Saw Blades And HSS References

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
Reply to
robinstoddart
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On Mon, 1 Dec 2008 10:32:34 -0500, the infamous "Wild_Bill" scrawled the following:
Nah, metals in quantities of less than 1% don't count.
-- The only difference between a rut and a grave...is in their dimensions. -- Ellen Glasglow
Reply to
Larry Jaques
[ ... ]
O.K. I propose another experiment:
1) Take about a #1 drill bit, and drill into mild steel just enough to make a cone almost the diameter of the drill bit.
2) Then replace it with a #50 known HSS drill bit, shift the workpiece just enough so the drill bit's point comes down on the sloped surface of the previous cone. (I'm assuming a drill press with little or no perceptible slop in the bearings).
3) Turn on the drill press, and bring the bit down into contact, watching it closely (with ey protection, of course). When the bit contacts the cone, does the bit proceed to drill right below its contact point, or does it bend towards the center of the cone?
4) If it bends, are you going to say that the drill bit is not HSS?
5) Now -- with a solid carbide bit of the same size, it will almost certainly break, but even it will bend a little before breaking.
Enjoy, DoN.
Reply to
DoN. Nichols
Sorry, Bill, I thought you might be willing to invest a little effort in learning something, when in fact it appears all you're interested in is hand waving arguments that support your preconceived notion that Starret, Lenox, Sandvik, et al are out to screw you.
Reply to
Ned Simmons
A very worthwhile demonstration DoN. Not that I'm not unfamiliar with a drill missing a centerpunch mark, though.
I welcome your demonstration as a generous sharing of wisdom in a kindly fashion (which many of us in RCM have been accustomed to in your replies).
The part that remains a mystery to me is that HSS can be wrapped around bandsaw wheels under enough tension to produce a note when plucked, and then bend, deflect, flex and endure feed pressure into a workpiece while continuously running around in a loop (plus the added continuous twisting/straightening of a blade on a horizontal bandsaw).. a metal composition which is a material that I know snaps because it's brittle (as brittle as glass, for a rough estimation).
I can, however, fully understand that high carbon steel alloys would perform as described above, due to applying specific controllable levels of annealing (with anticipated results) to the materials.
For some, it seems to be beyond comprehension that anyone could possibly doubt a manufacturer's claim? I question things, that's all. Some do, some don't.
Your use of the term bend is highly suspect, BTW. Perhaps there is a code that could be developed, for times when it's convenient to use common words to express infinitely complex principles.
The conclusion that I've arrived at is that the teeth tips can be HSS, with interruptions between the teeth, so in some cases (brands, processes) the HSS is not a continuous, brittle strip enduring all the extreme conditions described above.
I think I mighta just learnt something agin, and I can only hope that doesn't happen again too soon.
Reply to
Wild_Bill
On Tue, 2 Dec 2008 10:51:37 -0500, "Wild_Bill"
Example:- A 62.5 micron fibre optic fibre can bend to 1" radius (2"dia). It won't work properly because the light will tend to leak out, but it won't break. If you scale that up, you get a 25 thou thick sheet of glass being able to bend around a 15" diameter wheel without breaking.
Mark Rand RTFM
Reply to
Mark Rand
Thanks for the example Mark. Do you know of any sources of online information (or manuals, books) that describe interfacing lenses to fiber optic cable/bundles not just for light transmission, but the fibrescope type applications?
Do you know of sources for a visual image optic cable approximately 0.68mm (.027") in diameter (enclosed in a sheath)?
I have a used fiberscope with a significant number of broken fibres. I'm wondering if the cable can be replaced, because I suspect that it's unlkely that it could be shortened or repaired. The light carrying fibres (a loose bundle) in the fibrescope are fairly coarse by comparison, looking more like they could actually be worked with by hand. The overall size of the cable is 3mm diameter x about 3.3M.
I can see a very small optical window/lens element at the tip, but I know nothing about the end termination methods involved with fibreoptics. The limited information that I've discovered about mating lenses in optical equipment involves Canadian balsam (?) or special grades of epoxies.
I haven't seen the interface at the eyepiece end yet, and I'm curious about how that's accomplished.
Reply to
Wild_Bill
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
Reply to
matthew maguire
Fantastic, thanks again Matt.
It is extremely unlikely that I would've ever found out that much, or as concise information on my own.
Reply to
Wild_Bill
The fibers are typically two different glasses, selected for different index of refraction, one solid as the center, and the other hollow around the first. They are heated and the ends drawn apart, and the outer sheath collapses onto the inner core and they fuse together.
I have seen rigid fiber optic devices which have been made by drawing down the center of a bundle, then cutting it in the middle, grinding polishing it. The result is a bundle which will enlarge or shrink an image. You can get these from Edmund Scientific or Edmund Optics (I forget which sells that) as demonstration pieces.
You can also get ones where the fibers have been fused together and then twisted while still hot enough for the glass to bend, so the image is twisted 180 degrees.
I've also seen fiber optic bundles fused together in a hex, then the center drawn out to make a smaller hex bundle, gathered with more hex bundles to farm a larger one, then drawn again through about three cycles -- then cut into thin slices and the inner core is removed by chemical etching leaving a honeycomb prior to coating (vacuum evaporation of metal) to form a channel for electrons as part of an image intensifier tube. This was called a microchannel, and was used to intensify the tiny signals which were common in serious astronomy. The electrons bouncing along the tubes from side to side, and accelerated by a voltage difference between the ends of the tubes, keep kicking out multiple additional electrons every time they hit, thus increasing the signal strength.
Before microchannels -- larger intensifier tubes were made with rigid fiber optic bundles ground to a curve to match the electrostatic focusing in the tube, and ground to flat on the end -- joined to two other similar intensifier tubes by a silicone grease to couple the fiber images together.
This is normally for joining the surfaces (usually curved) of different glasses to build a lens with just the needed index of refraction. You'll find a lot of these joints in the more complex camera lenses (faster and zoom lenses), and even the early Zeiss Tessar design had four elements -- the rear two cemented together, then a space for the iris diaphragm and shutter, and then two more elements which had an air gap between them -- and for folding cameras typically had the spacing between these two lens elements adjustable for focusing.
Well ... typically the bundle for the image scopes is made by laying out fibers one at a time into a precise pattern, then fusing the ends (leaving the majority of the length loose for flexibility) and polishing the ends. The objective lens focuses the image on the flat polished surface at one end, and the eyepiece picks it up from the other end.
Aside from the occasional broken fibers (which increase with use), there are also occasionally misplaced fibers which move a dot from one place to another.
If *I* were to try to make an optimum quality image fiber bundle, what I would try to do is to lay the fibers in a loop and optically weld the ends together. (I've seen the device which does this with fiber optic lines used for telephone and network here in this neighborhood, and it is a neat device.) Anyway -- the welds would be scattered around the bundle, and the clamped group of fibers would be fused together (again two glass types -- the center for the optical signal, and the outer to protect the inner fiber and to fuse to adjacent ones). Once about two inches or so of fiber is fused into a rigid block, I would then diamond saw through the block and polish both ends to optically flat. This way, the fibers could not shift where the images are formed, and it does not really matter how much they shift in between, as long as they don't get broken. That's what the sheath is to prevent.
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But I *think* that the original mention of how small a radius bend you can put in a glass fiber was to suggest that thin HSS (which you had said was as brittle as glass) could be bent to an equally tight radius if it was no thicker than the glass fiber's diameter.
IIRC -- when someone in this thread mentioned solid HSS bandsaw blades, he did say that they were thinner than the usual carbon steel blades.
And from bending which I have observed in a HSS (actually cobalt steel) parting blade with a maximum thickness of 1/8", I would say that that can be bent into a circle of about ten feet diameter or so. And that is a *lot* thicker than any bandsaw blade which I have ever used.
Enjoy, DoN.
Reply to
DoN. Nichols
On Tue, 02 Dec 2008 22:33:34 -0500, the infamous Ned Simmons scrawled the following:
C: Both of the above.
Kids, please learn to play nicely with one another now. Thank you.
-- The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man. -- George Bernard Shaw
Reply to
Larry Jaques
Your reply is a great one, and a large serving of stuff to digest, DoN. Thanks for including the detailed info concerning the glass fibers. I had no previous knowlege of the glass strands other than some of the early ones were made in tall tower-type structures at one point IIRC.
I hadn't realized the necessity to keep the individual fibers in correct order/orientation to reproduce a proper image until you mentioned it. Yeah.. I could see where that would matter, heh.
The ITI brand fiberscope I mentioned was apparently a fairly good one, when it was new. It's one of the flexible ones (3mm dia.) that can be articulated near the tip by two fine stranded wire cables tied to a knob on the hand/eyepiece/body. Clever little gizmo that works similarly to the earlier mechanical remote control automotive outside side/rear-view mirrors (but only two opposed directions, not four).
I took Mark's mention of bending a thin glass fiber to suggest it would be possible with thin HSS, as you mentioned. I was originally thinking in terms of the traditional process of producing bandsaw blades, which would require the cutting edge to be .025" or .035" thick (as those are common thicknesses of bandsaw blades). From there, the strip of hard material that's typically the hardened tooth material area on bandsaw blades, is wider than the thickness by many times (looks like about 5 times wider or more). The wheels on my 4x6 bandsaw are maybe 10" diameter, a port-a-band maybe smaller, but larger wheels on big saws naturally, and the possibility of running a brittle material around wheels with the numerous high forces mentioned earlier, seemed highly unlikely to me.
Previous to Mark's example, Robin had referred to a somewhat new technology developed by Starrett, where two thinner ribbons/foils of HSS are fused to/with the region near the edge of the supporting band material, resulting in a "steel on HSS sandwich" at one edge of the band. Then, when the tooth profiles are ground or milled into the edge of this region, it leaves less than the full width of the HSS ribbons/foils to bend/flex/twist etc. (or possibly even interrupted HSS-clad teeth, the image wasn't very detailed and the description not very specific).
Ed had mentioned Sandvik solid HSS power hacksaw blades being thick but somewhat bendy.
As per your suggestion of 1/8" cobalt making a wrap around maybe a 10' wheel.. An extremely long 1/8" thick solid HSS saw blade would've been handy for the cruise ship retrofitters that were assigned the task of adding a section in the center of a cruise ship, so they proceeded to cut the ship in half, and added the section. I don't know that the story was true, but there was an online story about it, maybe a couple of years ago.
Reply to
Wild_Bill
It is called "Godwin's Law", and it declares the thread in which the invocation of the term "Nazi" (or perhaps also Hitler) to be terminated. Good advice, I think. :-)
Enjoy, DoN.
Reply to
DoN. Nichols

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