When trying to figure out how to determine bandsaw blade size, it is important to know the job that will be performed using that particular saw blade. Things like material, amount, and cut.
To help determine the proper bandsaw blade size for a particular machine, follow this formula:
For two-wheel bandsaws
- Adjust the wheels to their correct position (about the middle of the adjustment range) make sure the wheels are not adjusted to the extreme
- Allow for take-up to tension the band and for possible future blade re-welding. The middle of the adjustment range is best
- Band length = (R1 x 3.1416) + (R2 x 3.1416) + (2 x D)
- Measure the distance between the center point of each wheel (measurement D)
- Now measure the radius of each wheel (R1 and R2)
Use this formula to calculate the band length from your measurements
Most bandsaws will accept a range of blade lengths, sometimes with as much as 2” difference between the shortest and longest blades that the bandsaw will allow.
If there is no blade to measure, or there is need of a new blade that may or may not properly fit the bandsaw machine, then it becomes necessary to determine the range of lengths the machine can be expected to mount.
To accomplish this, try the following:
- Without a blade on the saw, lower the upper wheel as far as it will go by turning the tensioning knob counter-clockwise, until the wheel stops moving
- Measure the distance from the center of the upper wheel shaft to the center of the lower wheel shaft
- Raise the upper wheel as far as it will go
- Measure the center-to-center distance between upper and lower shafts
- Multiply the shorter shaft-to-shaft figure by two, since the blade covers this distance twice in a complete circuit
- Add one full wheel circumference, since the blade travels around half of the upper wheel and half of the lower (Circumference = wheel diameter x 3.1416)
- This sum is the saw’s shortest blade length.
The same steps will also determine longest blade length.
If the owner’s manual is still available, it will indicate an average length for both.
In practice, the bandsaw is capable of using saw blades a little larger than the shortest length to perhaps 3/8” or 1/2” less than the longest length.
Example:
- The shortest shaft-to-shaft distance on our Delta 14” bandsaw (with riser block installed) is 30”
- Max distance is 31-1/8”
- So the shortest blade length is 2 x 30” plus 14” x 3.1416
- or 60” + 44” = 104”
- The longest theoretical length is 62-1/4” + 44” = 106-1/4”
- expect the saw to handle any blade length from 104-1/4” to 105-3/4”
- The saw will use 105” blades knowing that a little more or less will work equally well
If you have an old saw blade that fits the bandsaw in use, then it becomes much easier to measure length.
- Mark a tip of the blade
- Align it with the zero point on a measuring tape
- Turn the blade along the tape until the tape returns to the mark
The exact measurement is just a target, by the way. If the saw blade measures 114-5/8”, there is no need to special-order that exact length. Try a 114” or 115” length saw blade. It is likely that either will work just fine.
These procedures are the best way to determine the right size bandsaw blade for a particular bandsaw machine.
