Proper detensioning of the bandsaw blade for periods of inactivity

[James Nugnes]

Now this might seem like a dumb as dirt question. So I apologize for that. All the bandsaws I have ever worked on before have either been large (not my own) or smallish (some of them my own). None until this one have had a tension handle. All the others have had tension wheels and some really small ones....tension knobs.

So this is my first with a tension arm/handle. I know the standard instruction is to take tension off the blade via the arm/handle while not in use. I think that means, just take some of the tension off as opposed to detensioning the blade all the way. All the way and the blade is just sort of hanging there draped over the wheels.

However if that is in fact what should be done, I am OK with it. Just does not make as much sense to me as simply taking max tension off the system while not in use. Just partially detensioning the system at least keeps enough there so that the blade stays pretty much where it should be just with less tension. Does that make the most sense or should one truly detension all the way, meaning drop the handle to its full detensioned position?

[Myk Rian]

How do you "partially" de-tension? Aren't those devices made to go all or none?
By the way, I never de-tension.

[John TenEyck]

I'm not convinced there's any benefit to de-tensioning other than for a carbide tipped blade perhaps. I have never done so in 30 years of using my bandsaw. Bearings, 15 year old Iturra spring, etc. all still fine. Never had a blade break except for Timberwolf and they run at low tension. Seems more like Marketing/Sales hype than engineering benefit.

John

[John McClanahan]

My understanding is that de-tensioning the blade for storage prevents the tires from getting a sort-of flat spot where the blade contacts the tires.

My Grizzly saw has a de-tension arm. If I move the arm to the full de-tension, the blade likes to shift around, so I leave some tension on the blade to keep it centered on the wheels.


John

[Chris Padilla]

I think if your bandsaw sits weeks at a time from inactivity (like mine does), then taking the tension off makes sense. If you use it daily, then I see no reason for it. I took a class from David Marks recently. He doesn't detension but then again he has 6 bandsaws he uses fairly regularly and really has no interest in detensioning them every night. :)

[James Nugnes]

Well there is a a little feel to the handle but not much. You are right in that they seem to be designed as an on/off device.

The handle can be used a bit more when you are first tensioning a blade. If you are searching for just the right spot, you can take some tension off with the handle with one hand and turn the wheel with the other. You can gain some adjustment range easily this way. When you are happy with the tension with the handle up, you are done.

I could see the value of using the handle to detension the blade for periods of inactivity as long as the blade was retained with enough tension to al least hold it in position. That is the marketing copy regarding the handle. Take tension off the blade, wheels and spring so that nothing is under tension for long periods of inactivity and then a flip of the handle and you are back and business. I would say to that, not if the blade has just been hanging there by a thread just sort of draped over the wheels. That does not seem like such a great idea.

[Peter Quinn]

My former saw (PM14) had a quick tension release that had two detents, one was to relieve tension from the saw, the other was full off for blade changes. The prior released just enough tension to let the spring mostly relax but not so much that blade alignment went haywire and things got out of place. The latter was for blade changes, so completely slack, blade falling off, you might have to be careful just pulling the handle back up as the blade could leave the guides and get off a bit requiring some effort to realign it on return to full tension. So if you have two detents, I'd use the first one. On bigger saws it takes just a few turns of the wheel to accomplish the same thing, not slack, just not completely tight for longer term storage. I'm not convinced it does much good, but I can't see it does any harm, so I do it to feel on the safe side.

[John Huds0n]

When I was shopping for bandsaw blades, I saw this on the Timberwolf Web Site and it made sense to me - so that is what I do

http://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.