Wavy lines in bandsaw cut

[Bert McMahan]

I'm working with my new bandsaw, a 10" Craftsman benchtop unit, to try to do some very small resawing- I'm doing roughly 1.5" thick walnut. I'm using a Powertec 3TPI 1/2" blade from Amazon that had decent enough reviews. I've set it up using the Snodgrass method and it seemed to go pretty well during setup, but I'm having issues.

Somehow I'm getting wavy lines going the thickness of the workpiece. I'm getting basically zero drift, and am holding the piece up to the fence as best as I can. Here are some pics:







I've tried going extremely slowly to not bog down the blade, but I still get the lines. In fact, when I push harder and bog down the blade a bit (not too much, just a slight change in sound) I don't get the wavy lines, but my cut isn't great. It's better than the wavy lines but nothing special.

So does this seem like a bad blade, bad setup, bad fence, bad technique, low blade tension... all of the above? This is my first bandsaw I got to tide me over until I could get a better deal on my local Craigslist. It's the same saw as the 10" Rikon which gets good reviews for a saw of this size. I've seen lots of advice on correcting drift but haven't seen this "ripple" effect before, and searching didn't help. I'm probably just searching the wrong terms though.

Any help would be greatly appreciated!

[Al Launier]

Unable to get pictures. Tried copy/paste to Internet, but no go. Can you post pictures?

A 3TPI blade, although good for resawing, is not especially good for finish, as you probably already know. But, if a faster feed is giving you an acceptable finish, go for it. What's important is to be sure the blade is clearing the sawdust and with a 3 TPI blade it should be doing that well.

How tall is the 1 1/2 thk piece as it stands against the fence?

As for the wavy lines you may be getting some harmonic effect from the blade. Try tensioning the blade more. If already very tight, try reducing the tension a bit.

Just saw the pictures. With the board only about a couple inches thick you should be able to resaw at a good feed rate, assuming you have enough HP and the blade is sharp with sufficient offset. How thick is the blade vs. the kerf width? Also,, is the base of the board square to the face that bears against the fence, i.e. any wobble?

[peter Joseph]

That may be the best cut you can get out of that saw. I had a similar one before upgrading. Few swipes with a smoother and those ridges will be gone.

[Lee Schierer]

As others have stated, it would appear that your 10" saw cannot properly tension a 1/2" blade.

[Bert McMahan]

Unfortunately the faster feed rate gives a "better" finish, but not a "good" finish. Either way I'm having to run the pieces through the planer to get them smoothed out. It's only a couple passes but I'd still rather not do it. Basically the wobbles are gone but there are some other marks just from the cut not being particularly stable- since it's a thin piece, I'm really able to push it through pretty quickly.

The fence is taller than the piece by about 1/2".

Here's the blade I'm using: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

There may be some slight wobble possible against the fence, but I was *really* holding it against the fence as rigidly as I could for that cut. The whole fence itself may be what's wobbling; I'll look into that next time I try some resawing. Regarding tension, I basically cranked the knob down as hard as I could, but it's a small knob and I'm not particularly "grippy" . I can still flex the blade a bit with my fingers so it doesn't seem particularly loose or tight, but I do want to make some type of extensometer to try to get some real data on it.

Peter, I'm hoping for a better finish than this- I ran across someone using a 10" Wen saw that was getting these results: https://imgur.com/T4xfwb4 and was blown away.

[Jim Becker]

Even with the biggest, baddest band saw and a quality blade, properly tensioned, it's unlikely you're going to get a cut smooth enough to be your finished surface with just sanding. It's the nature of a band saw. (a carbide tipped blade can come close, but that's not an option on a small saw) So using the planer (or hand planes) is going to be the process. With my MM16 and the 3 tpi blade that typically lives on it, I typically re-saw a 32nd or a 16th over and then bring all the workpieces to a uniform thickness at the thicknessing planer.

[Bert McMahan]

I'll stick a cheater bar on the tensioner and see if I can get this cranked down a bit, but it sounds like I'll be getting a new blade. Thanks for the tips.

[John Lanciani]

I'll stick a cheater bar on the tensioner and see if I can get this cranked down a bit...

This sounds like a recipe for heartbreak. You don't want the spring collapsed, and you certainly don't want to go beyond that point.

[andy bessette]

Your fence is not parallel with the blade's natural line of cut.

[Damon McLaughlin]

I has similar cuts on my Rikon bandsaw when I was using a 3tpi blade with Raker set teeth, when I bought a new 3tpi blade with a Skip tooth configuration I got a much smoother cut that required minimal sanding. I'm not sure what results you would get with a hook tooth configuration, I have one blade with hook teeth but haven't used it yet. If it were me I would try a skip tooth blade in the maximum width that your bandsaw is rated for before buying a new bandsaw.

[John TenEyck]

I would agree with others that that saw is likely not capable of putting enough tension on that blade for it saw really well. Your best bet given that limitation is to go with a narrower blade, and a thin one, too. A 3/8", 4 tpi Timberwolf is likely to cut much better. I've made nicer cuts than what you showed using a 1/4", 4 tpi Timberwolf on my 14" Delta.

No BS is ever going to five you a planed surface, but some can cut very well. This is the cut on some 8 - 10" red oak with a 1", 1.3 tpi carbide tipped Woodmaster CT blade.





John

[Mike Cutler]

I'll stick a cheater bar on the tensioner and see if I can get this cranked down a bit, but it sounds like I'll be getting a new blade. Thanks for the tips.

No, this is not the solution, and you can break your band saw.
I did some testing on band saw blades awhile back and I can tell you that a 1/2" blade can withstand in excess 80,000 psi of pressure and not break. In my test stand the blade actually sheared the bolts that were affixing it to the test stand.

[John K Jordan]

I'll stick a cheater bar on the tensioner and see if I can get this cranked down a bit, but it sounds like I'll be getting a new blade. Thanks for the tips.

As John said, don't do it! You'll likely overstress the saw and bend or break something. You can make a tension gauge with a dial caliper - there are threads about this here or I can copy the details.

In my experience wavy cuts are mostly due to insufficient tension. Dull blade can do it too. Guides not properly adjusted (too much slop).

JKJ

[Edwin Santos]

Your fence is not parallel with the blade's natural line of cut.

I think the above theory may be correct, and you can confirm or eliminate it in the following way:

Take any small board, and cut into it while guiding it along the fence, stopping just barely the distance of the blade's width such that the back of the blade is about even with the leading edge of the board. Turn the saw off, and keep holding the board down. When the saw comes to a stop, walk around to the back and look at the position of the blade in the kerf. Use a flashlight if your eyes are no better than mine. You want the blade to be exactly centered in the kerf. If the blade is pushed up to one side of the kerf or the other, your table needs to be loosened and adjusted with a few mallet taps. I am told that bandsaws have over sized holes in the table for this very adjustment capability.

Or if your fence can be adjusted for drift, you can adjust it instead of the table, but personally, I prefer to keep the fence adjusted parallel to the miter slot and then do the test I've outlined, and adjust the table as necessary. After I did these steps once, the concept of drift just drifted away.

[andy bessette]

OP--try a cut freehand, to a line, in the same material, and make note of the angle the workpiece takes while following the line. THAT is how far off your fence is from being parallel to the blade's natural cut line.