Carter, Iturra, Lenox, Starrett Comparison

[Mark Duginske]

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HANDBOOK, published in 1989, which is the best selling band saw book in the world but is black and white and has become outdated.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

[Scott Thomas]

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

[Mike Cutler]

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

[Phil Thien]

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.

[Mike Cutler]

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??

[Dennis Peacock]

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.

[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

[Al Willits]

"""""""""
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

[Ken Garlock]

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?

[Al Willits]

"""""""""
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

[Art Davis]

Okay, a newbie here---one who owns Mark's book as well as the one by Lonnie Bird, and have benefitted from both.

When I purchased my Grizzly G0555, I ordered Timberwolf blades. Tried their "flutter method," but all I could get was a heart flutter. Called them, and the rep there said, "Well, if it won't flutter, it doesn't really matter. Just set it up according to the tension adjustment on your saw." I have been doing that, and don't have any complaints. Resaw works fine, etc. (I have the six inch riser block and ordered the longer blades.) I do like the Timberwolf blades.

So, here's my question: how do those of you who have a lot of experience with the band saw adjust your blade tension? Frankly, after a long professional career of being a theoretician, here I find myself wanting the practical viewpoint. You can talk about stress, strain, Young's modulus, Hooke's law, etc, but it all boils down to a question of what will saw my wood the best. And I think that is an empirical issue, but one that seems to be "underaddressed" in the literature---including Mark's own fine book.

Anybody with any responses?

Thanks.

Art

[Pete Bradley]

Mark,

I think the answers may lie in the application of these gauges. Precision measurement is 5% about the tool and 95% about how it is used. It's really a science in itself, and few of us do enough to become experts.

My thoughts/questions:

1. Contact Starrett, explain who you are, and ask them about tension gauges. Starrett should be able to hook you up with someone who is expert not only with their gauge, but who can shed light on your questions.

2. Since the Carter gauge measures wheel load rather than measuring band strain directly, I expect it has to be calibrated somehow to account for band thickness and width (or c.s. area). How is this done?

3. When testing the Carter gauge, how did you determine the actual PSI at the band?

Pete

[David Rose]

Art,

I also started with TW blades. I couldn't get them to flutter (or to quit?) either. They were not steady, but never changed. This was on a Delta 14" US last model. This is my only rip saw and I ate those TW blades fast.

A fellow on the B. Pond found me a Lenox carbide blade at a good price. He convinced me to try it.

It took 1/32" or LESS planer cut to clean up the saw cut! I just used the minimal settings that TW recommended for their blades. That was about 3/8" blade if memory serves. It worked VERY well with no tracking adjustment. That may have been due to the teeth being wider than the band, but it was true.

Due to a "visitor" turning on the saw with no tension, I got a kink in the blade which I never could quite smooth out. I'm not sure that the new blade gives me quite the cut that the old one did, but it hasn't really been "tested" yet. I have tensioned it all the way up to 1/2" on the factory scale. I can tell little to no difference. I'm sure that the tension is fairly low. I have set the wheels as co-planer as feasible, added a riser block, use Cool Blocks adjusted well, changed the motor to 1HP with pulleys to up the speed to recommended, installed a brush, added half decent dust collection port, added a better table with tight insert, added link belt, squared up everything, basically I super tuned the saw. The saw will easily pass the nickel test.

This saw saw 6 TW blades in about 4 months before the carbide ones. The first carbide ran about 4 years before the accident. The new blade has seen little use. But if history repeats, tension will end up at around 3/8" with the factory spring. This is for resawing and ripping.

Oh, and I do release tension after each use. And I haven't broken a blade yet even on the 14" saw. One blade may not tell much, but we'll see with the second one.

David

Okay, a newbie here---one who owns Mark's book as well as the one by Lonnie Bird, and have benefitted from both.

When I purchased my Grizzly G0555, I ordered Timberwolf blades. Tried their "flutter method," but all I could get was a heart flutter. Called them, and the rep there said, "Well, if it won't flutter, it doesn't really matter. Just set it up according to the tension adjustment on your saw." I have been doing that, and don't have any complaints. Resaw works fine, etc. (I have the six inch riser block and ordered the longer blades.) I do like the Timberwolf blades.

So, here's my question: how do those of you who have a lot of experience with the band saw adjust your blade tension? Frankly, after a long professional career of being a theoretician, here I find myself wanting the practical viewpoint. You can talk about stress, strain, Young's modulus, Hooke's law, etc, but it all boils down to a question of what will saw my wood the best. And I think that is an empirical issue, but one that seems to be "underaddressed" in the literature---including Mark's own fine book.

Anybody with any responses?

Thanks.

Art

[James Carmichael]

Lots of good info out here, but I'm afraid Mark is giving his book away:-)

The trouble with any "scientific" test is that unless all conditions are precisely duplicated with the same object definitions for "quality of cut" and "outlast", you're comparing apples to oranges.

Bottom line is, go with what works for you.

[Bill White]

What time is it? Well, you first take a billet of stainless steel, mill the outside shape of the watch you want, contact a swiss watch movement mfg. co.,............
Now that I feel better, I tension 'til I get the smoothest cut, cut the part, and get on with stuff.
I have had good luck running the Timberwolf blades with my standard settings.
Bill