How to Tension Your Band Saw Blades
Get straight and even cuts with the right blade tension.
The tension of your band saw blade will have significant impact on the straightness of your cuts, especially with wood. To most woodworkers it is somewhat of an art to get the blade tension correct. Some people may listen for the tone when “plucking” the blade whereas others just have the “feel” for the blade on the saw. Here are some ideas to help everyone ensure they have the correct blade tension.
What Blade Tension Should It Be?
Band saw blades can take and require much more tension than the average person would believe. A typical carbon steel band saw blade will need to be tensioned anywhere from 15,000 – 20,000psi. A stronger blade such as bi-metal or carbide blades can take up to 30,000 psi of tension. More tension makes the blade more rigid and thus eliminating deflects in the blade while cutting. Cutting denser woods will require the maximum tension while normal materials can be lower or somewhere in the middle.
How To Measure Blade Tension
The band saw blade tension scale from the bandsaw is typically not accurate and usually read lower than the real blade tension. Smaller bandsaws are known to read worse whereas the large bandsaws will have close readings when they are new. The spring in the scale usually weakens with use and therefore get even less accurate as you use them. A separate blade tension meter is recommended for a more accurate measurement. I realize these can be expensive, but it is worth the price if you are cutting high volumes. Here are a couple more ideas if you are against buying a blade tension meter.
More Tension Measurement Methods
Since most bandsaws read tension low, you can set the tension for the next width setting. If you are trying to hit the maximum tension, this method will get your blade close. If you have a 1/2″ width blade, set the bandsaw width setting to 5/8″ and so on. Another more popular option is to set the deflection of the blade. To do this correctly, set the guides about a half foot off the table and tension the blade until it deflects just under 1/4″. Then test your blade with a scrap piece of wood and if it is still not giving you a straight cut bump up the tension a little at a time until you receive the desired cut.
If you are cutting dense hardwoods and require the maximum tension, I highly recommend a blade tension meter as that is the most accurate form of measurement. The price of the meter could save you on broken blades and ruined wood stock.