How to straighten bandsaw blade

[David Metzman]

Is there any way to straighten this bent bandsaw blade?


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I was cross cutting a small cherry log and sort of let it rotate -spin a bit while doing it and this happened. I guess I should have held it firm. The blade is basically new.

thank you for any advice

[Dwight Rutherford]

I don’t think so. I’d bite the bullet and buy a new one. Try Bandsawsdirect they carry Lennox blades.

[Al Launier]

If you don't have enough slack to cut & braze it and then cinch it back up on the saw, you might consider hitting it with a torch to locally soften it a bit to straighten it, and then torch it until red, quench in oil, then torch again to slightly draw it back to remove brittleness. Nothing to lose before throwing it out.

[Chris A Lawrence]

I wouldn't try to straighten a blade that badly bent. It doesn't take much bending to snap a bandsaw blade. Might want to build a sled to make that type of cut.

[Reed Gray]

Best and safest way to straighten it out is to throw it away and buy a new one. Cutting round stock requires a V sled to keep it from rolling, or super man type grip. Bending that one back far enough to get it straight would probably break it anyway.

robo hippy

[Don Bunce]

If you ever wanted to make a bow saw, you now have the blade material you need.

[David Metzman]

Thanks. I seem very good at making bow saw blades. This was a highland woodworking turners blade. David

[david privett]

it will never be perfect again but the heating idea might work if you take your time, then make it a ruffing blade till it pukes

[Steve Demuth]

You're talking about $20 to no more than $30 to replace it. Anything you do to try to straighten it is going to leave you with a broken or weakened blade, probably still not truly kinkless. I can't see it being worth the trouble.

And while you're getting a new blade, I strongly recommend spending time to build a sled. Lots worse things than a bang and a bent blade can come from cutting unsupported rounds or other hanging profiles. A sled with some good wedges and clamps will save blades, and quite possibly possibly more.

[John K Jordan]

David,

Any attempt at straightening will probably leave it useless even if it doesn't weaken the blade. Not only will you have the multiple bends to straighten but the blade will very likely be twisted. If not perfect, the blade will thump and vibrate in use and the cut may wander a lot depending on the damage. I too would recommend buying a new blade and learning from this!

What kind of prep on the log were you attempting? Preparing a bowl blank?

Just this Saturday I taught my second bandsaw class on converting green log sections into turning blanks. There are safe ways to do this, even with large and oddly shaped pieces.

It is never, ever, a good idea to crosscut something round on a bandsaw by hand, even if holding in very firmly. This is the classic unsupported no-no which is likely to destroy the blade, possibly damage the saw, and possibly cause injury. You can get away with it over and over but at some point it's gonna bite. Other unsupported scenarios are cutting into or along an overhang, cutting a chunk with an almost flat bottom that can rock against the table, cutting wood with poor integrity which suddenly becomes unsupported when a piece breaks (this happened to me years ago), and one I just heard of recently: letting a piece of wood on the table tilt into the blade while distracted. While the bandsaw is far safer than rotating saws people have still removed pieces of themselves.

One way to crosscut a round is to put it on a big v-block. I cut a kerf most of the way through the v-block. Another safe way with reasonable care is to use wedges on the front and back. This does require carefully holding the wedges in place during the cut which may be difficult in some cases. There are ways to hold the wedges in place, for example with hot melt glue or with screws into a part of the log which won't damage the blank. I keep a box full of wedges to support various sizes and shapes for ripping cuts (never crosscuts) but the best thing may be to cut wedges to fit that particular log.

But even better is to use another way to crosscut. (Even the bow saw mentioned will easily crosscut a log.) Depending on how much of this you do (I do a LOT) an incredibly handy accessory is an electric chain saw. I even use mine inside the shop on occasion. Quite safe to crosscut, rip, trim, flatten, and more with a chainsaw. (with safe chainsaw handling, of course!) My chain saws (or sawmill) are the first step in attacking "big" wood before taking it to the shop saw.

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I don't find a sled necessary for safely preparing any turning blank I've ever cut. For example, here is one batch of blanks I cut from logs sections with my 18" saw with a 12" height:

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One of two basic cuts will divide the log down the pith to let me cut any blank (except to make blanks that contain the pith which I don't do):

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After that, other cuts release the blanks.

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I generally cut blanks and dry them before turning but do make bowl blanks at times for turning green.

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JKJ


Is there any way to straighten this bent bandsaw blade?

I was cross cutting a small cherry log and sort of let it rotate -spin a bit while doing it and this happened. I guess I should have held it firm. The blade is basically new.

thank you for any advice

[Brice Rogers]

I've straightened a few blades and they "kind of" work. I used a pair of gas pliers. But they typically thump and wobble. If you had some blanks that might contain something like sand or rocks, etc., then maybe it would make sense to get a little more life out of the blade. But ultimately, you'll want to replace the blade. A restraightened blade will never be as good as a new blade.

Interestingly, I've never broken a wood blade. I've bent a few. I also have a metal bandsaw and have snapped a number of them. I've also fixed them using silver solder and a kerf or lap joint. But metal bandsaw blades are under much higher tension than wood bandsaw blades.

[Karl Loeblein]

David,

I braze my own blades from a bulk roll that I bought on eBay so my cost is around $6 to $7 each for 133" blades that fit my 18" bandsaw. I no longer worry about saving a bent or twisted blade at this price. S
earch youtube for videos on brazing bandsaw blades using silver solder with a propane or Mapp gas torch.

[Leo Van Der Loo]

You got away without getting hurt and or loosing parts of you, hang that blade on the wall behind your saw to remind you what can/will happen when crosscutting round logs/wood.

Do not gamble with trying to straighten this blade and taking some more chances to use it, want to get hurt ???

A bandsaw blade is not just a piece of steel, it has a hard part and unhardened part that can bend and cut, also by bending that blade it did not just bent, but twist and stretch the steel, straightening does not undo this and I doubt you will be able to do what a special mill and special hardening has done to get a blade that has strength in places and hard cutting edge at the other side to be a good bandsaw blade.

[Wes Henson]

Ditto with what everyone else has said. Pitch the blade. Make a V sled with some kind of clamp for round stock. Trying to round things in cross section is about the only time I've ever hurt myself on the Bandsaw.

Wes

[Alex Zeller]

John

In that last picture are you cutting a round blank just by hand? I made a simple jig that uses a 1/4" dowel that's adjustable. I put a shallow 1/4" hole in the blank so it can pivot on the dowel. The hole is in the center of the bowl so it gets removed.

[Al Launier]

David,

I braze my own blades from a bulk roll that I bought on eBay so my cost is around $6 to $7 each for 133" blades that fit my 18" bandsaw. I no longer worry about saving a bent or twisted blade at this price. S
earch youtube for videos on brazing bandsaw blades using silver solder with a propane or Mapp gas torch.


Karl I tried to PM you, but you have it turned off. I totally agree with you in making up your own BS blades. I do it not only for the savings, but more so just to learn how to do it and to get the satisfaction of being able to do it. I made my own brazing fixture to hold the blade while brazing, nothing fancy but it works, and use a Mapps torch. I wonder what your fixture looks like, if you also use a Mapps torch, and what you use for flux. Admittedly, the blade does thump a bit after grinding, but unless I need a cleaner cut it'll do.

[John K Jordan]

John

In that last picture are you cutting a round blank just by hand? I made a simple jig that uses a 1/4" dowel that's adjustable. I put a shallow 1/4" hole in the blank so it can pivot on the dowel. The hole is in the center of the bowl so it gets removed.

Yes, a jig is simple to make. I always cut by hand, even simpler.

I also cut blanks that would need a complicated jig.

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JKJ

[Alex Zeller]

I can cut off corners but trying to follow a line to make a round circle, I haven't had much luck. But the only band saw I have at the house is a cheap Delta clone. It's set up correctly but it wasn't built with quality in mind. I do have a nicer Laguna but use it where it's located so I might just buy something for my home shop. I asked because I'm wondering how much is me and how much is the equipment.

[John K Jordan]

I can cut off corners but trying to follow a line to make a round circle, I haven't had much luck. But the only band saw I have at the house is a cheap Delta clone. It's set up correctly but it wasn't built with quality in mind. I do have a nicer Laguna but use it where it's located so I might just buy something for my home shop. I asked because I'm wondering how much is me and how much is the equipment.

It's probably all you. (just kidding!) A reasonable saw is a help but you can cut good circles with nearly any saw if the blade is not too wide. I use 1/2" wide blades. One common rule-of-thumb is limit the curvature to a 3" radius, or a 6" circle, for a 1/2" blade. There is a tiny bit more going on there, such as the amount of set in the blade, the thickness of the blade, and if the back of the blade is "stoned" (radiused and smoothed with a sharpening stone or diamond hone while the machine is running.) I have no trouble cutting a 4" circle with the 1/2" blades I use but larger circles are easier.

I draw the circle with a big compass or easier, with this: https://www.amazon.com/The-Bullzeye-Woodturners-Center-Finder/dp/B004TK0JOO A clear template is wonderful for sliding around on a slab to find the best figure while avoiding any defects.

If the line is not easy to see I make it darker with an extra fine sharpie. On dark walnut I use a special fine-line white pencil. Cut in from the side and start rotating the blank, cutting just outside the line. I find the trick is to imagine rotating around the center, just as if using the jig. If I get a little too far outside the line I back up and clean up that part. If needed I make a cut to the outside so I can discard the waste then pick up the cut again. I've cut blanks up to maybe 8" deep this way. It's really not necessary to cut a perfect circle since small corners can easily be removed while turning, but I like to be able to see the wood and it sure makes the blank more attractive to a prospective buyer so I do this for bowl blanks I take to our annual club wood auction.

JKJ