Bandsaw "kickback?"

[Doug Burdelski]

I'm pretty new to bandsaws, having mostly used my table and miter saw for everything. I picked up a Rikon 10-306 last year and have only used it for a few small tasks. I needed to slice a small amount off of a live edge offcut for a project, and due to its small size and uneven edge, I didn't want to attempt running it through my table saw, so I did the "safe" thing and put on a new 1/2" Timberwolf 4tpi blade and set all of the guides.

Not wanting to start with my good piece, I took a piece of scrap - a (too small) ash coaster that I could resaw. I gently pushed the wood in against the fence and into the blade. After only a quarter inch or so, the piece was taken away from me by the saw with a bang and I felt a punch to the sternum. I shut the saw off and checked out the piece. One of the sections of coaster had effectively exploded and been thrown back at me, but not before damaging the throat plate of the saw.

I'm really not sure why this happened which has me kind of gun shy going back to the saw. I did follow up and started pushing a small piece of 2x4 scrap a bit through the saw when I noticed how unstable it was, as if the saw were about to grab the piece again. I took a closer look at the blade and noticed a big warp not far from where the blade is welded together. I am pretty sure this was not there before as I made sure all of the guides were not touching the blade before I turned it on for the first time. I suppose the blade could be another casualty of the incident. That said, I'm still not sure what caused the problem. Any ideas?

See the "warble" here:
https://i.imgur.com/ZdIxn1P.gif

This is as far as I got:
https://i.imgur.com/RFSjkPY.jpg

Piece missing:
https://i.imgur.com/TJpZ1Iy.jpg

And
Piece:
https://i.imgur.com/MLDgZZW.jpg

[Zachary Hoyt]

From the pictures it looks like the wood might have been cracked there, and broke loose when you were feeding it through. There are some other cracks visible in that same square. Short end grain slices like that are pretty weak, compared to a piece with the grain running the other way. I just had a bandsaw kickback incident last night, so I feel your pain. I had a shop made aluminum throat plate in my saw which got bent but I was able to straighten it again. I think that kind of phenolic material or whatever it is probably would need to be replaced. You can cut your own throat plates from aluminum if you get it the right thickness for the rabbet in your saw table. The blade could easily have gotten bent when the incident happened. It's difficult to straighten a blade perfectly, and it will also likely have an increased chance of breaking in that area, I think. I would advise a new blade, they're not too expensive compared to the aggravation and safety factors.

[Robert L Stewart]

I agree with Zachary, a new blade is in order.

[Doug Burdelski]

Agreed, I'll be shopping for a new one. A shame that I'd heard so many good things about Timberwolf and the first time I use it, it tries to kill me!

Looks like all my local Woodcraft shops are out of Timberwolf. Starrett are all that I can get in a 1/2" size for my saw.

As for the incident - how often does this sort of thing happen? Is there anything to look for in the future? I'd read/heard that band saws are pretty trouble free as long as you're not directly shoving your hand in the blade. I'd actually done some resawing with a narrower blade before without incident on stock from the same batch of coasters.

[johnny means]

Looks to me like you applied more force towards the top of the peice. The teeth bit in and rolled the piece downwards. I think this action forced the bottom of the front edge to kickbackward while simultaneously being push into the table. It's this action that broke the piece.

[Kevin Jenness]

See this similar recent post for more insight https://sawmillcreek.org/showthread.php?290280-Bandsaw-kickback-to-the-forehead

[Warren Lake]

not your question but your throat plate is cracked and your guides are set too high. Im no bandsaw expert with guys like John here but we were taught to have the guides pretty close to what the work is.

[Edwin Santos]

Looks to me like you applied more force towards the top of the peice. The teeth bit in and rolled the piece downwards. I think this action forced the bottom of the front edge to kickbackward while simultaneously being push into the table. It's this action that broke the piece.

I agree with this thesis. The issue has to do with the physics of cutting a piece that is small, and taller (or similarly tall) as it is wide. Even if you were pushing from the bottom, (notwithstanding the danger of such close proximity to the blade) physics is still not on your side because the blade has free rein to grab the workpiece and pull it forward.

This can be a treacherous cut, but sometimes you have to do it. In my experience the safe way to do so is with a carrier board. See below. The scrap of MDF is the carrier board. I have hot glued the workpiece to the carrier which I pushed along the fence.
Use the hot glue gun to run beads like a tack welder, and when done it will just pop off with a few dabs of denatured alcohol, leaving no residue behind.
Some people prefer good quality double stick tape, which is a fine option also.
Keep your blade guides low, just above the workpiece so you have that margin of safety also. In fact, always do that.
I'll bet the mishap damaged the blade which is why your later cut with the 2x4 was problematic.

When thing go wrong at the bandsaw, or any tool for that matter, it's always for a logical reason, and you're smart to investigate it and understand why. Be safe.


454183454184454185

[Doug Garson]

I agree with this thesis. The issue has to do with the physics of cutting a piece that is small, and taller (or similarly tall) as it is wide. Even if you were pushing from the bottom, (notwithstanding the danger of such close proximity to the blade) physics is still not on your side because the blade has free rein to grab the workpiece and pull it forward.

This can be a treacherous cut, but sometimes you have to do it. In my experience the safe way to do so is with a carrier board. See below. The scrap of MDF is the carrier board. I have hot glued the workpiece to the carrier which I pushed along the fence.
Use the hot glue gun to run beads like a tack welder, and when done it will just pop off with a few dabs of denatured alcohol, leaving no residue behind.
Some people prefer good quality double stick tape, which is a fine option also.
Keep your blade guides low, just above the workpiece so you have that margin of safety also. In fact, always do that.
I'll bet the mishap damaged the blade which is why your later cut with the 2x4 was problematic.

When thing go wrong at the bandsaw, or any tool for that matter, it's always for a logical reason, and you're smart to investigate it and understand why. Be safe.

Agree, as I suggested on the other bandsaw "kickback thread" anytime you are cutting a small or irregular piece, consider adding a carrier piece to ensure the piece is well supported thru the cut.

[Doug Burdelski]

Interesting how recent that other thread was. In this case the material side to the table was flat though.

I am not sure if I applied more force towards the top of the piece or not. I believe I was pushing the piece against the fence with my fingers and my thumb hooked around the back. My thumb may have been towards the top, however.

The pictures for the carrier board are not loading for me. I'm familiar with the concept on my table saw for jointing a piece and for shimming and flattening a piece on the planer.

[Jim Matthews]

Two things I do differently with my bandsaw:

I cut away the thinner pieces so they're not against the fence.

I use a pushblock to keep things steady, with my fingers clear.

https://www.hardwaresales.com/media/catalog/product/b/k/bk-micji-2a.jpg

[Rod Sheridan]

As others have said this is an unsafe cut when done by hand.

Your hand should be at least 6 inches away from the blade.

The cut you were trying to do can only be done with a sled of some type that holds the wood, or a wood handscrew or clamp such as a Bessey K body style.

Yes. you've ruined your blade, however fortunately you didn't lose any fingers.

Regards, Rod.

[Edwin Santos]

The pictures for the carrier board are not loading for me. I'm familiar with the concept on my table saw for jointing a piece and for shimming and flattening a piece on the planer.

Hi, I uploaded the photos again to my original post. I hope you find them helpful.

[John K Jordan]

These are the push sticks I use with the bandsaw when sawing small things.

454186

The "finger" on the top holds my end of the piece down, firmly if I need. The little flat does the pushing. I made these from osage orange since it is tough. One is thinner for when I'm cutting a thin slice. I usually use both at once - one pushing the wood into the blade and the other pushing the piece towards the fence from the side. This keeps my fingers away from the blade.

I often cut small, tall, thin, and other shapes of wood. All MUST be well supported at the blade all along the cut. Years ago I had a piece suddenly become unsupported when a hidden crack broke - it was much like Doug described, bang, rotated the wood, kinked (and ruined) the blade, broke the throat plate, and scared me. Some people have been injured with pinched fingers or worse.

I have a mantra I repeat in my head with every cut to remind me about hand position, stance/balance: "Where would my fingers go if the wood suddenly disappeared?" And the wood could suddenly "disappear" with a crack, catch, punky spot, etc, especially if pushing a bit too hard.

JKJ

[glenn bradley]

First off glad you're OK. Zachary posted a similar thread a day or two ago. Your pictures certainly help. In your case the material was flat against the table (Zachary's may have been as well, I'm not saying it wasn't) and looking at the piece and the cut you were making I would not have hesitated to make that cut. I would have used a carrier or push block to control a piece that small BUT, I do not know that this would have prevented the problem. Seems likely that the triangular piece tore away, jammed instead of cut, the insert cracked, and the resulting chain reaction ensued.

I don't see anything glaringly obvious that was done wrong except the lack of safety equipment; a push block, carrier, or whatever. That particular piece of material would probably have failed anyway unless some very unpredictable precautions were taken. The take-away looks like a greater respect for your fingers, the use of push blocks, and again; I'm glad you weren't hurt.

As woodworkers we use a number of tools and machines that can be considered dangerous. You don't need electricity to do damage. Just check out some of the ER trips caused by hand chisels to confirm that. We mitigate these dangers through safety practices. Just like a sky-diver, if we become jaded or casual in our approach to safety we will not like the price we may have to pay.

I have to be extra vigilant when doing repetitive work or the quick "one-off". It's so easy to let your guard down on the 8th or 9th repeated operation and I don't know how many accident reports start with a phrase like "I was going to do this one last thing" or "it was just a quick cut". When I feel my focus slipping I change the music, get a cup of coffee, or pop in and say hi to the wife. Stay vigilant, stay safe and have fun. ;-)

[Alex Zeller]

I try to think about what the tool is trying to do and the forces it will apply. For a tool like a table saw or jointer the cutter is round and the work is being done near the edge. As the cutters (teeth or blade) contact the wood the force it applies is towards the operator feeding the wood. There's some force pushing down on the table but the bulk is back towards you. You pushing the wood into the blade is the counter to that force.

With a bandsaw the force is straight down. This is why people tend to think they are safer. The force is going to want to rotate the wood. Think of a tire on a plane making contact with the runway as it lands. That's why it's extremely dangerous to try and cut something round on a bandsaw without something more than just your grip to keep it from spinning. The two forces that counter the bandsaw force are the length of the board and the bottom of the wood being flat. The bottom being flat is kind of obvious. But the length (isn't as obvious) is like a lever. A board 4' long allows the operator lots of mechanical advantage to keep what happened to you from happening. It also allows for lots of room to get a good grip on the wood to counter any forces the BS may apply.

My guess is what happened is that being so thin the main thing supporting it from rotating was the plastic throat plate. Being so short you had very little control over it so when the throat plate flexed it spun enough to put enough force on the wood to break off that corner. Once that happened there was nothing to stop the wood from spinning out of control. Had it been thicker some of the leading edge of the wood would have been on the steel table to better support it. Also being thicker there would have been more wood that needed to break. Had it been longer you would of been better able to counter the rotational force to begin with.

You didn't get hurt and you learned. To me that's not a bad day.

[Doug Garson]

Interesting how recent that other thread was. In this case the material side to the table was flat though.

I am not sure if I applied more force towards the top of the piece or not. I believe I was pushing the piece against the fence with my fingers and my thumb hooked around the back. My thumb may have been towards the top, however.

The pictures for the carrier board are not loading for me. I'm familiar with the concept on my table saw for jointing a piece and for shimming and flattening a piece on the planer.

In order to view pictures you need to be a contributer $6 a year allows you to see pictures and private messages.

[Mark Rainey]

Your hand should be at least 6 inches away from the blade.
.

Rod, do you recommend this for all bandsaw operations?

[Rod Sheridan]

Rod, do you recommend this for all bandsaw operations?

Yes.

For resawing I use the fence with a push block that keeps my fingers that far away, or push sticks that do the same thing.

For small items a sled or push block can be used, and for sawing curves if you can't keep your fingers away you can double sided tape it to a scrap of 1/4" ply...There are many ways to keep your fingers away from the blade.

Also of course, never have more blade exposed than is required, and I find a work light on the band saw can highlight the blade, as they can be difficult to see from some angles.....Rod.

[John K Jordan]

Also of course, never have more blade exposed than is required, and I find a work light on the band saw can highlight the blade, as they can be difficult to see from some angles.....Rod.

This ^^^^

Especially as the eyes age. I use three lights, one to the left, one to the right, and one very bright LED above my left shoulder.

454270

Best task light I've found - I have one at each lathe, sharpening, bandsaw, drill press, milling machine, and a spare in a box to take to demos. Fantastically strong magnetic base. I fasten a piece of steel plate to the plywood walls where needed, drill and tap to screw into a machine where possible.
https://woodturnerswonders.com/products/super-nova-lathe-lamp

JKJ

[Bob Riefer]

I try to think about what the tool is trying to do and the forces it will apply. For a tool like a table saw or jointer the cutter is round and the work is being done near the edge. As the cutters (teeth or blade) contact the wood the force it applies is towards the operator feeding the wood. There's some force pushing down on the table but the bulk is back towards you. You pushing the wood into the blade is the counter to that force.

With a bandsaw the force is straight down. This is why people tend to think they are safer. The force is going to want to rotate the wood. Think of a tire on a plane making contact with the runway as it lands. That's why it's extremely dangerous to try and cut something round on a bandsaw without something more than just your grip to keep it from spinning. The two forces that counter the bandsaw force are the length of the board and the bottom of the wood being flat. The bottom being flat is kind of obvious. But the length (isn't as obvious) is like a lever. A board 4' long allows the operator lots of mechanical advantage to keep what happened to you from happening. It also allows for lots of room to get a good grip on the wood to counter any forces the BS may apply.

My guess is what happened is that being so thin the main thing supporting it from rotating was the plastic throat plate. Being so short you had very little control over it so when the throat plate flexed it spun enough to put enough force on the wood to break off that corner. Once that happened there was nothing to stop the wood from spinning out of control. Had it been thicker some of the leading edge of the wood would have been on the steel table to better support it. Also being thicker there would have been more wood that needed to break. Had it been longer you would of been better able to counter the rotational force to begin with.

You didn't get hurt and you learned. To me that's not a bad day.


Thank you all for the great tips and diagnosis on this topic, I found it all very helpful to read. And I really was able to visualize work at the saw in a new light reading this specific post. Much appreciated.