B/s Blade Tension

[Brian Buckley]

I just received my Inturra band saw tension guage. After trying it on my MM 20 (with a 1" Lenox Pro III) I was amazed. To get 20,000 lbs, I had to crank down very hard. To the point it was dificult to turn the wheel. I relieived the tension on the B/S tension indicator as instructed by MM. Should I have to crank down this hard to get this much tension?

Brian

[Tom LaRussa]

I just received my Inturra band saw tension guage. After trying it on my MM 20 (with a 1" Lenox Pro III) I was amazed. To get 20,000 lbs, I had to crank down very hard. To the point it was dificult to turn the wheel. I relieived the tension on the B/S tension indicator as instructed by MM. Should I have to crank down this hard to get this much tension?

No way.

Definitely something wrong with the saw, the blade, or both.

Send them to me and I'll let you know which one just as soon as I can get around to it. :eek: ;)

[Alan Turner]

Please keep us updated. I just ordered the same guage, and run a 1" Lenox carbide on an Aggi 20. Louis Iturra told me that 30,000 was the right tension. Mine has not yet arrived.
Alan

[Brian Buckley]

Alan,
Talked with both Inturra and MM today. Inturra said it is probably from a weak spring. They suggested I change it. MM said not so, the blade might be too long. I am going to remove the blade tonight and measure it. I am also going to try a new 1/2 Lennox carbide blade. I will let you know the results.

Brian

[Alan Turner]

Brian,
Did Iturra state that the proper tension on the Lenox Trimaster was 30,000#? I seem to recall that he told me the pressure on all of the Lenox blades were to be 30,000#. If the blade is not too long, then a new spring would seem to be indicated. Wonder if I will find that with my Aggi as well? The new blade is on order also. The old one had a collision with a drywall screw, and the screw won. Ouch.
Alan

[Mark J Bachler]

I raise my guide on my MM 16 all the way up & tighten the wheel till I can only flex a 1/2" blade about 3/8" then make sawdust. On a resaw blade I tighten it up till I get a 440 "A" note off it when I tap it with a putty knife.

Hey, it works for me.

[nic obie]

Seems to me Iturra reccomends 20,000 psi, however I have been wrong before.

On my MM16 I don't have any trouble hitting 20,000 psi with a 1/2" carbide or the 1" blade that came with the saw.

[Dennis McDonaugh]

I use the same gauge and tension a Highland Hardware woodslicer to 25K with no problems on my MM16.

[Brian Buckley]

Alan,

Intura sugest a minimum of 20,000 lbs with a max of 30,000 lbs. I can get it to 20,000 lbs.. I just have to muscle the wheel. It should not be that hard to tension. It might be OK to operate this way, but I want to check another blade first.

Brian

[Norman Hitt]

Alan,

Intura sugest a minimum of 20,000 lbs with a max of 30,000 lbs. I can get it to 20,000 lbs.. I just have to muscle the wheel. It should not be that hard to tension. It might be OK to operate this way, but I want to check another blade first.

Brian

One thing to remember Brian, is that if you put on a 1/2" blade and tension it to 20,000#, it will not be nearly as hard to turn the Tensioning wheel as it would be when tensioning a 1" blade to the same tension. Just think about tuning a guitar string and the amount of strength it requires, and then imagine adding another string to that same tuning key and tensioning them both with that key at the same time, You would Really have to twist hard on that key to get them both in tune.

I'm not saying there couldn't be something wrong, but I would be very surprised if the spring is weak on that saw. Have you looked to see if the spring is fully compressed when you are reading 20,000# tension?

[Dee Dee Martin]

What was the outcome on this?

I got my Iturra gauge yesterday, and tensioned my Trimaster to 25K yesterday on my MM24. It broke in about 3 minutes of running. Scared the hell out of me.

I'm not sure what to do, now......

Blade was about 1.5 years old.
Used a fair amount.
I too had to really crank to get it to 25K.

[Tom LaRussa]

What was the outcome on this?

I got my Iturra gauge yesterday, and tensioned my Trimaster to 25K yesterday on my MM24. It broke in about 3 minutes of running. Scared the hell out of me.

I'm not sure what to do, now......

Not much choice except to buy a new blade, I guess. :(

By the way, there was a discussion (was it here or on Woodnet?) a couple weeks ago maybe about tensioning Lenox Trimaster blades.

Seems that the Trimaster only needs such ridiculous tension when it is being used to cut ferrous metals -- which is what it was originally designed for. When cutting wood much less tension is needed.

[Bill Arnold]

... By the way, there was a discussion (was it here or on Woodnet?) a couple weeks ago maybe about tensioning Lenox Trimaster blades. ...
See http://www.sawmillcreek.org/showpost.php?p=145113&postcount=27 and associated posts.

[Tom LaRussa]

See http://www.sawmillcreek.org/showpost.php?p=145113&postcount=27 and associated posts.
Thanks Bill,

That's exactly what I was thinking of.

:)

[Ken Garlock]

What was the outcome on this?

I got my Iturra gauge yesterday, and tensioned my Trimaster to 25K yesterday on my MM24. It broke in about 3 minutes of running. Scared the hell out of me.

I'm not sure what to do, now......

Blade was about 1.5 years old.
Used a fair amount.
I too had to really crank to get it to 25K.

If you think the blade is worth salvaging, I would get it welded together.

If you were using the 1" x .035" blade, the actual tension in the blade, at 25,000 psi is .035 X 25000 = 875 pounds. Since the tension is the same at any point in the blade, it is also 875# on the return side of the blade, the part that runs upward toward the top wheel. Hence the total tension load on the top and bottom bearings of the saw is 875 X 2 = 1750#. That should not be an excessive load on a large saw like the MM24. I would check the state of lubrication on the screw in the tensioning mechanism.

If you were using a 1/2" tri-master with a thickness of .025", and indicated 25,000# tension is really .5 X .025 X 25000 = 312.5# or 625# total bearing load.

It is easy to forget that a load of 25,000 psi is for a cross-sectional area measuring 1" X 1". 25,000 psi sounds like a tremendous load, but it really isn't when you adjust for blade cross-section.

Just my 2% dollar.

[Mark Singer]

If they won't replace it....get it welded!
What was the outcome on this?

I got my Iturra gauge yesterday, and tensioned my Trimaster to 25K yesterday on my MM24. It broke in about 3 minutes of running. Scared the hell out of me.

I'm not sure what to do, now......

Blade was about 1.5 years old.
Used a fair amount.
I too had to really crank to get it to 25K.

[Mark Singer]

I have the Agazzani 20" and just use the internal gague. I set it between 20 and 25 depending on the task....and it works great. There is ne reson to over tension the blade. It stresses the saw, bearings , etc and the blade as well. As long as it is performing well why add more tension?

[Mike Cutler]

I couldn't agree with Mark more. If the blade and saw are cutting as desired, to heck with the tensiometer.
On the subject of tensiometers, as someone that uses these devices on a contiuous basis, and calibrates them to NIST standards, there are many variables involved. Any commercial grade tensiometer should be used as a quick check or gross reference only. I know that anyone that bought one paid quite a bit for it, but use it for performance trending only. don't try to use one for a qualitative or quanatative analysis.
I'm not trying to be a jerk, or contradict Louis. Just trying to save folks some aggravation.

[Mark Singer]

The tension gauges are pricey, I don't have one. The old methods of listen to the sound of the blade. Or if it is cuttind a barrel shaped profile, increase the tension still work. Less can be more sometimes if you trust your instincts.