Bandsaw blade flexing while resawing

[Fred Voorhees]

I was recently attempting to resaw some six inch wide walnut and had some issues with the blade flexing out of alignment while sawing. Let me explain the situation so that some of you may offer suggestions as to why this happened.

First of all, before proceeding, I went over the entire saw setup, even had the table off to help in clamping down a fence in the proper drift setting for my saw, I had epoxied some wood to the underside of the table surface to smooth out that area for the clamping. So while I had the table off, I went over the entire assembly underneat the table. Properly aligned the 3/4" Timberwolf resawing blade with the guides (red oak guides) snugged up near the blade and right out to behind the gullets and the bearing just behind the back of the blade.

With the table back on the machine, I checked for squareness of the blade to the table surface and confirmed that. Did the same business with the upper bearing and guides and tensioned the blade to even a little more than the setting on the machine for a 3/4" blade. I set my resawing fence for the drift angle that my machine works at and clamped it down sufficiently. I was cutting wood that was roughly 1 to 1 1/4 inches thick down into roughly 3/8" thick for final milling down to 1/4".

I got a few in that were fairly well done, even did one that I maintained a roughly 1/16" leftover throughout the cut. Somewhere along the line, it began to become hard to push through and I realized that the blade was flexing out away from the fence near the bottom of the cut. I was cutting at a speed that I considered slow enough - don't think the speed of the cut was an issue. I did notice that the lower guides were "slightly" loosened up, but no enough to make me think that this was the problem.

I am using the standard guides and bearings that came with the 14" Jet. I would love to be able to competantly resaw when I need to, but at this point, I am still having a bit of a problem. Does anyone have any idea what may be the problem? Do I have to move up to good quality aftermarket guides and bearings?

[Jason Beam]

My top 2 suspects are:

Not enough tension - that Jet 14" saw is good, i have one, but to properly tension a 3/4" blade with the stock spring is a little tough. Drop to a 1/2" blade or put in that yellow Cobra spring that Carter sells and give it a go.

Dull blade - you said it worked okay for a little while then went haywire. That sounds like a dull blade to me. Walnut has been known to occasionally retain some gritty stuff in its pores, so it's not unthinkable that the blade dulled - but usually a dull blade progresses slowly - the symptoms tend to sneak up rather than just jump out.


A third possibility could still be feed rate. You should give it wood if it asks for wood, no more. If you are putting more than say a finger or two's pressure to feed it into the blade it's probably too fast. The thicker the cut, the slower ya gotta go, obviously.


My bet's on tension ... after a few slices, the blades heat up a bit and can stretch a little - this could throw off your tension some and if you're already barely reaching adequate tension that expansion can be enough to throw things off.

[george wilson]

The blade can make really cupped cuts inside the wood if it is pushed too hard,isn't sharp,not enough tension,as said above. It takes a fair amount of development of personal skill to learn how to get the best results from a bandsaw.

When I was toolmaker in Williamsburg,the furniture restoration guys used to come over to use my machines sometimes(I kept them in better shape than they did!)

These guys all had MASTER's degrees in their fields,which included use of woodworking machines. And me with only a Batchelor's

They had some 6" walnut they wanted to resaw. They could NOT stay within 1/4" of the line on either SIDE of the line. Total error= 1/2"!!!

I got on the saw,and showed them that it would saw exactly on the line. They were amazed,and wanted to know how I could do that. I told them in an Italian accent "You have to make love to the bandsaw". They thought I was kidding,but actually,it is true.

Another time,they wanted a 1/16" veneer sawed off the side of a 12" tall slab of very hard Cuban mahogany. While they watched,I put a new 1/4" 6 tooth Lennox blade on the saw,and sawed a perfect 1/16" veneer off of it. No waves,no deflection. Just scrape it smooth.

I tend to do everything with a 1/4" blade,and it works just fine if you know how to feel the feeding of the blade,set it up right,and,of course,have a sharp blade.

[Pete Bradley]

Somewhere along the line, it began to become hard to push through and I realized that the blade was flexing out away from the fence near the bottom of the cut.

Somewhere along the line, you tagged a nail in the wood, some dirt, the table insert, or one of the guides with the band. :D It's also possible that the band just got dull and/or hot. Try it with the band cool, if you still have the problem, swap bands and I bet the problem goes away.

Pete

[Kyle Iwamoto]

Another vote for #1 not enough tension followed by #2 dull blade.

Guides, IMO do not affect the cupping or deflection, as long as ther're adjusted properly. Some people claim to have 30 year old stock metal blocks in thier saws.

Is the blade in the center of the top wheel? One of the many things that affect cuts that I didn't see in your OP. Do you have a release lever, or do you always release tension? One of the things if you leave the saw tensioned, is the spring "wears out" faster.

[Bruce Wrenn]

Another vote for the 6 teeth per inch, 0.025", hook tooth, bi-metal blade. I have others, but that is what is on my saw. One of the problems of band saw blades is they are ATB, rather than raker teeth. Tips wear quickly, leading to drift, top to bottom. Most operations on a band saw are rips, not cross cuts.

[Myk Rian]

I use a 1/2" 3tpi Timberwolf on my Delta 14" with no problems. I think 3/4" is too much blade. Set your tension by the "Flutter method". That has always worked the best for me.

Since your guides are red oak, stay with those but bury the teeth in them. I soak mine in WD-40 and run them right up touching the blade.

[Michael Weber]

Okay, this 6tpi business goes against everything I have ever read about resawing. I understood the fewer teeth the better. I'm just curious, not trying to disagree with anyone. Can someone clarify or am I misunderstanding.

[Bill Huber]

I use a 1/2" 3tpi Timberwolf on my Delta 14" with no problems. I think 3/4" is too much blade. Set your tension by the "Flutter method". That has always worked the best for me.

Since your guides are red oak, stay with those but bury the teeth in them. I soak mine in WD-40 and run them right up touching the blade.


I agree 100%, I have a 14" jet and I use the same blade and have no problems at all. Mine cuts straight and I do not have to worry about drift.

I just think the 3/4 is to much blade.

[Jason Beam]

Okay, this 6tpi business goes against everything I have ever read about resawing. I understood the fewer teeth the better. I'm just curious, not trying to disagree with anyone. Can someone clarify or am I misunderstanding.

I think you're right. My rule of thumb is to try to shoot for between 6 to 12 teeth engaged in the total thickness of the stock I'm cutting. That is, if I'm cutting 1" thick wood, 6tpi is a good start (it'll be fast, but rough). 2" thick and 6tpi is about perfect - smooth and reasonably fast cutting.

Now when the board's 6" or more in width, it's tough to find a .125 tpi blade, eh? :P So in those cases, i try to keep my max below 24-30 teeth engaged completely. At 6" that's a 4tpi blade at most. At 12", a 2tpi would be great, but 3tpi will suffice if it has to. Timberwolf makes a variable 2-3 tpi blade that does well at 12" :)

Basically, the more teeth you have engaged in the board you're cutting, the slower it'll cut. The smoothness of the cut is affected, too, but only up to the point of loading - if there are so many teeth that the gullets fill up with sawdust before they exit the wood, there's a jam and that can cause the blade to do all sorts of roughing up of your surface. The above numbers are all trying to find that harmonious balance between cut speed and smoothness.

[Kyle Iwamoto]

I dunno about 3/4" blades being too much. I use a 3TPI 3/4" in my PM 14 and I have a riser, adding to potential blade problems. Mine has drift, but it doesn't cup at all. I use Timberwolf blades. I think. I resaw 8 inch stuff.

Theres a lot of discussion about 3 (or any amount) teeth in the work at all times. I've seen reports that claim this to be false, more likely a very old rule, (not an old wives' tale) and applicable to cutting very hard metals. I cut 1/4" resaw stock with the 3 TPI. Not a problem. I believe them that it may be more applicable to cutting metals, from a long time ago, when blade quality was much poorer.

Just my .02.

[Pete Bradley]

I think 6 teeth is more than optimal for a 6" resaw, but it should work in hardwood if you go slow. I use a 1/2"X3TPI "Timberwolf" most of the time.

3 teeth isn't a wives tale, but it's a minimum and it isn't a hard and fast rule. If you don't have enough teeth in the work, you'll have a tendency to splinter. For resaw, bands with more than 4 TPI or so are less able to carry away swarf, especially in tall cuts.

[Lee Schierer]

I'm certainly not an expert on resawing, but the few times I have done it that I have had problems, the cause was low blade tension. Everything I've read suggests that a 3/4" blade is too much for a 14" saw to tension properly, particularly if the saw is equipped with the factory spring.

I've read lots of discussions regarding adjusting the fence for blade drift and my fence has that ability, but what I find works best is to use a resaw finger type fence and draw a cut line on the piece to be resawn. Then move the board left and right as the cut progresses to stay on that line. Wood grain is never straight through a piece of wood and it will tend to deflect the blade, even a properly tensioned blade, as the blade will tend to follow the grain. The finger type resaw fence allows you to compensate for this uneven grain direction continuously. YMMV.

[george wilson]

The fewer the number of teeth,the quicker the blade gets dull. I know I am contrary to everyone else,and I am not doing production resawing,but I have made a 1/4",6 tooth blade do everything I wanted it to do,because I know how to feel the blade cutting.

[William Falberg]

Jason Beam +1

Also: the set angle on those 3/4" blades is one point something (I forget) and woefully inadequate for deep resaw cuts under any but optimal tension and alignment circumstances. If you can't get enough tension out of your spring you should try resetting the teeth a smidgin.

[Cliff Rohrabacher]

A third possibility could still be feed rate. You should give it wood if it asks for wood, no more. If you are putting more than say a finger or two's pressure to feed it into the blade it's probably too fast. The thicker the cut, the slower ya gotta go, obviously.

This is a rather difficult trick to learn. Impatience and habit work against it.
It is also, I believe, the greatest obstacle to most efforts and re-sawing or even sawing accurately while following a line on flat work.

Too much pressure cause the blade to drift around. In flat work this means the blade deviates from the path you intended. In re-sawing the blade deviates in way you can not even see until you finish the cut. Then you have concave and convex surfaces and a ruined piece.

And in re-sawing there are other factors that exacerbate the problem. The saw dust builds up in the gullets of the teeth of the blade. In the lower portions of the cut path that packing can really force a blade off course.

[John Thompson]

I'm in the camp of too wide a blade on the stock springs to get proper tension.. too many teeth for re-saw (3-4 for gullet space to carry away waste) and agree with the poster that stated guides are not really all that important on re-saw. And that's not to say a 6 tpi won't work but it's too slow and will likely heat to the point of dis-temper if it is a carbon blade especally on tall stock.

Good luck...

[Jeff Duncan]

"These guys all had MASTER's degrees in their fields,which included use of woodworking machines. And me with only a Batchelor's

They had some 6" walnut they wanted to resaw. They could NOT stay within 1/4" of the line on either SIDE of the line. Total error= 1/2"!!!"

:confused: So what school did these guys graduate from with a masters in woodworking and not have a clue as to how to bandsaw a piece of Walnut??? My 2 year old son could probably maintain those tolerances:rolleyes:
Not for nothing but it doesn't take much bandsaw or skill to maintain 1/16" on that type of cut. I know since I can do it;)

It sounds like the posters blade is dulling and trying to follow the grain of the wood instead of a straight line. I didn't see him mention any cupping as you'd likely see from an under-tensioned blade. My guess is the blade has dulled and a new blade will resolve the issue.
good luck,
JeffD

[Fred Voorhees]

Well, certainly a lot of ideas being thrown around on this subject. To be sure, the 3/4" blade really hasn't had a lot of use over the few years that I have had it. I think I'll try a narrower blade and see if that works....though the suggestion of cutting again with a "cold" blade might have some merit and deserves a shot also. I sure wasn't forcing the stock through the blade and the fence was set for the drift. Now, I have to admit, that the news of a using a narrower blade caught me off guard since I had always heard that a wider blade is better for resawing...or is that bit of advice of a narrower blade because of my having the Jet 14" and not a heavier duty machine? Thanks guys for the advice and input and I welcome more if anyone has any ideas and comments. And I almost forgot, I always "de-tension" the blade when it is not in use.

[Pete Bradley]

You'll see a lot of advice on woodworking forums to "use the widest band you can". In general this is bad advice. I'd say "use the band that the saw runs most effectively". That takes some trial and error and it's usually smaller than the widest band the saw will run.

There's also a lot of misunderstanding that comes out of a section of Duginske's book on "beam strength". You can't really apply static beam theory to a band saw blade, it was simply making the statement that a deeper band has more resistance to certain kinds of bending. The depth of the cross section is only one factor in cut quality, and often its much less significant than other factorss.

On my 20" old iron Delta, I run a 1/2"X3TPI for resaw, and I've done high-quality resaws of a 13" oak log with a 3/8"X4TPI (a had just a couple of cuts, didn't want to take the time to switch bands). If you were looking for a starting point to find the optimum, both of these would be good choices.

[Bill Swanson]

I have also found that a single point fence works best on my saw. I draw a line on the board, set the single point fence and use light pressure.

I have this one that I made. http://books.google.com/books?id=gC25oJuA02gC&pg=PA110&lpg=PA110&dq=single+point+band+saw+fence+resaw&source=bl&ots=QY-r7OLubx&sig=FbRVvlP4Y0Rc_6ox8AsRs8SfUJk&hl=en&ei=LKaEStSeNpG0NrCNsNUE&sa=X&oi=book_result&ct=result&resnum=1#v=onepage&q=single%20point%20band%20saw%20fence%20resaw&f=false

I hope this helps.

[Charlie Plesums]

.... I set my resawing fence for the drift angle that my machine works at and clamped it down sufficiently....
Most of the things I would have said about tension and dull blades have been said. However, this statement concerns me... the drift angle depends on the blade, not on the machine. When a blade is new, I rarely find any drift angle. As the blade gets old and dulls (or the tooth set is pushed out from going over the wheels or the phase of the moon is bad), the drift angle changes. When I have to add a significant drift angle, it is time to change blades.

[Chip Lindley]

Many will argue the point that a perfectly set up bandsaw will have no drift, but rather than invest all that time and effort to reach *Resaw Nirvana* I just adjust my fence for each blade's individiual drift! Hey! It Works!

I have had great success with 1/2" 4T Starrett bi-metal blades to resaw up to the 6" max of my '92 model Delta 14". Slice after slice of 1/16" white oak veneers peel off the blade (as long as I start with a perfectly flat surface jointed board.

There are always exceptions, getting good results with a 3/4" blade, as with the owner of a PM 14" saw above! But old PM 14" BS's are very heavy and stiff saws compared to almost all others. ( my Delta included)
For everyone else, 1/2" blades have 50% LESS metal than a 3/4" blade to tension correctly. Why MESS with SUCCESS?

[Fred Voorhees]

Most of the things I would have said about tension and dull blades have been said. However, this statement concerns me... the drift angle depends on the blade, not on the machine. When a blade is new, I rarely find any drift angle. As the blade gets old and dulls (or the tooth set is pushed out from going over the wheels or the phase of the moon is bad), the drift angle changes. When I have to add a significant drift angle, it is time to change blades.

Charlie you are correct. I did mean the blade and not the machine. Being that I have always thought that resawing should be done with the 3/4" blade, that is what I determined the blade drift with and that is what I have a drift angle sample made up for. So when I want to resaw, I mount the 3/4 blade and line up the sample with the edge of my table and it's a simple task to line up the fence to coordinate with the angle.

[Howard Acheson]

I would bet on the blade being dull? How old is it?

On a somewhat different point, if you have a 14" bandsaw, you will be better served to use a 1/2" 3tpi resaw blade. A 3/4" blade does not sit on a crowned tire securely and can tend to wander.

[Cody Colston]

This thread has turned into a pretty good treatise on bandsaw use.

I think a 3/4" blade is too much for a 14" saw. Even if you replace the spring, the frame of the saw, especially with a riser block, is not strong enough to tension a 3/4" blade correctly.

A 6 tpi blade would probably resaw fine in dry wood but don't try using one to resaw green logs or lumber. DAMHIKT

On my 17" Grizzly, for a long time, I used 3/4' blades for resawing but have recently started using 1/2" blades. I've found that I can get as good or better cuts with the narrower blade.

As for drift, the blade is the cause of some of it but also the machine set-up. If your blade is not tracking precisely on the crown of the tires, it will tend to drift either right or left, depending on which side of the slope it's on.

That's my $.02...this is a great discussion.

[William Falberg]

Cody Colston +1

With this exception: the frames are generally strong enough, it's the springs and tensioning slide mechanisms that are letting you down.

[george wilson]

I never asked where the Master's degree bandsaw users went to school. But,It was fairly consistent that they were very inept machine users. I think they were at their best with a small watercolor brush in their hands!!

Don't get me wrong,many of the technicians were very good at restoration work.They just didn't seem to use machines that much. They didn't ask me for help when they got their fancy new building. It even has mahogany window surrounds.They went and ordered the craziest machines!!! One thing they bought was a large Rockwell drill press. this was for a wood shop. The drill press was a metal working drill press. It did not run fast. It had a long spindle hanging down that had a #2 MT hole in it. So,they had to get a drill chuck with a #2 MT shaft on it to stick in the spindle. It ran way too slow to effectively drill small holes in wood.

Then,they bought a VERY LARGE Rockwell tilting cutoff saw. This was for a very small metal working room they had. So,they were calling me,wanting to know if I had something to TRADE them for the saw,which was too big. Since it cost $4000.00,I said "What do I have that is worth that? My thickness planer?" Eventually they gave it to us. I FOUND THAT THE BLADE WAS ON BACKWARDS. They had complained about its poor performance!!!

They kept the place well stocked with cheaply hired interns who were still getting their Master's degrees. One of them was a woman,36 years old,who was STILL in school. She had NEVER had a job. Thet got lots of rich kids like that!!! They really did. Rich,and wanting to find some way to make a contribution to the World.(Whether or not they had the brain for it!).

This girl came over to my shop wanting to rip a few pieces of wood. They were about 4" wide,and 3/4" thick,about 18" long. Needed to be ripped down into 2" pieces. She was terrified of the saw,and holding her face WAY to 1 side,and shielding it with her hand. Goggles and all. She actually stood on the RIGHT side of the fence,pushing wood on the left side with a long push stick!! The wood rattled like crazy!!!How she was supposed to keep it against the fence eludes me. After she left,I told her department head that he had better see that she learned to use the saw before she cut her hand off!!


This girl finished her internship,which was some years long. She got a job in South Carolina at a smaller establishment there. She stayed there for 1 year. Then,she went back to school to study BUSINESS!!!!!

Her successor had also been in the same shop as her. He told me that she had ordered a shop full of machines,and they were still in their crates when he arrived!!! She had done NO restoration work,but had helped the custodial staff clean up,and had helped make fake foods to put on the dining table for display,meaning pies that looked normal,but were full of dry beans so they wouldn't go bad so soon.

I could go on,but am tired of typing. It was just silly.