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I have been looking into a tool that can test blade tension.? ?I changed my saw blade tensioning so that I had a 3/8" NC stud with a nut and thrust washer for tightening the blade.? ?I would tighten the blade until it ran straight then gave 3/4 turn extra for proper tensioning the blade.? ?Recently, I am stumbling onto a different method which uses your cell phone and a tone prediction tool by J. Phil Thien:
For my saw, I calculated that the blade tension should make a tone that is between 97 to 107 Hz.
I talked to a guy who builds bicycle wheels.? He is using a cell phone app to determine the tone of a plucked spoke (apparently, this is the new "way" to determine spoke tension).? ?The app is called:? "Gates Carbon Drive" and is found in the Apple Apps store (and I imagine the Google Play Apps store as well).? ?I downloaded the app and reset my blade tension so it is right in the middle of the range as predicted by J. P. Thien.
How do all of you set your blade tension?? ?I certainly don't want to purchase a blade tensioning tool that costs more than the bandsaw.
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On 10/27/2021 6:08 PM, David Pidwerbecki wrote: I have been looking into a tool that can test blade tension.? ?I changed my saw blade tensioning so that I had a 3/8" NC stud with a nut and thrust washer for tightening the blade.? ?I would tighten the blade until it ran straight then gave 3/4 turn extra for proper tensioning the blade.? ?Recently, I am stumbling onto a different method which uses your cell phone and a tone prediction tool by J. Phil Thien:
For my saw, I calculated that the blade tension should make a tone that is between 97 to 107 Hz.
I talked to a guy who builds bicycle wheels.? He is using a cell phone app to determine the tone of a plucked spoke (apparently, this is the new "way" to determine spoke tension).? ?The app is called:? "Gates Carbon Drive" and is found in the Apple Apps store (and I imagine the Google Play Apps store as well).? ?I downloaded the app and reset my blade tension so it is right in the middle of the range as predicted by J. P. Thien.
How do all of you set your blade tension?? ?I certainly don't want to purchase a blade tensioning tool that costs more than the bandsaw. Dood , yer main' this WAY more complicated than it needs to be . -- Snag Race only matters to racists ...
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I tighten ‘em. A matter of ‘feel’ is all.
No gizmos or hi-tech stuff, just a ‘yeah…..that’s good….that’ll do it’.
?
And, I just check ‘em now & again, the same way.
?
Other Bill
?
?
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Show quoted text
From: [email protected] [mailto:[email protected]]
On Behalf Of David Pidwerbecki
Sent: Wednesday, October 27, 2021 4:08 PM
To: [email protected]
Subject: [4x6bandsaw] Band saw blade tension
?
I have been looking into a tool that can test blade tension.? ?I changed my saw blade tensioning so that I had a 3/8" NC stud with a nut and thrust washer for tightening the blade.? ?I would tighten the blade until it ran straight then
gave 3/4 turn extra for proper tensioning the blade.? ?Recently, I am stumbling onto a different method which uses your cell phone and a tone prediction tool by J. Phil Thien:
For my saw, I calculated that the blade tension should make a tone that is between 97 to 107 Hz.
I talked to a guy who builds bicycle wheels.? He is using a cell phone app to determine the tone of a plucked spoke (apparently, this is the new "way" to determine spoke tension).? ?The app is called:? "Gates Carbon Drive" and is found in the Apple Apps store
(and I imagine the Google Play Apps store as well).? ?I downloaded the app and reset my blade tension so it is right in the middle of the range as predicted by J. P. Thien.
How do all of you set your blade tension?? ?I certainly don't want to purchase a blade tensioning tool that costs more than the bandsaw.
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I use a Craftsman 80" bandsaw at a job that is identical to one I own.? I replaced the blade (1/2") about a year ago, and it broke a few weeks ago making a straight cut.? Upon examination, I could see that there had been a crack where it broke, and there were 5-6 other cracks in the blade.? The saws have a scale for tensioning (based on blade width), and this one had been adjusted correctly, but seemed really tight compared to my saw (which has the same adjustment and has never had a broken blade).? When I replaced the blade this time, I used much less tension ("1/4" I think), and the saw has been running great ever since.? Before it broke, the saw had been making clicking noises that became louder and more frequent as time went on.? I searched for a cause a few times, but never saw the cracks.
The point here is that over tightening will definitely cause breakage.? I know my 4x6 is sensitive to tension- too little or too much will cause tracking issues.
-Dave?
On Wednesday, October 27, 2021, 05:32:59 PM PDT, Bill Armstrong <bill_1955@...> wrote:
I tighten ‘em. A matter of ‘feel’ is all.
No gizmos or hi-tech stuff, just a ‘yeah…..that’s good….that’ll do it’.
?
And, I just check ‘em now & again, the same way.
?
Other Bill
?
?
From: [email protected] [mailto:[email protected]]
On Behalf Of David Pidwerbecki
Sent: Wednesday, October 27, 2021 4:08 PM
To: [email protected]
Subject: [4x6bandsaw] Band saw blade tension
?
I have been looking into a tool that can test blade tension.? ?I changed my saw blade tensioning so that I had a 3/8" NC stud with a nut and thrust washer for tightening the blade.? ?I would tighten the blade until it ran straight then
gave 3/4 turn extra for proper tensioning the blade.? ?Recently, I am stumbling onto a different method which uses your cell phone and a tone prediction tool by J. Phil Thien:
For my saw, I calculated that the blade tension should make a tone that is between 97 to 107 Hz.
I talked to a guy who builds bicycle wheels.? He is using a cell phone app to determine the tone of a plucked spoke (apparently, this is the new "way" to determine spoke tension).? ?The app is called:? "Gates Carbon Drive" and is found in the Apple Apps store
(and I imagine the Google Play Apps store as well).? ?I downloaded the app and reset my blade tension so it is right in the middle of the range as predicted by J. P. Thien.
How do all of you set your blade tension?? ?I certainly don't want to purchase a blade tensioning tool that costs more than the bandsaw.
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??? ??? So something between a G & a A .
On 10/27/2021 4:08 PM, David
Pidwerbecki wrote:
toggle quoted message
Show quoted text
I have been looking into a tool that can test blade tension.? ?I
changed my saw blade tensioning so that I had a 3/8" NC stud with
a nut and thrust washer for tightening the blade.? ?I would
tighten the blade until it ran straight then gave 3/4 turn extra
for proper tensioning the blade.? ?Recently, I am stumbling onto a
different method which uses your cell phone and a tone prediction
tool by J. Phil Thien:
For my saw, I calculated that the blade tension should make a tone
that is between 97 to 107 Hz.
I talked to a guy who builds bicycle wheels.? He is using a cell
phone app to determine the tone of a plucked spoke (apparently,
this is the new "way" to determine spoke tension).? ?The app is
called:? "Gates Carbon Drive" and is found in the Apple Apps store
(and I imagine the Google Play Apps store as well).? ?I downloaded
the app and reset my blade tension so it is right in the middle of
the range as predicted by J. P. Thien.
How do all of you set your blade tension?? ?I certainly don't want
to purchase a blade tensioning tool that costs more than the
bandsaw.
|
Hi all Tension of the blade IS important.? It's got to be above the minimum, so the blade doesn't buckle under the weight of cutting and below the maximum where it cracks.? The correct stress is 15000psi min / 20000psi?max for carbon steel blades and 20000psi min / 25000psi max for bimetal blades..
The bandwheels on a 4x6 are smaller than the?minimum diameter for 0.025" thick bimetal?blades, so they?should not be run at the blade manufacturers normal?bimetal stress range of 25-30000psi (I did a lot of testing at 27500psi and kept breaking blades even when everything else was correct).? Carbon steel blades are never run that high anyway. I'm a big fan of real measurements where I can trace back to numbers I can be sure of. I've investigated the vibrating string formula Phil Thien uses and I couldn't make it work.? A Fast Fourier Transform app showed the blade produces more of a chord (2 dominant frequencies and the 1st harmonic of each) than a pure tone and I couldn't decide which was the primary frequency to plug into the equation to get the tension.? Phils formula gives a frequency, but I'm not sure it is the?frequency that will give the required stress in the blade so I abandoned it. I've looked at 5 other methods to tension the blade, from strain gauges to hydraulic pressure pots. There is only one that I KNOW gives reproducible and accurate readings of tension on ANY 4x6 bandsaw ever made (actually it's independent of the saw altogether) :?? - Calibration data for a Park Tool TM1 bicycle spoke tension meter, to read tension of a 1/2"x 0.025" sawblade?
?The blue one in the photo?is a genuine Park Tool TM1, it's very accurate and, when measured against one a friend bought 10years ago, they gave readings within 1/2 a division on the scale (~4%) of each other, in the use range.? So if you buy one anywhere in the world you'll get one the same as mine. Unfortunately it costs $80US.? The Black and red one on the right is a ZTTO TC1 Chinese copy,?off AliExpress.? It's identical in every respect I could measure, costing $16US, but gave different readings! Luckily it can be calibrated to read the same as a Park Tool TM1 in the range that's important to us, by taking it to any bike shop that fixes wheels on competition bicycles, and turning its calibration screw until it reads the same as the TM1. (It looks like the spring is not the same 'spring rate', even though the dimensions were the same). Notwithstanding what Dave said about using the Gates belt tensioning app now, all bike mechanics will have a Park Tool TM1 in their tool cabinet. We really need only the tension at 2 points (mid-point of the carbons steel range and mid-point of the bimetal range), for blades with big gullets (3 & 4TPI)?and for ones with little gullets (6-24TPI) (different cross sectional areas)
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Park Tool TM1 Scale Reading ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 17500psi? ? ? ? ? ? ? ? ? ? ? 22500psi Blade TPI? ? ? ? ? ? ? ? ? ? ? ?(Carbon steel)? ? ? ? ? ? ? ? ?(Bimetal) 3 to 4TPI? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?9? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 11.5 6 to 24TPI? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 10? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?12.5 ??
I calibrated it the same as Park Tool does. The blade was tensioned to those psi stress values with a loadcell spliced into it (load cell calibrated at the local university's Engineering School). Then?the spoke tension meter was clipped on and the values read off the scale. You'll be surprised, the?minimum blade tension is a lot higher than you think.? If you get a ZTTO TC1?you'd calibrate it similarly.? Go to a bicycle shop and ask the mechanic to find a spoke that reads ~11 on his TM1, then clip your TC1 on and screw the spring tension adjusting screw in or out until it reads what the TM1 read.? Mine was significantly over-reading (said the blade was at a lot higher tension than it actually was) and needed 9 turns out on the screw to get the same reading.? The mechanic will tell?you the ZTTO is crap and he's right if you want to do wheel building, as all the spoke tension calibrations?given in the ZTTO's instructions are identical to the TM1, but they don't read the same.? However it's very satisfactory for our use once calibrated this way (but still wouldn't be any good for spokes!) - jv.?? ?
I have been looking into a tool that can test blade tension.? ?I changed my saw blade tensioning so that I had a 3/8" NC stud with a nut and thrust washer for tightening the blade.? ?I would tighten the blade until it ran straight then gave 3/4 turn extra for proper tensioning the blade.? ?Recently, I am stumbling onto a different method which uses your cell phone and a tone prediction tool by J. Phil Thien:
For my saw, I calculated that the blade tension should make a tone that is between 97 to 107 Hz.
I talked to a guy who builds bicycle wheels.? He is using a cell phone app to determine the tone of a plucked spoke (apparently, this is the new "way" to determine spoke tension).? ?The app is called:? "Gates Carbon Drive" and is found in the Apple Apps store (and I imagine the Google Play Apps store as well).? ?I downloaded the app and reset my blade tension so it is right in the middle of the range as predicted by J. P. Thien.
How do all of you set your blade tension?? ?I certainly don't want to purchase a blade tensioning tool that costs more than the bandsaw.
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II came across the method described in this post awhile ago, but haven't tried it yet myself, but if it works, it's a low cost method to set bandsaw blade tension using a digital micrometer and two small clamps.
Regards,
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On Thu, Oct 28, 2021 at 02:23 AM, John Vreede wrote:
The correct stress is 15000psi min / 20000psi?max for carbon steel blades and 20000psi min / 25000psi max for bimetal blades..
John,?
Excellent explanation. Thanks
I had no idea they made a spoke gauge. "You stated the correct tension is higher than you might think" and I agree. It needs to have a lot of tension. The strength of the blade under straight tension is significant but weakens significantly if deflected and it also fatigues the metal in the blade over time. Of course a deflecting blade doesn't cut as straight either.?
So get this...? My HF band saw frame starts to deflect significantly under high tension. In fact this is how I set my tension, I watch for deflection and stop at about 1/8" or a bit less. My first thought is, this deflection could be made into a tension gauge but my second thought is, how in the heck did you ever get enough tension to break blades or shorten blade life. So far I have never had a blade break, at least not after I aligned everything and set it up correctly. I've been running the same blade for 7 month now. I know that's not a good indicator in itself but I can say it has cut a lot of metal and I suspect it will be dull before it ever breaks.?
Also 17,000 PSI seems extreme and higher than the saw is capable of. PSI - Pounds per square inch? Square inch of what? Are you saying this force on the blade would be the same as hanging a 17,000 lb weight on the blade? Or maybe half this amount seeing as how you are tensioning two halves of the same blade? Still, even 8500 lb seems extreme.
I'm not doubting your information, I'm just looking for clarity.? And thanks for the info.
Mark
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On Thu, Oct 28, 2021 at 07:42 AM, Terry Lund wrote:
I came across the method described in this post awhile ago, but haven't tried it yet myself, but if it works, it's a low cost method to set bandsaw blade tension
Now that is cool. In my opinion it's important to have enough tension but also not that critical. I think that there is a wide range of tension that will work well. Still, without any sort of reference it's hard to know if you are in the ball park. You could use this method one time just to get a feel for where the ball park is.?
Thanks for the info, Mark
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Maybe I'm wrong, but the caliper method seems more academic than practical to me -- how many of us have calipers that can accurately measure tenths?? The ones I have can display a "5", i.e., .0005", but I take that with a rather large grain of salt.?
But I COULD see some kind of attachment that uses a .0001" DTI.? It could be two pieces that clamp onto the blade.? The DTI would attach to the end of one and the other would have a flat for the DTI to press against.? Since the range for your typical DTI with this resolution is just a few thousandths, you also might want to implement some kind of fine adjustment to make it easier to set up.?
Another approach might be to make a one-piece device with a flexure in the middle -- once you get the DTI set up all you need to do is attach the thing to the blade.? As long as the blade elongation doesn't exceed the flexure's elastic range it should last forever.? I imagine the body of this one might look a bit like a C clamp with a short length of spring steel (old hacksaw blade?) in the middle.
Mark
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I apologize if this has already been mentioned, I haven’t been following this thread. However in the Apple AppStore is an app called Inkleind Bandsaw Tensioning??that uses the sound of plucking the blade.
I have never used it myself. A few years ago, I read a blog post about the development and testing that went into it. Hope this helps,
Jeremy
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On Oct 28, 2021, at 12:55 PM, Mark Kimball <markkimball51@...> wrote:
?Maybe I'm wrong, but the caliper method seems more academic than practical to me -- how many of us have calipers that can accurately measure tenths?? The ones I have can display a "5", i.e., .0005", but I take that with a rather large grain of salt.?
But I COULD see some kind of attachment that uses a .0001" DTI.? It could be two pieces that clamp onto the blade.? The DTI would attach to the end of one and the other would have a flat for the DTI to press against.? Since the range for your typical DTI with this resolution is just a few thousandths, you also might want to implement some kind of fine adjustment to make it easier to set up.?
Another approach might be to make a one-piece device with a flexure in the middle -- once you get the DTI set up all you need to do is attach the thing to the blade.? As long as the blade elongation doesn't exceed the flexure's elastic range it should last forever.? I imagine the body of this one might look a bit like a C clamp with a short length of spring steel (old hacksaw blade?) in the middle.
Mark
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Hi guys Jim's calculation is dead correct, except all the blades I use are 0.025" so the weight acting through the saw frame is just that much higher.? Jim, I don't know of any 0.022' thick?blades, but it's?not the first time I've come across someone saying their blades were 0.022".? Can you re-mic your blade and report back because the spoke meter tension calibration would be different for that particular thickness of blade. As far as I knew, the standard 1/2" wide blade thicknesses were only 0.020", 0.025", and 0.035". The 2-clamps-and-digital-calipers method is the basis of an engineering 'strain gauge'. They use it because strain is directly proportional to stress (the psi we talked about) through 'Youngs modulus'? ? ?? ? ? Youngs Modulus = Stress ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Strain
so? ? ?Stress = Youngs modulus * Strain
Youngs Modulus is pretty much the same for all high tensile steels at 30,000,000psi, (210,000MPa),? and Strain in engineering terms is just '% stretch'. So you can pick a certain length of saw blade, say 4" (100mm), and measure how much it stretches when you tension up the blade. Commercial ones, like the Lenox one pictured, use a very sensitive DTI and ones that are any good cost $350-500US.? You just calibrate the DTI dial in Stress units (psi ) but the DTI just is measuring change in length.???They are preferred by blade manufacturers for setting bandsaw tension because the measurement is independent of all considerations of bandsaw size, even blade thickness! So can be used on the biggest industrial band saw in a saw mill that might be 8" wide x 1/8" thick (1 sq inch cross section) that really does need 15000 lb (3 tons!) tension to get to minimum, all the way down to a 1/8" wide x 0.018"?hobbysaw? blade. HOWEVER the change in length from no tension to full tension is just ~0.002" ! So you have?got to reliably measure at least 10x smaller than?that to be able to discern under- and over-tension. That is way beyond what anyone can do with 2 clamps and a digital caliper.? Even the professional?ones, like the Lenox, are reported in the woodworking press as being really difficult to get reliable measurements from. I can see why; the measurement you are looking for is pretty much the same as the error in the measurement so you get huge % errors. Another thing, that especially?plagues a 4x6 for this instrument, is that at zero tension the blade is not straight so where do you start measuring from? Especially if you're only going to measure a change in length of 0.002"?? I thought about making one from cheap digital calipers, but, when you can get a knock-off Park Tool TM1 and calibrate it for <$20, that will reliably measure what you want,?why bother.
Fatigue cracking of a blade is a matter of giving?it enough stress reversals above its?elastic limit.? The blade goes round the wheels and bends too far, according to a graph I've seen from the (now defunct I believe) 'Hack and Bandsaw Manufacturers Association of America'. They reckon that the minimum for 0.025" thick blades is ~12" (~300mm) diameter, so at ~7.5" (190mm) ours are waay under size.? This means, as the band goes around the wheel, the outside stresses up above the tensioning stress in the blade (while the stress on the inside?falls) and then the stress relaxes as it bends straight again .? Stress reversals. The back of the blade is polished, but the gullets are comparatively?rough?from grinding the teeth, so fatigue cracks always start there - jv? ? ??
On Thu, Oct 28, 2021 at 02:23 AM, John Vreede wrote:
The correct stress is 15000psi min / 20000psi?max for carbon steel blades and 20000psi min / 25000psi max for bimetal blades..
John,?
Excellent explanation. Thanks
I had no idea they made a spoke gauge. "You stated the correct tension is higher than you might think" and I agree. It needs to have a lot of tension. The strength of the blade under straight tension is significant but weakens significantly if deflected and it also fatigues the metal in the blade over time. Of course a deflecting blade doesn't cut as straight either.?
So get this...? My HF band saw frame starts to deflect significantly under high tension. In fact this is how I set my tension, I watch for deflection and stop at about 1/8" or a bit less. My first thought is, this deflection could be made into a tension gauge but my second thought is, how in the heck did you ever get enough tension to break blades or shorten blade life. So far I have never had a blade break, at least not after I aligned everything and set it up correctly. I've been running the same blade for 7 month now. I know that's not a good indicator in itself but I can say it has cut a lot of metal and I suspect it will be dull before it ever breaks.?
Also 17,000 PSI seems extreme and higher than the saw is capable of. PSI - Pounds per square inch? Square inch of what? Are you saying this force on the blade would be the same as hanging a 17,000 lb weight on the blade? Or maybe half this amount seeing as how you are tensioning two halves of the same blade? Still, even 8500 lb seems extreme.
I'm not doubting your information, I'm just looking for clarity.? And thanks for the info.
Mark
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The method I use was posted on rec.crafts.metalworking.? First tou tighten the blade as much as you can with your hand, then you throw a shop rag on the tensioning knob and see how much tighter you can get it.? This method has served me well on my HF unit for many years. - Ed
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I guess that would be close to my method. I'd snug it up until it no longer slips when you're cutting something. Any tighter than it needs to be to prevent slipping just creates alot of forces on other parts. I've run a bandsaw for about 50 years. We had a small machine shop,usually 6 guys. In all those years I never even heard blade tension mentioned. Before we got our bandsaw ( a wells,my dad was friends with him) we used a jet power hacksaw,what a nightmare. When my mom and dad died I bought the jet from the estate because my dad still used it in his barn,so I tuned up the motor and put new belts on it and lubed it up and it's back to working like it did way back then. Sometimes I wheel it out from under my workbench to saw a 4x4. ?? Back to bandsaw,I'd say just snug it up and saw with it and if it slips tighten a hair more.
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That bandsaw tension gauge chart posted on modelenginemaker dot com does not specify the width or thickness of the blade used to calculate those values. The person posting that chart specified a modulus of elasticity as 29,000,000 for steel but he didn't say what alloy or grade of steel. These metal cutting band saws use blades that come in different widths and thicknesses and even different alloys. Some are single layer, some are multiple layer such as bi-metal blades.
Personally I would not rely on that chart as there are too many variables not stated and are therefore unknown.
?- Raymond
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Ed -? I tested your method and it's perhaps a little high (depending on if the threads are greased or not) My go-to method for many years was very similar:- Tighten it as hard as a normal person can (not a gorilla?or a wimp) without?any aids (like a rag). but I never knew whether that was correct or?not. I have the gear now, so set up the blade with the load cell and standard tensioning rod&knob?per the picture and tested it. - With degreased?threads (as it comes from?the factory) with one hand and no rag or other aid, I could only get it to 230lb tension which?is ~21000 psi?stress.? This is just over the limit for a?carbon steel blade and only marginally tight enough for a bimetal blade
- Degreased, one hand?+ rag could get it to 270 lb tension which is ~25000 psi the upper limit of what you should run a bimetal blade.
- With grease?on the threads and knob/washer/casting and one hand/no rag I could get it to 250lb tension, ~23000 psi just over the midpoint of the bimetal blade?
- With grease, one hand?+ rag could get to 300lb tension ~28000 psi, well over the limit for bimetal on the small wheels of a 4x6.
- With grease?+ rag and two hands I could get it to 330lb >30000psi
From these tests, if?you're normal strength like me, greasing the threads and doing it up as tight as you can?with one hand only, the tension will be right on the money.?My problem is that it takes time to get it that tight and it hurts my hand, so I prefer to use other?methods. But if you only tension the?blade once in a blue moon, then it's a pretty good method.
James -? It actually?needs to be tighter than '...just not slipping ...' , unless you have the bow weight wound back to where there's?not much weight on the teeth in the cut (i.e. bow weight <5lb). If this works for you, the bow weight will be significantly less than you could apply (8lb max on a 4x6 ) with good tension, so the saw will cut slower than it safely could. Low blade tension and bow weight >5lb sends the blade into a degree of 'elastic lateral torsional?buckling', where the top edge of the blade tips sideways. Then the blade?cuts off angle.The more bow weight, the more it tips. It's elastic so the blade just straightens up without damage?afterwards, often pinging away from the cut face at the end - jv
On Sat, Oct 30, 2021 at 9:45 AM n5kzw < n5kzw@...> wrote: The method I use was posted on rec.crafts.metalworking.? First tou tighten the blade as much as you can with your hand, then you throw a shop rag on the tensioning knob and see how much tighter you can get it.? This method has served me well on my HF unit for many years. - Ed
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John,
How is your load cell set up to measure tension.? where can i get a load cell appropriate for this?
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Hi George S-type load cells?work in both tension and compression and these ones have a 7/16 UNC threaded hole in top and bottom, which I made pivot pin type connections to. The blade is just silver soldered to the connectors. Because I bought the loadcell and the reader as a pair, the loadcell just plugged into the reader. Totally Chinese instructions that I could not decipher and?no amount of pressing and holding buttons?etc could I make it read in Lb's or Kgs though its supposed to.? The reader?reads in units of 20g, Reading of 10,000 units = 200kg. A minor pain in the butt but otherwise its been faultless.?? When I calibrated it against the research grade 500kg loadcell on the tensile tester at the engineering school, the thing calibrated perfectly with slope of 1:1 and intercept of zero, so no need to worry about the accuracy of these $20 loadcells.? Even the $5 Airport luggage weigh scales were as accurate. All loadcells?creep a little if left under load, I found?out too, but if you read it within a minute or two it's stable. Easiest to get off AliExpress see the attached Word doc with some screenshots of searches - jv
On Sun, Oct 31, 2021 at 9:22 AM George Taylor, IV < gtaylor@...> wrote: John,
How is your load cell set up to measure tension.? where can i get a load cell appropriate for this?
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Hi George I found the calibration data for the 200kg loadcell Not actually zero intercept?but 3 in 8000 is near enough see graph attached
On Sun, Oct 31, 2021 at 9:22 AM George Taylor, IV < gtaylor@...> wrote: John,
How is your load cell set up to measure tension.? where can i get a load cell appropriate for this?
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John, ? Thank you very much – your knowledge is greatly appreciated and valuable to the community. ? George ?
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From: [email protected] On Behalf Of John Vreede Sent: Saturday, October 30, 2021 6:56 PM To: [email protected] Group Moderators < [email protected]> Subject: Re: [4x6bandsaw] Band saw blade tension ? S-type load cells?work in both tension and compression and these ones have a 7/16 UNC threaded hole in top and bottom, which I made pivot pin type connections to. The blade is just silver soldered to the connectors. Because I bought the loadcell and the reader as a pair, the loadcell just plugged into the reader. Totally Chinese instructions that I could not decipher and?no amount of pressing and holding buttons?etc could I make it read in Lb's or Kgs though its supposed to.? The reader?reads in units of 20g, Reading of 10,000 units = 200kg. A minor pain in the butt but otherwise its been faultless.?? When I calibrated it against the research grade 500kg loadcell on the tensile tester at the engineering school, the thing calibrated perfectly with slope of 1:1 and intercept of zero, so no need to worry about the accuracy of these $20 loadcells.? Even the $5 Airport luggage weigh scales were as accurate. All loadcells?creep a little if left under load, I found?out too, but if you read it within a minute or two it's stable. Easiest to get off AliExpress see the attached Word doc with some screenshots of searches - jv ?
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John Vreede
Terry Lund
Mark
