Does bandsaw blade tension matter?

[Randall J Cox]

I guess, although I have ceramic guides underneath, I never saw sparks because I was always looking at the wood and the cut. That in addition to the sparking has to be going on under the table and downward I would guess. As I have used my BS in this configuration for years, as have others no doubt, maybe its a non issue like Van says. Now I will wonder or worry about this when I use it. Of course I could always change from ceramic to some other guide configuration....its a free country - so far. Randy PS I always seem to find BS discussions interesting, I guess because I'm always wondering if there is a better way to do it... Randy

[Doug Garson]

I commented on the video a year ago and got a response from Ethan. His main point is that drift is caused by set in the blade and the Little Ripper avoids drift by preventing putting a set in the blade. Here's my question and his response.

Question

Great video, can you comment on the blade you used? You demonstrated that the saw setup (or lack of it) is overcome by the Little Ripper, can it overcome a bad blade?

REPLY

EthAnswers by Stockroom Supply1 year ago

Great question Doug!I may use your question in a future video.First off the little ripper does not eliminate blades drift, rather it prevents it. If I put a blade on my saw that already drifts the Little Ripper will not fix it. But the Little Ripper never allows you to put drift into your blade.You have to remember a standard bandsaw blade has about 0.025" kerf....if I reduce that set by 0.001" on one side of my blade its going to cut about 7-8% the opposite way. It's very easy to do this freehand, against a fence by binding the blade or twisting the blade with a resaw pin.Long story short...As long as you don't damage the set the blade will cut perfect. I've been at woodshows cutting osage orange with dirty nasty bark all weekend with the same blade. By the end of the weekend the blade is incredibly dull..but dull equally on both sides. Therefore still cuts perfectly straight.Hope this answers your question!

[Lee Schierer]

I commented on the video a year ago and got a response from Ethan. His main point is that drift is caused by set in the blade and the Little Ripper avoids drift by preventing putting a set in the blade. Here's my question and his response.

Question

Great video, can you comment on the blade you used? You demonstrated that the saw setup (or lack of it) is overcome by the Little Ripper, can it overcome a bad blade?

REPLY

EthAnswers by Stockroom Supply1 year ago

Great question Doug!I may use your question in a future video.First off the little ripper does not eliminate blades drift, rather it prevents it. If I put a blade on my saw that already drifts the Little Ripper will not fix it. But the Little Ripper never allows you to put drift into your blade.You have to remember a standard bandsaw blade has about 0.025" kerf....if I reduce that set by 0.001" on one side of my blade its going to cut about 7-8% the opposite way. It's very easy to do this freehand, against a fence by binding the blade or twisting the blade with a resaw pin.Long story short...As long as you don't damage the set the blade will cut perfect. I've been at woodshows cutting osage orange with dirty nasty bark all weekend with the same blade. By the end of the weekend the blade is incredibly dull..but dull equally on both sides. Therefore still cuts perfectly straight.Hope this answers your question!

From where I sit the "Little Ripper" is just a fancy fence. It still holds the board in a precise alignment to the blade parallel to the miter slot as the piece is being cut. The piece being cut can't move and the off cut is free to move as it sees fit. So, Ssumiing I'm cutting veneer thick strips off a larger piece, If aligned my fence to the miter gauge slot and then put the piece being cut against the fence so the cutoff was free to move isn't that the same effect as using the "Little Ripper". I'm not forcing the blade to cut away from my fence and the piece being cut stays rigidly aligned with the fence. I would just have to joint the face against the fence before starting my cuts unlike cutting veneer of of a rough cut board that was demonstrated in the video.

[Van Huskey]

You have it correct Lee. The only issue is when the offcut is away from the fence you have to reset the fence for each cut vs having the offcut on the fence side. One option that makes resetting the fence quick and easy is the Driftmaster fence from Laguna.

[Chris Parks]

I have always taken the simplistic view that blade drift is caused by the blade not being truly parallel to the fence taking for granted that is a sharp blade and tensioned correctly and I have yet to be let down using that view. I have tried for a while now to come up with a jig/device that would accurately and quickly show the alignment while the saw is running and the angle can be corrected by using the tracking adjustment. it can be done statically but it is a major PIA every time an adjustment has to be made.

[Doug Garson]

I think the Little Ripper is more like a slider than a fancy fence. Once you attach it, it ensures your workpiece moves in a straight line without any effort from you, unlike a fence where you need to maintain firm pressure to keep the workpiece against the fence and like you said you need to joint the piece before you start. Full disclosure I don't have one but I have a shop made sled which does the same thing. The real advantage is when you start with a raw log and you want to resaw it into boards or veneer.

[glenn bradley]

I saw this the other day and just sort of ignored it. Apparently many of us have been cutting veneer with a fence incorrectly for years ;-)

resaw veneer (1).jpg . resaw veneer (2).jpg

[Doug Garson]

I have always taken the simplistic view that blade drift is caused by the blade not being truly parallel to the fence taking for granted that is a sharp blade and tensioned correctly and I have yet to be let down using that view. I have tried for a while now to come up with a jig/device that would accurately and quickly show the alignment while the saw is running and the angle can be corrected by using the tracking adjustment. it can be done statically but it is a major PIA every time an adjustment has to be made.

My experience is that that is not the case on a bandsaw. As I said earlier, I have a shop made version of the Little Ripper. I damaged a blade once and obviously put a set in it. I tried to use it with my sled. It would immediately drift and it was impossible to resaw with it. Without the sled, I could hand feed a workpiece and it cut fine. The angle you need to feed the workpiece at to cut straight is a result of the set in the blade. I replaced the blade with one without set and I could resaw with the sled with no issues. The replacement blade was located on the wheel the same as the first blade so it was the blade set not the angle of the blade that made the difference.

[Chris Parks]

My experience is that that is not the case on a bandsaw. As I said earlier, I have a shop made version of the Little Ripper. I damaged a blade once and obviously put a set in it. I tried to use it with my sled. It would immediately drift and it was impossible to resaw with it. Without the sled, I could hand feed a workpiece and it cut fine. The angle you need to feed the workpiece at to cut straight is a result of the set in the blade. I replaced the blade with one without set and I could resaw with the sled with no issues. The replacement blade was located on the wheel the same as the first blade so it was the blade set not the angle of the blade that made the difference.

If I read that correctly you agree with me.

[Doug Garson]

If I read that correctly you agree with me.

Then I read your post incorrectly. I thought you said "I have always taken the simplistic view that blade drift is caused by the blade not being truly parallel to the fence ". I meant to say that blade drift is the result of loss of equal set on both sides of the blade so the blade does not cut straight because one side cuts more than the other which is what Ethan explained in his response to my question. So even if your blade is parallel to your fence it won't cut straight if it has a set. By set I mean it cuts more on one side than the other. In the example I described it was dramatic. I could follow a line on the workpiece freehand and cut a pretty straight cut but the workpiece was definitely not parallel to the blade. If I tried to cut parallel to the blade using the sled the cut would wander off line immediately. I've had similar experience trying to cut straight along a fence aligned parallel with a blade with set. The cut wanders off line no matter how hard you try to keep the workpiece against the fence. At that time I didn't understand what was happening.

[Chris Parks]

I am sure I qualified my response by saying a well sharpened blade which by definition will not have any differences in set from one side to another. Taking that for granted I absolutely stand by what I wrote, get the blade parallel to the fence, the correct tension, bearings or guides set correctly and there will be no "drift". It has certainly worked for me over many years.

[Doug Garson]

My bad, I guess I missed the words "a well sharpened blade which by definition will not have any differences in set from one side to another. " in your earlier post. That said, I think the main advantage of the Little Ripper or a shop made sled is when slabbing small logs on a bandsaw. The main disadvantage is that it relies on "a blade that does not have any differences in set from one side to another " since, unlike a fence, it cannot be adjusted for drift.

[Van Huskey]

I have always taken the simplistic view that blade drift is caused by the blade not being truly parallel to the fence taking for granted that is a sharp blade and tensioned correctly and I have yet to be let down using that view.

When I read this it makes me think we use the word drift in this situation differently. What you are calling drift I consider part of the setup of the saw. The blade should initially be setup perfectly parallel to the fence (and the miter slot if you are using it) but in my lexicon blade drift is when the blades actual cut is different from the actual setup ie when it is setup perfectly parallel to the fence but the result of the cut is not parallel. While there can be multiple causes of drift the cause most often seen is a difference between the set or sharpness on one side of the blade compared t the other, this is the basis of Ethan's hypothesis in the original video. This can be a result of poor manufacturing tolerances or use/abuse of the blade.

An analogy for the set/sharpness issue is the front tires on a car.* When both tires have the same pressure and the steering input is zero the car moves forward in a perfectly straight line. When you reduce the pressure in one tire (analogous to having a set/sharpness differential between the sides of the blade) the car no longer goes straight, it turns in the direction of the tire with the lower pressure. The bandsaw cut will also veer off. The video suggests that cutting with the offcut against the fence will induce this sharpness/set differential as a result of binding the blade I am not sure I agree this can happen but it depends on the kerf vs backer width and the tooth to the back of the blade distance. My gut tells me the kerf is wide enough on most blades to prevent the binding of the back of the blade but I would have to measure and investigate that.

The core of the video's message is to start with a blade with correct set and sharpness and don't do anything to impact the left-right balance of those attributes. This is absolutely correct and the Little Ripper helps to accomplish that, however, it is by far not the only means to that end, which is the key.




*1 this analogy assume the tires are physically the same and the suspension is set exactly the same on both sides of the car, in other words the pressure in the tires is the only variable

[John K Jordan]

I often dull the teeth on one side of the blade quicker than the other. I cut and dry a lot of woodturning blanks. After dry and before use, I sometimes make "skimming" cuts to square up warped blanks and expose the wood to evaluate and check for cracks and such. Since I have the block to the left of the blade and since the dust collector pickup is to the right the left teeth get dulled a bit quicker than the right. Since the blade is still cutting well overall, sometimes the tendency to drift is my cue to sharpen or replace.

[David Ragan]

My rather limited experience is this:

When am cutting pricey veneer, I put the band on, tension it, get correct riser height, and then cut an appropriate piece of scrap a couple inches

Shut down saw; leave blade in cut as is

I then go around to back side of table w a light illuminating my view....I’m looking down the cut, from the back (horizontally) to see how to minutely adjust the fence so that the blade runs exactly parallel to the surface of woodin the cut

My experience is in this way I get a very smooth sawn surface requiring minimal further work

NB: I said nothing about my $400 Starrett BS tension gage that I have buyers remorse over


YMMV