Tension meter on bandsaw blades?

benush26 · Post by **benush26** » Mon Jan 06, 2014 4:41 pm

It's still too cold to go out in the shop so time for reading. I picked up my copy of "Care and Repair of Shop Machines" by John White and found an interesting article regarding the use of a tension gauge (he makes an inexpensive one from hardwood and nails) to accurately set up the blade tension on a bandsaw.

30,000 psi is his recommendation for 1/2" blade .0125 thick. However, he states that most "home" saw manufacturer's recommendations of 15,000 psi. He also states that after a few years use, the tension spring loses its set and should be replaced.

For blades 1/4" and smaller I use the "flutter" method and am comfortable with it, but for larger blades I seem to rely on the tension spring measurement

I have the "Wood Slicer" fore resawing and was wondering....

1. Does anyone measure the tension (stretch) of the blade?

2. Has anyone ever found recommendations by Shopsmith on a maximum tension setting for their bandsaw? Part of this question is driven by the geometry of the Shopsmith versus a Jet, etc., and what stresses the Shopsmith saw can reasonably handle. After all they do suggest bending the shaft for realignment.

3. Has anyone replaced their tension spring as a part of maintenance (as compared to rebuilding the handsaw)? If you did, was there a noticeable difference in reliability of the scale?

I do realize that some never back the tension off, some always back it off after use and presume that many do a combination of both dependent upon time and mental state

!

If I can find a more accurate method to set tension, I am more than willing to try.

Thoughts, ideas, input? Also, feel free to hijack this thread if it starts down any other path! Though we know that NEVER happens.

Be well,
Ben

dusty · Post by **dusty** » Mon Jan 06, 2014 5:06 pm

I have watched Shopsmith users pluck the blade while adjusting blade tension but I do not know if that works or not. I am hard of hearing (too many hours in a noisy cargo aircraft) in addition to being tone deaf.

I trust the tension indicators on my Shopsmith band saws.

JPG · Post by **JPG** » Mon Jan 06, 2014 5:10 pm

psi? I do not unnerstan the si part.

15 ton seems excessive.

However a 1/2" x .0125" blade has an area of .00625 in² so 30,000 psi becomes 187.5 lbs, more reasonable. realize the 'spring force' is twice that.

So I guess that was the intent(why not just say 187.5#?).

As for the SS spring, I believe it's deflection is well within the lower end of the elastic range. Constant tension on the arm is another matter(it is not a spring).

SS does not recommend setting tension beyond the 1/2" setting.(remember that arm!)

I consider the calibrations a starting point anyway. The blade will tell you if tension is 'ok'.

heathicus · Post by **heathicus** » Mon Jan 06, 2014 5:11 pm

I find my tension indicator to not be useable. I don't even look at it. My system is to put it as tight as it feels right for it to be based on nothing more than my personal experience and ignore the indicator. Once that is set and as long as I leave that same blade on, when I'm done sawing, I'll release the tension 3 full rotations of the hex wrench. When I'm ready to saw again, I'll tighten the hex wrench 3 full rotations and I'm good to go.

robinson46176 · Post by **robinson46176** » Mon Jan 06, 2014 6:17 pm

I have owned several bandsaws and two bandsaw sawmills. The Shopsmith is the only one with any form of tension gauge. I always just sat the others by flex and by ear and of course by how it sawed.

I do like the SS tension gauge and will like it better after I get around to making a wrench hole and a gauge window.

My first bandsaw was about the same weight as a VW (lots of cast iron) and had 24" wheels. It was about 7' tall. I can best describe it as sturdy and scary...

It was very old and didn't have a guard of any kind when I got it. The first thing I did was make it a simple wooden guard over the wheels to catch the blade if it came off. The contractor I got it from had just been using it all open. When a 3/4" wide blade that long snaps or runs off of the face side it qualifies as a major scary event...

.

nuhobby · Post by **nuhobby** » Mon Jan 06, 2014 7:06 pm

After a couple of years dabbling in old handsaw sharpenings, I have some thoughts about the bandsaw blades, perspective-wise....

- I don't think an 11-inch bandsaw like the SS would necessarily need as much blade tension as a bigger 14-inch bandsaw (especially one with riser blocks).

- A saw with a lot of lateral set to the teeth needs to do more work than one with little set, provides the chips get ejected OK in both cases. Usually you don't see much discussion of the tooth-set.

- Dozens of other variables I think come into play. Ultimately, if you get a good cut, you're doing more "right" than "wrong".....

reible · Post by **reible** » Mon Jan 06, 2014 7:11 pm

benush26 wrote:It's still too cold to go out in the shop so time for reading. I picked up my copy of "Care and Repair of Shop Machines" by John White and found an interesting article regarding the use of a tension gauge (he makes an inexpensive one from hardwood and nails) to accurately set up the blade tension on a bandsaw.

30,000 psi is his recommendation for 1/2" blade .0125 thick. However, he states that most "home" saw manufacturer's recommendations of 15,000 psi. He also states that after a few years use, the tension spring loses its set and should be replaced.

Interesting number of .0125 thick. The wood slicer is "thin at .022", other blades are typically thicker then .022 so what blades are being discussed?

For blades 1/4" and smaller I use the "flutter" method and am comfortable with it, but for larger blades I seem to rely on the tension spring measurement

I have the "Wood Slicer" fore resawing and was wondering....

The highland site has directions how to set the wood slicer and I think that works well for their blade and others.

1. Does anyone measure the tension (stretch) of the blade?

I do not and have not seen a reason to think I need to.

2. Has anyone ever found recommendations by Shopsmith on a maximum tension setting for their bandsaw? Part of this question is driven by the geometry of the Shopsmith versus a Jet, etc., and what stresses the Shopsmith saw can reasonably handle. After all they do suggest bending the shaft for realignment.

3. Has anyone replaced their tension spring as a part of maintenance (as compared to rebuilding the handsaw)? If you did, was there a noticeable difference in reliability of the scale?

The tension spring on the shopsmith should never reach its limit and bend. It should never need replacing. You might want to check the adjustment if you think you are having issues as it is something that can be adjusted.

I do realize that some never back the tension off, some always back it off after use and presume that many do a combination of both dependent upon time and mental state !

I'm a back offer, OK there might be a night or two that I forget but as soon as I see it I take care of it. The addition of a window on mine helps as a glance is all that is needed to see the status. I think it the right thing to do for most saws, that is unless you find in your instructions to leave the tension on....

If I can find a more accurate method to set tension, I am more than willing to try.

The tension setting is a guideline not the law. A good place to start and sometimes it works fine. If the cuts are looking bad, bowed, etc then something is not right and tension could be the problem. If the blade is fluttering then you should finding the problem.

Thoughts, ideas, input? Also, feel free to hijack this thread if it starts down any other path! Though we know that NEVER happens.

Be well,
Ben

Here is the woodslicer pdf in case you don't have it.

http://www.highlandwoodworking.com/library/resaw.pdf

I have a copy in my notebook(loose leaf) but after a couple of times you will do it without have to reference it.

Ed

edflorence · Post by **edflorence** » Mon Jan 06, 2014 8:32 pm

FWIW...Somewhere along the line I read, or at least I think I did, that a good rule of thumb for the SS bandsaw was to set the tension just a hair tighter than the gage setting for the size blade you are using. This seems to work well, but I am not sure where I picked up this bit of lore (or myth).

db5 · Post by **db5** » Mon Jan 06, 2014 9:01 pm

[quote="dustyI trust the tension indicators on my Shopsmith band saws.[/quote"]

Thank you for that, Dusty. Someone trusts a tension indicator from somewhere. Watching CNN, Fox News, MSNBC, local news and the weather channel as well as reading USA Today, Wall Street Journal and the local "liar, liar, pants on fire" publication I can't trust any of them. They all measure tension differently and that band saw blade is about to snap with a horrible outcome (or not, depending on what you watch, listen to, or read).

So your recommendation on trusting SS on the tension issue is welcome. But wait. . .Dusty? Dusty is that really your nom-de-plume? Does that mean that you have limited vision because of all the smoke, dust and debris that gets in your eyes? If so, perhaps you are a good candidate for Congress in the next election. You have two qualifications; limited vision (or blindness) and trust which is most important. Trust is everything. If you have the third qualification, the ability to lie with a straight face and keep lying you are a shoe-in. Trust however, is the key.

If you can't trust your mother or your elected officials who can you trust? Shopsmith. Or not.

If there was anything here that offended anybody, anywhere, anytime then it was unintended and I am deeply sorry, regretful and abjectly apologetic. That was not my intent and if you like your insurance you can keep it; if you like your doctor you can keep your doctor. And if you accept my apology then I am confident that you trust me to be forever honest, truthful, keeping only your interest at the forefront, forsaking any personal gain or profiteering on my part and will look forward to supporting my candidates for election/re-election in the next mud-wrestling competition in your state. Please do not PM me. I get enough grief from just having cable TV.

Thank you and God Bless You and God Bless America.

JPG · Post by **JPG** » Mon Jan 06, 2014 9:41 pm

[quote="db5"]Thank you for that, Dusty. Someone trusts a tension indicator from somewhere. Watching CNN, Fox News, MSNBC, local news and the weather channel as well as reading USA Today, Wall Street Journal and the local "liar, liar, pants on fire" publication I can't trust any of them. They all measure tension differently and that band saw blade is about to snap with a horrible outcome (or not, depending on what you watch, listen to, or read).

So your recommendation on trusting SS on the tension issue is welcome. But wait. . .Dusty? Dusty is that really your nom-de-plume? Does that mean that you have limited vision because of all the smoke, dust and debris that gets in your eyes? If so, perhaps you are a good candidate for Congress in the next election. You have two qualifications]
Sorry, no cigar!

Dusty cannot meet the third criteria.

Not too sure about the first either!

Why on earth would anyone want to Post Menopausal you?