These two questions are very good questions and are asked very often. Everyone who saws should consider how fast their saw is spinning, no matter who made the sawmill.

I am going to reveal from experience some facts that have been tried and tested. I will also give some myths that are not true and have little or no relevance to the formula for calculating belt speed.

You must first consider the power of your sawmill. I will give some guidelines. The reason we consider power first is the fact that we need torque to keep the speed of the band sawmill constant.

Sawing logs is like a heavy truck going up a long, high hill. The truck cannot go up the hill in the highest gear it has or could use to go flat out. You have to downshift to a lower (slower) ratio to get the torque level up for hill climbing. With a band sawmill, it is advisable to proportion the sawing effort as if we were pulling a long hill all the time.

When considering horsepower, keep in mind that if the band sawmill has a hydraulic system and the pump is mounted to take power from the saw’s motor, you will lose 5-10 horsepower. For example, a 25 hp hand sawmill will cut faster and harder than a 25 hp sawmill with a hydraulic pump that takes power away from the blade.

If I’m judging how fast to make a band sawmill, I’d rather stay in a safe zone and spin the blade slower and have higher torque than spin too fast and have low torque.

Another consideration in band sawmills with 30 hp or more is friction. When the blade exceeds 5,500 feet per minute, it has to deal with a higher level of friction in the body of the blade. In the past, we thought if we had the horsepower and torque, we could speed the blade up and cut faster. Over time we realized that this is an error due to friction.

In some sawmills we could work up to 7,000 feet per minute. This caused a lot of friction and when the band saw blade hit some opposing knots or hard places, the blade cut poorly. At the same sawmill we lowered the band to 5,500 and the sawing problem disappeared.

You would think that it would slow down production. In fact, it increased production and the blades lasted longer, all because we increased our torque and reduced friction. When friction is reduced, the band saw blade is more stable.

The power of your sawmill is the most important factor in deciding how fast to turn a sawmill. There are other factors such as the diameter of the wheel and the roundness of the wheel. In the guidelines you’ll notice the progression of the more hp the faster you can spin the band saw blade around the band wheels up to a certain point and I think you have to be careful when exceeding the max point.

Note: All speeds are rated feet per minute (fpm) for gasoline or diesel engines. When considering electric motors, keep in mind that they have 25-30% more torque than gasoline/diesel engines.

Here are some guidelines: 8 hp max speed 3,500 fpm, 12 hp max speed 4,000 fpm, 16-18 hp max speed 4,500 fpm, 25 hp max speed 5,000 fpm, 30 hp and above max speed 5,500 fpm.

One thing that doesn’t matter for speed is the size of the band saw wheel, but remember that the roundness of the wheel does. If the wheels are true in roundness, they can run at top speeds. I will add that larger wheels have benefits only when they are really round. Consider this: an 18-inch wheel that is true is better than a 30-inch wheel that is not true.

Is it necessary to change the speed for frozen records?

Yes, we have shown that it will help when a belt is spinning at over 4,800 feet per minute. It will give best results when sawing frozen logs to reduce belt speeds to 4800 fpm or less.

I think what happens in frozen logs when the tooth hits the cutting area, the grain is cut along with the moisture partially thawing under the impact and friction and the dust going down the throat of the blade will freeze against the body of the blade and will act like a brake pad pressing against the body of the band saw blade.

This in turn causes heat and causes the belt to stretch and cut poorly. Slowing down the band saw blade under these conditions allows the tooth to get a slightly larger dust bite and the larger dust will not go down the throat as easily as before.

Every little help we give each other here is positive. Also, at a slower speed, the belt doesn’t have to deal with the level of friction and won’t get as hot, and this will keep the belt stronger, as hot metal weakens.

A formula to calculate band saw wheel circumference (length around the wheel per revolution).

Band Saw Wheel Diameter X 3.14 = _____ then divide by 12 the total is in feet and inches.

26-inch bandsaw wheel example: 26 x 3.14 = 81.64 and then dividing by 12 is 6.80 feet around the wheel. So if I want my band to run at 5,500, I divide 5,500 by 6.80 = 808. 808 rpm is how fast I want the band saw wheel spindle to turn.

Bottom line: the band saw blade needs constant speed with more torque than it needs speed. If you adjust the speed to match the horsepower and torque, you will have a great band sawmill.