De-tension bandsaw blades when not in use?

[ChuckM]

Snip

I even know of a cabinet maker that slackens coping, and fret saw blades when not in use.

I'm one of them, with my Knew fret saw (for a good reason: it uses screw friction to hold the tensioned blade in place, and you don't want those screws worn out prematurely)!

As I said, small or hobbyist bandsaws and narrow blades should deserve different considerations, and I'm not surprised that industrial type or huge bandsaws (metal or woodworking) may have different maintenance needs, just like a mining truck may be serviced and maintained differently from a SUV.

As I dug a little more on this topic online, I found many better known and seasoned woodworkers splitting on this issue as well, although I have yet to find any published materials (books or magazines or manuals) that suggest detensioning is unnecessary for any non-industrial bandsaws intended for hobbyists. Perhaps someone should do so, offering their reasoning and research data to support it.

I found someone quoting online a sawblade maker (Timber Wolf blades) saying this:

  Suffolk Machinery----

"You are somewhat correct. We do recommend de-tensioning to reduce stress on the saw but more so to reduce stress on the blade. De-tensioning is more critical to narrower blades than wider blades although tension/strain is relative to the size of the blade and sawing application. We run as much as 37,500 psi on wider blades such as our 2" x .052 thick blade vs. 9,000 psi on a 1/4" blade. Therefore, we recommend it on all blades. "

Since everyone on either side is happy with what they've been doing, they should keep their practice.

Edit: Mark Duginske (who also patented the cool blocks, among other things) has this to say in his book (2007, 2014): "Releasing the tension is good for extending blade and tire life, though, contrary to popular misconception, it has no effect on the spring...."

 

[grbmds]

Yesterday I asked Alex Snodgrass (Carter Products) whether taking the tension off the blade is recommended or not. I consider his recommendations valid. He responded that he does take tension off at the end of each day, but it was to avoid flat spots on the bandsaw tires and not related to the blade. Since there are potential flat spots, especially at the top and bottom, more vibration is likely when the saw is turned on the next time. However, after the tires warm up, the flat spots disappear and the vibration disappears. No permanent damage to either the blade, the wheels, or the tires, results. I'm sure everyone will continue to do whatever they have been doing, but keeping tension on doesn't appear to be a practice which causes any permanent problems. That has been my experience also.

 

[ChuckM]

Interesting that you mentioned Alex who does the Bandsaw Clinic in the Woodworking Shows (for over 15 years?). He is on record to have said (check out one of the youtube videos) to the effect that no one knows a bandsaw better than its manufacturer. At the request of Chuck Bender, he recently installed, among other items, a quick-release tensioner in Chuck's Delta bandsaw. Chuck's video shows his step-by-step process.

 

[Jiggy Joiner]

I don’t know if it matters or not, I slacken the blades usually at the end of the day. It takes seconds, to slacken or tension, so certainly not a problem.

If it doesn’t matter, why do all the manufacturers instruct owners to carry out the procedure in the user manuals?

I’m pretty sure a slackened blade is going to cause zero issues in that state, I can’t imagine the same can be said for a tensioned blade, no matter how minimal?

I even know of a cabinet maker that slackens coping, and fret saw blades when not in use.

The manufacturers that state this practice, like I said previously, are the ones that build light weight welded steel saws.

They are probably well aware the components will wear out faster. 

No where, in any literature did Yates American say to detension this saw.

Sent from my SM-N960U using Tapatalk

My machines are commercial, and a heavy duty pro model, they are by no means lightweight. All built in the UK.

From other posts here, it’s clear to me, that slackening a blade, is doing less harm than tensioning one does. It doesn’t matter how big or small the difference, the warnings are there in the manuals, from lightweight to big heavy cast machines. Often the warnings are accompanied by an explanation, stating why this practice is recommended.

Everybody is free to make their own decisions, over many years, I’ve found that reading the actual manual is a wise decision, and taking heed of it is also good advice.
I’ll carry on de tensioning, as the benefits outweigh the negatives (in my opinion)

 

[WarnerConstCo.]

I don’t know if it matters or not, I slacken the blades usually at the end of the day. It takes seconds, to slacken or tension, so certainly not a problem.

If it doesn’t matter, why do all the manufacturers instruct owners to carry out the procedure in the user manuals?

I’m pretty sure a slackened blade is going to cause zero issues in that state, I can’t imagine the same can be said for a tensioned blade, no matter how minimal?

I even know of a cabinet maker that slackens coping, and fret saw blades when not in use.

The manufacturers that state this practice, like I said previously, are the ones that build light weight welded steel saws.

They are probably well aware the components will wear out faster. 

No where, in any literature did Yates American say to detension this saw.

Sent from my SM-N960U using Tapatalk

My machines are commercial, and a heavy duty pro model, they are by no means lightweight. All built in the UK.

From other posts here, it’s clear to me, that slackening a blade, is doing less harm than tensioning one does. It doesn’t matter how big or small the difference, the warnings are there in the manuals, from lightweight to big heavy cast machines. Often the warnings are accompanied by an explanation, stating why this practice is recommended.

Everybody is free to make their own decisions, over many years, I’ve found that reading the actual manual is a wise decision, and taking heed of it is also good advice.
I’ll carry on de tensioning, as the benefits outweigh the negatives (in my opinion)

But they are probably welded steel construction with small arbors and bearings?

Not in any manual or literature on any American made bandsaw since about 1880, earliest machinery catalog I own.

Sent from my SM-N960U using Tapatalk

 

[Jiggy Joiner]

Interesting that you mentioned Alex who does the Bandsaw Clinic in the Woodworking Shows (for over 15 years?). He is on record to have said (check out one of the youtube videos) to the effect that no one knows a bandsaw better than its manufacturer. At the request of Chuck Bender, he recently installed, among other items, a quick-release tensioner in Chuck's Delta bandsaw. Chuck's video shows his step-by-step process.

Exactly, as I mentioned earlier, the manufacturers know the machines they build, better than us.
Why would we have reason to believe their advice is nonsense, or doesn’t really matter?

 

[mattbyington]

Wow, thank you everyone for such an interesting discussion. I've read everyone's comments, some real great tips in there. I really appreciate everyone's point of view.

Matt

 

[Oldwood]

Another factor is the diameter of the wheels. The 20 to 36" wheels don't stress the band like the 12 to 16" saws do. This stress causes fractures in the gullets of the teeth.

The bandsaws I have owned are a 36" and 24" both big heavy saws and I never detensioned the blade.

I don' think the saws like Darcey owns are going to have a problem and the large wheels cause very little stress on the bands.

 

[junk731]

I don’t know if it matters or not, I slacken the blades usually at the end of the day. It takes seconds, to slacken or tension, so certainly not a problem.

If it doesn’t matter, why do all the manufacturers instruct owners to carry out the procedure in the user manuals?

I’m pretty sure a slackened blade is going to cause zero issues in that state, I can’t imagine the same can be said for a tensioned blade, no matter how minimal?

I even know of a cabinet maker that slackens coping, and fret saw blades when not in use.

The manufacturers that state this practice, like I said previously, are the ones that build light weight welded steel saws.

They are probably well aware the components will wear out faster. 

No where, in any literature did Yates American say to detension this saw.

Sent from my SM-N960U using Tapatalk

My machines are commercial, and a heavy duty pro model, they are by no means lightweight. All built in the UK.

From other posts here, it’s clear to me, that slackening a blade, is doing less harm than tensioning one does. It doesn’t matter how big or small the difference, the warnings are there in the manuals, from lightweight to big heavy cast machines. Often the warnings are accompanied by an explanation, stating why this practice is recommended.

Everybody is free to make their own decisions, over many years, I’ve found that reading the actual manual is a wise decision, and taking heed of it is also good advice.
I’ll carry on de tensioning, as the benefits outweigh the negatives (in my opinion)

Curious as what what Bandsaws are still made in the UK or are we talking about vintage stuff like Wadkins.

 

[Jiggy Joiner]

I don’t know which UK companies still make band saws nowadays, as most are gone.

Ours are old but not vintage, well not 1880 anyway.

We’ve got two from Wadkins, and the other is either Start Rite, or Meddings.

 

[Bob D.]

The attached are from old Rockwell/Delta Bandsaw manuals, one for a 1946 14" model and the other for a 1964 20" Metal/Wood bandsaw.

Both recommend detensioning the blade when not in use.

 

[Joe Jensen]

Engineer here adding to an old thread.  Metal flexes and returns to it original shape unless flexed far enough to reach "Plastic Deformation".  This is where it bends and stays bent.  If the saw doesn't flex far enough to reach plastic deformation it will return to its original shape.  As far as metal fatigue, regular tension/detention will likely be harder on the blade and the saw than leaving it tensioned all the time.  The tires could develop a flatter spot with tension all the time.  So if you detention to protect, it's likely you are protecting the tires and not the saw or the blade.  I have a 1967 Tannewitz 30" and the manual says nothing about detentioning.

 

[WillB]

Great input....
After reading this thread, its obvious to me, one size does not fit all regarding this issue.
A few points I never thought about introduced here... the large diameter wheels, 20-36" bend the blade  a LOT less vs. smaller diam wheels...so comparing a 16" saw vs. 36" saw regarding this issue is like night n day.

Seems the blade gullets are also effected, as well as wear on the rubber.
I de tension because I don't use the saw often, and feel the added tension can add wear to blade, rubber and bearings.  While bearings on smaller saws might not fail keeping it tensioned, my guess is the bearings do wear, making them a bit less precisioned when running.  Whether that is a problem, depends on what you use the saw for.  My guess is, for re sawing, de tensioning might reduce rubber and bearing wear, possibly allowing higher precision thin veneer cuts.  For rough cross cuts, or cutting thin wood, cant see any benefit in de tensioning...

I also agree, the manufacturers tend to know more than the users, even if they are erring on the safe side.