bend, flexible).

The carbon steel drill will not retain its hardness unless you run it at a very low speed. This is not true of good bimetal hole saws.

I've cut many allen wrenches this way when an abrasive saw was not handy. Lots of box and open end wrenches, too, but they're usually not nearly as hard as allen wrenches.

It's formed before heat treat.

Clearly a hole saw is not as fussy as an endmill, but that doesn't mean that the edge can't be made from a similar material. Some spark testing comparing hole saws with drills or milling cutters might be instructive.
--
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