How should I tension my bandsaw blades?
The correct tension of a bandsaw blade is vital to get good life out of the blade. Generally speaking you should tension the blade so that it does not slip whilst working and reference should be made to your manufacturer's manual for detailed advice. Periodically, adjustments may be necessary to compensate for band stretch in use but it is good practice to remember to relieve the tension when the machine is not in operation.
I don't know what blade length I require, is there a way of working this out?
Adjust the wheels to their correct position (about the middle of the adjustment range)
Referring to the diagram below, measure the distance between the centre point of each wheel in mm. (mesurement D)
Now measure the radius of each wheel in mm. (R1 and R2)
Use this formula to calculate the band length from the measurements you have taken:
Band length = (R1 x 3.1416) + (R2 x 3.1416) + (2 x D)
Ensure the wheels are not adjusted to their extremes, you need to allow for take-up to tension the band and also for possible future blade rewelding. Around the middle of the adjustment range is best.
How should the guides be set on a vertical machine?
If you use your bandsaw to cut metal, then a good cutting fluid (with extreme pressure additives) is vital to prolong the lifespan of the blade. There are very few metals which do not require cutting fluid and it should be used with virtually all steel and steel alloy products. It is necessary to choose between a water soluble fluid or a neat cutting fluid, particularly when bi-metal blades are being used. It is generally more economical to use water soluble fluid where the materials being cut fall into the low carbon, low alloy, general purpose category. Better results will be achieved with neat cutting oil where high carbon, high alloy and stainless steels are being cut. Sufficient fluid should be used to ensure the work piece is kept cool and to flush swarf from the blades teeth. Insufficient fluid will allow the work piece to warm up and allow swarf to cling to the blade causing choking and the teeth to strip.
Does a new bandsaw blade have to be "run in"?
Most blades are very accurately heat treated and have an extremely sharp cutting edge and a "running in" period is strongly advised for maximum blade life. The best way to do this is by running the blade at a feed pressure reduced by around one third for the first 500 sq.cm. of cutting. It is important to ensure that the blades surface speed is not reduced and to avoid vibration, shock or mechanical abuse.
How do you recoil a bandsaw blade for storage?
Coiling a bandsaw blade is easy to demonstrate but difficult to describe. First of all wear protective gloves, then hold the blade out in front of you as if looking at a clock face with your hands holding the blade in the three o'clock and nine o'clock positions - both your thumbs will be pointing upwards. Now turn both your wrists at the same time in a clockwise direction (ie. twisting the opposite way for each hand) bringing your hands together and down towards your body as the blade coils. Some people prefer to twist both their wrists in an anticlockwise direction, it makes no difference as long as each hand is going the opposite way. Good luck and don't forget to wear gloves!
