Tuning and configuring your bandsaw
to resaw wide boards or cut veneers

One use of a bandsaw is for cutting curves in relatively thin wood - sometimes called scroll work. Most any decent bandsaw, with a fairly narrow blade, will do a sufficient job. Of course, if you need to cut inside a "hole" or do very fine cuts with sharp turns, a real scroll saw works better, but is slower than a bandsaw, and doesn't handle thick wood.

Another use of a bandsaw is for rough cutting thick wood such as bowl blanks. A powerful saw with a sturdy, tilting table is a great help, but more important is a special blade. The blanks are often cut in green wood, so a thicker blade, with an even wider kerf, is required to keep the wet sawdust cleared.

In my opinion, the challenging bandsaw job is resawing... cutting thin pieces off wide boards, often dry hardwood. The target may be a piece of wood 3/8 inch thick (such as the side of a small drawer), or it may be a veneer, well under 1/8 inch thick.

How thick?

If you choose to cut a board 1/4 inch thick, to "veneer" onto another structure, sooner or later it will likely separate, warp, or split. The differences in expansion and contraction of different types of wood, over the seasons, creates huge internal stresses that will try to pull the wood apart. On the other hand, if the decorative outer wood is very thin (the nominal thickness of much commercial veneer is 1/42 inch - .024"), the wood doesn't have strength to move sideways (properly glued down, it follows the movement of the underlying material), and expansion or contraction becomes a minute change in thickness.

There is no magic thickness, above which, you always have a problem, and below which you are always safe. As a rough guideline, if your saw cuts roughly, then start with 1/8 inch (.125") and by the time you have sanded the "veneer" smooth, you should be fine. If you can cut very smooth veneers (requiring minimal sanding), 1/16 inch (.063") is a reasonable starting point, although I occasionally cut veneer much thinner than that. Since a resaw kerf is often .05" to .06" (roughly 1/16 inch) this means you could get 6 or more veneers out of a 3/4 inch thick board.

Where is the fence?

I am often asked whether the "product" cut from a block of wood should be left of the blade (along the fence) or right of the blade, with the stock along the fence. There are arguments for both. If the product is left of the blade, the fence does not have to be adjusted for each subsequent cut, but the work has to be smooth enough to rest firmly against the fence for each cut. With a cheap bandsaw that produced imperfect surfaces, I had to joint the stock before each cut (but I liked the approach since it gave me one "perfect" surface for each piece cut). With my good bandsaw, the cut is good enough that I typically cut 3-4 or more veneers before jointing the stock again. Those who argue that the veneer should be on the right and fall away from the stock as it is cut get good results too, and continue to have the same smooth side of the stock against the fence, but the fence has to be adjusted for each cut.

Factors for success

As we are cutting through a very thick (tall) piece, our success is determined by many factors.

• A tall stable fence to keep the wood steady (Be sure your work piece is flat and smooth, so it rides well against the table and fence). The "point" fences (a vertical bar aligned with the tip of the teeth) allows you to follow a line on the edge of the board if your saw wanders, but a well-tuned saw allows you to use a flat fence, and cut thinner, smoother pieces. The accuracy with the point fence is determined by your ability to follow a line, compensating for the wander of the cut, rather than the flatness of the fence.
• Feather boards or operator(s) to keep the wood tight against the fence ahead of the blade. With difficult cuts I sometimes get someone to help hold the wood against the fence.
• Steady feed rate. If you will be doing a lot of resawing, consider a power feeder. People who use a power feeder on a bandsaw swear by them.
• A blade that does not deflect or wander sideways
• If the blade is pushed to the rear (while cutting), it will tighten the rear of the band, and reduce the tension on the front (teeth) thus making it easier for the teeth to wander. A wide blade helps to resist deflection to the rear, thus reducing the sideways deflection of the teeth.
• High blade tension to minimize deflection
• Few teeth with large gullets to clear the sawdust out - when resawing you may be producing more than 10 times as much sawdust as a normal cut, and if the kerf is packed full of sawdust, the blade will seek an easier path
• Good bandsaw tuning
• The side-guides should not touch the blade constantly (to prevent heat build up), but should be VERY close to prevent deflection (if a folded piece of paper fits between the blade and guide, it is too far away). Mine act "nervous" - with the saw running but not cutting, they are so close to the blade that they twitch from moving air and dust. Front-to-back, the side guides should be close to the gullet since that is the part that wants to wander. Euro guides, roller guides, ceramic guides, cool blocks, wood blocks all work fine, even though everybody has a favorite.
• The thrust bearing should only touch the blade during the maximum cut, but should be close enough to prevent the gullet and teeth from touching the side guides when they are pushed to the rear by the force of the cut. Note that if the blade is poorly adjusted, and runs hard against the thrust bearing, there will be heat and stress on the gullet, leading to cracks in the gullet, and eventually a broken blade.
• The fence should be adjusted parallel to the natural cut angle of the blade. New blades normally will cut "straight ahead" but as the blade wears, and the teeth are bent by the tires, the direction the blade cuts naturally is at a slight angle. Draw a line about an inch from the edge of a board, and cut it without using the fence. When you are "half" way through and are pushing straight into the blade, stop, and notice the angle of the board - this is the natural cutting angle of the blade. The fence should be adjusted to that angle.
• With crown tires, the blade should be on the center of the wheel. With flat tires, the teeth of a wide blade hang off the front edge of the wheel. It doesn't make sense to try to have the teeth of a very narrow blade hang off the tires, so many users with flat tires put the back of a narrow blade at the same place the back of a wide blade rides, to simplify adjustment of the guides.
• Smooth tires and balanced wheels. The surface of the wheels must be absolutely smooth and stable when spun without a blade (if the tire has a bump, sand it out). If the wheel is out of balance, the same point will always be at the bottom when the wheel stops - get it balanced.
• A sharp blade - only expect a few hours use (as low as 2, never more than 5-10 hours) from a normal steel blade, and normal blades are generally not worth sharpening. A carbide tip blade is a good investment if you will be using it a lot, and have a saw that can provide good tension and alignment. Some carbide blades can be sharpened, but I have had reason to replace carbide blades before they need to be sharpened.
• Blade lubrication - you don't need (or want) a wet blade like metal cutting bandsaws or some sawmills use, but most vendors recommend lubricating the blade. Some folks spray some cooking "Pam" on a rag, and wipe it on the blade while moving it backwards by hand. This apparently does not leave enough residue on the wood to interfere with any finish. I wax my blade with furniture paste wax, similar to the other metal woodworking surfaces (the cast iron tables).
• The back edge of some blades are rough, and can be "tuned" or rounded slightly with a sharpening stone (some people buy a special "stone on a stick"). If you have a Lenox carbide blade, do not use a stone... the blade is factory rounded in the back, and Lenox considers the grinding a "modification" of the product, potentially voiding any warranty.

Choice of blades

For resawing, the width of the blade should be close to the maximum the bandsaw will handle. A smooth cut is very important, so an investment in a carbide tip blade is worthwhile. To use the maximum size, every guide, adjustment, and clearance may have to be in a specific "perfect" position, so some argue that one size less than the max is ideal, so adjustment is easier.

The number of teeth per inch (tpi) depends on how fast you are sawing and the thickness of your workpiece, but for starters, consider 3 tpi a large number for resawing. My current favorite blade (1 inch Lenox Woodmaster CT) has 1.3 tpi, .035 inches thick, kerf .051 inches. The Woodmaster CT only comes in 1 inch, 2 inch, etc. Another favorite is the Lenox TriMaster which alternates between 2 and 3 teeth per inch, .035 thick, kerf .065, and comes in a wide choice of widths including 1 inch. The TriMaster has more teeth, with larger pieces of carbide for each tooth, so costs proportionally more than a Woodmaster CT. A blade wider than 1 inch is theoretically better, but the readily available wider blades are also much thicker, so I only use 1 inch even though my bandsaw will support an even wider blade.

If you are sawing wet (green) wood, such as milling lumber or cutting bowl blanks, you need a wider kerf (the wet sawdust expands) and perhaps a thicker blade. None of the carbide blades I have seen are suitable for cutting green wood. Of course, for bowl blanks you will be cutting curves, and therefore want a narrower blade as well. Many people use a 3/8 or 1/2 inch wide blade for bowl blanks, in a special "model" oriented to green wood.

The "Wood Slicer" (from Highland Hardware), also sold as the "Bladerunner" (by Louis Iturra) has a cult following for resawing dry hardwood. It is a very thin blade (.022 inch, .03 kerf) which removes less wood, variable tooth pitch which runs quieter, takes less tension (20,000 psi - see below), and requires less power. With less metal doing the cutting, it doesn't last as long, but it is far less expensive than a carbide tip blade, and reportedly gives very smooth cuts.

My favorite source for Lenox carbide tip blades is Industrial Blade - excellent service and the best prices I have found. For non-carbide blades consider the highly regarded Timberwolf blades. They are designed to operate with a lower tension, which can be an important factor with cheaper bandsaws. Suffolk Machinery has a website about Timberwolf blades, but they only take orders by telephone, with very knowledgeable operators, quick service, and low prices.

Blade Tension

The minimum tension for a safe cut is slightly more tension than just enough to make the blade stop fluttering, no matter what type of blade. Set the guides as far apart as possible, and increase the tension until the blade runs smoothly - or decrease the tension until the blade starts to flutter, then increase it slightly. (On many saws you have to change the alignment after changing the tension.) Timberwolf recommends that you use their blades at this minimum tension, while others often recommend a higher tension if your saw can handle it. The Bladerunner/Wood Slicer typically is run at 20,000 psi. The Lenox carbide blades are typically run between 22,000 and 30,000 psi - I shoot for about 25,000 psi.

There are three confusing factors involved in blade tension...

• Force is the pull of the spring - pounds. It is proportional to the amount the spring compresses until the spring's coil loops contact, so can be measured by the amount the end of the spring moves - the position of the end of the spring.
• Stress = Force divided by area of cross section - pounds per square inch. If a blade is twice as wide, then there must be twice as much force to get the same stress on the blade. If the blade is twice as thick, there must also be twice as much force. And, of course, twice as wide, twice as thick needs 4 times as much force.
• Strain is the amount the blade stretches, proportional to stress.

Stress (not force) is the key factor in blade tension. A low tension blade typically runs around 7,000 psi stress. High tension blades often run as high as 25-30,000 psi. Since it is related to the cross section area of the blade, the stress doesn't depend on the thickness or width of the blade.

Bandsaw tension gauges measure the compression of the spring (proportional to force), then indicate the appropriate setting for different blade widths. Most bandsaw gauges don't specify what thickness blade they are calibrated for, which is why they may be perfect for one blade, but are often misleading for other blades. My bandsaw's indicator says it is for a blade .019 inches thick (I have never had a blade that thin). Therefore, on my saw, if I use a half inch blade .035 inches thick, the tension indicator needs to be set for a one inch blade to get the recommended tension on the thicker half inch blade.

Measuring stress is done by measuring strain. The elasticity (Young's modulus, E) of most steel is 30 million psi. The elongation L is the Stress divided by E. If we have 30,000 psi stress on the blade, the blade will elongate (stretch) 30,000 / 30,000,000 or 1/1000 of it's length. If we measure over 10 inches, we should see 10/1000 or .01 inch stretch. If we see .005 inches elongation over 10 inches, we have 15,000 psi blade tension. Measuring over the longer distance is generally more accurate. Once you establish how far apart you can connect a measuring device to your blade, I suggest making a chart for each thousandths of an inch strain (stretch), and the corresponding stress. Measuring should be done with the blade at a constant (room) temperature... when the blade gets hot through use, it will expand - comparable to the amount it stretches from tension.

You can buy a bandsaw blade tension gauge (that really measures strain) for $135 to $350, or you can make one from a cheap ($7) dial indicator and a couple spring clamps. Usually there is a connector on the back of the dial indicator, such as this, that can be clamped to the blade.

An L or T shaped set of scrap wood allows the probe to be connected to the blade as far away as convenient (for greater accuracy), with whatever offset is required to align with the dial indicator. In my case I use a scrap of wood that allows the clamps to be 12 inches apart. Therefore the chart for each thousandths of an inch stretch with the clamps 12 inches apart indicates 30,000,000 /1000 / 12 then .001 inches stretch = 2,500 psi blade tension, .002 inches stretch = 5000 psi, ... .009 inches stretch = 22,500 psi, .010 inches stretch - 25,000 psi, etc. That chart was taped to the side of my machine. (Remember that the dial indicator doesn't have to be set to zero... just note the difference as you tension the blade.)

Or you can do what the majority of bandsaw users do - just make some cuts and if you get good results, be happy and keep going.