Resawing problems. Boards coming off, wedge shaped

[dirk martin]

I've jointed the face of my board nice and flat. It's 8" wide. I want to resaw it. Black Cherry.
I'm using a Mini Max MM24 bandsaw.
I put my board on edge, and proceed into the saw nice and slow.

The board is coming off the blade, wedge shaped.
But, read closely before you say my blade is dull. It's thicker at the top, and thinner at the bottom.
I understand a dull blade will wander during the cut, but what's causing a wedge shaped cut?
The blade feels very sharp to my thumb.
In other words, the blade is bowing away from the fence at the top of the cut, but not at the bottom.
The board I just resawed comes off the saw thicker at the top, and thinner at the bottom.
And, the kicker is, the top of the board is very close to the upper guides....compared to the bottom guides, which are under the table. So, it's really hard for the saw to do, what it's doing.

What gives?

[Loren Woirhaye]

Make an auxiliary fence face and shim it with paper until you attain a more acceptable consistency.

Some people get a thrill from fiddling with machines to resaw perfect wide veneers. I don't work that way. I prefer to resaw boards in the 4-6" width range and the setup is more forgiving that way. As with a lot of things, it depends on the sort of work you do, the woods you use and the ways you prefer to invest your time.

[Jamie Buxton]

Is this a saw which has resawed well before? If so, I'd try a new blade. In my experience, the only way to know a blade is dull is that it starts misbehaving. It may still feel sharp to the thumb, and may look good, but it stops cutting correctly, it is done.

If this is a new saw which has never resawed properly, well, there are a lot of possibilities.

[Steve Juhasz]

Are you sure the table is square to the blade? A tilted table would produce wedge shaped boards.

[mreza Salav]

That bandsaw should have no problem resawing much larger boards if the setup is proper. Several things could be the cause:
- is the blade tensioned properly?
- Does the cut start straight (i.e. the board is completely parallel to the blade travel) or maybe the edge of the board isn't quite square to the table?
- Are you using the fence or just relying on the edge of the board to keep it upright? If the first case is the fence 90 degree?

[dirk martin]

Thanks for all the replies. A tilted table is the first thing I checked, Steve, because what you wrote is indeed true.
I've resawed with this saw for years and years.
The table is 90 degrees to the blade.
Yes, it does start straight...and continues as such, thru about 1/2 the board....as long as I go very slow.
I am using a fence, and it is square to the table, and parallel to the blade.

I've had this happen before, and the only way to solve it is to mount a new blade.
I figured putting on a new blade, was kinda like me taking my blood pressure pills (it's a fix to the problem, but what's causing the problem wasn't found)
I hate doing that, as I'm not getting much mileage out of these blades....and I really find it hard to believe that that is the problem....but I guess indeed it is....I dunno.....

[James Conrad]

How are the guides set? Any chance the blade is being pushed to one side into the guide wearing the teeth and causing the blade to wander, does it always wedge cut in the same direction? If the setup is without fault, and I'm having issues, changing the blade does the trick 9 out of 10. I use Lennox bi-metal blades 3,4 and 6 tpi 1/2" for resawing all widths on my MM20.

I'll also add, if you usually get good blade life and then suddenly not, something is amiss. Are the teeth over hanging the tire, recheck drift, tension, guides, table/blade square in all directions, is the blade hitting somewhere else in its run - pretty much run through the motions...

[dirk martin]

James, I used to use a Lennox bi-metal, years ago, and it did me well.
Maybe I need to go back to it....it's been a while since I used one.

Why are you using a 1/2" on your MM20, rather than a 3/4", or 1" ?

[James Conrad]

Hi Dirk, the 1/2 inch just works well for me. Perhaps because of its smaller width I don't have to tension as much as a wider or thicker kerfed blade, it just came about through experimentation. I also use a fence to match the height of what I am resawing and stack feather boards the same height with pressure right at the blade. It works well for me, just before our recent move I resawed 60-80 veneers in domestic and exotics 7-12"+ in width, changed blades once, used 2 blades, with the change 3/4 through the job. With each blade change I check everything mentioned above along with cleaning, lubricanting and dressing the blade. Let me know if need more info.

James

[John Stankus]

Are you sure the table is square to the blade? A tilted table would produce wedge shaped boards.

Another question is: Is the edge that the board standing on square to the face riding on the fence? The original posting mentioned that the face was jointed flat but not that the edge was square to the face.

John

[Jeff Duncan]

The fact that it's starting out correct and then moving mid cut says to me it's either blade tension or blade not being sharp. If your using a plain steel blade like the Woodslicer for re-sawing your not going to get too far in my experience. I found they dulled way too quickly for what I wanted to do. I switched to a RSK Carbide blade which cuts a bit slower but really very clean. I've had it on for some months now, just finished up re-sawing several hundred bd. ft. of Walnut for door skins and it's still going strong. The price of the carbide are hard to swallow....but now I believe it's probably cheaper in the long run;)

good luck,
JeffD

[Mel Fulks]

I would use a 1 inch blade with 2 teeth per inch . With that 1/2 inch blade there must be too many teeth.

[James Conrad]

I would use a 1 inch blade with 2 teeth per inch . With that 1/2 inch blade there must be too many teeth.

Huh? Who says only 2tpi works for resawing?

[Mel Fulks]

Not saying it's the only thing . I do think it allows you to cut faster without deflecting the blade. Many times I have seen some other employee try to resaw one or two boards without changing to a more appropriate blade ,the result is they usually ruin one side of the board and just net one piece.....and dull the blade and fail to change it. I will not dull a blade and waste time over some cheap board ,and have always made that clear to management . When working where there is
no dedicated resaw ,I have occasionally changed bandsaw to two tooth blade to resaw some expensive wood .

[Myk Rian]

are you sure the table is square to the blade? A tilted table would produce wedge shaped boards.
this ^^^^^^

[Jim Matthews]

That's a VERY good question.

There are so many things that could cause this problem;
this one is simple to confirm.

[Jim Matthews]

If there's an appreciable curve, I suspect blade tension is insufficient.

If there's just the taper (thicker at the top, thinner at the bottom) - and it starts after the cut
I wonder if the blade is heating enough to increase over it's length and take a slight curve.

I'm fighting the same inconsistency in resawing and now doubt that the upper and lower guides are properly aligned.
Any twist relative to the blade could account for this; the top of the blade turned toward the fence,
the bottom guide twisting the blade away from the fence steering the cut.

I'm going to try resawing (next time) with the guides removed entirely, just to see how the saw tracks on it's own.

[James Conrad]

When things start to go odd resawing, I stop and check everything, I also believe because I do this I have far fewer problems arising. A few things have been really helpful - a full height fence, feather boards the entire height of the work piece, I 4S the board and rotate end for end after each slice to account for small blade shifts and I align the fence for drift. I've heard a hundred times "well if your bandsaw is set properly you don't have to account for drift, look at so and so expert, blah blah blah." All I have to say for that is, if you want to come down to my shop and prove to me you can set up my bandsaw so I have one less thing to adjust, have at it! It's a bandsaw, drift happens.

So, ah, ya set up is important.

[Mel Fulks]

Dirk ,you don't have to do much googling to see that 2 teeth per inch will help you. Don't let the fact that some have the skill and time to resaw with a finer blade make you think that is better. Recently I saw a guy going across part of Grand Canyon on high wire, he is obviously highly skilled but I'd rather rent the donkey.

[Prashun Patel]

I don't think I saw this mentioned:

Is your resaw fence parallel to your blade and square to the table? When you push the piece through, are you pressuring against the fence or the table? I always use a feather board which pushes the piece against the fence; the alignment of the fence becomes more critical than the perpendicularity of the table - especially on tall resaws when you pressure high on the fence where a small misalignment is amplified.

I'm less inclined to think it's a blade sharpness issue; that usually just results in wandering or bowing for me - not a strictly beveled cut.

[Brian Kincaid]

I never worried too much about whether the fence was square to the table, only that the top of the fence was the same distance to the blade as the bottom of the fence. Since it is described as a 'wedge' I expect this is a bigger problem than 1/32".

Here would be my top three in order of troubleshooting:
1) Is the wood releasing tension (bow/cut/twist) when cut? If so you will need to use a point fence.
2) Is there a knot or something that is forcing the blade offline?
3) Is the wood held flush to the fence through the entire resaw? I use feather boards.
4) Are the guides set properly with the blade at tension? The blade should track without touching any part of the guides.

-Brian

[Jim Neeley]

If the first part of the cut is straight and it moves to an angle cut partway through, you must look at what changed during the cut.

Heating is one possibility.

Cutting fast enough that the gullets are incapable of carrying away all the dust thats cut is another.

I suggest making a test cut moving the wood s-l-o-w-l-y... One time, one scrap of wood. Moving it slowly will lead to more blade heating so if it leans more it would help point to that being a likely culprit,

Just my $0.02.. YMMV.

Jim

[Alan Lightstone]

I tension my blade as much as I can (I would personally go as high as your saw allows without fully compressing the spring - which with your MM24 should be impressive) and use a full height tall Driftmaster resaw fence and spring-tensioned resaw guide. Since taking that approach, I have no problem resawing 10-12 inch boards on my Laguna 14SUV, so a far smaller, far less capable bandsaw then yours.

I had a problem a few years ago with wedge shaped cuts, and built John Lanciani's full height resaw guide. Plus I do use a 0.75" RSK blade (should be too big to tension properly on my saw, but Laguna suggested it, and it works well), FWIW. Works well for me.

Anyway, here's a shout out to John's resaw guide. I built it, and it has made a world of difference. Not necessary to resaw well, but it sure does help:http://www.sawmillcreek.org/showthread.php?178546-Veneering-Resawing-questions

[dirk martin]

I'm pretty sure if I applied that much tension, with the MM24, the blade would snap.

[Alan Lightstone]

Might be. It's certainly a beast compared to mine. That being said, I would significantly increase the tension and try again.

[johnny means]

Is your fence adjusted for drift? Try resawing a board without the fence. Use a line marked on the edge of the board to guide your board freehand. If your cut comes up square you may need to align your fence.

[Keith Weber]

Recently I saw a guy going across part of Grand Canyon on high wire, he is obviously highly skilled but I'd rather rent the donkey.

There's no way I'd ride a donkey on a high wire!

[Pat Barry]

Dirk ,you don't have to do much googling to see that 2 teeth per inch will help you. Don't let the fact that some have the skill and time to resaw with a finer blade make you think that is better. Recently I saw a guy going across part of Grand Canyon on high wire, he is obviously highly skilled but I'd rather rent the donkey.

If he only made it across part of the Grand Canyon on the high wire then I'd certainly recommend a donkey

[Mike Leung]

When things start to go odd resawing, I stop and check everything, I also believe because I do this I have far fewer problems arising. A few things have been really helpful - a full height fence, feather boards the entire height of the work piece, I 4S the board and rotate end for end after each slice to account for small blade shifts and I align the fence for drift. I've heard a hundred times "well if your bandsaw is set properly you don't have to account for drift, look at so and so expert, blah blah blah." All I have to say for that is, if you want to come down to my shop and prove to me you can set up my bandsaw so I have one less thing to adjust, have at it! It's a bandsaw, drift happens.


So, ah, ya set up is important.


No drift here on both my Inca 342 with a 1/4" blade and my Laguna LT14SE with a 1" resaw king.

[Metod Alif]

Here is what works for me (much duplication from other replies): tall auxiliary fence for wider stock. Fence parallel to the blade, pressing the stock against the fence. Adequate feed rate: when I feel (or is it a figment of my imagination) that the blade kinda self-feeds the stock. I use low tension. When I tension the blade, I observe how it loses its slack - moves horizontally. When the movement stops, I give it another half-turn with the tension wheel. The same approach worked for my earlier Delta-14" (still OK with my friend who ought it from me - she is using my advice :)) and my current MM16. Lennox 3/4" - 3tpi bi-metal blade. I think that my friend uses 1/2" same kind blade.

Best wishes,
Metod

[Gus Dundon]

I agree with Metod. If you're feeding the log too fast, it will cause the blade to deflect more which results to wedge shaped boards. With 3TPI blade , a moderate feed rate should be applied.

[dirk martin]

Ok, but doesn't it seem odd he's recommending low tension? Everyone else says crank up the tension. This seems like a radical departure from the norm.....

[James Conrad]

Ok, but doesn't it seem odd he's recommending low tension? Everyone else says crank up the tension. This seems like a radical departure from the norm.....

He is describing the tensioning of the blade by the flutter method. You don't do it while cutting.

[Mark A Johnson]

Try going back and recheck your BS setup. Back off all the guides and make sure that your blade is running center on the wheels. Before you reset the guides making sure the table is square to the blade. And recheck your fence, you can a aux fence for taller pieces. If its still net cutting true, replace the saw blade. Using a good saw blade thats is set correctly you shouldn't need a drift fence.

There are some articles on FW and there is also some stuff on Timberwolf site about setup. I went through the same on my BS when I went to cut some Australian Burls, replacing the saw blade resolved the issue.

Nice saw hope that helps

[Metod Alif]

Ok, but doesn't it seem odd he's recommending low tension? Everyone else says crank up the tension. This seems like a radical departure from the norm.....
Going easy on the tension was not my idea. I figured, if it works for some highly competent woodworkers, it is worth trying. Keep in mind that a bandsaw works on a 'pull stroke'.
Many years ago, Fine Woodworking magazine had an article advocating high tension. A while later they reconsidered - and the 'expert' was not writing for them anymore.
If a saw is properly tuned, a dull blade will still cause problems, even if the operator's skill is adequate.
What I find odd is that many do not evaluate/analyze various information or misinformation. Every progress is, in essence, a departure from the norm.
Best wishes,
Metod

[dirk martin]

Every progress is, in essence, a departure from the norm.

Metod

Wow....love that phrase.
me thinks ill carve that into a sign.....

[Erik Loza]

Dirk, late to the discussion and not sure if you have made any headway with this but here are my thoughts...

"Low tension" is not where you want to be on the blade. At least not on this task. That is, in my experience, the #1 cause of cutting performance complaints among my owners: Inadequate blade tension. That being said, I usually see a wandering cut with too low of tension, not a cut trapezoidal in profile, so I kind of don't think tension is the culprit here. But it is never a bad idea to try a different blade in any case, just to eliminate that as a possibility.

As others have already asked, have you confirmed that the cast iron table is 90-degrees too the blade and that the fence is co-planar to the blade as well as likewise 90-degrees to the table? Also, have you checked that the guidepost is plumb to the cast iron table through its full travel? On big resaw-capacity machines like the MM24, if that adjustment is not correct, the guidepost can travel quite a bit away from plumb as it gets cranked up or down. Lastly, if you are resawing much tall stuff at all, it is just a good idea to either fabricate or to purchase an auxiliary tall fence. It just makes everything easier. This is the auxiliary fence that my colleague, Sam, fabricated for one of his MM24's. Nothing fancy, just a tall fence of solid wood that has countersunk holes and can be screwed to the cast iron fence (which was drilled and tapped for machine screws)....

http://i75.photobucket.com/albums/i315/erikloza/Mini%20Max%20Bandsaw%20Works/VeneercuttingonMM16.jpg

Also, what blade is this if I can ask? Not sure if it was mentioned already.

Thanks,

Erik Loza
Minimax USA