Blade deflection on Bandsaw - only some times. Why?

[Erik Loza]

I have never personally experienced "drift" on any flat-tired (Euro-built) bandsaw. In talking with owners, I sometimes hear "drift" get tossed around when the phenomenom they are describing is actually blade "wander" (a result of inadequate blade tension...) but in my experience, it is practically impossible to get a blade on a flat-tired bandsaw to actually "drift" during the cut if the blade tension is right. I've had blades accelerate during a cut if the wood has irregularities or voids in density but never actually cut anything but parellel to the fence.

This is all assuming we are talking about a straightline cut, not a curved one.

Erik Loza
Minimax USA

[Kevin Nathanson]

My 24" Agazzani doesn't drift either. You can back off the guides completely, top and bottom, and it cuts straight with 30000psi tension on a 1" Trimaster. Obviously the guides are needed for a curved cut. That was the main reason I killed my woodmaster CT that I wrote about earlier; the guides were backed off and allowed the blade to twist too much when I cut a curve.

K

[Phil Thien]

Are you speaking from experience, Phil? My MM20 has zero "drift" and the lead angle is parallel to the blade (a 1" Lenox trimaster currently). I tend to think Dirk has a tension problem myself, I know that when I run my saw with the 1" blade set to a measured 30,000 psi tension that deflecting the blade is extremely unlikely.

The only bandsaw I've owned with flat tires was an Inca, and it drifted. But I've also used a friend's Laguna with flat tires, and it also drifted.

Of course, if flat-wheeled saws didn't draft, I kinda doubt Laguna would sell the DRIFTMASTER fence, which features adjustments for drift, LOL.

[Pat Barry]

Advance to 14:10 of this video...

Eric, Thanks for the link to the MinMax video demo. Very interesting. Looks like a very well built machine. I do see at about 17:20 the person doing the demo goes into the details for setting the blade guides in order to do some straight leg blanks.

[dirk martin]

Advance to 14:10 of this video...

http://www.youtube.com/watch?v=NFHQB-ZLS84

That statement would be correct if we were talking about smaller bandsaws but with industrial-grade machines (Centauro/ACM/Agazzani), there is enough frame strength in the machine that we can let blade tension and tracking do the work that the guides otherwise are compensating for on lighter-duty bandsaws.




Dirk, I'm not here to argue with anyone. Plain and simple: This is a setup issue. And I can tell you that because I have personally done the cuts you are trying on an MM24 and had zero issues. That's not me being cute or saying that someone doesn't know what they are doing. That's just being honest.



Erik Loza
Minimax USA

As I stated originally, I too have cut hundreds of boards of soft maple, with no issues.
Again, this is only happening *occasionally*, with some red oak. The minute I go back to soft maple, or grab a different piece of red oak, I'm good.

I haven't mentioned this, but I do indeed have a professional tension gauge....I just can't find the darn thing.
I'm in Jamaica right now, but when I get back, I'm gonna look hi-and-lo until I find it, and I'll see where I'm at.

I still can't imagine not using my thrust bearing with every cut, regardless of the tension.
Years ago, when I first got the saw, I used a Trimaster 1", and resawed for 3 years with that blade before it wore out. And, I relied on that thrust bearing with each and every cut. Feeding so slow as to not need a thrust bearing would reduce my production rate to such a volume, that I'd probably have to triple my prices on thin boards.

In your last paragraph, Erik, you mentioned rippng several hundred board feet....I'm ripping nothing...I'm resawing only.

[Erik Loza]

Dirk, how many board feet are we talking about per run, here?

You might actually need a larger saw and three-phase motor.

Erik Loza
Minimax USA

[Tai Fu]

I notice most lumbermills use carbon steel blades, no bimetal or anything fancy. I always wonder why... maybe they thought they rather get cheap blades and not cry when they hit a hidden nail or rock...

[Erik Loza]

I notice most lumbermills use carbon steel blades, no bimetal or anything fancy. I always wonder why... maybe they thought they rather get cheap blades and not cry when they hit a hidden nail or rock...

Cost is probably a factor but also, skip-tooth blades cut a lot faster than flat-kerf blades like a carbide will. Any flat-kerfed bandsaw blade is going to be sensitive to feed rate and pressure.

Erik Loza
Minimax USA

[Phil Thien]

I have never personally experienced "drift" on any flat-tired (Euro-built) bandsaw. In talking with owners, I sometimes hear "drift" get tossed around when the phenomenom they are describing is actually blade "wander" (a result of inadequate blade tension...) but in my experience, it is practically impossible to get a blade on a flat-tired bandsaw to actually "drift" during the cut if the blade tension is right. I've had blades accelerate during a cut if the wood has irregularities or voids in density but never actually cut anything but parellel to the fence.

This is all assuming we are talking about a straightline cut, not a curved one.

Erik Loza
Minimax USA

So why are the fences adjustable for drift, and why do the manuals go into the procedures for adjusting the fences for drift?

Here is a Minimax manual which covers drift:
http://valleywoodworkers.org/shop/Mi...0Saw%20MOM.pdf

Kind of strange they'd go through the trouble of making a fence adjustable, and discussing the adjustment in the manual, if the saws never drift.

[john lawson]

When a blade gets dull and you feed too fast the gullets don't get clear of sawdust before the tooth exits the wood. The result is more heat and a duller blade. If the blade gets dull equally (all tips have equal wear) then the blade will tend to continue to cut straight.

If the blade gets dull unequally it will tend to "drift". All of the drift I have seen in a bandsaw has been the result of a dull blade. I use Trimasters so when one starts to get dull I don't just throw it away. And I have had to resaw with a blade that demonstrated drift. And I do have a Driftmaster fence now.

I believe you can induce "drift" with the setup of the bandsaw, but that is probably taking it out of factory settings for the bottom wheel.

Again, my experience says you can have drift from feeding too fast or a dull blade. Combine the two and you don't have a chance.

[Erik Loza]

So why are the fences adjustable for drift, and why do the manuals go into the procedures for adjusting the fences for drift?

Here is a Minimax manual which covers drift:
http://valleywoodworkers.org/shop/Mi...0Saw%20MOM.pdf

Kind of strange they'd go through the trouble of making a fence adjustable, and discussing the adjustment in the manual, if the saws never drift.

Phil, that manual was created over ten years ago, right after the first MM-series were introduced. At the time, this series of machinery was being first introduced to the US market and the gentlemen who wrote the manual were trying to use terms folks would understand. If we wrote in the manual, "Don't worry about blade drift", the folks would be even more confused than they actually are and that doesn't benefit anyone. We described scenarios that folks more accustomed to domestic bandsaws would have experienced. "Yes", the fences on all MM-series bandsaws are adjustable for parallelism to the blade (as they should be...) but I have set up hundreds of our bandsaws and stand by my earlier statement: If the tension is right, that blade is not going anywhere but in a straight line. Especially with a 1.0", 30,000psi blade. Again, this is from firsthand experience.

If you want to discuss this with me in depth, feel free to shoot me a PM. If you just want to argue, I don't know what to tell you there...

Best,

Erik Loza
Minimax USA

[Pat Barry]

Phil, that manual was created over ten years ago, right after the first MM-series were introduced. At the time, this series of machinery was being first introduced to the US market and the gentlemen who wrote the manual were trying to use terms folks would understand. If we wrote in the manual, "Don't worry about blade drift", the folks would be even more confused than they actually are and that doesn't benefit anyone. We described scenarios that folks more accustomed to domestic bandsaws would have experienced. "Yes", the fences on all MM-series bandsaws are adjustable for parallelism to the blade (as they should be...) but I have set up hundreds of our bandsaws and stand by my earlier statement: If the tension is right, that blade is not going anywhere but in a straight line. Especially with a 1.0", 30,000psi blade. Again, this is from firsthand experience.

Eric, your video guy spends time discussing the simplicity of the drift adjustment right about 5:30 of the clip. Obviously the machine needs to have drift adjustment. Yours is a selling point.

[Erik Loza]

Eric, your video guy spends time discussing the simplicity of the drift adjustment right about 5:30 of the clip. Obviously the machine needs to have drift adjustment. Yours is a selling point.

Pat, I was the guy shooting the video. Sam mentioned it for the same reason it originally appeared in that manual: To explain an adjustment in terms the lay-user would understand. In other words, it is easier to just say, "Here's the drift adjustment", which everyone gets, than to go into a long explanation (as you can see from this thread, LOL!) about how it really does not come into play in the real world.

The user manual and in particular, the video are not really the places to try to "de-bunk" someone's concept of machine setup, for the reason that many users willl never experience "drift" at all (I think Kevin and John made comments to this effect, earlier....). So, yes, we use the term "drift adjustment" to describe the parellel adjustment of the fence but do not spend too much time on it due to the fact that "blade drift" may never even come up as an issue for many or even most operators.

Hope this makes sense,

Erik Loza
Minimax USA

[Ken Fitzgerald]

I closed this thread.

You can disagree without being uncivil , confrontational or argumentative.

When it gets to be nothing more than arguing for the sake of arguing, the thread is worthless as far as being informational or educational.

This isn't the friendly, civil behavior expected here at SMC.