Author Topic: De-tension bandsaw blades when not in use?  (Read 2339 times)

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Offline mattbyington

  • Posts: 458
De-tension bandsaw blades when not in use?
« on: February 21, 2020, 04:50 PM »
Hey team,

I started a thread about an N4400 I bought recently. The blade came yesterday. I'm so, so excited to use it this weekend.

A very basic question and apologies in advance. I have never owned a bandsaw before.

Should I be de-tensioning the blade after working, or leave it tensioned 100% of the time?

Thanks so much in advance.

Matt

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Offline Bob D.

  • Posts: 1571
Re: De-tension bandsaw blades when not in use?
« Reply #1 on: February 21, 2020, 04:59 PM »
I always do with mine. And to remind myself I have a caution sign on the BS next to the power switch to check blade tension before use.

I printed this out on some bright yellow paper and glued it to one of those fridge magnets you get in junk mail sometimes.

-----
It's a table saw, do you know where your fingers are?

Offline rmhinden

  • Posts: 253
Re: De-tension bandsaw blades when not in use?
« Reply #2 on: February 21, 2020, 05:15 PM »
I have a Delta 14" bandsaw with extension.  I do not de-tension the blades, except with I am changing the blades.   

Doesn't seem to have harmed it in the 25 years I have owned it :-)

Bob


Offline ben_r_

  • Posts: 1268
Re: De-tension bandsaw blades when not in use?
« Reply #3 on: February 21, 2020, 05:18 PM »
N4400 owner here and I ALWAYS de-tension any blade I have on my bandsaw even if its only going to be sitting over night. Its just not that hard to re-tension it the next day and why risk blade deformation?
If at first you don't succeed, redefine success!

Offline Mike Goetzke

  • Posts: 495
Re: De-tension bandsaw blades when not in use?
« Reply #4 on: February 21, 2020, 05:26 PM »
I de-tension mine - I thought it was more to prevent the tires from deforming than anything else.

Mike

( Edited - when I de-tension I usually don't loosen it all the way because some blades come close to falling off the wheels if you do. )


Found this on Suffolk Machinery web page (lots of other info there too- https://www.suffolkmachinery.com/six-rules-of-sawing.html ):

ALWAYS DETENSION YOUR BANDS
When you are done cutting for the day, take the tension off your blade. Band saw blades, when warmed up from cutting, always stretch; and upon cooling shrink by tens of thousandths of an inch each cooling period. Therefore, blades, when left on the saw over tension themselves and leave the memory of the two wheels in the steel of the band, which will cause cracking in the gullet. When you leave the band on your saw under tension, not only do you distort the crown and flatten out the tires (which makes them very hard), but you also place undue stress on your bearings and shafts. Believe it or not; you can, and will damage your wheel geometry sooner or later and considerably shorten bearing life. You are also crushing your tires or V-belts.
« Last Edit: February 21, 2020, 05:34 PM by Mike Goetzke »

Offline Jiggy Joiner

  • Posts: 961
Re: De-tension bandsaw blades when not in use?
« Reply #5 on: February 21, 2020, 05:26 PM »
It’s good practice to slacken the blade after use. It’s usually just the turn of a lever, and sometimes lock.
I made warning stickers for our bandsaws, they are stuck near the on off switches.
Not slackening the blade will cause stretching, and depending on how temps change, can be quite drastic and cause tyre issues. Stretching causes premature wear too.

Definitely slacken it of when not in use, at least at the end of each day.

Offline WarnerConstCo.

  • Posts: 4112
    • Warner Mill Works
Re: De-tension bandsaw blades when not in use?
« Reply #6 on: February 21, 2020, 05:54 PM »
Never.

Sent from my SM-N960U using Tapatalk


Offline kevinculle

  • Posts: 322
Re: De-tension bandsaw blades when not in use?
« Reply #7 on: February 21, 2020, 07:26 PM »
14" Delta with riser block...I leave my saw blade tensioned with no apparent ill effects.

Online derekcohen

  • Posts: 412
    • In The Woodshop
Re: De-tension bandsaw blades when not in use?
« Reply #8 on: February 21, 2020, 08:48 PM »
Matt, many will say that they do not de-tension, but I always do so. My concern is not so much the blade stretching and fatiguing, but the compression of the tyre. The 1" carbide CT requires the highest down force from the N4400.

Regards from Perth

Derek

Offline vkumar

  • Posts: 468
Re: De-tension bandsaw blades when not in use?
« Reply #9 on: February 21, 2020, 10:23 PM »
The only thing is that you absolutely have to remember to tension it before you turn it on.  If you dont  you might end up trashing your blade, tires etc.
Vijay Kumar

Offline Cheese

  • Posts: 7022
Re: De-tension bandsaw blades when not in use?
« Reply #10 on: February 21, 2020, 10:53 PM »
Ya, this is one of those Chevy vs Ford debates.

I purchased a new 8-speed 14" Delta band saw for cutting metal and wood in 1994. The tension with a 1/2" wide blade has never been released since I purchased it.

The original tires are still good, the bearings are fine and it cuts straight.

I've revisited the idea of retrofitting a de-tension arm on the saw many times. Not because I've had issues with the cutting but rather because it makes changing the blade a lot easier.

Don't know Matt...this is a toss-up.
« Last Edit: February 22, 2020, 09:06 AM by Cheese »

Offline tjbnwi

  • Posts: 6207
  • Cedar Tucky Indiana
Re: De-tension bandsaw blades when not in use?
« Reply #11 on: February 22, 2020, 12:30 AM »
Don’t install the blade—problem solved [big grin]

I don’t detension the blade on my Rikon.

Tom

Offline ChuckM

  • Posts: 1553
Re: De-tension bandsaw blades when not in use?
« Reply #12 on: February 22, 2020, 12:43 AM »
The newer ones are easy to detension (and tension) and it just takes a second or two. Mine has a threaded rod to unwind...and still, I detension mine everytime after each use.

Offline chewy

  • Posts: 86
Re: De-tension bandsaw blades when not in use?
« Reply #13 on: February 22, 2020, 01:41 AM »
I've never detensioned mine. Sounds like an accident waiting to happen!

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Offline Bob D.

  • Posts: 1571
Re: De-tension bandsaw blades when not in use?
« Reply #14 on: February 22, 2020, 07:47 AM »
The only thing is that you absolutely have to remember to tension it before you turn it on.  If you dont  you might end up trashing your blade, tires etc.

Oh, believe me, YOU WILL trash them.


Don't ask.. :-(
-----
It's a table saw, do you know where your fingers are?

Offline kcufstoidi

  • Posts: 877
Re: De-tension bandsaw blades when not in use?
« Reply #15 on: February 22, 2020, 08:39 AM »
A total and complete waste of time that can be extremely dangerous. I've run my Felder FB600 since new in 2011, through 10's of thousands of lineal feet of cutting with a Woodmaster CT and never released the tension and had no ill effects that these types of discussions generate. The CT takes an extreme amount of tension that the N4400 can't really achieve to the max potential out of the blade. You have to run it with the spring completely compressed to get any where whats needed and its a complete PIA to tension and detension. This type of info is continually repeated and based low end bandsaw with junk construction and soft rubber wheels not something you find in higher end machines like the Hammer N4400. But as always believe and do as you want it will not make any difference to me.

Offline ChuckM

  • Posts: 1553
Re: De-tension bandsaw blades when not in use?
« Reply #16 on: February 22, 2020, 08:57 AM »
Haha. This sounds like the plugged version of "Tails first or pins first" debate.

I think the older, smaller bandsaws and the width of the blade (e.g.,1/8") should be treated differently. Newer bandsaws I have looked into do come with user-friendly detensioners.

It is true that forgetting to tension the blade before turning on the machine could lead to blade damage if the situation is not corrected soon enough. But detensioning is not necessarily the same as loosening. My solution is to leave a block of wood in front of the blade marked in color: "Tension." So far, it has worked...for over 20 years. Others have put their reminders on the power switch like this: https://www.pinterest.ca/pin/683702787154890818/

If in doubt, I would check with the manufacturer whether or not the new saw needs detensioning.
« Last Edit: February 22, 2020, 12:53 PM by ChuckM »

Offline grbmds

  • Posts: 1976
Re: De-tension bandsaw blades when not in use?
« Reply #17 on: February 22, 2020, 09:18 AM »
I don't detention and haven't seen any problems develop over time on my bandsaw. I now own a Rikon 10-325 and, over the 5+ years I've owned it I have not had any problems that I can associate with not detensioning.

Some articles I've read say that, if the saw is used everyday, detensioning is probably not a significant issue. If it's not used everyday, the articles say, possible flat spots can develop and extra stress is placed the blade. I think the danger from forgetting to tension the blade again when using the saw is a bigger issue. I have never noticed the saw running rougher because of flat spots and I've never had a blade fail.
Randy

Offline kcufstoidi

  • Posts: 877
Re: De-tension bandsaw blades when not in use?
« Reply #18 on: February 22, 2020, 09:19 AM »
Every bandsaw and setup has to be treated differently but few understand this simple concept. The discussion here is the OP has a quality bandsaw and is trying to use a 1" blade his saw can't really handle, that pushes it to limit. An 1/4" blade on this saw is no different because of the rubber hardness and the fact it really doesn't deflect like an old 14" Delta would. You will get more damage from the teeth cutting the rubber, tensioning has nothing to due with this. Every bandsaw manufacture that supplies to a potential hobbyist buyer will put the disclaimer in to detension to cover their butt. Even with heavy cutting the blades don't get very hot and the minimal heat they develop has very little effect on the rubber.

Offline ChuckM

  • Posts: 1553
Re: De-tension bandsaw blades when not in use?
« Reply #19 on: February 22, 2020, 09:29 AM »
Every bandsaw manufacture that supplies to a potential hobbyist buyer will put the disclaimer in to detension to cover their butt.

Could they tell if something goes wrong with the machine under warranty whether the problem is due to not detensioning?

Offline Jiggy Joiner

  • Posts: 961
Re: De-tension bandsaw blades when not in use?
« Reply #20 on: February 22, 2020, 09:51 AM »
We have two commercial bandsaws and a heavy duty pro model. All three are from different manufacturers, and all the user manuals recommend slackening the blade off at the end of each working day.
Ours just have levers, and fine adjustment, so tensioning and de tensioning is a slight turn of a lever.
As I mentioned, we have warning stickers at the on/off switches, so nobody forgets.
I slacken the blades off out of habit, as it was how I was taught years ago.

Each to their own I guess.

Offline kcufstoidi

  • Posts: 877
Re: De-tension bandsaw blades when not in use?
« Reply #21 on: February 22, 2020, 10:01 AM »
Well you are either the sheep, the dog or sheep herder. Your choice. Some old info we were taught is just that, and it just keeps getting passed forward like gospel.

Offline ScotF

  • Posts: 2742
Re: De-tension bandsaw blades when not in use?
« Reply #22 on: February 22, 2020, 12:20 PM »
I do - to prevent issues with the tires. It is simple on mine to unscrew the tension wheel to the right tension. If you are using daily then this would be less of an issue.

Offline Df1k1

  • Posts: 97
Re: De-tension bandsaw blades when not in use?
« Reply #23 on: February 22, 2020, 12:23 PM »
Laguna bandsaw owner. I always de-tension then leave the door open as a reminder to re-tension the blade. Not sure if it makes a difference but I would rather err on the side of caution. There certainly is nothing wrong with reducing the tension but there may (or may not) be an issue with tension 24/7.
Same reason I always unlock the tension on my fence on my saw stop.  Heck, probably doesn’t make a difference but I feel better

Offline ChuckM

  • Posts: 1553
Re: De-tension bandsaw blades when not in use?
« Reply #24 on: February 22, 2020, 12:35 PM »
Laguna bandsaw owner. I always de-tension then leave the door open as a reminder to re-tension the blade.
Snip

Now, that's clever.

Snip
Same reason I always unlock the tension on my fence on my saw stop. 

I know of no table saw users who intentionally leave their saw fences in tension. Some probably forgot to release the lever after making the last cut.

A Rikon 14" bandsaw product description I came across includes this: "...a release lever lets you instantly loosen blade tension to prevent premature blade fatigue and wear to the saw's bearings, tires and spring." Myth or truth (or sales pitch)? Your call.
« Last Edit: February 22, 2020, 12:54 PM by ChuckM »

Offline Bob D.

  • Posts: 1571
Re: De-tension bandsaw blades when not in use?
« Reply #25 on: February 22, 2020, 01:09 PM »
I release tension as I said on my bandsaws, but thinking back I worked in a pipe fab shop for many years and we never de-tensioned the blades on those bandsaws. We had a couple Marvel tilt head vertical bandsaws, I don't remember the particular model but it doesn't matter, we cut 16" WF beams, pipe, and all sorts of steel with them but never released the tension at the end of the day. Didn't seem to bother them one bit.

I do it on my wood bandsaws because that's what the manual advises. It takes only a second but YES it does open you up to the possibility of starting the saw with the blade de-tensioned. Like every other tool in your shop you have to engage your brain first, then proceed to operate the tool which includes ensuring the blade is clear of any obstruction and ready for action.

And yes, I did once screw up and start my 12" bandsaw without checking the tension. Ate the tire on the upper wheel and destroyed the blade. Lesson learned and 15 years later no repeats. :-)
-----
It's a table saw, do you know where your fingers are?

Offline Cheese

  • Posts: 7022
Re: De-tension bandsaw blades when not in use?
« Reply #26 on: February 22, 2020, 01:48 PM »
...but thinking back I worked in a pipe fab shop for many years and we never de-tensioned the blades on those bandsaws. We had a couple Marvel tilt head vertical bandsaws, I don't remember the particular model but it doesn't matter, we cut 16" WF beams, pipe, and all sorts of steel with them but never released the tension at the end of the day. Didn't seem to bother them one bit.

Good point Bob, thinking back over the years in the machine shops and the engineering model shops, metal cutting band saws were never, ever de-tensioned. The only time the blade tension was released is when the saw blade broke.  [tongue]

Offline WarnerConstCo.

  • Posts: 4112
    • Warner Mill Works
Re: De-tension bandsaw blades when not in use?
« Reply #27 on: February 22, 2020, 02:24 PM »
Big difference between a real industrial cast iron saw, with large bearings and large spindles.

These welded steel saws with small arbors and small bearings wont last as long and the manufacturer knows that tension will decrease that time even more before components fail.

It's how they cya. 

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Offline ChuckM

  • Posts: 1553
Re: De-tension bandsaw blades when not in use?
« Reply #28 on: February 22, 2020, 03:05 PM »
If detensioning were indeed meaningless, shouldn't at least one bandsaw manufacturer seize the opportunity and release a bandsaw model that promoted "detension or retension totally not required" as its a selling point?


Offline Svar

  • Posts: 1996
Re: De-tension bandsaw blades when not in use?
« Reply #29 on: February 22, 2020, 03:12 PM »
Manufacturers that recommend de-tensioning should be adding auto switch. You can't start the saw unless it is tensioned. One could probably DIY it too.