Bandsaw Blade Tracking Adjustments Etc.

[JPG]

This thread contains a LOT of conjecture and outright guessing regarding the upper wheel cant, the wheel beveled surfaces etc.

Some earlier posts by me are not consistent with my current understanding.

The upper wheel is 'canted' apparently about .6 degrees. The top of the wheel is closer to the case than the bottom of the wheel.

When the cant angle is correct, a 1/4" blade properly tensioned will ride on both the upper and lower wheels about 1/8" in from the back edge of the tires.

Both the upper and lower wheels are slightly beveled(back edge of the tire has a greater od than the outer edge). This bevel is half of the cant angle(.3 degrees).


All this causes the back of the blade to be canted(.3 degrees) relative to the table(front to rear). The blade cuts deeper into the bottom of a workpiece than the top.

The table can be shimmed to be normal to the blade, but that creates a non-horizontal table surface.


This represents conclusions from discussions in other threads as well as this thread. It has been a long journey getting to this point. I firmly believe we now have an accurate understanding of the beast. The SS bandsaw is truly different.

[dusty]

This thread contains a LOT of conjecture and outright guessing regarding the upper wheel cant, the wheel beveled surfaces etc.

Some earlier posts by me are not consistent with my current understanding.

The upper wheel is 'canted' apparently about .6 degrees. The top of the wheel is closer to the case than the bottom of the wheel.

When the cant angle is correct, a 1/4" blade properly tensioned will ride on both the upper and lower wheels about 1/8" in from the back edge of the tires.

Both the upper and lower wheels are slightly beveled(back edge of the tire has a greater od than the outer edge). This bevel is half of the cant angle(.3 degrees).


All this causes the back of the blade to be canted(.3 degrees) relative to the table(front to rear). The blade cuts deeper into the bottom of a workpiece than the top.

The table can be shimmed to be normal to the blade, but that creates a non-horizontal table surface.


This represents conclusions from discussions in other threads as well as this thread. It has been a long journey getting to this point. I firmly believe we now have an accurate understanding of the beast. The SS bandsaw is truly different.

You have made statements similar to these several times. I am at a loss to determine what causes you to have concluded this. Please explain. Pictures and/or drawings would be helpful.

[JPG]

A thorough review of this thread(as well as some others) will reveal the 'source'(s).

Thee has been a source for some of it.

Now I understand not 'seeing' the various angles and how it all comes together.

Later today I will attempt to help visualization of it all by manually creating a sketch with exaggerated angles. Those pesky fractional angles are way too subtle! Some have been known to miss them entirely!

[JPG]

A 'sketch' illustrating the cant angle exaggerated.

C° is the upper wheel cant angle.

C° / 2 is the wheel bevel angle and is the deviation from a square tire face.

Notice the blade is drawn as a rectangle. The sides of the blade must be 90° relative to the back or the blade 'will twist' due to tension difference between back and front edge.

A bit crude, but should 'enlighten'.

[dusty]

Thank you. I now understand what you were attempting to communicate.

With this in mind, if I measure the bevel angle are you telling me that the proper tilt angle IS twice that measured value?

I have two band saws. The upper wheel cant on one of them, measured with a Wixey type device, is .4° and on the other the cant is .5°. Small numbers for a wood shop. So small that I have no way to measure the bevel angle so we have to utilize your calculation (which is quite logical). The bevel on the band saw wheels must be on the order of .25°.

Now that I know that bit of valuable information - what, if anything, can I do with it. Not much because I don't trust the angle gauge readings to be accurate at that level.

[JPG]

I cannot tell you the 'proper' cant angle since I do not know what it is other than by using a straight edge, ruler, and geometry. Since that yields something around .6 degrees I also question the accuracy.

We have in the past relied on straight edges and distance from straight edge to the opposite wheel to 'determine' cant.

Only recently has the info from CS indicated the position of the back of a 1/4" properly tensioned blade relative to the back edge of the tire be the way to check it. Mine(both) run about 1/4". IIRC CS said 1/8".

I think actually measuring the angles is not productive either. But informative none the less.

[dusty]

OKAY, we are using the same sheet music. The song is entitled "Mine Works, I Ain't Changing".

[jsburger]

I cannot tell you the 'proper' cant angle since I do not know what it is other than by using a straight edge, ruler, and geometry. Since that yields something around .6 degrees I also question the accuracy.

We have in the past relied on straight edges and distance from straight edge to the opposite wheel to 'determine' cant.

Only recently has the info from CS indicated the position of the back of a 1/4" properly tensioned blade relative to the back edge of the tire be the way to check it. Mine(both) run about 1/4". IIRC CS said 1/8".

I think actually measuring the angles is not productive either. But informative none the less.

I think that as long as the blade stays on the wheel and runs toward the back (as designed) the actual distance from the back of the wheel is not that important.

Since it was time to grease the upper wheel on my band saw I took it off. Once off the saw the taper of the wheel is very very evident. When installed on the saw it is very hard to see, at least to my eye. Presumably due to the cant in the opposite direction.

OK, I bought this band saw new in 1994. The tires have no cracks and are perfectly flat across them with no ridges or compression from the blade. I have always released the tension.

I balanced the wheel on the bench and put a square up against it. There is a very obvious bevel to the rim. I don't have a digital angle gauge but I balanced my analog gauge on the top of the wheel. Everything sat on it's own with no help from me. The angle gauge read four degrees which is in line with what the square showed. I believe someone said CS said four degrees.

I have not measured the upper wheel shaft cant because the reference surface is the lower wheel shaft and my band saw mounted on a power stand. I will have to remove the belt and pulley.

Again, the wheel bevel is very obvious once the wheel is removed from the band saw.

[dusty]

The bevel became somewhat obvious to me but maybe we aren't talking about the same thing.

Does this image of my band saw wheel depict the way you measured the bevel?

[jsburger]

The bevel became somewhat obvious to me but maybe we aren't talking about the same thing.

Does this image of my band saw wheel depict the way you measured the bevel?

Oh bother, I forgot to attach the picture. Looks like the angel is about the same.

Yes we are talking about the same thing. It is very obvious to me when the wheel is removed from the saw just by looking without the square but not obvious at all when the wheel is installed even if you know it exists.