Blade deflection on Bandsaw - only some times. Why?

[dirk martin]

I'm running a new Woodmaster C carbide tipped bandsaw blade, on a Minimax MM24 bandsaw.

Resawed 3" soft maple all day, for 4 days straight.
Today, I switched to 3" red oak.

Several board's resawed (1/8") just fine, then all of a sudden on one of the boards, I saw the blade was deflecting away from the fence, and my slice was significantly thicker. When the slice was done, the cut was very non-smooth. The face of the stock was wavy, or ripply, after it came off the blade. I'm not saying "curly"...as in figured wood. This is actually a non-smooth surface.

In any event, I switched to a different board, and it sliced fine.
Then, another board caused the blade to deviate about 1/2 way thru it's length such that the leading edge of the slice was 1/8", and the trailing edge 1/4"...or greater.

As soon as the board comes off the blade, it snaps back to straight and true. When it starts to deviate away from the fence, it really puts a lot of pressure on the board that's between the blade and the fence.

I'm using a stock feeder, and feeding these 3" board very slowly.

I have *a lot* of tension on the blade, and really don't feel it's a tension issue. I'm afraid of breaking the blade if I pull it any tighter.

My side guides are kissing the blade, well.

Any ideas? Is this really just due to the grain of some of the red oak I'm resawing? I look at the boards, and I don't see anything crazy at all. Plus 3" stock is putting the saw on virtually no load....it slices very very easy...at least until the blade starts to deflect.

If I go back to soft maple, or cedar...all is well.

[Pat Barry]

I have *a lot* of tension on the blade, and really don't feel it's a tension issue. I'm afraid of breaking the blade if I pull it any tighter..

Is this even possible to do, because it would seem that you need more tension. Just not sure that breaking the blade is something you need to worry about. How much tension can a blade take before tensile failure occurs?

[Dave Mcintire]

The only time I have seen this is with a dull blade.

[dirk martin]

This saw is capable of putting a lot of pressure on a blade.
Can anyone else chime in on whether or not I should crank it up even more?

This saw has a scale on it, and I'm already off the scale....tho I hear the scale is very inaccurate.

[dirk martin]

The only time I have seen this is with a dull blade.

Awww, man, don't tell me that....
I got this Woodmaster C on Jan 7th of this year....don't tell me it's dull already.....

[Ken Fitzgerald]

Dirk,

Give Mini-Max a call and see if they can connect you with Sam Blasco. I will bet he could answer your question quickly!

[dirk martin]

I'd like to clarify, it's a Woodmaster CT, not Woodmaster C.

[Erik Loza]

That kind of deflection would either be from inadequate tension or from a dull blade.

Erik Loza
Minimax USA

[James Conrad]

I would have to agree with tension and/or dull blade, I've also seen an overly tensioned blade do wonky things. If you have done a solid 4 days of resawing as you say, it's enough to dull a blade even in pine. You may have pushed the blade into a guide by mistake, dulling one side...

Aside from that, check you setup for square and drift.

[Jim Matthews]

Were any of the maple boards live edge? Lots of interesting things are found in bark.

*****

I have the same problem with a basic 1" blade for resaw on my MM20.

I'm at the top end of the tension scale, and find that this occurs (as with yours)
at the finishing end of cuts in harder woods.

I wonder if it's because the feed rate is too high, and the blade is overheating.
This could lead to expansion sufficient to take the tension out of the blade.

When you stop to check, and the blade cools - the tension appears correct.

****

My take on this is that the squared portions of your stock should be verified, first.
If the stock to be resawn isn't dead straight, and absolutely flat the forces will
try to pull the board away from the fence, and the blade will deflect.

Check all the basic stuff as JC mentions above, verify the stock for square and straight.
All that remains after that is the blade.

[Erik Loza]

I just noticed that you are using a power feeder. If the feed rate is too fast, that may be creating issues as well. Or at least exaggerting existing ones.

Erik Loza
Minimax USA

[Andy Pratt]

The only time I have had an unexplained issue like this with a new blade was when it had been rubbing on the metal guard (guard shifted during blade installation and I didn't notice the noise since it was just barely rubbing on the teeth) and was prematurely dull. I did trouble-shooting on every other imaginable cause because "It can't be dull, I just put it on" before comparing the teeth to another blade and finally figuring out what had happened.

[Don Huffer]

I would say your blade is dull. It's important that the blade cut and clear the chips in order to maintain desired results. Remember the blade is actually bending back before it wonders sideways. The sideways cut is the byproduct not the initial problem. After it flexes back and then to the side. A great deal more heat is generated which only compounds the problem. The blade more than likely will not behave as it should no matter how much tension you put into it.

Al

[dirk martin]

I would have to agree with tension and/or dull blade, I've also seen an overly tensioned blade do wonky things. If you have done a solid 4 days of resawing as you say, it's enough to dull a blade even in pine. You may have pushed the blade into a guide by mistake, dulling one side...

Aside from that, check you setup for square and drift.

So you're telling me that 4 days of cutting, with a Lenox Woodmaster CT carbide tip blade, in soft maple, is all the duration I'll get out of that expensive blade?
I've gotten more than that, out of a regular bimetal blade from Timberwolf.

[dirk martin]

Were any of the maple boards live edge? Lots of interesting things are found in bark.

*****

I have the same problem with a basic 1" blade for resaw on my MM20.

I'm at the top end of the tension scale, and find that this occurs (as with yours)
at the finishing end of cuts in harder woods.

I wonder if it's because the feed rate is too high, and the blade is overheating.
This could lead to expansion sufficient to take the tension out of the blade.

When you stop to check, and the blade cools - the tension appears correct.

****

My take on this is that the squared portions of your stock should be verified, first.
If the stock to be resawn isn't dead straight, and absolutely flat the forces will
try to pull the board away from the fence, and the blade will deflect.

Check all the basic stuff as JC mentions above, verify the stock for square and straight.
All that remains after that is the blade.


None of the boards had live edges.
I am feeding at a very slow rate.
I have stopped my blade quickly, using the saw brake, and then felt the blade, and it's barely warm.

Also, realize that when I notice this behavior, it usually doesn't happen on the next board.
It's not like once it starts drifting away from the fence, it does that from then on.
On the next board, it's usually just fine.
And, again, this is only happening in my red oak.
The board stay against the fence just fine. It's the blade that will start drifting away...putting tremendous pressure on the stock that's between the blade and the fence.

[dirk martin]

I just noticed that you are using a power feeder. If the feed rate is too fast, that may be creating issues as well. Or at least exaggerting existing ones.

Erik Loza
Minimax USA

I'm feeding at about 9 ft./min.
I'll slice board after board after board, just fine, then all of a sudden on one board, it will start drifting away from the fence. I'll immediatly flip the switch on my stock feeder down to 3 ft./min....to no avail.
After that board finishes, and the board snaps back into place, the next board will slice fine again.

[dirk martin]

The only time I have had an unexplained issue like this with a new blade was when it had been rubbing on the metal guard (guard shifted during blade installation and I didn't notice the noise since it was just barely rubbing on the teeth) and was prematurely dull. I did trouble-shooting on every other imaginable cause because "It can't be dull, I just put it on" before comparing the teeth to another blade and finally figuring out what had happened.

If that was the case, wouldn't it be exhibiting this poor behavior on every board?

[dirk martin]

I would say your blade is dull. It's important that the blade cut and clear the chips in order to maintain desired results. Remember the blade is actually bending back before it wonders sideways. The sideways cut is the byproduct not the initial problem. After it flexes back and then to the side. A great deal more heat is generated which only compounds the problem. The blade more than likely will not behave as it should no matter how much tension you put into it.

Al

So, I should expect to burn through a $137 blade, every 4 days, is what you're saying ?

[James Conrad]

Certainly resawing for 4 days straight will take its toll on any blade, it's not as sharp as it was on day one. I have a MM20 and have done a pile of resawing with it, sometimes its just the way it goes with blades. As was mentioned before, it sounds like tension or dull blade. I'd guess when it wandered the first time it was pushed into a guide a dulled one side, but that's about all we can do is guess without being there. Change blades, check your setup and repeat. I've found resawing is very tactile work, a power feed may not be the best option.

[dirk martin]

Again, if it's a dull blade (like the blade I had loaded previous to this one), wouldn't I have this difficulty with every board?
Also, why do I get the feeling that if I wasn't using a stock feeder, folks would be saying "with that much resawing, you should be using a stock feeder."?

[James Conrad]

We aren't there, we can't detect every nuance in your setup, you're ultimatly going to have to figure it out for yourself, all we can do is provide suggestions, but if you don't try anything suggested what's the point in asking us?

What have you done to solve the problem? Have you tried changing blades? Have you removed the blade and reinstalled it, thoroughly inspected it, cleaned it, checked your fence, power feed, checked for drift, retensioned the blade, squared everything up to the blade, checked your guides and reset them...... If the blade is fine then it's your setup, if your setup is good as well then it's something with your machine.... This is basic band sawing 101 you have to be a bit of a detective sometimes.

[Jim Matthews]

So, I should expect to burn through a $137 blade, every 4 days, is what you're saying ?

That doesn't sound right, to me.
These things are built for this purpose, and should last.

Since you answered my novice questions above, what's left?

The blade might need some touching up with a file or diamond hone.
I don't suppose a sharper blade would make this worse.
http://www.woodturningvideosplus.com/resharpen-bandsaw-blades.html

The board in question might have wild grain constrained by the feeder.

I resaw with hand pressure, and don't have a mechanism clamping the board in place.
I wonder if you can do a test, feeding the offending board through?

Is it just the species - Red Oak - or did yours come from a tree that lived a hard life?

This is a pertinent problem to many of us, and worthy of further exploration.

[Erik Loza]

Dirk, two thoughts:

1.) Use the stock feeder on its slowest gearing. That's how we do it. You are probably dulling the blade by going faster.

2.) During the cut, what percentage of time does the rear of the blade push into the thrust bearing? More than 50%? Once in a while? Never?

Erik Loza
Minimax USA

[Myk Rian]

Is there by chance some squirrly grain in a few of the boards?

[dirk martin]

Dirk, two thoughts:

1.) Use the stock feeder on its slowest gearing. That's how we do it. You are probably dulling the blade by going faster.

2.) During the cut, what percentage of time does the rear of the blade push into the thrust bearing? More than 50%? Once in a while? Never?

Erik Loza
Minimax USA

We did try the stock feeder on it's slowest setting, and it *seemed* to help...but we still had the issue.
During the cut, the rear of the blade is pushing into the trust bearing 100% of the time....how could it not? The thrust bearing is the only thing keeping the blade from going off the rear of the wheels.

I'm really thinking that it's simply "crazy grain" in the offending red oak. The grain doesn't look wild to the eye, however, when we go to a different board, or to cherry, or to a piece of maple, all is fine.

[dirk martin]

Is there by chance some squirrly grain in a few of the boards?

That's my vote, Myk. I really can't think what else it could be.

Does anyone know how high I can tension the Woodmaster CT? I'd really hate to break it.

[Kevin Nathanson]

Does anyone know how high I can tension the Woodmaster CT? I'd really hate to break it.

Well, I've broken one, the same size as yours, but it was because I "pulled" it off the wheel by cutting a curve too aggressively. (Yes; stupid. I know.)

I used to tension it to ~30,000 psi with a Starrett gauge and had no problems with it. That was about as tight as I could go on my Agazzani 24 without binding the tension springs. BTW mine cut great right up to the point that it disassembled itself. I use a Trimaster CT now because I wanted to see if it cut any smoother. It doesn't, so the next time I'm a moron (AND need a new blade; otherwise the bar is set way too low...) I'll go back to the Woodmaster.

K

[Jim Matthews]

During the cut, the rear of the blade is pushing into the trust bearing 100% of the time....how could it not? The thrust bearing is the only thing keeping the blade from going off the rear of the wheels.



I think this is the important concept in play - blade tension should be sufficient to track straight and stay on the tire.
Otherwise, the feeding force is exceeding the rate at which the blade can eject the chip.

I've seen resawing done with no guides used.
(It was an enormous Crescent, with a 3/4" skip-tooth blade.)

I'll defer to the experts on this, but I was under the impression that guides were there
to keep you from twisting the blade. Tension and alignment are what keep the blade
cutting straight and on the wheels.

If I'm hitting the rear guide wheels on my Carters, I'm feeding too fast.

[john lawson]

I have had similar experiences with carbide tipped blades, and it did not take 4 days.

It does sound like it is dull, or at least duller than when you started. I have had good luck slowing down the feed rate on a carbide tipped blade as the blade gets duller.

I use mostly Lenox Trimaster, but the same thing happens over time. If you can slow down the feed rate.... when that doesn't work the blade is shot. I have had two blades resharpened but they did not last very long, maybe 20% of the life of a new blade.

If your feeder is too fast you may have to feed by hand. I feel your pain on the cost of the blade, that sucks.

[Erik Loza]

...During the cut, the rear of the blade is pushing into the trust bearing 100% of the time....how could it not? The thrust bearing is the only thing keeping the blade from going off the rear of the wheels...


...blade tension should be sufficient to track straight and stay on the tire...Otherwise, the feeding force is exceeding the rate at which the blade can eject the chip....I've seen resawing done with no guides used...


This ^^^

Obviously, I am not right there so this is just my best guess but it sounds like you have a somewhat dull blade coupled with too aggressive a feed rate and possibly, not enough tension. What is happening is that the feeder is jamming the blade into the thrust bearing and then overpowering the bandsaw's static tension, causing the the blade to wander all over the place. Like when you try to drive a screw too agressively with a cordless drill and the screw pops out sideways withouth driving directly in.

As Jim has pointed out, you should be able to perform the cut with no guides on the saw. Let blade tension and tracking do the work for you. That is assuming a sharp blade (which you may or may not have at this point). And, I would go with the slowest gearing on the feeder. I know your set can do what you want, you just need to get it dialed in...

http://i75.photobucket.com/albums/i315/erikloza/Mini%20Max%20Bandsaw%20Works/Samfeedingbandsaw2.jpg


...Does anyone know how high I can tension the Woodmaster CT? I'd really hate to break it.

I have more experience with the Tri-Master than the Woodmaster CT but would assume it is still in the 30,000psi range. Have you researched this on their site at all? Also, an aftermarket tension gauge might not be a bad investment in your case. Best of luck with it.

Erik Loza
Minimax USA

[Ed Aumiller]

I would say wierd wood...

Sometimes that will happen also if blade if running too slow...
Speed up blade speed, reduce feed rate....

[Matthew Hills]

Can you dull a tooth by cutting too slow? (thought I'd heard that somewhere)

[dirk martin]

First of all, I'd like to thank everyone for all the feedback. This has been very enlightening, and a tremendous help.


Having said that....
I woudn't dream of resawing wood without a rear thrust bearing (mine's a ceramic white disc that doesn't spin), even with a new blade.
Right now, I feed at a rate, such that I get thru a 6" x 24" long board in about 30 seconds.

Ok, I need something explained to me.
When I hear of folks shopping for a bandsaw for resawing, I often hear, "you're gonna want a lot of horse power. Resawing will tax a saw, and show you what it's made of."

If I'm not pushing the saw, such that the thrust bearing is even coming into play, then it seems as tho I'm not *working* my saw one bit. I may as well be using a 16" saw @ 3hp, rather than a 24" @ 5hp.

Are you telling me that if I had a 16" bandsaw, and was feeding at the slow rate you're suggesting, that a 3hp saw may bog down, where a 5hp wouldn't?

My sister is running a 24' Grizzly saw (5hp). She too has a ceramic disc for a thrust bearing. She says with every slice, the blade is against that thrust bearing during the entire cut, and sparking. She produces a serious amount of thin stock, and has been doing this for years.

It sounds like you're saying she's using it inappropriately. Well....if you're telling me to slow down, and creep along at a rate whereupon the blade touches the thrust bearing only occasionally, then I've got to do some serious re-figuring on my thin wood orders, because my production rate is going to fall thru the floor.

And, if she is using her Grizzly wrong, .....well, her wrong way is gonna dance circles around my right way. Like I said, she's been running the Grizzly like this for years. And, she's using regular Timberwolf carbon blades. I asked her how often she replaces them, and she said 'When my arms start getting tired from pushing too hard'. On her typical day, she'll produce 200-300 thin boards.

I bought a 5hp Minimax, because I had to get some production done. I wanted a saw that wouldn't bog down, as I fed boards into it, at a decent rate. Using my stock feeder at its slowest setting, is NOT a decent rate in my book. If you're telling me that I'm abusing my saw, then I have a MM24 for sale, and I'll go get me a Grizzly, which can clearly handle *my abuse*.

[Phil Thien]

Still sounds like drift to me. Let me ask you a question: Have you aligned your fence for drift, or is it square to the table?

And I disagree with the others that if the blade is hitting the thrust bearing that you're feeding too fast.

[Kent A Bathurst]

Resawed 3" soft maple all day, for 4 days straight.
Today, I switched to 3" red oak.



That kind of deflection would either be from inadequate tension or from a dull blade.


I got this Woodmaster C on Jan 7th of this year....don't tell me it's dull already.....

Dude - the blade cannot read a calendar. It only reads footage of lumber.

My money is with Eric on the dull blade. Coupled with a switch to some serious density.

Try a fresh blade and see what happens.

[john lawson]

I'm not an expert on this and others may be so they can chime in, but I have a 24" Centauro (SCMI/Minimax) and I have resawed quite a lot of wood. It has a max resaw of 12" (now maybe 13" since I put Laguna ceramic guides on it). My Centauro has a 3 hp motor. That motor has never really bogged down. I have noticed though that the taller I am resawing, say 12" and the harder the wood, the more stress it puts on the motor. If my blade is dull it will put even more strain on the motor/saw. And you can feel it and hear it. That is when I slow my feed rate.

If you imagine the mechanics of cutting with a bandsaw, the trueness of the cut is determined by the sharpness of the blade (all the teeth sharpened evenly) and the beam strength of the blade. I have been taught that the beam strength of the blade is determined by the thickness and size of the blade combined with the tension on the blade. So a 1" blade that is say .043" thick and tensioned to 25000 psi will have more beam strength than one that is 3/4" and .043 thick and tensioned to 25000psi. All other things equal, the larger blade will have more beam strength and track truer. The smaller blade may cut just fine and you will never know the difference, until the blade starts to get dull. A 5 hp saw will help you use that beam strength when your blade gets dull, but eventually problems will start to appear. One other thing, there is a real science on gullet size and shape that I can't address, but suffice to say that small gullets and many teeth per inch will result in heat and a dull blade. A fast feed rate will make it happen much quicker. Too slow may make it happen. Most bandsaws don't need a 5 hp motor except in rare circumstances, but it sure is nice to have.

I use ceramic guides on my saw and so far they are far superior to the Euro guides I had earlier. I have owned and used Euro guides on a 16" Laguna, and 18 Laguna HD, and at one time had some heavy duty Carters on my current saw. In my opinion you have a good setup. Nothing against the Euro guides, they worked OK, but I sure do like the ceramic

[Pat Barry]

Obviously, I am not right there so this is just my best guess but it sounds like you have a somewhat dull blade coupled with too aggressive a feed rate and possibly, not enough tension. What is happening is that the feeder is jamming the blade into the thrust bearing and then overpowering the bandsaw's static tension, causing the the blade to wander all over the place. .

..., you should be able to perform the cut with no guides on the saw. Let blade tension and tracking do the work for you. ..

Good luck with that! No blade guides?? I don't / won't buy it. That statement goes against logic and everything I've ever seen regarding bandsaw set-up.

[Chris Parks]

The answer to most BS problems can be found here...

http://www.youtube.com/watch?v=wGbZqWac0jU

he knows what he is talking about and dispells the drift thing once and for all. BS's do not drift if set up correctly despite what folk lore says.

[Phil Thien]

The answer to most BS problems can be found here...

http://www.youtube.com/watch?v=wGbZqWac0jU

he knows what he is talking about and dispells the drift thing once and for all. BS's do not drift if set up correctly despite what folk lore says.

MiniMax bandsaws don't have crowned wheels/tires, they're flat. And they are inclined to drift.

Furthermore, Mr. Snodgrass doesn't seem to understand how spring scales work as tension indicators. Differences in length won't change the built-in tension scales on 99% of bandsaws.

[dirk martin]

Good luck with that! No blade guides?? I don't / won't buy it. That statement goes against logic and everything I've ever seen regarding bandsaw set-up.

Thank you Pat!
I couldn't agree more.
But...I'll be open minded.

Tell you what Eric, I'l load up a new blade, back off all my guides, and then feed a board in on my stock feeder's slowest setting.
Will you replace the blade, if it comes off?
And, I want to use my stock feeder, cuz I don't what to be anywhere near that baby if/when the blade pushes off the wheels.

[Erik Loza]

Good luck with that! No blade guides?? I don't / won't buy it. That statement goes against logic and everything I've ever seen regarding bandsaw set-up.

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.



...Tell you what Eric, I'l load up a new blade, back off all my guides, and then feed a board in on my stock feeder's slowest setting.
Will you replace the blade, if it comes off?
And, I want to use my stock feeder, cuz I don't what to be anywhere near that baby if/when the blade pushes off the wheels.

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.

You mentioned being dismayed at having to pay for multiple blades. I was just talking to a customer yesterday whose hobby is drag racing. When he told me how much money he spent on tires, clutches, and other stuff that be basically had to throw away at the end of each track event, I was shocked. He buys clutches, uses the once or twice, then throws them out. That's just for testing and this is hobby!

It sounds to me like you are dead-focused on this specific setup for your needs and that is fine, but could it be worth it to take a step back, eliminate the variables one at a time, then see where you stand at that point? It sounds to me like at this point, we probably have a dull blade, possibly have an under-tension problem, and most definitely have a feet rate problem.

I can tell you, for example, that if I was planning to rip several hundred board feet of stock on a bandsaw, my first choice for a blade wouldn't be a carbide blade. That's because unlike a skip-tooth or AS blade, the flat kerf of a carbide does not clear as much volume of chips during the cut and thus, is more prone to dulling and more sensitive to feed rate. If I needed to run several hundred board feet, I might just use a 1.5" skip-tooth blade, then go the jointer afterward. Or I might just do it on the table saw. But, I would approach it methodically and let the best practice present itself.

As always, just my 2-cents.

Erik Loza
Minimax USA

[Phil Thien]

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.


No bottom guides/thrust bearing on that model?

[Erik Loza]

No bottom guides/thrust bearing on that model?

Yes, but way below the table. Not a "gimmick cut", in other words.

Erik Loza
Minimax USA

[John Lanciani]

MiniMax bandsaws don't have crowned wheels/tires, they're flat. And they are inclined to drift.

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.

[Chris Parks]

MiniMax bandsaws don't have crowned wheels/tires, they're flat. And they are inclined to drift.

Furthermore, Mr. Snodgrass doesn't seem to understand how spring scales work as tension indicators. Differences in length won't change the built-in tension scales on 99% of bandsaws.

You should write and set him straight.

[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/Mini%20Max%20MM20%20Band%20Saw%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/Mini%20Max%20MM20%20Band%20Saw%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.