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Thread: Carter, Iturra, Lenox, Starrett Comparison

  1. #1

    Smile Carter, Iturra, Lenox, Starrett Comparison

    Carter, Iturra, Lenox, Starrett Comparison

    There have been a number of questions and comments on the Feb. 2007 article Woodworker’s Journal concerning the comparison between the four readily available tension gauges: the Carter, Lenox, Iturra and the Starrett and the saw’s built-in gauge.

    That article is based on a number of tests that I did for my new book THE NEW COMPLETE GUIDE TO BAND SAW, which is designed to update the BAND SAW HANDBOOK, published in 1989, which is the best selling band saw book in the world but is black and white and has become outdated.

    No field of woodworking has more confusion that the topic of blade tension. I acquired all of aftermarket tension gauges and tested them. The results were all over the board. I was confused. To help me sore it out I hired Aaron Gesicki who has an undergrad and Masters degree in metallurgical engineer with 30 years of experience with GM and Cat making engine parts. For the article I did the photography and the drawings and developed a series of questions. Aaron wrote the article. This is the first article that I know of that compares the gauges to each other. Our test may not be perfect but it is a start and we are open to suggestions for more testing.

    One of the SMC members criticized the article because it did not give the mechanical gauge numbers compared to the electronic Carter. When Aaron tested the Carter electronic ( which is modern technology) it measured the equivalent of 15,000 psi (292 pound of wheel load) for a 1/2” blade (see the article). This was the reading when the built-in saw gauge registered on the 1/2 mark. At that setting the Starrett was in the 13,000 psi range, Lenox 10,000 psi and the Iturra was all over the board from 8,000 to 12,000 psi but usually on the low side.

    Along with research by an electrical engineer we working on a technical paper covering the relationship between blade tension, sharpness, wheel alignment, pitch etc. If you have suggestions for testing methodologies let me know. Please ask questions here rather than emailing me or sending me a private message.

    Mark Duginske

  2. #2
    Mark, I didn't read the article, but would like to know how the psi was determined.

    Was it done by measuring deflection?

    ie; xxxpsi required to cause the blade to deflect .100" (hypothetical) at a given height above the table, or at the center point between the wheels.

    To me that would show a true reading to actually compare the guages to each other

  3. #3
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    Mark.
    We are beginning to get significantly away from woodworking it would appear.

    Let me first premise this post by stating that I do in fact own your original "Bandsaw Handbook". I can assure you that is well worn and has been loaned out, on multiple occision, to people that have had issues with the 14" bandsaw. It is the most complete reference I know of for the bandsaw.
    You are a fine author,and should be very proud of this book. I expect your update to the book to be equally as valuable as the original. I cannot comment on the magazine article, as I haven't seen it.

    The area of contention, it would appear, lies with the use of the tension gauges, and the application.
    From the data presented I can assume that the Starret, Lennox and Carter were repeatable, and the Itturra was not. This would tell me that the mechanical properties of hysterisis are better in the first three gauges, than the last.
    The Carter, being an electronic device , is essentially the same as the two pure "mechanical devices. the difference being that the distortion of the test fixture's metal is being applied to a piezoelectric crytal changing the oscillation frequency of the crystal as force is applied or releived, or it is two pieces of known wire acting as the plates of a capacitor, and referenced to a center null wire. The difference in capacitive reactance of the two wires, relative to the center can be measured an used in an electronic circuit, as can the frequency changes of the crytal.
    There are more sophisticated instruments that operate on different principles, but I doubt that they were used. They cost 10's of thousands of dollars.
    To establish the actual "accuracy" of these devices. They would have to be tested to a known standard, in a lab, using NIST traceable standards. Then the OEM bandsaw tension gauge could be compared to these devices and a qualitative, and quanitative value can be assigned. for a given force applied. This testing however could cost you thousands of dollars to have done, and is not really worth it in my opinion.
    The Carter, Starret, and Lennox could be used with equal effectivness. Each of them would unifromally tension a bandsaw blade in a repetive nature. The Ittura would not based on the info provided. The only thing I can't assume right now, based on info provided, is which one is actually the most "accurate"
    From the Carter, Starrett, and Lennox a baseline value could be assumed, and changes made to tension could be referenced back to this baseline value and a table could be developed to indicate the effects of tension on the blade.
    It wouldn't really matter which one was used, as long as only one was used , and it was used consistently. If you prefer the Carter, you should use that one.
    Using Young's modulus, for the given material that the blade is made of, the amount of "strectch" could be measured using a vernier, and the data obtained from that could be compared to the indication on the Carter, and the OEM bandsaw tension indicator.
    From these three devices a table could be developed. if the Carter and the vernier are in agreement, and the OEM tension indicator is at 1/2". It's an odds on bet that the bandsaw tension meter is "accurate enough".
    Even though I have access to calibration labs and standards, and could easily "calibrate" any of these devices to NIST standards. I've never seen the need. I use the tension meter on the bandsaw and then look at the cut, and change tension based on what I see. I've also used the vernier method that John Steven's outlined here on the board as a cross cal. All of the tension argument goes out the window as soon as that blade heats up anyway becuase it just changed everything.

    My eMail address is.

    Michael_J_Cutler@dom.com


    Please feel free to email, or contact me, or have Aaron email me and I can see if I can set up to cal any of those devices to NIST standards in our lab should you desire it. It may take me a little time to fabricate a cal fixture and contact the vendors for calibration procedure. Starrett would be the easiest, Starret t should actually have a comercial grade cert on the device, but it can be done.

    Mike Cutler
    Last edited by Mike Cutler; 02-01-2007 at 5:23 AM.

  4. #4
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    This thread is bumming out this Iturra gauge-owning guy!

    Pete

  5. #5
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    Quote Originally Posted by Pete Brown
    This thread is bumming out this Iturra gauge-owning guy!

    Pete
    Don't let it Pete.
    Most of my post is so esoteric,I really don't see much value in anything I wrote as applied to woodworking. In the end it's a piece of wood going through a blade,and then through a jointer,planer,or sander.
    If your Itturra gauge is helping you and giving you confidence in your bandsaw setup. Keep using it. Regardless of which tension device you used, that has been mentioned, all would eventually end up in a drawer once you got a "feel" for it.

    Please don't let anything I posted have any effect on how you work.
    Last edited by Mike Cutler; 02-01-2007 at 5:24 AM.

  6. #6
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    Mark,

    I'm an owner of The Bandsaw Book as well, and I thought it proved invaluable when I was setting up my 16" Walker Turner bandsaw. Even though I'm a novice at woodworking, I was able to get it well tuned up using your book.

    But even though I'm a novice at woodworking, I do know something about research methodology. (Part of my day job is to conduct clinical medical research.) I think your Woodworker's Journal article was trying to address two separate issues, of which your tests and measurements only really addressed one.

    The two issues raised in your article are: [1] does setting up a bandsaw to very high tension (>15,000 psi) affect bandsaw operations, and [2] how accurate are the meters on bandsaws and aftermarket tension gauges?

    The data you've presented clearly addresses the second point. Based on your findings, I believe that there is a lot of variance when it comes to aftermarket gauge accuracy. The only thing I would add to your testing are the points Mike already made about comparing the gauges to a known outside reference. You seem to be making the assumption that the electronic Carter tension gauge is accurate due to modern technology. As a pediatrician, I can assure you that home ear temperature probes sold to parents are nowhere near as accurate as your $2 mercury thermometer, even though the ear probe is much more modern technology.

    However, regarding the first point -- does increasing tension result in a better cut, or is it unnecessary -- your data so far does not address that at all. The best support for this is your reference to manufacturers recommending 15,000 psi as the tension for their blades. But I think we all know that manufacturer specs can be as accurate as aftermarket tension gauges when it comes to woodworking machine specs. In order to properly test this issue, a series of cuts need to be made at different tensions, while keeping all other parameters equal, and the results compared.

    Your data supports the conclusion that aftermarket gauges can be inaccurate, and that the gauges provided on the bandsaw are at least usable for measuring blade tension in the 15,000 psi range. Your data does not support the conclusion that therefore there is no reason to tension above 15,000 psi.

    On a side note, I do have a question. My Walker Turner bandsaw actually does not have a tension gauge on it at all. Is there a recommended way for setting the tension besides getting an inaccurate aftermarket gauge?

  7. #7
    Quote Originally Posted by Mike Cutler
    Using Young's modulus, for the given material that the blade is made of, the amount of "strectch" could be measured using a vernier, and the data obtained from that could be compared to the indication on the Carter, and the OEM bandsaw tension indicator.
    From these three devices a table could be developed. if the Carter and the vernier are in agreement, and the OEM tension indicator is at 1/2". It's an odds on bet that the bandsaw tension meter is "accurate enough".
    But isn't that precisely how these gauges work? They attempt to measure the stretch in the blade, don't they?

    If the devices tested give repeatable tests that don't match one another, I don't understand how introducing another device (vernier) that functions the same way is going to answer any questions???

    I know I must be looking at your suggestion wrong.

  8. #8
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    Quote Originally Posted by Phil Thien
    But isn't that precisely how these gauges work? They attempt to measure the stretch in the blade, don't they?

    If the devices tested give repeatable tests that don't match one another, I don't understand how introducing another device (vernier) that functions the same way is going to answer any questions???

    I know I must be looking at your suggestion wrong.
    Phil.
    Yes they do measure the "stretch" of the blade. The vernier would measure the actual elongation of the blade. From this value the amount of lbs/force could be derived based on the known modulus of steel.
    The vernier would provide another independent method of determining the amount of force.
    The indication from the vernier and the aftermarket tension gauge could be compared to another and then compared to the OEM tensoin indicator on the bandsaw. From ths a rough baseline value could be derived.
    I'm trying to get enough independednt measurements to form a table.

    The after market tension gauges could also be checked by clamping them to a beam and suspening known amounts of weight off of them to replicate the wheel force, in lbs, applied. Then multiplied by the cross section of the blade and the modulus value. This could be a pretty accurate and cheap way of validating the values obtained from the aftermarket tension gauges.
    Your last post in the original thread is correct in it's assumptions. I believe though,that three of the tension gauges are repeatable, and one was not.
    Maybe I read it wrong??
    Last edited by Mike Cutler; 02-01-2007 at 5:20 AM.

  9. #9
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    While this is not directly related and we are starting to dive into the "science" of tension guages.....

    Please remember, no bashing of person or manufacturer or the post will be edited or deleted.
    Thanks & Happy Wood Chips,
    Dennis -
    Get the Benefits of Being an SMC Contributor..!
    ....DEBT is nothing more than yesterday's spending taken from tomorrow's income.

  10. #10
    Hi Mike,

    Not that I can shed much light on this subject 'cause your "way over my head" on the technical aspects of blade tension.

    In the other thread Mark Duginske wrote these specifics regarding the tension gauges mentioned in the article;

    "3.The Carter gauge is the most accurate for this application (a tired woodcutting band saw). The spring gauge in the saw is adequate and more accurate than the mechanical gauges. Of the mechanical gauges the Starrett was the most accurate in terms of psi reading. The Lennox was most precise (repeatable). The worst is Itura which has a calibration problem and often does not return to zero. With the faulty Itura gauge we got 15,000 psi readings as low as 8,000. Which means that if you use the Itura gauge you could be almost doubling the tension on your saw. No wonder parts are bending or being broken."

    Of course of the 3 mechanical gauges... which one do you think I own....

    From my prospective; I just want to repeatably tension my saws for the proper tension for what ever size blade the job calls for....

    It's like my television...I don't care how the picture got there....

    It's like my computer... I just want it to work... of course this is why I fired Bill Gates and bought an Apple

    jim
    Life is just a series of projects.........

  11. #11
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    """""""""
    The best support for this is your reference to manufacturers recommending 15,000 psi as the tension for their blades.
    """""""""

    Consider I'm a newbie, and of the tighten it till it works, method of setting tension, the people I bought my TimberWolf blades from said, I needed less tension than normal, does seem to work though.
    ??

    Al

  12. #12
    Quote Originally Posted by Mike Cutler
    Phil.
    Yes they do measure the "stretch" of the blade. The vernier would measure the actual elongation of the blade.
    I've been guessing (wildly assuming) that part of the difficulty w/ the blade-based gauges has been getting them correctly installed, and extrapolating their measurement over just a few inches of blade to the rest of it.

    When you suggested using a Vernier, I pictured a set of calipers c-clamped to the blade as has been discussed here and elsewhere before.

    I just can't imagine this is a good way to measure how much a 80+ inch blade is stretching. But again, I will qualify this by saying I've only done some redumentary experiments on my own bandsaw w/ a digital caliper.

    It does seem to me that the Carter gauge is actually the equiv. of a digital scale. It is measuring force applied rather than trying to measure the blade. Which is probably a smarter way to do it if the option is available to you.

    I will continue to use the built-in gauge and my gut.

  13. #13
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    Quote Originally Posted by Jim Dailey
    Hi Mike,

    Not that I can shed much light on this subject 'cause your "way over my head" on the technical aspects of blade tension.

    In the other thread Mark Duginske wrote these specifics regarding the tension gauges mentioned in the article;

    "3.The Carter gauge is the most accurate for this application (a tired woodcutting band saw). The spring gauge in the saw is adequate and more accurate than the mechanical gauges. Of the mechanical gauges the Starrett was the most accurate in terms of psi reading. The Lennox was most precise (repeatable). The worst is Itura which has a calibration problem and often does not return to zero. With the faulty Itura gauge we got 15,000 psi readings as low as 8,000. Which means that if you use the Itura gauge you could be almost doubling the tension on your saw. No wonder parts are bending or being broken."

    Of course of the 3 mechanical gauges... which one do you think I own....

    From my prospective; I just want to repeatably tension my saws for the proper tension for what ever size blade the job calls for....

    It's like my television...I don't care how the picture got there....

    It's like my computer... I just want it to work... of course this is why I fired Bill Gates and bought an Apple

    jim
    Jim.
    It was never my intent in my post above to infer that any of those tension devices were of a lesser or greater quality. I was trying to limit my resonse solely to the instruments that Mark currently has available for use.
    To the best of my knowledge. Louis Itturra does not make the tension device that bears his name in his basement. It is being made by someone for him.
    It works on the same principle as the Starrett, and should be a pretty rugged little device. The particular one that Mark has may be damaged, or did not adhere to the spec's that Louis specified. If it were mine I would have returned it, regardless of manufacture, or origin.
    Mark and company have 4 tension devices available to them, by four different vendors. It would be difficult to state that each one is a statistical representation of that product, and that every device each manufacture produced, of the same product line, would yield the same result. As with all things, sometimes you get a great one and sometimes a not so great one right out of the box. It would be unreasonable to expect Mark to purchase 10 or 20 of each one and do a comparison across the devices.
    Unless you have reason to believe that your tension gauge is not working properly, keep using it. If you have reason to believe that it is not working contact Louis Itturra. In the conversation I had with Louis a few years back, I found him to be a very engaging individual that cared about the services he provided, and the products that bear his name.

    I guess the point is. "If it ain't broke, don't fix it"

  14. #14
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    I told myself not to do this

    I said that I would not post again on this subject. So much for that.

    First off, Mark, I plan on buying your new book. ( I have the BS book by Mr. Bird and was underwhelmed by it. )

    I too, as you may have guessed, own the Ittura gauge. I was surprised and dismayed that it performed so poorly. I accept your comparison, and will at some point get the Starrett gauge.

    So now the new question: I have been puzzled for sometime about the claim by Suffolk Machinery that their blades require lower tension to operate satisfactorily. It seems to me that the science of steel making is well understood. If Suffolk Machinery had a new and better blade, the rest of the world would also have it, via industry publications, or metallurgical analysis.

    I spent one afternoon using google to explore for silicon steel blade material, and didn't find anything. Maybe it is so common, that it is not worth mentioning? Yes, I could have missed something important...

    Soooo, why does the Timber-Wolf blade require/use lower tension as opposed to other brands?

    Any metallurgists out there?
    Best Regards, Ken

  15. #15
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    """""""""
    Soooo, why does the Timber-Wolf blade require/use lower tension as opposed to other brands?
    """"""""

    Well I now know I'm not the only one wondering.....

    Al

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