How tight is tight enough?
Modern band saw blades are made from better steel and require different tensions than one us ed decades ago. But how you do know what tension to use and how do you calibrate your saw?
Modern blades can handle pressures from 15,000 to 30,000 psi without problems when using larger blades. Keep in mind that smaller blades (1/4 to -3/8”) do not ne ed and should not be subject to these high pressures.
You ne ed to calibrate your saw and develop a table of pressures for the common blade sizes you use. See the table below for an example taken for an 18” Laguna Bandsaw with various blades.
Now that VIWG has purchas ed a Iturra Design blade tensioning Gauge, you can calibrate your saw and take the guesswork out of the process.
For a general rule of thumb:
For sawing wood in the range of 1-2 inches thick, tension the blade to 8,000 to 10,000 psi. when using a ½” blade.
For resawing hardwoods set tensions in the 10,000 to 15,000 psi range for m ed ium size blades and go up to 20,000 psi if using a ¾” or larger blade-assuming your saw can handle these pressures.
Example of blade tensions and indicat ed dial reading from a Laguna 18” Bandsaw
Values in table are measur ed bland tensions in psi
Blade width |
5* |
10 |
15 |
20 |
25 |
¼” |
20,000 |
38,000 |
54,000 |
||
3/8” |
10,000 |
22,000 |
33,000 |
43,500 |
|
½'' |
8,000 |
16,000 |
23,000 |
30,000 |
|
¾” |
4,000 |
8,000 |
11,000 |
14,000 |
17,000 |
* These are the numbers on the Laguna blade tension gauge.
Comments:
For a ¼” blade the lowest value on the saw tensions scale is too much pressure for this blade. It ne ed about half this much tension for normal work.
For blades ¾” or larger this bandsaw cannot achieve tensions over about 17,000 psi; in other words you can't get near the upper tensions that these blades can take (30,000 psi).
When you borrow the guild gauge, mount a series of the blades you use, measure and record their tensions and make a table like this one and mount it on your saw for future reference.
Bryan Kemper
March 2008