Resaw Problem

[Tim Bridge]

I am trying to resaw some walnut veneer and I am getting some thickness variation.
The board is 6" wide and 12" long.
I have resawed next to the fence (inside) and outside the blade with the same result.

On the leading edge into the blade I get .016" and the trailing edge is .026"
From top to bottom I get a variation of .003"

The top to bottom variation is a squareness adjustment but .003" is not bad.

I can't tell if the variation I am getting between leading and trailing ends is due to the way I am feeding the board or an adjustment.

Is this an adjustment I could make to fix or human error?

[Scott DelPorte]

Hi Tim
Are you accounting for drift angle when you cut? Assuming your blade is tensioned correctly and sharp, you can sometimes compensate by adjusting the fence angle a little "off square" if the cut is drifting consistantly to one side.

Scott

[Erik Loza]

What machine and what blade?

Erik

[Al Launier]

Hi Tim
Are you accounting for drift angle when you cut? Assuming your blade is tensioned correctly and sharp, you can sometimes compensate by adjusting the fence angle a little "off square" if the cut is drifting consistantly to one side.

Scott

My thoughts exactly.

[glenn bradley]

What machine and what blade?

Erik

I'll wait for this as well. I am assuming you are re-surfaceing the sawn surface before each additional pass(?). I do this by jointing a face, jointing an edge and planing to thickness . . . cut off a piece of veneer, replane, cut off a piece of veneer, replane, etc.

[Tim Bridge]

It's a 1999 Laguna LT 16 Italian fitted with ceramic guides with a 1-1/4" Resaw King blade and a Driftmaster fence.

[Tim Bridge]

I haven't replaned after each cut. It's a good idea.
I adjusted for drift by centering the blade in the cut as Laguna recommended. Is there a better way to get this more accurate?

[Scott DelPorte]

You mention .010 variation in a foot. If it is consistent, you can try to adjust the fence and see if you can remove it. I adjust my fence for drift just using a trial and error method. I just make small drift adjustments until I can cut consistent slices and then cut to the outside of the blade so I am only jointing once. If you move the fence for each cut and cut from the outside (like on a meat slicer), some of the error from your cuts on either side of the piece (top to bottom variation) will cancel out and you should get more even thickness on each piece compared to always cutting from the inside. At least that has been my experience cutting thin stuff.

The only other thing I can think of that you might want to check while you are at it is your blade tension. I'm not familiar with that particular saw and whether it can fully tension an 1 1/4 blade (I assume it can), but I go off a gauge that measures actual blade stretch rather than the little indicator on the saw.

[David Kumm]

If the saw is the regular ACM 16" and not a heavier resaw machine, the 1.25" RK probably can not tension enough. I had an LT 18 and even with an upgraded spring, I doubt it would tension that blade. I used a 1/2" Trimaster as even the 3/4" was running at low tension. You can resaw and get acceptable results with a carbide blade at 10,000 lbs but all the planets need to line up. A 3/4" RK is as big as I would go on that saw. The RK has a thin band so it tensions easier but will also wander more under low tension and the stress of a too fast cut. Dave

[Scott DelPorte]

As a reference, I will usually tension the blade between 25,000 and 27,500 psi, which is toward the low end of the "green zone" on my gauge.

[John TenEyck]

What David said. Drift is usually caused by one of few things: a blade with too low tension, a dull blade or one with uneven set, or the blade isn't adjusted properly on the wheels and is steering left of right. Adjusting for drift means something is wrong; find it and fix it and your saw will cut straight and parallel with the miter slots. Only then is a BS truly useful, at least in my world.

It sounds like your saw cannot adequately tension the blade you are using. By adequate tension I mean 25,000 psi. But before you buy another one, have you tried adjusting it on the wheels? If it wants to cut left move it further back on the upper wheel, further forward if it steers right. Rip some scrap until it cuts dead straight, then try taking another slice of veneer, using light, steady pressure. Be sure to start with flat stock with a squared edge, and that your fence is truly parallel with the blade.

John

[John K Jordan]

After I got a Starrett bandsaw blade tension gauge I quit using blades over 3/4" - my 18" Rikon simply couldn't tension them properly without what I felt was too much force and stress on the components.

JKJ

[Tim Bridge]

The nameplate on the saw says it is rated for an 1-1/4" blade. When I use the tension gauge on the saw, and set it for an 1-1/4" blade it maxes out.

From what some of you are saying the saw blade max size may be exaggerated and I should use a narrower blade.
If the tension gauge on the saw isn't very accurate what should I use?

[David Kumm]

Tension gauges on a saw are only a reference for setting the tension close to what you have determined as the best for each blade. The graduations really don't relate to much. For the gauge to read what is really appropriate for a certain size blade, it would need to know the recommendation for that blade, or at least the thickness of the band itself. Saws usually allow for wider blades than they can tension. They use the width of the wheels as the determining factor. I use a Starrett or Lenox gauge because each saw and blade has it's own sweet spot and I'm not bright enough or musical enough to do it by feel or ear. Dave

[Andrew Hughes]

Bad resawing always points back to a blade getting dull or dull.New blades cut fast and straight.
I really wish bandsaw blades would last longer.
The truth for me is I try to use one blade for everything and it doesn't take much to spoil the tips.
Ive not found tensioning to make that much of a difference.

[Robert Engel]

Tim,

I've identified a few areas you could take a look at that have helped me.

Assuming the saw is well tuned, of course.....

1. I've found a 1/2" resaw blade works better than a wide blade and I can really run the tension up a 1/2" blade (as you've found you can't on a wide blade). Forget the gauge, I run my guide all the way up (12" on my saw) and look for no more than 1/8" deflection with a reasonable amount of force. The tension indicator will usually be between the 3/4 and 1" setting on a 1/2" blade.

2. I've tried point of contact fences and standard fences and I prefer the latter. I keep several on hand of different heights. I clamp them to the table, not the fence.

3. Keeping a lot of EVEN pressure against the fence. I often use a hand held feather board the same width as my resaw, especially critical when the board gets below 3/4" thick and starts to cup a little.

4. Feed rate. I have to keep reminding myself "Slow it down". Two things happen: a) if blade gets hot bad things happen , b) blade more susceptible to feed into the grain.

5. Which leads me to grain direction. Never thought about it before, I kind of discovered especially in softer woods, the principle is the same as planing. you want the grain direction so that if self feeding occurs, it will force blade against fence. When this happens, I'm checking blade tension, but just a thought.

6. Rejoint after each pass is a must.

[Prashun Patel]

If you are certain your fence and stock and table are perfectly square to the blade, then I suspect it's your blade tension. 1 1/4" is mighty thick for a some saws.

[John K Jordan]

The nameplate on the saw says it is rated for an 1-1/4" blade. When I use the tension gauge on the saw, and set it for an 1-1/4" blade it maxes out. From what some of you are saying the saw blade max size may be exaggerated and I should use a narrower blade.
If the tension gauge on the saw isn't very accurate what should I use?


My 18" bandsaw also specifies up to 1-1/4" but I think this is advertising hype intended to increase market share. In my opinion, even 1" blades are too big to use "comfortably" on my saw. I mean I can tension them to the mfgrs specs but from the extreme force I have to apply it feels to me it is stressing things so much I worry about premature wear or even bending of components. This feeling is only based on my lifelong experience with mechanical things. I have also switched to using 1/2" blades for nearly all of my sawing. I resaw occasionally but mostly process green wood (up to 12" thick) into turning squares, make jigs, rip and crosscut when I don't want to fire up the other saws, etc.

As I mentioned, the built in tension indicator on all saws I tested was way off.

There are several ways people recommend to tension without a gauge. Almost every person teaches with authority their way is the way to do it, that they've been doing it this way all their lives, and it will work for everyone else. I don't know, but the exact use of some of these might depend on the thickness, width, and material of the blade.

- Most methods involve tensioning then applying a subjective "some" or "moderate" pressure on the center of the blade and look for some amount of deflection. No where is the amount of side pressure defined. Some don't even indicate whether the guides should be fully raised first: deflection over 3" would be different than deflection over 12".

- Others recommend plucking the blade from the side and listening for the musical tone of the vibration. Again, the tone is not defined. This relies on experience.

- Some people simply recommend to use the built-in tension gauge and just set it to the number of the next largest blade. As someone mentioned, this isn't even enough on at least some saws.

- I'm certain there are others I've forgotten since every year I am more elderly and feeble minded.

The tension gauge always works repeatably, on every blade and every saw but they can be expensive. Counting my sawmill I use five bandsaws so I justified the cost, especially if I use it to check bandsaws for other people.

Iturra Design offers, or at least did offer, an inexpensive gauge in their catalog. I used to buy a lot from them when the 14" Delta was my primary saw but I haven't tried to call them lately. (They are phone or mail only, no internet the last I checked). Here is a scan of their 2010 catalog. Tensioners are on page 54.

https://drive.google.com/file/d/0B3YESquFADxsOEV3SlFvblhoVDQ/view

I purchased a Starrett from them years ago (hey, I like Starrett tools) but the price is probably more now.

The design of these tension gauges is simple: a sturdy frame, a calibrated dial indicator, a spring, an arm on a pivot, and a couple of clamps. A hobbyist machinist could make one.

Hey, another way would be to borrow a friend with a tension gauge (or just borrow the gauge), set your tension, then mark your saw, or pluck, press, or whatever to get a feel for the correct tension is for your particular blade.

Note: I make no claim to be an expert on bandsaws (or anything else). All I know is what I have learned from my own experience. The rest is from what I have been told or read or watched on videos, and I take most of that with critical skepticism until I test it myself.

JKJ

[John Lanciani]

See post #11 here; http://www.sawmillcreek.org/showthre...wing-questions (http://www.sawmillcreek.org/showthread.php?178546-Veneering-Resawing-questions)

More than happy to show you in person if you're nearby.

[John K Jordan]

See post #11 here; http://www.sawmillcreek.org/showthre...wing-questions (http://www.sawmillcreek.org/showthread.php?178546-Veneering-Resawing-questions)

More than happy to show you in person if you're nearby.

John,

Ok, I'm impressed and I'm not easily impressed!

I have to build one of these, or something similar.

I don't resaw veneer too much but when I do it is usually for gluing in as layers between thicker wood for woodturnings, getting it more accurate would save time at the drum sander. An example, walnut between cherry and basswood for chip carving, side grain to end grain as per a tip from Frank Penta:

339843

JKJ

[Erik Loza]

1.25" blade is too much for that machine. I don't even use a 1.25" blade on the MM16's. It sounds like blade wander to me, due to inadequate blade tension. I've never used an ACM that old but it may not be able to tension even a 1" carbide, as others have mentioned.

I would try a Lenox-diemaster II and see what you get. Best of luck.

Erik