Bandsaw Tension Indicator

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Project by Oldtool posted 11-11-2013 06:48 PM 2644 views 1 time favorited 9 comments Add to Favorites Watch

Conventional wisdom suggests that band saws be taken out of tension when not in use for long periods of time, a philosophy to which I subscribe. However I often find myself second guessing as to whether or not I performed this function after leaving the shop, so after many trips back to check for this at all hours of the night, and one day’s visit only to find that the saw was under tension for a prior couple of days, I decided to do something about it.

Ebay purchases consisted of one (1) sewing machine flexible lamp, for about 14 dollars, and ten (10) micro-switches for about $5. The lamp was chosen because it contained a magnetic base, a flexible arm, and most importantly (to me) it is an LED lamp, which means low power consumption (0.5 W) – yet still pretty bright.

The micro-switch selected was chosen for the flexible activation arm with a roller on the end, and a much higher power rating than I need at: 15 Amp / 1/2 HP at 125 & 250 Volts.

Mounting the switch on a scrap piece of plywood cut to fit the tensioning arm of my bandsaw, along with two H-F rare earth magnets on the other side, as shown in the photos, I opened & wired one of the lamp’s power wires through the switch.

The mounting of the switch as shown allows tripping when the upper wheel mounting assembly rises up when tensioned, and with the assembly held in place by the magnets thus making it adjustable for different blade tensions / mounting heights. In this case though, adjustment for a 1/4” blade at a lower setting works for the 1/2” blades as well, due to the flex in the switch arm and roller.

I leave the lamp plugged in at all times, with the lamp base switch always on, so the lamp only powers on when the saw is under tension, is used as a work lamp, and can only go off when the tension is relieved. Now when I turn out the shop lights, if these is a glow at the saw, tension release is needed.

My only problem now, what to do with the other 9 switches. Got to work on this, any suggestions?

-- "I am a firm believer in the people. If given the truth, they can be depended upon to meet any national crisis. The point is to bring them the real facts." - Abraham Lincoln

9 comments so far

View BubingaBill's profile


297 posts in 1888 days

#1 posted 11-11-2013 07:23 PM

Great idea! I kept waiting to see where you used the other 9 switches!

-- Measure twice and try not to cut your thumbs off!

View nuttree's profile


280 posts in 3528 days

#2 posted 11-11-2013 08:50 PM

Ingenius idea and executuon

-- I only went out for a walk and finally concluded to stay out till sundown, for going out, I found, was really going in. -John Muir

View Biff's profile


126 posts in 2218 days

#3 posted 11-12-2013 01:02 AM

Great idea! I personally never release the tension on any of my bandsaws and I haven’t had a problem. I think if they are used regularly the blade doesn’t take a set. IMHO it’s a needless thing to worry about but your solution is well executed!

-- Interested in Oregon property? Visit me at

View Oldtool's profile


2738 posts in 2394 days

#4 posted 11-12-2013 02:08 AM

I think the reason for tension release is to avoid a flat on the tire, but then again I’m no expert. If your machine is used daily, perhaps this doesn’t occur for you. In any event, I like the tension release theory, don’t like to leave any machine in a stress condition, just my way of thinking.

Thanks for the comments all.

-- "I am a firm believer in the people. If given the truth, they can be depended upon to meet any national crisis. The point is to bring them the real facts." - Abraham Lincoln

View Hybridwoodworker's profile


28 posts in 2336 days

#5 posted 11-12-2013 03:29 AM

Blast gates to turn on the DC

Create a foot switch for your router

Do the same thing on your drill press. Set it so a work
Light comes on with a small movement of the quill. Never leave the light on that way


-- Life is hard, it is harder if you are stupid.

View bch's profile


296 posts in 2893 days

#6 posted 12-12-2013 10:18 PM

This is positively brilliant. Wonderful job!

-- --bch

View WOODCEPTUAL's profile


84 posts in 2102 days

#7 posted 09-13-2015 11:24 PM

Very clever! :D

-- The only difference between try and triumph is a little umph... and many a splinter in the hands! ;)

View Arlin Eastman's profile

Arlin Eastman

4251 posts in 2765 days

#8 posted 09-13-2015 11:51 PM


You will have to help me out with this.

Since I no longer remember much about Bandsaws why do you have to take the tension off of the blade everyday if you use it everyday?

I guess I will have to start but never realized I had to and thought it was only for replacing the blade.
Thanks for any advise.

-- It is always the right time, to do the right thing.

View Oldtool's profile


2738 posts in 2394 days

#9 posted 09-14-2015 12:13 AM

A discussion about bandsaw tension is like the old debate over dovetails – pins or tails first, only here its de-tension or not.
Some say they never take tension off their bandsaw & nothing comes of it, while others always relieve tension when finished with the saw.
I always relieve tension, because it can’t hurt anything, while not doing so “may” stress the blade, and flatten the tire.
I relieve tension on all my tools when finished, like: loosening the screw that bows the blade on my Stanley & Veritas scrapers, etc. This is my preference, due mainly to my belief that stress over time is not a good thing, while relieving it can’t possibly have any negative effects.

Hope this answers your question, but if not I’ll be glad to discuss further, or you can search here in LJs for other discussions and forums concerning this topic.
Have a great day.

-- "I am a firm believer in the people. If given the truth, they can be depended upon to meet any national crisis. The point is to bring them the real facts." - Abraham Lincoln

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