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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, normally 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 (I have seen many examples in museums where 1/8 inch or thicker "veneer" has delaminated from the substrate). 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.

Exception: I wanted to use commercial drawers for a project, but some of the drawers had to have shaker fronts - rounded 3/8 inch overlay on 3 or 4 sides, not available from my vendor. I bought drawers with cherry sides, planed the front thinner, and laminated premium 3/8 inch thick cherry wood on the front, with the necessary overhang. I am not worried about the fronts coming off, since it is cherry glued to cherry, with similar expansion characteristics, with the grain aligned, but I would not consider doing it if the species were different.

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.

Laguna has a "driftmaster" fence that can also be installed on non-Laguna bandsaws, with easily precision-adjusted fence position. This fence makes it practical to cut veneers that fall away from the stock.

Factors for success

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

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. Therefore, to allow easier adjustment, some argue that one size less than the max is ideal. As you move to wider blades, they also become thicker; I stopped at a 1 inch wide blade rather than the 1.5 inch my saw will handle, to keep the thinner blade.

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.

How long does a carbide blade last?

A recent discussion on the MiniMax User Forum provided some insight

A person doing a lot of resawing made the comment that "a single person in a furniture shop may not have to change their blade for years." That is me - I cannot contribute personal experience to lifespan for heavy resawing.

Further discussion on that forum suggested that 600-800 linear feet of resawing curly tropical hardwood, 6 or more inches high, might wear out a blade for resawing, but it would still be adequate for other less demanding uses. Highly abrasive wood might kill a blade in 400 linear feet. Those results were confirmed by another user, for both the Lenox TriMaster and Woodmaster CT. That doesn't sound like much, but it is probably more than a full day's work, and equates to a blade cost of about 15 cents per linear foot resawed.

My current favorite blade (1 inch Lenox Woodmaster CT) with 1.3 tpi, .035 inches thick, kerf .051 inches. The Woodmaster CT only comes in 1 inch, 2 inch, 3 inch, etc. The 1 inch wide blade is now also available in 2 tpi. Another favorite is the Lenox TriMaster which alternates between 2 and 3 teeth per inch, .035 thick, 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 the kerf is .065 rather than .051 for the Woodmaster CT), and with the extra carbide costs proportionally more than a Woodmaster CT. My bandsaw will support a blade wider than one inch. However, even though wider blades are theoretically better, the readily available wider blades are also much thicker, so I only use 1 inch wide blades.

My favorite source for Lenox carbide tip blades is Industrial Blade - excellent service and the best prices I have found (1-800-SAW-BLADe in California).

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

On one forum, one person had great results with the Laguna Resaw King, but another person's Resaw King blade broke, and Laguna said it was his fault for excess tension, even though they had refused to specify the recommended tension. I have tried the Resaw King from Laguna, but prefer the Lenox blades.

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" blade designed to cut green wood (such as the AS series from Timberwolf).

For non-carbide blades I use Timberwolf blades from Suffolk Machinery. They have been highly regarded for years, but there are some recent complaints about lower quality welds. Based on my dealings with them, I bet they would fix that and apologize, but I haven't had a problem. They are designed to operate with a lower tension (about 7-8,000 psi), which can be an important factor with cheaper bandsaws. Suffolk Machinery is the importer/distributor, has a website with lots of good info about Timberwolf blades. For years they would only take orders by telephone (1-800-234-7297 in New York), with very knowledgeable operators, quick service, and low prices for these "premium" blades. Recently they have added the ability to select and order blades on-line. Watch their web site for occasional "buy a few and get one free" sales.

Some of the woodworkers I highly respect have started to recommend Ellis over Timberwolf, as a very good, far less expensive blade. I have not personally tried them, but the recommendations are so vigorous and widespread, I will certainly give them a try (when my supply of Timberwolf blades is depleted). One user suggests calling them (800-383-5547) with what you want to do and they will help you select the best blades.

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 tracking after changing the tension.) Timberwolf recommends that you use their blades at this minimum tension, often around 7-8,000 psi, 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.

Tension theory

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

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. The force you have to apply (the tension knob on the saw) is a lot greater for a large blade, but the tension, measured in psi, is the same for the large and small blades. 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, but the force required to achieve that stress (blade tension) does depend on the width and thickness 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 ½ inch blade .035 inches thick, the tension indicator on my saw 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, in other words, measuring the amount the blade stretches. Here is the science behind it: 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 (tension) 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 in those 10 inches. If we see .005 inches elongation over 10 inches, we have 15,000 psi blade tension. For each .001 inch of elongation measured over 10 inches, we have 3,000 psi of 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 (blade tension).

On my saw, I can easily measure 12 inches apart. Using the numbers above, that means I should get 12/1000 or .012 inches stretch at 30,000 psi, or .001 inches for every 2,500 psi of blade tension. Therefore if I want 25,000 psi, I tighten the blade until I get .01 inches stretch. It doesn't matter what size blade I use, the .01 inches stretch is 25,000 psi. Of course, if I have a big blade, I will have to use more force - tighten the wheel a lot harder - to get the same blade tension than the force I would need to get that same tension on a small blade.

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.

Simplistic Tension calculations

After you go through the calculations above, you will find that for every 3,000 psi tension, your blade will stretch 1/10,000 of it's length (1/10,000 of any portion of the length you measure). If you are measuring over 10 inches, that portion of the blade will stretch 10/10,000 inch for each 3,000 psi tension (.001 inch). If you measure .003 inch stretch in that 10 inch section, you have 9,000 psi overall blade tension. .004 inch stretch is 12,000 psi tension. .008 inch stretch is 24,000 psi tension. .01 inch stretch is 30,000 psi tension.

If you can measure over more than 10 inches, the reliability of the calculation improves; just expect a proportionally larger amount of stretch.

When you attach the gauge the blade is likely loose. As you tighten the blade, the "floppy" looseness will go out first. Start measuring the stretch when the blade starts to stretch instead of just becoming straight. It is hard to describe but easy to see.

Simple Tension Gauge

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.

4743
4742

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 for a long time, but is so simple that I just remember it now. (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.