Blade tension can make or break your bandsaw’s performance.
Proper blade tension is a crucial safety measure to consider when operating your bandsaw. Blade tension that is too tight could strain the blade and cause it to break. Blade tension that is too loose can make your blade come off the track and cause serious injuries/ damage.
Too much or too little tension is also a significant cause of poor cutting performance on your band saw.
Finding the right blade tension is a challenging task. There are many methods and theories out there, and you need to find one that works for you.
For instance, some people recommend plucking the blade like a guitar until it produces a specific musical pitch with a clear tone. Without any doubt, this method works for some musically inclined woodworkers. But how practical and accurate is it for the majority who don’t have musical knowledge?
Other theories claim that you find the tension that is comfortable for your bandsaw. The suggestion is good but too vague for people to understand.
Below are practical steps on blade tensioning to help you adjust your bandsaw correctly for accurate cuts.
Find the Correct Tension
The first step towards finding the proper tension is from the scale on the bandsaw. In this case, you will need to make the necessary adjustments.
While the saw is still unplugged, apply more tension on the saw blade. Using moderate force, push the blade’s side with your finger until it deflects about a quarter inch from its usual position.
Repeat this process regularly and in the same way until you develop a feel of the correct tension for a particular blade.
Note: Applying too much tension on the blade could cause premature breakage, poor tracking, and overall bandsaw damage.
For best results, ensure that you use a blade that serves your specific needs. No blade can do all jobs.
Most manufacturers recommend a tension of 15,000 psi – 20,000 psi for a standard carbon-steel blade. But stronger blades such as carbide-tipped, bimetal, and spring-steel will need a higher tension of 25,000 – 30,000 psi.
Measure the Tension
Most bandsaws have inaccurate blade tension scales. The springs used in these tension scales weaken as the saw ages, further reducing their accuracy.
The best and most accurate method to measure your bandsaw blade tension is by using a tension meter. But tension meters are pricier (about $300).
There are other tensioning methods, but none is more accurate than the tension meter. For instance, you can tension the blade by eye. Raise the guides off the table about 6 inches and push the blade. The blade should deflect no more than a quarter inch.
Blade Tensioning for Resawing
Resawing thick hard stocks is the most demanding task placed on a bandsaw blade. If the blade has inadequate tension, it will bow, and the stock may get damaged.
A blade needs enough beam strength for resawing. Beam strength is the ability of a blade to resist deflection.
One sure method of achieving beam strength is using proper blade tension – the maximum recommended by the manufacturer.
Maximum blade tension cannot damage the bandsaw. However, this tension is recommendable for the most demanding cuts like sawing thick and dense stock. It is also applicable for occasional, brief periods of resawing.
Methods of Setting or Adjusting Bandsaw Blade Tension
The Flutter Method
This method is simple and highly recommended by saw and blade manufacturers. It works as follows:
- Unplug the bandsaw
- Install the blade, set the lower and upper blade guides the furthest they can go outwards or remove them. Then, remove the throat plate from the table.
- Center the blade on top of the wheels. While turning the top wheel by hand, adjust tracking and then close the wheel covers.
- Turn the tensioning hand-wheel on your bandsaw until the tension gauge gets at or slightly above the recommended blade width tension.
- Connect the saw to a power source and turn it on as you make the necessary adjustments to blade tracking.
- While the saw is still running, release some tension slowly until the blade begins to flutter.
- Increase the tension gradually until the fluttering stops. Tighten the tension wheel at a 1/4 or 1/2 turn.
- Power down the saw. Reset its upper and lower guides.
Make sure that you de-tension the blade after use. A quick-release tensioner is ideal for this purpose. Some bandsaws lack this feature. In such a case, relax the tension after every use with a number of turns after every use.
Then, the next time you need to use the saw, tighten the wheel the number of turns you made earlier to bring it to the correct tension.
Using Blade Tension Gauge
There are built-in and stand-alone blade tension gauges. The stand-alone models are a bit expensive for an average woodworker.
You attach the gauge to the blade, and when you pull it away, it gives you a tension reading in psi. Adjust the blade tension accordingly to match the manufacturer’s recommendations.
This method is easy and effective for adjusting your blade tension. But if you prefer a more practical approach, this one may not excite you.
Using Hand Pressure
This method involves raising your guidepost 6 inches off the bandsaw table. Then, push in from the side of the blade and measure the blade’s deflection. You will get a 1/4-inch deflection.
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If your blade is 3/8-inch, the deflection rises to about 1/2-inch. For this process, you need moderate pressure and a lot of practice.
Whichever method you choose, be sure to make a test cut in a piece of scrap material before proceeding to the actual project. This way, you can identify any awkward issues and correct them early. It also allows you to practice and perfect your skills.
Can You Over Tension a Bandsaw Blade?
Yes, excessive tension stresses the bandsaw and its blade. Overtensioning the blade results in metal fatigue which can damage the saw’s wheel shaft. The blade can also break if flexed back and forth repeatedly under enough force. Bandsaw blades can only tolerate a particular maximum force. If the pressure exceeds the endurance level a lot of times, the shaft will automatically fail.