Squaring bandsaw blade to miter slot

[MstrCarpenter]

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Setting up a bandsaw is exactly like setting up a TS.  Adjust the table so the miter slots are parallel with the blade, and the fence parallel with the miter slot.  The only difference is the position of the blade on the tires of a BS is not fixed like it is in a TS.  Putting it initially on the center of the upper wheel simulates that fixed position of the TS.  

John

John, I'm trying to grasp this concept. If I have a 3/8" blade on my saw, am I supposed to hold a straight edge against the side of the blade and measure front and back to the miter slot, and move the table 'til I get it the same? If you told me to hold a straight edge against the back of the blade on both the right and left sides and make the miter slot square to it then I would agree that's a good starting point. I was taught in high school to always move all the guides out of the way when I swapped blades, then track the blade a little behind center of the upper wheel. The blade would track closer to center on the lower wheel. Only after it tracked well could I move the guides as close as possible without touching. I haven't done it since high school but we used to file a scarf joint and braze the blades. Some of them were tough to get tracking right. Anyway if we were going to rip or re-saw, we marked a board and free-hand cut a foot or so, then leaving the board in place, set the fence against it at whatever angle, if any, was needed. If it was way off I would track the blade forward or back. This has worked well for me since then. Perhaps my saw's tables are already close enough to square that it's easy to get the cut line parallel to the slot.

[jteneyck]

John, I'm trying to grasp this concept. If I have a 3/8" blade on my saw, am I supposed to hold a straight edge against the side of the blade and measure front and back to the miter slot, and move the table 'til I get it the same? If you told me to hold a straight edge against the back of the blade on both the right and left sides and make the miter slot square to it then I would agree that's a good starting point. I was taught in high school to always move all the guides out of the way when I swapped blades, then track the blade a little behind center of the upper wheel. The blade would track closer to center on the lower wheel. Only after it tracked well could I move the guides as close as possible without touching. I haven't done it since high school but we used to file a scarf joint and braze the blades. Some of them were tough to get tracking right. Anyway if we were going to rip or re-saw, we marked a board and free-hand cut a foot or so, then leaving the board in place, set the fence against it at whatever angle, if any, was needed. If it was way off I would track the blade forward or back. This has worked well for me since then. Perhaps my saw's tables are already close enough to square that it's easy to get the cut line parallel to the slot.

Yes, that's right, lay a straight edge along the side of the blade (between the teeth) and adjust the table so the miter slot is parallel with it.  If you like setting the blade behind center on the top wheel, fine, but you will have less ability to move the blade further back should you change blades and that one needs to be tracked a little further back.  You should only have to adjust the table once.  A good blade should cut straight and parallel with the miter slot when running on the center (or behind center in your case, though I'm not sure it will) of the top wheel.  If it won't, and you are confident the blade is good, then something else is wrong.  

The benefit of this approach, which is exactly what Grizzly says in their manuals, I'm not advocating anything original or new here, is that you don't have to skew the fence to adjust for drift and you will get square cuts off the miter gage.  

FWIW, Grizzly says to put the blade on the center of the top wheel.  On the bottom wheel the blade will ride slightly forward of center.  This is what gives the blade stability.  It also lets it cut straight and parallel with the miter slot, once the table has been adjusted.  I'm not sure that will be true if the blade is positioned behind center on the top wheel, except if that's where it needs to be because the weld isn't truly square or the teeth have different set from one side to the other.  What I'm saying is, center on the top wheel is optimum and allows the most flexibility for adjustment should it be needed.  

I hope that helps.  In the end, whatever works best for you is correct.  This is just what Grizzly and some others recommend and has worked well for me.


John

[MstrCarpenter]

Yes, that's right, lay a straight edge along the side of the blade (between the teeth) and adjust the table so the miter slot is parallel with it.  If you like setting the blade behind center on the top wheel, fine, but you will have less ability to move the blade further back should you change blades and that one needs to be tracked a little further back.  You should only have to adjust the table once.  A good blade should cut straight and parallel with the miter slot when running on the center (or behind center in your case, though I'm not sure it will) of the top wheel.  If it won't, and you are confident the blade is good, then something else is wrong.  

The benefit of this approach, which is exactly what Grizzly says in their manuals, I'm not advocating anything original or new here, is that you don't have to skew the fence to adjust for drift and you will get square cuts off the miter gage.  

FWIW, Grizzly says to put the blade on the center of the top wheel.  On the bottom wheel the blade will ride slightly forward of center.  This is what gives the blade stability.  It also lets it cut straight and parallel with the miter slot, once the table has been adjusted.  I'm not sure that will be true if the blade is positioned behind center on the top wheel, except if that's where it needs to be because the weld isn't truly square or the teeth have different set from one side to the other.  What I'm saying is, center on the top wheel is optimum and allows the most flexibility for adjustment should it be needed.  

I hope that helps.  In the end, whatever works best for you is correct.  This is just what Grizzly and some others recommend and has worked well for me.


John

Thanks John, this is why I like this forum. We can have different opinions, and even explain and discuss them respectfully. More important than that we try to help other woodworkers regardless of skill.

[FS7]

Thanks John, this is why I like this forum. We can have different opinions, and even explain and discuss them respectfully. More important than that we try to help other woodworkers regardless of skill.

I like it because I learn a lot. I'm not bad, but I don't consider myself anywhere near the skill level of most here.

In this case it's interesting because I see both sides. In fact, I can see both working together. Having the blade square to the miter slot (and the fence square) means it should cut as straight as possible without having to adjust for blade drift at the fence. Using the inherent skew in crowned tires can also help adjust for blade drift as the cut line should change. My guess is that if the center of gravity of the blade (across its width) is directly over the crown of the tire and it is aligned to the table, it should cut very straight. If not, then it's going to be working against several other factors.

I can see why most people throw their hands up and say that a bandsaw isn't a precision tool in this regard, but I also know that many here have well-tuned bandsaws that can saw 1/32" veneers from a 7" piece of lumber (or maybe even wider). That's what I want to get out of my bandsaw and discussions like this only help those of us who don't use them as much as we thought we would because we aren't entirely sure of what we're doing.

[Roly]

I like it because I learn a lot. I'm not bad, but I don't consider myself anywhere near the skill level of most here.

In this case it's interesting because I see both sides. In fact, I can see both working together. Having the blade square to the miter slot (and the fence square) means it should cut as straight as possible without having to adjust for blade drift at the fence. Using the inherent skew in crowned tires can also help adjust for blade drift as the cut line should change. My guess is that if the center of gravity of the blade (across its width) is directly over the crown of the tire and it is aligned to the table, it should cut very straight. If not, then it's going to be working against several other factors.

I can see why most people throw their hands up and say that a bandsaw isn't a precision tool in this regard, but I also know that many here have well-tuned bandsaws that can saw 1/32" veneers from a 7" piece of lumber (or maybe even wider). That's what I want to get out of my bandsaw and discussions like this only help those of us who don't use them as much as we thought we would because we aren't entirely sure of what we're doing.

What I don't understand is why the position of the blade on the crown has much effect if the blade guides above and below the cut are holding it in position.   Seems like they should have a way to adjust the angle.   Roly

[jteneyck]

What I don't understand is why the position of the blade on the crown has much effect if the blade guides above and below the cut are holding it in position.   Seems like they should have a way to adjust the angle.   Roly

The angle of the blade is determined by how it sits on the top wheel.  Trying to use the guides to control the angle of the blade is looking at it the wrong way.  Set correctly, they don't even touch the blade until the blade starts to deflect left or right.  The purpose of the guides is to assist the blade to keep cutting straight when you are cutting curves.  For ripping and resawing guides play no role.  

John