The Mfgr of my bandsaw tells me I should always release the tension after the day’swork. Yet none of my woodworking friends bother to do this.
Is it really necessary? Does leaving the tension on when the saw is not used (for days or weeks at a time) cause any problems at all with the tires, the blade, the tension spring, or other parts of the machine?
I know this has probably been discussed here before, but I found no mention of it in the outline.
I would be grateful for any advice/thoughts any of you might have.
Replies
In a word, yes. The blade will be in constant tension thus shortening its useful life. At the very least, the blade will stretch gradually, requiring more and more tensioning, which brings us to the spring. The spring will be under constant compression and will fail prematurely (especially when the blade is overtensioned and the spring is compressed to the point where it cannot do its essential function--spring back). The tires will be squeezed between the blade and the wheels, possibly deforming the tires, or worse, the wheels. In extreme cases, even the frame may suffer deflection.
Having said that, I believe that not detensioning the blade is usually a result of forgetfulness and inconvenience. The first, of which I am occasionally guilty, can be addressed over time by establishing a routine (or at least leave a reminder by the light switch). The second can be solved with upgrades like the Carter Quick-Release (handy but spendy) or something as simple as replacing the star knob with a crank so tensioning and detensioning goes a lot faster.
>> At the very least, the blade will stretch gradually ...
I'd want to see some numbers on that. AFAIK, bandsaw tension is well within the elastic limit of the kinds of steels used for blades.
No hard numbers, I'm afraid, just intuition and some experience. I find that some of my older blades require a little bit more tension than when they were newer. However, it might be other factors contributing to this like, for example, worn or deformed (as a result of not detensioniong regularly) tires causing blade slippage and requiring increased tension to maintain adequate tracking. At any rate, if your figures support your assertion, then I would certainly cede to your argument.
I have 2 bandsaws - an 18" Grizzly that I use only for resawing, and a 12" Craftsman that is used for all other bandsaw work. The Grizz uses 1" blades so I suspect that the tension is high. So high, in fact, that I stripped the threads on the original "factory" bolt that sets the tension. I use a 1/2" or smaller blade on the Craftsman so I suspect that the tension is much lower. I release the tension on the Grizz after each use and have had no problems. I've had the saw about two years. Have had the Craftsman 11 years and the only time the tension is released is when blades are changed. Both saws work fine. Conclusion: I don't really know if releasing the tension on a large saw is necessary, but I don't think it needs to be done on a saw with a small blade. Not a scientific study, but one case based on empirical data.
yes release the tension. You save your spring, your frame, your precious bearings, and your threaded rods that help keep tension. springs and threaded rods are easy to replace. However prolonged tension can cause your bearings to go bad, they are a pain to replace.
I had a 14" Jet BS and forgot to release the tension one day. When I used it next, it made a terrible racket. the metal piece that is used to adjust the upper wheel had become weak and actually bent. I was using a half inch Timberwolf blade with out lots of tension ... but clearly enough tension to destroy a piece of the saw. Bottom line is that I never leave my BS with tension after working. (I sold the Jet and now have an 18" Laguna ... a much better BS but that's another story.)
John
hi guys - just found this forum and thanks for the bs discussion. i have a mm16 - used mostly for resawing veneers. the company says there's no need to detension after using - that the bearings can stand the stress. i recently bought a bs blade tensioning gauge. when i tensioned the blade with gauge - it went way past where i usually go - using the "give the blade moderate finger pressure with a 1/4" deflection" - i mean way past. i do de-tension after the work is done - i figure the less stress the long-term better.
jerry
Hi nikkiwood:
Do release the tension. It will double the life of the bearings and tires
Good luck, and be safe
Dennis
Edited 1/7/2003 12:24:03 AM ET by DENIS364
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