Bandsaw Resawing: How To Set Fence So Blade Cuts Exactly At Middle

[John Poole]

On a band saw, I want to resaw some Port Orford cedar decking (5 1/2" x 1 1/2" x whatever length) to basically get two thinner boards of equal thickness from one, e.g. 5 1/2 x 11/16" x whatever length. I want to maximize my yield and therefore minimize the loss on thickness. Ideally, 1 1/2" split into two less 1/2 the size of a saw kerf (theoretical 1/8")should yield 11/16" (3/4" - 1/16") without planing. I'm finding that the method of setting my fence so it placed the blade smack in the middle of the width of the board proved problematic.


Resaw_diagram2.jpg


I tried to approximate the one half mark, then by hand turning the bandsaw wheel and pushing the work into the blade I create a light cut, almost a scar or sratch, of where the line is. I then flip the wood piece upside down and do the same thing. If my fence is exactly 1/2 the wide of the board away from the center of the blade, the both scratch marks will be in the same place and the pieces should be of equal thickness in an ideal cut. If they are off, then I need to nudge my fence 1/2 the distance between the two scratch marks to resolve the distance between them.

What I found was using this eyeball blade-scratch method, I couldn't accurately nudge the fence so that both cuts were in the same "trench" [saw cut]. When I thought I was close enough, I proceeded with the cut only to learn come planing the pieces that I was off by good deal as one piece planed and the other did not start planing until the 3rd run-through on the planer; basically one piece was several 16ths thicker. I take light cuts on my planer.

Does anyone have a method they use to basically place a fence 1/2 the thickness of a given board from the center of the blade? I like techniques that do not require setting to some ruler, but rather by fit or slight of hand using geometry. Like some other tricks of the trade, I'm guessing there is some manner which does not require squinting and determining if two saw kerfs are perfectly in alignment or not.

This leads into another problem I'm wondering about: how do you determine the center point of a rectangle that is not a square? A combination square with a 45 degree angle accomplishes that task for squares. If I mark the center point of a rectangle, then I could try aligning the blade in front of the center-point mark while holding the piece securely against the fence and then locking the fence once that sweet spot is arrived at.

[Andy Shearon]

This leads into another problem I'm wondering about: how do you determine the center point of a rectangle that is not a square? A combination square with a 45 degree angle accomplishes that task for squares. If I mark the center point of a rectangle, then I could try aligning the blade in front of the center-point mark while holding the piece securely against the fence and then locking the fence once that sweet spot is arrived at.

I might be missing the point of your question, but if you want the center point, draw a diagonal line between the corners, and the intersection is the center.

Andy

[David Wong]

Have you determined that blade drift is not causing the cut to wander? Several 16ths seems like more than a measurement error.

[John Poole]

Yes, but the act drawing on a rectangle is subject to a high degree of variance. For example, the width of the lead, the alignment of the ruler/bar offset from the corner to allow for the marking instrument's width. Drawing on a square surface using a Starrett combination square will be highly accurate because of the 90 degree holder. With a rectangle, you do not have that built-in stabilizer. I recall wrestling with rectangular ends trying to draw lines form corner to corner resigning myself to the fact that center point might be several thousands of an inch off and that it doesn't matter -- I wasn't doing high precision work. There's got to be some trick that doesn't depend on your eyesight and lead thickness that assures making a mark at the precise center.

[John Poole]

I had not considered that, but will do so in further tries. Thank you.

[Harvey Miller]

Do you know the three pin method? Drill three equidistant holes in a piece of wood and push in pins (straight nails). The centre nail should be flush to the jig face. Then angle the wood jig so the two outer pins are tight against the sides of your board and give the centre nail a whack (or you can scratch in a centre line if the nail is just proud). That will mark the mid point of the board.
As for the the bandsaw, I’m no expert on bandsaws but I’d try the same thing with the band saw running and watching the cut line. For me ‘wasting’ a 1/4” of wood is worth it in my time and frustration level.

[Brian W Smith]

A very slight tangent.........

To begin with,it's rare that we use a pce "straight off the bandsaw"....or any "saw" really.Meaning there's almost always a second op.In the rare occasions we may be looking for a particular "finish" on,say a pce of rough cut siding.Our tolerances for this would be also,"rough".It sort of goes with the territory.

Trying to minimize waste....maxing out a yield......or in anyway making the cut somehow "better",is always at the forefront however.So your question has some validity.I'd have a dial calipre and a D.I. at the ready for any BS work,but that wasn't part of your criteria.....so,good luck and keep at it.

[Brian Tymchak]

Not saying this is the best method, and I'm certainly not a pro with a bandsaw, but I've had reasonably good luck resawing boards in half by using a tip I learned here on SMC. Take a square, setting it to as close to 1/2 the width of the board as you can, but not needing to be exact. The closer the better though. Then mark a line down the center of the entire edge of the board using that square. Then, do the same thing from the other side of the board so that you end up with 2 lines close together. The true center of the board lies between these 2 lines. Then as you cut, keep the blade as close to the center of these 2 lines as you can. Instead of using a fence directly, I used a point guide on my fence that allowed me to make minor corrections as the blade wandered a bit. You definitely want to crank up the tension on the blade to minimize the drift. And you have to slow the feed rate down as you resaw to clear the saw dust. that will also help to minimize the blade from wandering in the cut.

[John Coloccia]

There's something that doesn't add up here. You were trying to split a 1 1/2" piece of wood, you did all of this careful setup, and when you were done you were off by nearly a 1/4"?? That's a HUGE amount to be off, even if you just eyeballed the entire setup.

Generally, I just measure and make a little mark on the board. Then, I either grab a pencil and draw a centerline freehand, using my fingers as a guide, or if I'm feeling industrious I grab a marking gauge. No reason to do all this board flipping and stuff like that.

But that 1/4" is just gargantuan on a 1 1/2" piece of wood. Is something else going on? The blade bowing, maybe? Maybe try cutting some test strips, maybe an 1" x 1", and see if you can reliably cut those in half.

[jim gossage]

I built a small hardwood block that rides on my bandsawfence rail and can be locked down just like the fence. You can use this blockand some feeler gauges to exactly dial in your fence. Let’s say you need to move the fence 0.01” to the right: place a 0.01” feeler gauge to the right of the fence head, slide the block up against the feeler gauge, tighten the block on the rail, remove the feeler gauge, then slide the fence head against the block and tighten the fence. You could also use this block to set up your cut in the first place without making the test cuts: measure your blade kerf and wood thickness with a caliper, subtract the kerf from the thickness and divide by two to get your final thickness, slide your fence against the left side of the blade until it just touches the teeth and then lock it down, slide the block against the fence head and tighten it, loosen the fence and use your caliper to move the fence to the left by exactly the final thickness of the wood and lock it. I just tried this and got within 0.005”
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[Jim Matthews]

I adapted the Rockler Thin rip jig to describe the same width from the blade on the "free" side of the cut.

I true the face that rides the fence and square the edge that lies on the table.
Those stay against the fence and table, for all cuts in resawing.

After I take a pass, I advance the fence until the next face reaches the Thin Rip Jig wheel.

This all presumes you've got a properly adjusted blade set to track straight.
That's a big presumption, really and the bane of my resawing attempts.

I follow the method shown in the video below.

http://www.rockler.com/thin-rip-tabl...FSbxOgode1UA0g

[Jim Finn]

I resaw a lot. Mostly cedar and maple, and some oak and walnut. To find the center I just measure as best I can from each side of the wood and cut between the marks as has been suggested by Brian. I use high tension on my 5/8" carbide blade from Grizzly and a resaw fence. A sharp blade is imperative. I replace my blades as soon as they start to require more pressure to move the wood through the saw. Expensive, true but then so is wood.

[Kent Parker]

Hey neighbor John,

Whereas careful measurements are important to achieve your goal there are additional factors to consider. Drift has already been mentioned to you and are we to assume the planks are uniform in thickness with edges square to the sides ? Cutting a piece free hand in two will give you an understanding of your bandsaws capacity and the direction that the fence should be placed, ignoring the edges of your table as reference. Cedar is considered a softwood however Port Orford cedar is very resiny which contributes to friction during cutting. During cutting the wood chips tend to expand when they leave the “mother ship”. You’ll need a blade that can evacuate the dust quickly to prevent choaking or stalling the blade, so blade hook angle and set need to be considered. The long pieces you’re working with are large levers and if not supported in their length and held securely to a tall fence can easy flex your fence, the blade and any feather board (s) your using. Additional factors could include the HP of your saw and the rate in which you feed your wood and the bearing support mechanism of the blade.

The fence you’ve seen in front of my house is entirely Port Orford cedar. Much of it resawed on a small, old Delta band saw with an underpowered ¾ hp motor. Photos below of my set up. Oh and the beer bottle was just placed in the photo for height comparision...honest..

Cheers,

Kent

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[John McClanahan]

So, is that green bottle some kind of lube?


John

[Kyle Iwamoto]

Dumb question #1, did you joint/plane at least the bottom and side that rides the fence?

I use the Kreg resaw fence that is curved, allowing you to adjust for blade drift. You could try that.

OH, and Kent, you should not be drinking beer and putting it on your table. It leaves those rust "O"s that are hard to get out. Use a coaster.