I saw this on LinkedIn.com (tension or strain)

[James Heisbert]

I saw this in a group at LinkedIn.com - http://www .linkedin.com/groupItem?view=&srchtype=discussedNews&gid=1779950 &item=140306570&type=member&trk=eml-anet_dig-b_pd-ttl-cn&ut=2g4PVzqjpU3Ro1.

The folks there were having conversation about blade tension. Most of them stated that the right term is strain and not tension. That tension and strain are two different things. I have observed that all woodworkers in any forum site use the term “tension” and not strain. This made me confused. Can somebody tell me what’s right? Thanks.

[Ole Anderson]

I would say that tension is the force that you exert on the blade to stretch or strain it.

[Andrew Pitonyak]

I did not follow the link, but...

One definition of Tension is the state of being stretched tight, or, to apply force that tends to stretch something.

Strain is a force tending to pull or stretch something to an extreme or damaging degree.

So, when I stretch my leg, I put my muscle under tension. If I apply too much tension, I may pull or strain my muscle.

[Erik Loza]

That may be technically correct (though I never really thought about it until now...) but even if it isn't, that would be like taking issue with engine builders or auto mechanics referring to a car engine as a "motor". It technically is not a motor but the term is so commonplace that it's not worth taking issue with.

Just my 2-cents...

Erik Loza
Minimax USA

[James Heisbert]

So by applying tension, you’re actually straining the blade? Is there any difference? I am not neglecting the fact that most of us here are experienced band saw users but those people on linkedIn are big time in machining business or industry.

[Jim Rimmer]

Sometimes discussions like this put too much tension on my brain and put me in a strain.

[John Coloccia]

Without reading the whole thing, when an engineer or a scientist talks about tension and strain, they mean:

Tension - the force applied to the object
Strain - the amount the object physically deforms

Generally, strain will be in units of length, is often given as a ratio. Tension will be in units of force. The spring scale on the BS generally indicates tension, and the "tension gauges" for BS blades (with little dial indicators on them) measure strain.

edit: having read through the above
PSI is not a measure of strain. For example, if you have a bolt torqued down with a preload of 1000PSI, if you apply a 500 PSI force trying to stretch the bolt the STRAIN on the bolt is still 0, because the bolt won't budge until you've reached 1000PSI. Hence, one reason it's important to torque down certain bolts properly is so that they have enough preload to resist straining and subsequent metal fatigue. Cylinder head bolts come to mind.

All that said, unless you really need to be precise for some reason, most people will use the terms interchangeably as it pertains to bandsaw blades. Tension and strain on a bandsaw follow each other, so it's somewhat pedantic to make a distinction for most BS conversations. You could say, "I think you need to increase the tension" or "I think you need to increase the strain on the blade", and both mean precisely the same thing.

[Tom Walz]

Tom Walz • Is this a language issue?

In canada they may use the term "dish saws" while the US uses "hammer saws".

From a Phsyics standpoint I would think that putting anything under tension would be putting a strain on the material. Neither Machinery's Handbook 24th ed. or Handbook of Chemistry and Physics 74th ed. define either term.

Over 30 years I have learned that it is incredibly important to find out what someone means by the term they use. (I have never found that telling someone they are wrong helps communication.) We sell a lot of "braze alloy" to folks who call it "silver solder". Of course it is most technically correct to call it "braze filler metal". The same is true with "carbide" which is actually "cemented tungten carbide".

Over 30 years in the business my language has become more and more that of the customer. Maybe 10 years ago I had a peer reviewed journal request a paper on some of my research. I wrote it as I ordinarily would and it was rejected for "over use of colloquial language". I rewrote it so that it was much harder to understand and ti was accepted.

Finally, I know Paul smith Personally and Professionally. I have a great deal of respect for him and his knowldege of the art of sawing as it is actually practiced and described in actial use. However, he is in Texas and the language does vary regionally.

[Joe Kieve]

If you said to your wife, "your face would stop a clock". She'd probably slap yours. But if you said to her, "honey, every time I look at you, time stands still". She'd probably kiss you. Have you not said the same thing?

My 2 cents

Joe

[glenn bradley]

Too much time on minutia, not enough time in the shop

[James Heisbert]

This came up with a language issue and I better agree with most of you. I can think of a common saying, “..it’s the thought that counts!”

[bob hertle]

After a 35 year career as mechanical engineer/machine designer here, I can assure you that the guys in that conversation do not have a clue as to what they are talking about!

Regards
Bob

[James Heisbert]

I scanned through Paul Smith and Tom Walz’s profiles. They are both owners of different sawmill companies.
And both have long experience in years.

[Scott T Smith]

I scanned through Paul Smith and Tom Walz’s profiles. They are both owners of different sawmill companies.
And both have long experience in years.

James, I think that you meant to say Sawmill Supply companies, not sawmill companies. I don't think that either one runs a sawmill; rather they sell supplies such as blades and bands to those that do.

[Steve Baumgartner]

After a 35 year career as mechanical engineer/machine designer here, I can assure you that the guys in that conversation do not have a clue as to what they are talking about!

Regards
Bob

Agreed! But rather than increase the misinformation I say: get out any freshman-level mechanical engineering text and read the part about strength of materials. If that's too much effort, then don't fuss the technical stuff.

edit: that sounded like I was criticizing Bob, but I meant the non-engineers out there, not him