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:

https://i.imgur.com/KSFdYgu.jpg

https://i.imgur.com/iYyf4CE.jpg

https://i.imgur.com/Tj2BhJG.jpg

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/B01E4U26L2/ref=oh_aui_search_detailpage?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" :D. 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.

https://lh3.googleusercontent.com/fOUFn2ZtgctP4kOL-CF1BoV_3Mt4hfaBD-Eok-NyLcqu41c33iL3BN1xe6jsN37ZNOAd0wf-z-Iaxl2qBR3C9bsUyKA2xq9qaS47yQucFaQBJK0hF5ned-10Gvwl-xsDb1W9YJDhNGFAMjksCMsaKf2y70lMQRm5yZ-2CGTzoEKeBUN9ShzHVH2Dm9bt-Vy2Hom83xqbLlL2PZCtGmwVwfyIRwsZ0zMBHdDXZ48hlIPsz8M dViBJKYBjlY5YUL5vPMBNKmtEl-XnL9uoEzmuToUhupl4G-IOisqcTuJGg_NQhkLiLLPGm_Ygrx43ePg7AkF4QqSc8oe7Hlfy inlxmmZqJni9t1HNdH3qOdmv4PgrrIchy7x6sh-6UL68lghnf0z-4E-cxWk6YzoCPNmzIbVdJJo9f9Pvi-5eo9dv9VH7dMLRTh_54voskT2HX0kXmQ6Y7hsMiDWTASTs9o2U R-1ZCUu3GKioskU8FYLP9W6-ehvu-g1z3s4_M_1OCS5WGz4oJVoXi_XwsQclV-8PweDblWTtSFmZT-PyZSci3PUEEQ-GBy6wBut3WrCkKtPCFP52KwKcbK3t7AB9InpWUZPuwlS2p9UjP btiLEAr94I=w640-h480-no



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.

[Bert McMahan]

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.

The cheater bar is so I can grip the tiny knob better. I won't collapse the spring- I just don't have quite the manly grip that the designers envisioned when they made the tensioning knob :)

This bandsaw doesn't have a tension indicator on it and I haven't looked at the spring directly. The knob on top is just fairly small and slippery. I won't be cranking it so tight that things fail, I just can't grab the thing tightly enough. If it had a handle or something on it I could easily get the right tension.

I'll try a freehand cut and check for drift. I have checked the blade parallelism to the table when I first set it up, but I will recheck it to make sure it didn't get bumped somehow.

I'm also starting to wonder if the blade I got is just kind of sucky. I'll try a better brand with 1-2 more TPI since the saw doesn't have enough oomph to cut anything very thick anyway.

I'll also look into making a tension gage to put on there. I already have a couple of dial indicators that should to the job, I just need to make the brackets for them. Heck I can probably just make it with some clamps or something for a "how close am I" tension check. I should need to measure about 2 thou if my math is correct to get me to around 20 ksi.

[John K Jordan]

...
I'll also look into making a tension gage to put on there. I already have a couple of dial indicators that should to the job, I just need to make the brackets for them. Heck I can probably just make it with some clamps or something for a "how close am I" tension check. I should need to measure about 2 thou if my math is correct to get me to around 20 ksi.

Here is a picture and instructions on using a digital caliper as a free tension gauge.

http://www.sawmillcreek.org/showthread.php?250388-Bandsaw-blade-tension&p=2640833#post2640833

Or buy a Starrett tension gauge. It comes in a very nice red box.

JKJ

[Derek Cohen]

I don't think that you will get a better surface with more blade tension. Blade tension will aid in keeping the blade from wandering side-to-side (as will sharp teeth), and your cut is straight - indicating sufficient blade tension in a sharp blade. The surface is rough owing to too much set on the teeth of the blade. The answer is to get a better blade.

Regards from Perth

Derek

[andy bessette]

That waviness does not come from tooth set.

[John TenEyck]

You will never get 20 ksi on a 1/2" blade with a saw like that. Can't be done on a 14" Delta either. You will be lucky to get 12, but I would rather doubt that, too. But if you can it should cut just fine with a good blade. If you do measure the tension (a set of verniers and two tiny clamps are all you need) and come up with less than 10 ksi, then definitely go with a narrower blade. I'd just go there straight away if I were you, but I understand the resistance. I'm hard to convince most of the time, too, until I get to the conclusion myself.

John

[Derek Cohen]

That waviness does not come from tooth set.

Simple to test this: try a different blade.

Regards from Perth

Derek

[andy bessette]

No need to buy another blade. Just cut to a line as I suggested.

[Nick Decker]

Couple of things: I used a couple of those Powertec blades that Amazon sells, on a 10" Rikon that I had for a while. Regardless of whatever good reviews they got on Amazon, I found them to be cheap garbage, basically.

I don't think the Snodgrass method of blade centering (centering the gullets on the wheel) works for a small saw with crowned wheels. Centering the gullets will cause the blade to present a skewed angle to the wood; hence, drift.

I'd try a better quality blade, probably max 3/8" on that saw, and center the whole width of the blade on the upper wheel. And, please don't use a cheater to tension the blade. Very bad idea.

I would add that I followed a somewhat similar path as you. I bought the 10" Rikon, more or less, to kind of get an introduction to bandsaws. I learned a couple of things quickly: 1) They are addictive and 2) I needed a bigger saw. :)

[Ted Phillips]

Lots of good suggestions here. I've got one of these small bandsaws as well. I'd recommend getting a better blade - and keep it clean. This will solve a lot of problems. Also check the tires to see if they are wearing prematurely - replacing them can help your blade track better.

And one last suggestion - check your table to make sure it is exactly 90 degrees to the blade. Sometimes the blade wavers when it gets pulled out of line by the grain of the wood and if the saw isn't cutting at 90, then it flutters.

[glenn bradley]

I don't think that you will get a better surface with more blade tension. Blade tension will aid in keeping the blade from wandering side-to-side (as will sharp teeth), and your cut is straight - indicating sufficient blade tension in a sharp blade. The surface is rough owing to too much set on the teeth of the blade. The answer is to get a better blade.

Regards from Perth

Derek

I'm in Derek's camp if you have to use a bandsaw for these cuts. With the size of your stock and the desire for a good finish I would make these cuts at the tablesaw. Since no one has mentioned that I assume it is not an option. I expect to deal with saw marks off the bandsaw as a matter of fact in using this machine. Different blades and feed rates will vary your result but, you are not going to get hand plane, planer or even tablesaw finishes off a bandsaw. Minimizing the follow up is the goal.

I just factor in a run through the planer or wide sander as a follow up to a bandsawn surface. When re-sawing multiples from a single blank my routine is something like:
- Joint and plane the blank square.
- Resaw a piece off the blank.
- Re-run the blank through the planer to get a good face.
- Resaw a piece off the blank.
- Repeat till done.

One has to pause and reflect on the amount of effort being spent on trying to make something do a certain thing versus just altering the process. That is, I have found myself spending much more effort trying to achieve a perceived goal than the amount of effort required to just do it differently. It is part of my personality that can get away from me if I let it.

[Bert McMahan]

Thanks for the tips everyone. I did some more playing around with it last night and learned a couple things. First, this saw doesn't have a spring in it (that I can see, at least) so it's hard to say when I'm over-tensioning anything. I was able to get a better grip without a cheater and added tension, attempting the flutter method; this seemed to be doable as the flutter went away, but alas the crazy amount of waviness remains. No amount of hand-applied tension made any difference, so I gave up that route.

I have also ordered one new blade and will likely order a second slightly different one. Looking at the blade a little more closely it definitely seems to just be a sucky blade. It appears from a cursory inspection that each tooth is bent to one side or the other just slightly in an alternating pattern. I think there must be a few teeth that are way more bent than others, and they're just gouging the work. Running the part through faster means the wonky teeth are hitting at a lower rate than running it through slowly, hence the better cuts. Just a theory right now.

Regarding the surface finish achievable by a bandsaw- I have seen plenty of bandsaw cuts that are far, far better than what I'm seeing here. Perhaps the pictures don't do it justice but the waviness is completely unacceptable when I've seen much smoother cuts on similar bandsaws before. There's something wrong with either my saw or my technique, probably both ;)

Last, the suggestion for using the table saw is a good one. This particular project with the stock I had would result in much less waste if I used the bandsaw than the table saw; I wanted 3 pieces sliced through the thickness. With my table saw I'd have only managed two slices, and I was hoping to get more usage out of this piece of wood. I am of course able to plane down the parts I showed in the original post, and I'm still ahead of where I'd have been with the table saw in terms of material usage, but it took much more time than just using the table saw in the first place.

I'll post back once I try with a different blade. What's everyone's favorite 3/8" or maybe 1/4" blade for a small saw?

[John TenEyck]

Glenn, your approach is what I used to do. Then I read from several members here how they could get glue ready quality straight off their BS when cutting veneer. With a Woodslicer blade (which I am not endorsing) on my 14" Delta I found I could get beautifully smooth surfaces, too, but any movement of the wood during the cut would bind the blade. Then I stepped up to a Grizzly 0636X and put a 1", 1.3 tpi Woodmaster CT blade on it. Now I get the cut quality I showed above with every cut. There is no need to rejoint or replane the stock after making a cut. As long as the stock doesn't cup or bow you can take slice after slice, saving time and increasing the number of veneer slices I get from a board.

How is it that the Grizzly can do this but the Delta can't? Blade type and the ability to tension it.

John

[John K Jordan]

...
Looking at the blade a little more closely it definitely seems to just be a sucky blade. It appears from a cursory inspection that each tooth is bent to one side or the other just slightly in an alternating pattern. I think there must be a few teeth that are way more bent than others, and they're just gouging the work. Running the part through faster means the wonky teeth are hitting at a lower rate than running it through slowly, hence the better cuts.


Bandsaw blades often have an alternating pattern to the set - e.g., left, right, center, left, right, center. You can check if one tooth is out of spec by holding something like the end of a ruler just barely not touching one of the teeth and rotate the upper wheel slowly by hand. If a tooth or so is way out of whack it will hit when the others don't. Check both sides.

However, the type of waviness you showed in the photo is probably not, in my experience, due to tooth set. That would leave a series of scratches, further apart when you cut faster. I've seen that when the blade is waving back and forth. When it happened to me it went away when I tensioned the blade properly. It might also be worse if a fairly wide blade is running well on the front of a crowned wheel so the back is pressing hard and the front can wobble back and forth. (I am by no means an expert but I get good results. I tune my bandsaws so the blade tracks in the middle of both upper and lower wheels. I like Duginske's book for how-to.)

If the blade is dull all bets are off. Run your thumb upwards over some teeth and see if you can feel the sharpness. If you aren't familiar with what it should feel like you might not be able to tell. Blades can do all kinds of bad things if not sharp, especially if not sharp or damaged on one side. A new blade will let you feel the difference instantly. BTW, I generally sharpen my blades several times before I install a new one. Depending on the wood a blade can get dull quickly, especially one made from cheap steel.

As mentioned earlier, if the guides are too loose this can allow blades to wander, especially if there are other problems such as tension or tracking. The blade can start to twist one way in a too-wide gap between the guides, then twist the other way, back and forth. The standard simple advice is to adjust the guides so there is gap between the blade and the guides the thickness of the paper in a dollar bill. I used to use a 2-dollar bill for good luck before I got the bandsaws figured out. :) Be sure to back off ALL guides before starting to adjust so none are touching the blade.

Most bandsaws have some type of thrust bearing that touches the back of the blade when it flexes as you push the wood into it. No part of the blade should touch this rear bearing or guide when you are rotating the blade by hand. If it does, it can put too much pressure on the blade and really mess with your cut, especially if other things on the saw are not right.

Another thing that will play havoc with the cut - a damaged blade. If it was ever caught in a kerf the blade probably has a bend in it. Sometimes these are difficult to see. If you removed the blade and lay it flat on, say, a flat concrete floor you might be able to see. Also, put a piece of wood or small square close to the side of the blade and rotate the upper wheel by hand - you might see if there is a bad place. While checking, see if the back of the blade runs true as well.

I'm sure you know this, but if problems persist on that little saw ... get a better saw! (Easier said than done!) I'm sure all of the 100s of people who have read this thread will gladly contribute a couple of bucks. Mine's in the mail. :)

JKJ

[Robert Hazelwood]

I used to have the Rikon version of this saw, and it would work pretty well with a 1/2" woodslicer, certainly much better than what you are getting from that amazon blade. But the woodslicer is thinner gauge than most other blades so it is easier to tension. Still, it had to be cranked down pretty tight, but no cheater bar was necessary :) A thin kerf blade makes a lot of sense for straight cuts on this saw since it requires less power to cut, because the motor is pretty anemic.

The woodslicer (or Kerfmaster from spectrum supply, same thing) doesn't come any narrower than 1/2", but as I said, this saw should be able to handle it. You can also look at the Lenox flexback blades, which are pretty thin and are available in 1/4" and 3/8" widths.

[Nick Decker]

"What's everyone's favorite 3/8" or maybe 1/4" blade for a small saw?"

I don't recall if I ever tried a 3/8" blade on my 10" Rikon, but a 1/4" seemed to work fine. Woodcraft sells Starrett blades in that width range, I'd check to see if they have one to fit your saw.

[Steve Peterson]

"What's everyone's favorite 3/8" or maybe 1/4" blade for a small saw?"

I don't recall if I ever tried a 3/8" blade on my 10" Rikon, but a 1/4" seemed to work fine. Woodcraft sells Starrett blades in that width range, I'd check to see if they have one to fit your saw.

I would go with a 1/4" blade for that saw. A wide blade that the saw cannot tension properly is not helping.

Steve