Bandsaw tensioning redux

[roger wiegand]

I've plowed my way through more than I ever wanted to know on the topic.. (eg https://sawmillcreek.org/showthread.php?50949-Carter-Iturra-Lenox-Starrett-Comparison/page7) as well as later threads.

On my little bandsaw I can twang on the blade and guess that the tension will be about right for what I want to do. My problem comes with my new-to-me Centauro-made MM20 with the broken tension gauge. It looks like replacing the factory gauge involves some fairly major disassembly of a saw that is otherwise working perfectly. -- and then, per the myriad earlier discussions of built in spring gauges, may not be particularly accurate or reproducible.

I thought that a third party gauge might make it easy to set the blade with some reproducibility. I don't care that much about "real" accuracy, I'd just like to be able to consistently get the same tension in the correct ballpark. With the enormous resaw blade in the saw now my "by feel" methodology is failing me-- I can push it or twang it, adjust the tension by two full turns and feel no difference-- it's just stiff, no matter what.

So, per the earlier thread from a 15 years ago-- Carter, Iturra Lenox Starrett -- it looks like the Carter is no longer sold, can't find it on their web site. I tried to contact Iturra a couple months ago for a different part and had no response to email or phone calls, so are they out of business? EZTension won't work on blades this large. That leaves Lenox and Starrett. Does it matter between them? A Starrett seems to cost a couple hundred more, it that just inflation due to the name?

Is there a better way that doesn't involve spending hundreds of dollars? I'm not interested in building a DIY device, I just want a quick check to tell me that my tension is in the right ball park-- that I'm not cranking it down so hard I'm in danger of breaking something.

Or is it worthwhile to tear the saw apart and replace the OEM gauge (assuming the part is available) instead?

[Mike Kees]

Roger ,I bought a tension gauge from a guy on The auction site. Custom machined with a table engraved on the back for tensions/per deflection measured ,with a Mitoyu gage. There are other ways to get to this. John Teneck (I know I screwed up the spelling ,sorry John) on this forum posted his device to tension. If I had not already bought one I would have used John's design. All a tension gauge does is measure the elongation of the blade as it is tensioned. I believe there is a tension gauge device in John Whites book "Care and repair of shop machines" as well ,but it has been awhile since I have looked at the book.

[John K Jordan]

From past experience and from the advice of people smarter than me, I'm convinced, as you read, that the gauges on the bandsaws are NOT useful. Some say that without other means, setting it to the next highest mark might work (e.g., set to 3/4" mark for a 1/2" blade.) On my 18" Rikon I have to set it to nearly the mark for a 1" to get the tension I want for a 1/2" Lenox blade as measured by the gauge. I use the gauge only when switching to a new blade then make a note of the indicator position on the saw for future blade changes.

I bought a Starrett years ago before the price skyrocketed. All of these gauges are the same - a dial indicator, a lever that moves, and two places to clamp to the blade - one on the fixed body of the gauge and the other on the spring-loaded pivoting arm. The gauge is clamped to the blade with tension released then the tension is increased. The gauge simply measures the stretch in the blade when tension is applied. The magic of a commercial bandsaw blade tension gauge is the dial of the indicator is calibrated in PSI instead of thousandths of an inch or such. So to answer your question, there is no effective difference between the various gauges other than the price and the name.

The Starrett:

466534

You can make a functional gauge yourself with a standard dial indicator. Make a frame with clamps from aluminum, plastic, or wood. It will work just as well. You can make marks on the gauge dial for the tensions you want or just use the simple math to convert. Some pictures below show gauges made differently but the function is the same.

Another thing - if you know someone with a gauge they may be willing to bring it over and set the tension for a specific blade so you can repeat it later. (I've done this for several local people - I'm afraid the drive to your house might be a bit much. :)) If there is no useful parts remaining on the new saw for this you might devise a pointer or at minimum, experience how much deflection is needed for a specific side force to approximate the desired tension. Or listen for the frequency of the "twang"!

If you belong to a club that is not mostly broke, they may be willing to purchase a gauge that members could use. I recently did a bandsaw demo at a large woodworking club and afterwards they told me they planned to purchase a gauge for the club.

You can also rig up a dial caliper with a couple of clamps and measure the blade stretch that way to calculate the tension. One message here described this method and had a photo. I think I even saw photos of a shop-built gauge built like the commercial versions.
I have saved many messages and files related to measuring tension, some pointing to messages with photos and some with the math needed. I can dig those up if needed but I probably can't get to it for a few days.

Some other photos from the forum:

466536 466537


BTW, I tried calling Louis Iturra just now and for the first time in my many calls over the years he didn't pick up. Of course, it's Saturday so I'll try again next week. With the current health uncertainty, I sincerely hope he isn't ill.

JKJ




I've plowed my way through more than I ever wanted to know on the topic.. (eg https://sawmillcreek.org/showthread.php?50949-Carter-Iturra-Lenox-Starrett-Comparison/page7) as well as later threads.

On my little bandsaw I can twang on the blade and guess that the tension will be about right for what I want to do. My problem comes with my new-to-me Centauro-made MM20 with the broken tension gauge. It looks like replacing the factory gauge involves some fairly major disassembly of a saw that is otherwise working perfectly. -- and then, per the myriad earlier discussions of built in spring gauges, may not be particularly accurate or reproducible.

I thought that a third party gauge might make it easy to set the blade with some reproducibility. I don't care that much about "real" accuracy, I'd just like to be able to consistently get the same tension in the correct ballpark. With the enormous resaw blade in the saw now my "by feel" methodology is failing me-- I can push it or twang it, adjust the tension by two full turns and feel no difference-- it's just stiff, no matter what.

So, per the earlier thread from a 15 years ago-- Carter, Iturra Lenox Starrett -- it looks like the Carter is no longer sold, can't find it on their web site. I tried to contact Iturra a couple months ago for a different part and had no response to email or phone calls, so are they out of business? EZTension won't work on blades this large. That leaves Lenox and Starrett. Does it matter between them? A Starrett seems to cost a couple hundred more, it that just inflation due to the name?

Is there a better way that doesn't involve spending hundreds of dollars? I'm not interested in building a DIY device, I just want a quick check to tell me that my tension is in the right ball park-- that I'm not cranking it down so hard I'm in danger of breaking something.

Or is it worthwhile to tear the saw apart and replace the OEM gauge (assuming the part is available) instead?

[Richard Coers]

Maybe it's my farm boy lessons, but I've never fussed over blade tension. I tighten until it's tight, and saw. I've never leased the blade tension over 45 years. Blade sharpness, finger tip control on curves, and feed speeds are the real critical factors in my opinion. I did a room screen 25 years ago and I wanted to resaw a panel taller than would fit under the top guides. I put on a new blade, took off the top guides including the thrust bearing, and got 3 panels out of a 7/8" piece of stock. That verified to me that super guides and tension gauges are overrated. I also have watched Woodmizer bandsaw mills cut 24" logs with just two rollers and a shoulder on back of the rollers. The blade is not guided on both sides with bearings either.

[Eric Arnsdorff]

I have used this app from Inkleind with success (his twin turbo vice is very cool as well).
https://www.in-kleind.com/inkleind-bandsaw-tensioning

I got lucky and received the Starret gauge with my MM24 I bought used from a fellow SMC member. I have used it on my 1” blade and it seems very repeatable as well as giving me good sawing results. I wouldn’t have purchased it due to its cost but it is nice to have for the reassurance.

I haven’t compared it to the app yet. I’ll go do that and let you know how the app compares to the gauge.

[John TenEyck]

Well you said you don't want to build anything, but if you change your mind here's the gauge I made. I use it to check the tension on my BS and my sawmill. It works as well as a commercial meter for the price of a dial gage and an hour of your time.

https://sites.google.com/d/1deYVS01kWg8M7TBd7AyIPWur6mYCy0bL/p/1neIeXS8z0-GeYbb4uw1VMTreLM6I2Ily/edit?pli=1&authuser=1

John

[Tom Trees]

Just so you know, the tension gauge is adjustable on a lot of the Italian saws.
If the Bowden cable is snapped, you could replace it, but I'd guess it only came loose.
I happened to loose the little clamp which was on the end of the cable, inside the plastic reader box.
Haven't found it yet, but made do with making a clamp from a plug, seems good.

If it is snapped then it wouldn't be hard to replace, but you'd need to take a good few measurements beforehand,
wheel protrusion from cabinet with beam and shims, and take the pair of pins out of the shaft.
I will say, beware, beware, beware of those split pins on the screw, if you damage them they might never come out again.
I'm sure there is a wee tool for the job, I tried making some to no avail, and had to cut my hand wheel off to service my machine, as someone damaged it beforehand, and everything was assembled backwards.

I'm under the impression that it should look something like this,
but awaiting on confirmation as I did attempt some happy Centaurolizing with the welder,
Seems from someone who helpfully replied on youtube, with a newer design ACM made Laguna, that I went too far, :(
so is causing some rubbing on the carriage underside at the moment, I can see witness marks from the pin
so likely I need to grind some off again, or weld and drill a hole a bit lower down, possibly.
It might be helpful, should it annoy you not to have the gauge, hope I'm not derailing the thread, and you want an actual system of measurement
rather than something ball park.
All the best
Tom

466554466556

[Bill Dufour]

Seems like a belt tension gauge could be adapted.
Bill D

[roger wiegand]

Well you said you don't want to build anything, but if you change your mind here's the gauge I made. I use it to check the tension on my BS and my sawmill. It works as well as a commercial meter for the price of a dial gage and an hour of your time.

John

I was mis-thinking how these gauges work. Looking at your design, there is no tension applied to the frame. I was thinking there was and not understanding how wood with bolted joints could not move as much or more than the few thousandths of an inch that you're trying to measure. But the top and bottom pieces, if I understand correctly now, are not even connected. Thanks for the link and photos, that really looks quite doable!

Now if I can just figure out how to print the document from Google!

[John TenEyck]

I was mis-thinking how these gauges work. Looking at your design, there is no tension applied to the frame. I was thinking there was and not understanding how wood with bolted joints could not move as much or more than the few thousandths of an inch that you're trying to measure. But the top and bottom pieces, if I understand correctly now, are not even connected. Thanks for the link and photos, that really looks quite doable!

Now if I can just figure out how to print the document from Google!

That's correct. You are directly measuring the tension in the band. Also correct, the top and bottom pieces of wood are not connected. The dowel pin only loosely fits in the hole in the upper piece, just to maintain alignment. It's a simple build. Better still, it's simple to use.

As John J. pointed out, I only use the tension meter to find out what setting my onboard pointer registers for each size band I use. Knowing those values, I use the onboard gage when changing blades. So while you wouldn't have to repair your onboard gage you will find it easier to use once you know where it should be pointing for any particular blade.

John

[Alan Lightstone]

As John J. pointed out, I only use the tension meter to find out what setting my onboard pointer registers for each size band I use. Knowing those values, I use the onboard gage when changing blades.
John

OMG!! That's so much better an approach then I've been using. I take out the Lenox gauge with each blade change, and get the blade to the optimum tension (I usually go for 25K).

Nice tip, John...

[Eric Arnsdorff]

I did compare my Starret tension gauge with the Inkleind app and I was very impressed with the accuracy (relative to my uncalibrated but expensive gauge :-) ) and repeatability of the app for my setup!

I made sure to pretension the gauge and the values on it were repeatable compared to my bandsaw gauge. As expected my bandsaw gauge isn’t close to what it should be reading but at least is somewhat repeatable. I could make a new scale for it but I doubt I ever do more than a pencil mark on it.

466588 466589
466590 466591
466592 466593
466594 466595

Note: The best I can determine the tension should be between 15-20 ksi. My bandsaw is a MM24 (Centauro S 600P) with a 1” carbide tipped Lenox Woodmaster CT blade. I measured 60” between wheels for the input to the app.

[Tom Trees]

I was going to edit my post, but can't, so to address my concern I might add, it turns out that pin moves further away
from the carriage when the blade gets tensioned, :):):):)
and the rubbing marks was coming from dropping the wheel down extremely low.
Guessing the noise is from the thrust bearing and not the pin!
466618

[lowell holmes]

I set my bandsaw tension using the flutter method and it works for me.
I let the blade flutter and then tighten it until the flutter stops and then I tighten it 1 revolution of the tension crank.
It works for me.

[Curt Harms]

About the simplest bandsaw blade tensioning gauge I've seen is to use a digital caliper. Open the jaws about 5" and clamp each end to an untensioned blade. Zero the readout and begin to tension the blade. Every .001" of blade of blade 'stretch' = so many PSI of tension. The magic is knowing the formula - which I don't. I had it some place but no idea where it got to.

[John TenEyck]

About the simplest bandsaw blade tensioning gauge I've seen is to use a digital caliper. Open the jaws about 5" and clamp each end to an untensioned blade. Zero the readout and begin to tension the blade. Every .001" of blade of blade 'stretch' = so many PSI of tension. The magic is knowing the formula - which I don't. I had it some place but no idea where it got to.

Young's Modulus x blade stretch / caliper opening = psi

30,000,000 x 0.001/5 = 6000 psi

John

[Tom M King]

I just pluck the back of the blade until it sounds about right.

[Andrew Seemann]

I just pluck the back of the blade until it sounds about right.

That is just for rough tuning. For fine adjustment, you need to push your finger on the side of the blade to check deflection:)

It's low tech, but it works. I don't think I have ever seen a bandsaw blade tension gauge in person.

[roger wiegand]

That is just for rough tuning. For fine adjustment, you need to push your finger on the side of the blade to check deflection:)

It's low tech, but it works. I don't think I have ever seen a bandsaw blade tension gauge in person.

As noted, those two techniques are the one's I've used for decades. I just have no frame of reference for the big, heavy resaw blades on the new saw to know how much it should bend or the note of the twang. Thanks to a kind Creeker I'll shortly have a gauge that will provide that reference point.

[Tom M King]

I do the same for anything from the 1/8" blade on one of the 10" saws, to the 1" blade on the 24" saw. The first cut, if you want to make a test cut, will show if it's okay. Never had a problem with bad cuts, or broken blades.

[Curt Harms]

Young's Modulus x blade stretch / caliper opening = psi

30,000,000 x 0.001/5 = 6000 psi

John

Thanks John.

[Randy Heinemann]

I don't use a tension gauge. It seems like a waste, especially if the gauge is pricey. For about 10 years I've followed Alex Snodgrass's (Carter) setup process and I get consistent great results. His recommendation is to check the tension on the blade inside the cabinet on the rear where you can rest your finger on the frame and push consistently. If the blade is tensioned so that you can deflect the blade about 1/4" without turning your finger white, he says that always works for him. I sometimes add a little bit more tension, but generally that's what I follow. It works for him. More importantly it works for me.

[Warren Lake]

Tom,

A440 ?

more words
more words
what to Mimes do when on a forum

[Tom M King]

Not sure if I'm the Tom that question was intended for. I should have put my two posts together. I get paid to produce work. Haven't had much time, or at least, don't take much time to worry about theory.

Here are my two posts in this thread, that should have been together:

I just pluck the back of the blade until it sounds about right.

I do the same for anything from the 1/8" blade on one of the 10" saws, to the 1" blade on the 24" saw. The first cut, if you want to make a test cut, will show if it's okay. Never had a problem with bad cuts, or broken blades.

[John TenEyck]

Not sure if I'm the Tom that question was intended for. I should have put my two posts together. I get paid to produce work. Haven't had much time, or at least, don't take much time to worry about theory.

Here are my two posts in this thread, that should have been together:

I just pluck the back of the blade until it sounds about right.

I do the same for anything from the 1/8" blade on one of the 10" saws, to the 1" blade on the 24" saw. The first cut, if you want to make a test cut, will show if it's okay. Never had a problem with bad cuts, or broken blades.


An inexpensive, simple to make, and accurate tension gauge is a great help to those of us less gifted. I can report that on my Grizzly G0636X it's really easy to over tension a 1" carbide blade. I went from 24 ksi to 42 ksi in about 1/2 turn of the tension wheel. 24 ksi is a great operating range for a carbide blade where you get good performance and long life. 42 ksi will give even better performance but likely substantially lower life. At $165 for that blade I want to know what the tension is.

John

[Tom Trees]

Since some have mentioned it already..
I'd love to hear what a 1" 24 ksi blade sounds like when plucked, and if that tone is much different to say a 3/4" blade of the same type,
or even if those welded tips change/deaden the note compared to regular blades.
Any talk on this is very interesting, and I'm very appreciative of John's wee remarks now and again.
Going to be a bit more careful from now on, thank you.

Any other tips or other remarks on how much white finger you get from doing the half or quarter inch deflection test would also be
graciously appreciated.
I reckon probably half of the folks using a large machine are waiting for someone very fimiliar with these ksi figures to post a video on this subject,
as they have a wee bit to go yet before they use their bandsaw to close to its capacity.
Small bit of a rabbit hole to go down for me to spend a week getting to grips with everything, even after watching a few videos on the subject,
I'm not really anything the wiser after watching some ForrestMFG videos either.

Hope this thread keep going
Thanks
Tom

[Tom M King]

I would have to do each to think about what it sounds like. I couldn't begin to tell you. It's not something I think about. Probably as much feel as sound.

[John Lanciani]

An inexpensive, simple to make, and accurate tension gauge is a great help to those of us less gifted. I can report that on my Grizzly G0636X it's really easy to over tension a 1" carbide blade. I went from 24 ksi to 42 ksi in about 1/2 turn of the tension wheel. 24 ksi is a great operating range for a carbide blade where you get good performance and long life. 42 ksi will give even better performance but likely substantially lower life. At $165 for that blade I want to know what the tension is.

John

Careful, theres a good chance youre right at the limit of the spring and stacking it if you went from 24k to 42k in a half turn. This is the perfect example of why measuring tension accurately is so important as we approach the limits of our machines.

[Eric Arnsdorff]

I'm not sure about the 42 ksi. I'm not a metallurgist and I haven't studied the properties/materials of bandsaw blades. I do understand that properly heat treated carbon steels (with alloys) can provide well over 100 ksi yield strength. I typically use 30 ksi for a quick strength analysis for construction carbon steels to get me in the ballpark. This is also why I'm tentative to go much beyond the 20 ksi that I've seen as an upper end for bandsaw blade tension. I don't have any calibrated methods to measure this and before having an uncalibrated gauge I've tried to use some of the flutter methods and such because going from a flutter to no flutter seems to be the safe side of blade tensioning.

My understanding of how bandsaw blades are joined is it is typically a resistance weld at the seem that is simply ground flat.

Will bandsaw blades really take the 40 ksi (or more due to uncertainties)?

[Eric Arnsdorff]

Since some have mentioned it already..
I'd love to hear what a 1" 24 ksi blade sounds like when plucked, and if that tone is much different to say a 3/4" blade of the same type,
or even if those welded tips change/deaden the note compared to regular blades.
Any talk on this is very interesting, and I'm very appreciative of John's wee remarks now and again.
Going to be a bit more careful from now on, thank you.

Any other tips or other remarks on how much white finger you get from doing the half or quarter inch deflection test would also be
graciously appreciated.
I reckon probably half of the folks using a large machine are waiting for someone very fimiliar with these ksi figures to post a video on this subject,
as they have a wee bit to go yet before they use their bandsaw to close to its capacity.
Small bit of a rabbit hole to go down for me to spend a week getting to grips with everything, even after watching a few videos on the subject,
I'm not really anything the wiser after watching some ForrestMFG videos either.

Hope this thread keep going
Thanks
Tom


Tom I don't have anything definitive on the tones for carbide tipped blades either. The Inkleind app uses the tone method and does have an entry for if the blade is carbide tipped or not. So I assume that Andy Klein found that it did have some impact. Maybe look through what he posted to see if he offers any tidbits on this. Or send him a note to see if he'll share more of his data.

As far as the tone for different width blades goes - quite clearly this does have an impact on the tone. Both science and musical instruments support this and there is a lot of science around this aspect. The unsupported distance, thickness and width are all factors in the resonate frequencies.

Maybe you're asking if we could hear the difference. This is a very different question. My musician friends can hear things I cannot to a level that amazes me. I'm not gifted musically in any fashion. I can barely tell the difference between a $5 radio and a $50,000 sound system (other than one usually is louder than the other). So I'd say that some people could definitely use this method by ear and achieve very good results. I cannot so I use other tools.

One further item is the 24 ksi value you mentioned. As I indicated in my previous post - I have seen the range of 15-20 ksi as recommended. There's not great info on this other than experimentally seeing how good my cut is and using a consistent method to tighten the blade. There seems to be a lot of variations between gauge measurement methods (although stretch/strain as measured with my Starrett gauge would seem to be a reasonably accurate measurement method for tension/stress). I've even contacted Lenox who said to ask my bandsaw manufacturer. My bandsaw manufacturer states in the manual to ask the blade manufacturer. Neither on of them are very useful. So until something better comes along I'll just go with how my blade seems to be cutting and trying to be consistent with how I tension the blade.

[Erik Loza]

My experiences with Italian bandsaws:

-Never used or felt the need for a tension gauge, either on-machine or handheld.
-The #1 cause cause of unsatisfactory cut quality or performance was caused by inadequate blade tension. Every new owner seemed afraid to hurt their machine by cranking on it. There is literally nothing you can do to hurt a Centauro. The blade will snap long before anything happens to the machine, so keep cranking.
-#2 cause of poor performance was owners setting the guides too close on the wider blades. That actually could create a wandering cut in addition to torching the thrust bearings.
-I always used the flutter test "plus a little more" on 1" carbides. The blade will go long before the actual machine has issues.
-IMO, you don't really need max tension unless you're cutting something really tall, like veneers, milling, etc. Again, I never used a tension gauge but can probably say that for the average 8/4, 12/4, etc resaw job, I was probably using a lot less then 25K psi or whatever. Sure, you need really specific tire pressure for a race car but it doesn't matter if you're just to the corner store for some milk. My rule of thumb always was to try to use the minimum amount of tension needed for whatever the cut was. You just get to a point where you can feel the machine cutting smoothly, no weird sounds from the guides, etc.

Just what worked for me.

Erik

[John TenEyck]

Careful, theres a good chance youre right at the limit of the spring and stacking it if you went from 24k to 42k in a half turn. This is the perfect example of why measuring tension accurately is so important as we approach the limits of our machines.

It wasn't even close, John. When I had 42 ksi on the 1" blade the spring still had a lot of air between the coils. Grizzly claims the G0636X can tension a 1-3/8" blade. Extrapolating my measurements on the 1" x 0.035" blade shows it indeed should be able to reach at least 25 ksi on a 1-3/8" x 0.042" blade. It is a very robust saw.

You are absolutely correct that we need to be able measure tension accurately. This might be even more important on lower stiffness saws than ones with high stiffness. My 14" Delta will not tolerate more than about 12 ksi on a 1/2" blade, even though the owner's manual says you can use blades up to 3/4". Many an upper yoke have been broken on those saws when folks have tried to run high tension on those wider blades. At 15 ksi on a 1/2" x 0.025" blade the upper guides on my saw will deflect at least a blade width to the right. The Iturra spring I have on it is actually not of all that much value because the frame can't handle the forces involved. So while my G0636X is happy running a 1" blade the 14" Delta is best suited to a 1/4" blade.

John

[John Lanciani]

It wasn't even close, John. When I had 42 ksi on the 1" blade the spring still had a lot of air between the coils. Grizzly claims the G0636X can tension a 1-3/8" blade. Extrapolating my measurements on the 1" x 0.035" blade shows it indeed should be able to reach at least 25 ksi on a 1-3/8" x 0.042" blade. It is a very robust saw.


John

That's good to know John. The MM20 that I recently parted with could only achieve 18ksi on a 1" trimaster with the stock spring fully compressed. Once I replaced the spring (with a properly sized off-the-shelf die spring from McMaster) and could accurately and repeatably tension up to 30k it was routine to cut 12"-16" wide veneer 1/16" thick that was ready for the vacuum press right off of the blade.

And yes, for those of you wondering; a trimaster cuts significantly better as the tension is increased.

[Tom Trees]

Nice one Eric, I wasn't aware that Andy had any content regarding the subject.
Strange that the algorithm didn't suggest that for me.
Gonna luck him up to see if I can learn anything.
Thanks
Tom

[John TenEyck]

Eric, Lennox rates their blades for tensions up to 30 ksi, at least the carbide one I use. My friend has the same G0636X as I with the same 1" Woodmaster CT blade on it with 25 ksi on it. He never releases the tension. It's been on his saw for at least 2 years now and still cuts really well.

This article in FWW may be helpful, too: https://www.finewoodworking.com/2012/11/09/setting-bandsaw-blade-tension

John

[John TenEyck]

That's good to know John. The MM20 that I recently parted with could only achieve 18ksi on a 1" trimaster with the stock spring fully compressed. Once I replaced the spring (with a properly sized off-the-shelf die spring from McMaster) and could accurately and repeatably tension up to 30k it was routine to cut 12"-16" wide veneer 1/16" thick that was ready for the vacuum press right off of the blade.

And yes, for those of you wondering; a trimaster cuts significantly better as the tension is increased.

Several of the vaunted Euro machines struggle to put 25 ksi on blades the manufacturer says they can handle. Do they cut OK at 18 or even 15 ksi? Sure, but as you said, not nearly as well as they will at higher tension. As some folks here have pointed out in other threads, when the tension is high enough guides are almost irrelevant to cutting straight. And that makes deep resawing and especially slicing veneer of consistent thickness much, much easier.

John

[John TenEyck]

From Lenox:

https://support.lenoxtools.com/hc/en-us/articles/360014833917-How-much-tension-can-a-bi-metal-blade-handle-

John

[Erik Loza]

I do think that main tension springs fatigue if you keep a really stiff blade like a carbide tensioned for long periods of time. That is not a machine issue, it's a spring issue. Let's not confuse this with a FRAME STRENGTH issue, which is the primary limitation when trying to put 1" carbides on less robust machines. Also, I found the Woodmaster CT to be more forgiving as far as tension requirements than the Tri-Master, which was the "original" carbide blade and not really designed for wood cutting in the first place.

Erik

[John TenEyck]

I do think that main tension springs fatigue if you keep a really stiff blade like a carbide tensioned for long periods of time. That is not a machine issue, it's a spring issue. Let's not confuse this with a FRAME STRENGTH issue, which is the primary limitation when trying to put 1" carbides on less robust machines. Also, I found the Woodmaster CT to be more forgiving as far as tension requirements than the Tri-Master, which was the "original" carbide blade and not really designed for wood cutting in the first place.

Erik

I wasn't suggesting the machines were at fault Eric, but the springs they put on it were. John L. proved that by changing the spring on his MM20; 18ksi with the factory spring, 30 ksi with an aftermarket one, the saw happy with either. There was another thread on here a year or two ago with another (brand new) Euro saw that couldn't put 25 ksi on a 1" blade, yet it was rated for 1" blades. Again, it was the spring that wasn't up to the task. But we as consumers buy a machine with a spring. If the manufacturer claims it can handle a blade of X width we expect that it will be able to do so w/o compromise. What that point of compromise is is open to interpretation, but it's clear that blades perform better at higher tension. Anyone who has done anything more than casual evaluation will know that to be true. Lenox buries the info. deep on their website, but it's there; their blades are rated for up to 30 ksi. To me that means that machines rated for a blade of X width should be able to apply something close to 30 ksi on that blade.

Cheap springs or ones that must be over compressed to tension a blade definitely will fatigue. Quality springs that operate within their rated range do not over any practical period of time. Look at overhead cam springs in automotive engines. They do their job for years w/o complaint.

John

When I put 24 ksi on the 1" Woodmaster CT on my G0636X the on board tension meter is within a pointer tip of 1". I can't remember if it's above or below but it's really close. And that, to me, means that Grizzly thinks that reasonably high tension gives better performance and designed that saw to deliver it without compromise. Better still, it's a pleasure to use.

John

[Eric Arnsdorff]

Nice one Eric, I wasn't aware that Andy had any content regarding the subject.
Strange that the algorithm didn't suggest that for me.
Gonna luck him up to see if I can learn anything.
Thanks
Tom

Tom I'm not sure if there are different versions out there but on my iPhone app the parameters have a setting for if it is carbide tipped or not. I've attached a screenshot.
466739

[Eric Arnsdorff]

From Lenox:

https://support.lenoxtools.com/hc/en-us/articles/360014833917-How-much-tension-can-a-bi-metal-blade-handle-

John

I'm not sure how to take this spec. Are they saying not to exceed 30 ksi? If this is the case then I wouldn't want to tension it at 30 ksi (which will have uncertainty associated with it) then startup and other stresses from cutting could easily exceed this limit and then stretch or break the blade. Maybe they are saying tension to 30 ksi isn't an issue and the elastic limit is much higher.

This was the response I received from Lenox.

466740

It does sound like others are using tension above 20 ksi and some are indicating above 40 ksi. Since the 30 ksi value corresponds to the typical low strength carbon steel elastic limit along with these indications, I'm going to stick with 20 ksi as an upper limit.

I'm not a power bandsaw user but in my hobby shop I've never broke a blade. I have made some bad cuts (most due to lack of user skills and some due to blade condition). A little added tension and/or a sharper blade has always seemed to make things work for me. Others commenting here have much more bandsaw experience than I do.

The FWW article John posted indicates the 15-20 ksi value I've seen. But it does indicate going up to 25-30 ksi for carbide tipped blades. I don't know why this is. I expected they simply welded the tips onto the same metal but maybe they use a different alloy because of the this added welding process.

I share the concern for blade tension because I only use my saw on occasion as a hobbyist and I change blades. I want a good cut first try and I don't want to break my blades (or the machine but most of my machine damage concern has been eliminated with my new to me 24" bandsaw). I'm sure others here who use bandsaws much more than myself have become comfortable with how to tension the blade by "feel".