# Theory behind this accident *GRAPHIC*



## nckheinrich (Mar 1, 2018)

Hey I hope this is allowed it does contain a tiny bit of blood.

This is the accident I had earlier. It was entirely my fault as I ignored many warning signs and contributed to it.

What happened was, I was using my cross cut sled and it had been getting hard to push. I know it needed waxed but I wanted to push through and get this lumber milled up. In the process I had used the skeletonized table on my saw to grab and pushed the sled forward. This is my contribution to this accident.

Now the mechanics I was pushing forward and it kicked a tiny bit. So i pulled the slide back and pushed forward again making the first cut slightly bigger. This time the second the wood touched the blade it jumped back a ton. 

What are your thoughts as to what happened.

My theory is that A. I had clamped both ends to tight (i find this highly unlikely but meh) and the board was cupping on the edge grain. I did put the cup towards the sled fence. So my theory is that when I cut into the board the cup opened up and put pressure outwards closing the cut, then with the clamps it prevented the board from releasing the added tension....

Any other thoughts?


Things I learned. If the sled sticks wax it right away. Don't stick fingers in holes behind the board. Wear gloves (probably wont do this)


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## Steve Neul (Sep 2, 2011)

It appears the sled was made out of too thin material for one. This makes it less solid. The main thing was the runners on the sled probably swelled up do to humidity and became stiff. Wax may have helped a little but the runners that fit in the dado slots need to slide freely. I believe when you started pushing harder to get the sled to move it raised up out of the dado slots and caused the kickback. I have a sled that was doing the same thing. I had to take a sharp chisel and scrape wood off the sides of the runners to make it fit correctly. 

As a general rule when you are doing something that feels cumbersome is when you are setting yourself up to get hurt.


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## nckheinrich (Mar 1, 2018)

*nckheinrich*

This sled is trash so next one is going to be an upgrade. Thicker wood. My runners when first built slide freely but wasn't much play. Your saying I need to have some wiggle room or just when they swell shave a bit off?



Steve Neul said:


> As a general rule when you are doing something that feels cumbersome is when you are setting yourself up to get hurt.


Yea i definitely ignored some safety rules here and learned a painful lesson


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## Steve Neul (Sep 2, 2011)

nckheinrich said:


> This sled is trash so next one is going to be an upgrade. Thicker wood. My runners when first built slide freely but wasn't much play. Your saying I need to have some wiggle room or just when they swell shave a bit off?
> 
> 
> 
> Yea i definitely ignored some safety rules here and learned a painful lesson


Yes there should be at least as much wiggle room as the miter gauge does. 

Just so you know I used my sled probably a half dozen times overly stiff before I took the time to scrape the runners. I knew it was wrong so I kept my hands well away from the blade when I was doing it just in case. My sled is different from yours in that it's made to miter molding and I wasn't using it very often and was too busy to fix it.


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## woodnthings (Jan 24, 2009)

*Another approach, not seen very often ......*

On a small size portable table saw, which yours appears to be, you can use the outboard edges of the table as the guides for the sled rather than the miter slots. You just make 1 X runners that are located on the right and left sides of the sled and hang down enough to allow the sled to slide without binding, at least 1" . Obviously, the table's edges must be free from any paint or imperfections as they become a sliding surface.


We are also assuming they are machined surfaces and are parallel to the miter slots OR that the blade can be adjusted parallel to the outboard edges. It's a bit of thinking outside the box, but mechanically it will work. It will still require at least a 1/2" thick top for the sled and front and rear rails/fences to prevent squeezing or pinching the blade, and you can't cut though either of the fences/rails! 



I made this large sled for my Craftsman table saw which does use the miter slots and Maple runners:

https://www.woodworkingtalk.com/f27/table-saw-sled-build-49218/


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## johnep (Apr 12, 2007)

If I had a table saw, I would buy a metal mesh butchers glove.
johnep


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## Tony B (Jul 30, 2008)

That sled itself was an accident waiting to happen.
Clamping the board on both sides of the blade was also inviting trouble.
I also think the saw table was too small to hold that board safely.
Also, if the saw was on the floor, were u bending or sitting or otherwise positioned where you were not balanced to have complete control of the sled?

You are very lucky to still have your fingers.


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## TimPa (Jan 27, 2010)

you made 2 mistakes. 


one by placing the concave edge against the fence, as you said, as it cut though you pushed the board against the fence closing the kerf up against the blade. seen this many times on miter and radial arm saws. best to place the convex edge against the fence, or place a small wedge behind the bow so th board can't pull in.


second, you had what we call a "near miss" in the safety industry, and you chose to ignore it. many accidents are preceded by a near miss! 


smaller job site saws require more attention to safety in my opinion.


I hope you injury heals fast and well for you!


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## Steve Neul (Sep 2, 2011)

One more thing to add I didn't think of before is if that saw is like the Ryobi saw I have the dado slot is only about 1/4" deep. You shouldn't be using a sled on a saw like that. The slot isn't deep enough for the sled to stay on the saw no matter how good it is made.


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## woodnthings (Jan 24, 2009)

*That's why I suggested .....*



Steve Neul said:


> One more thing to add I didn't think of before is if that saw is like the Ryobi saw I have the dado slot is only about 1/4" deep. You shouldn't be using a sled on a saw like that. The slot isn't deep enough for the sled to stay on the saw no matter how good it is made.



I suggested using the outboard edges of the table itself as guides for a sled on the smaller type saws. It would give you more control and eliminate any possibility of "lift off" during a cut. 

Sometimes on a jobsite, the construction crew will clamp or screw a guide rail to the bottom of a sheet of plywood and run that rail against the outboard edge of the table. There are a zillion DIY tablesaw fences you can buy or build to improve the fence on your small jobsite tablesaw:
https://www.youtube.com/results?search_query=+temporaty+undermount+table+saw+fence


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## Tony B (Jul 30, 2008)

A small saw is made for small work. You were asking too much of it. Just because the motor is able to cut thicker boards doesn't mean it should.


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## Larry42 (Jan 10, 2014)

You were really lucky!
You ignored the warning! Lesson learned?
Wrong tool for the job.


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## TomCT2 (May 16, 2014)

clamping both sides of a cut ensures that if anything goes wonky, you'll get a serious binding / kickback / splintering / pieces flying / bad scene.
had that clamp flipped off and engaged the saw blade . . . 

that said, your initial instinct was absolutely correct - when it doesn't feel right, it isn't.
listen to yourself - you are a lot smarter than the internet.

you need to stop right there and figure out why things are not going to plan.


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## Mikhail2400 (Jun 20, 2018)

Im very glad you escaped with such minor injuries and I guess all the folks above have covered what you did right or wrong so Ill just mention some thing about runners. They dont have to be made out of wood. You can purchase metal ones of course but theres lots of materials you can use that dont swell. I had some HDPE sheet stock left over from a project and I cut two runners out of it. The HDPE slides very nicely in the slots and it does not expand/contract with humidity changes. Im sure like anything else it changes a bit with temp changes but not enough that I have ever noticed. Just a FYI and good luck with your next sled.


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## woodnthings (Jan 24, 2009)

*smart VS experienced*

I have a lot of experience using powered saws, tablesaws, circular saws and chain saws. My experience with sawing down trees and bucking logs also can be used in working with the woodworking saws.
When you cut a long log that is supported only on either end, it compresses the wood at the top of the cut. That's why your blade with get stuck before you can saw all the way through it. You have to make a "V" cut rather than a straight down vertical cut OR push up underneath the cut with a support log. 



When the workpiece compresses against the rotation of the blade it will attempt to stall, OR kickback. The Laws of Physics never stop working to allow for human mishaps. Compression and Tension are forces well known to physics and should always be considered when working with wood. When ripping some woods there are hidden "tension" forces holding the wood together and they only appear during the cutting process, and are often unexpected. Learning some of these causes and effects sometimes comes from experience, unfortunately.


Crosscutting rarely produces kickbacks when properly supported by the miter gauge with an extended wood fence on either side of the blade. It's very easy to bolt on a 1" X 4" about 30" long rather than using a sled, which is large and cumbersome. I have several miter gauges fitting in this way and use them all the time:


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## nckheinrich (Mar 1, 2018)

Thanks guys for the info and ideas. I'll look into the undersaw for next sled. Yea, I don't think I could have lost my fingers but am damn lucky I didn't break any.


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## Tony B (Jul 30, 2008)

You dont think you could have lost any fingers?
Accidents like that happen in a flash. According to a few woodworkers I have met that lost fingers or has serious surgery to reattach, all said the same thing..
"I didnt know I lost my fingers until I saw them laying on the table saw"

I'm sure we have more than a few on here that lost at least partial fingers. Maybe they can chime in.


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## Tool Agnostic (Aug 13, 2017)

There were many things wrong about this cut. I am most bothered by the way that the board was clamped laterally against the sled fence with the two bar clamps, one on each side of the blade. 

If I were to design a clamping method most likely to result in a kickback, that "lateral squeeze" would be it, even with only one clamp. Once the wood starts to lift, the tension in the clamp would actually help lift the back of the wood and contribute to the kickback. 

The second clamp makes it MUCH worse. The two-clamp arrangement with a concave bend against the fence seems almost designed to pinch around the back of the blade. 

A clamp on the waste side is a very bad idea, too. There is a basic principle of table saw use that the wood on one side of the blade must always be free to move. That's why you don't use two fences, one on each side of the blade. That's why featherboards and thin rip guides are placed before the wood reaches the front of the blade. That's why you keep the rip fence away from the side of the wood when you make crosscuts with the miter gauge. 

Clamping laterally against a sled fence? Bad idea. Anchoring both sides of the wood to be cut? Also a bad idea. In addition, I would have tested the empty sled on the non-running saw to make sure it slides smoothly. If it doesn't, fix it before making cuts.


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## unburled (Mar 10, 2019)

Were you using the saw on the ground as pictured? Yikes.


There is no way the clamping as pictured actually straightened the bow in the stock. It may have looked like it, but only because the sled warped to matched.


My approach would have been to first cut the board in half either free hand on the table saw or used a regular mitre gauge, then make a second cut with the sled to make a trim cut at the correct angle.


I make lots of cuts free hand on the table saw, including long rips, and still have all nine fingers, though one is attached with only a bit of skin. It gets in the way sometimes. On days when it is not bleeding, I'll sometimes I wear gloves to keep it more in line. When it is bleeding, the bandaging is too fat to get the glove on. My doc says what doesn't kill you makes you stronger, and will also bolster my immune system in this case. I trust him. For what it is worth, Malcom Gladwell is writing a book about people that have this approach to life/healthcare. He's the guy that wrote "Blink: the power of doing without thinking". He's titled this new work, "Doing the Double Take it With a Grain of Salt". It's in collaboration with Trump, so it's due out the day impeachment hearings commence. That aside, I do in truth make lots of freehand cuts on the tablesaw.


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## unburled (Mar 10, 2019)

I just now noticed that I have 10 fingers again. Cool! Maybe I'm part frog.


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## Pineknot_86 (Feb 19, 2016)

johnep said:


> If I had a table saw, I would buy a metal mesh butchers glove.
> johnep


Not advised. You can lose your whole hand when the blade grabs the metal mesh and pulls the whole thing into the blade. IMHO, and being around heavy manufacturing for years, gloves have no place around moving or rotating machinery. I got a worse cut while making a salad- three stitches for $310. Should have gone to medical school.


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## FrankC (Aug 24, 2012)

Anyone that cuts freehand on a table saw is looking for trouble, any suggestion to do it is not the responsible thing to do.

This is not one of those debatable topics where my way is better than yours and open for discussion by good little boys.


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## woodnthings (Jan 24, 2009)

*Yes, but ......^*

There are just some occasions where there is no other way, no other tool. I can remember the "one" time where the cut was about 48" long on a triangle shaped piece of Melamine. The was no edge to register against the fence since the cut was not parallel to any edge. I cut slowly and carefully, allowing the saw blade to be free within the kerf so it would not jam. The blade had enough set to the teeth that the kerf was wider. Yes, it was intimidating, but it went well and I was glad when I was finished. :surprise2:


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## unburled (Mar 10, 2019)

*^^ YES, and*

It's worth it for the adrenaline, but not for the cortisol. Another common freehand is trimming to a scribe, or ripping a taper, or grabbing a hand full of rippings to crosscut into kindling, or one-off cuts that don't need to be exact. Table saws are one of the safer tools.


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## CharleyL (Jan 13, 2019)

unburled said:


> Table saws are one of the safer tools.


Not when you violate almost every safety rule in the book about using table saws. You are lucky that you weren't using a 3 or 5 hp saw, but then at least you wouldn't be working at floor level. You need to go back to table saw 1101 and start over. You have done almost everything wrong, and you are very lucky that your injury was as slight as it is.

Some of the rest of you need to take a table saw 101 refresher for some of the suggestions made. I'm 77 and have used table saws almost daily since I was 12 and began at 8 with no kick backs and no blade contact injuries. Learn to operate it safely or the next time you won't be as lucky.

Charley


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## FrankC (Aug 24, 2012)

woodnthings said:


> There are just some occasions where there is no other way, no other tool. I can remember the "one" time where the cut was about 48" long on a triangle shaped piece of Melamine. The was no edge to register against the fence since the cut was not parallel to any edge. I cut slowly and carefully, allowing the saw blade to be free within the kerf so it would not jam. The blade had enough set to the teeth that the kerf was wider. Yes, it was intimidating, but it went well and I was glad when I was finished. :surprise2:


You don't own a circular saw, jigsaw, or a hand saw, there were many other ways of doing it, you choose a way that was unsafe and put yourself at risk, and now you are advising others to do that as well because you have decided they have no other choice.

Come on guys, show a little responsibility for what you are posting.


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## woodnthings (Jan 24, 2009)

*Advising others? ...... that's a stretch!*



FrankC said:


> You don't own a circular saw, jigsaw, or a hand saw, there were many other ways of doing it, you choose a way that was unsafe and put yourself at risk, and now you are advising others to do that as well because you have decided they have no other choice.
> 
> Come on guys, show a little responsibility for what you are posting.



No one is "advising others" here. We are just saying it is done, has been done and the circumstances under which that happened and in my example, one time that I can recall. The safety police will always object to anything with risk involved. The worst thing that could have happened to me was a kick back and that's why I explained about the large size of the piece, the feed rate and the blade's tooth set, which minimized that potential. You/we can preach and pray all you/we wish, but you/we have no control over what others will do .... just saying. I'm not advising, just explaining. :vs_cool:


I suppose I should have stated that in bold print at the bottom?


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## unburled (Mar 10, 2019)

3 people died in 2017 in the US making wooden kitchen cabinets, NAICS code 33711.


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## johnep (Apr 12, 2007)

OK I agree re a metal glove, However, they are made of a fine mesh so should be somewhat hard for a fine tooth saw blade to get hold of. Probably best is to get a saw stop.
However would prevent cuts when using a chisel or sharp knife.
It is up to the individual to decide for themselves with advice. Have a look at the "damage" thread.
johnep


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## Steve Neul (Sep 2, 2011)

It doesn't matter how much experience a person has or how good they are occasionally something is going to blow up in your face. The trick is to always be prepared for it and respond to it. I was taught that if something goes wrong don't fight with the machine and just reach for the sky. You might get hit with a piece of wood but that is usually just a bruise. In time with experience you know instinctively which way the wood is going to go in the event of a kick back so you just don't ever put your hands in that path where it will be carried into the blade. You also keep your hands free so when it happens you can get away from it.


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## woodnthings (Jan 24, 2009)

*Really?*



unburled said:


> 3 people died in 2017 in the US making wooden kitchen cabinets, NAICS code 33711.



I don't think I was one of them, fortunately. :|


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## unburled (Mar 10, 2019)

*yes*

Yes, according Bureau of Labor Statistics, but having been released under the Trump administration, that could be an alternative fact you know.


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## nckheinrich (Mar 1, 2018)

CharleyL said:


> Not when you violate almost every safety rule in the book about using table saws. You are lucky that you weren't using a 3 or 5 hp saw, but then at least you wouldn't be working at floor level. You need to go back to table saw 1101 and start over. You have done almost everything wrong, and you are very lucky that your injury was as slight as it is.
> 
> Some of the rest of you need to take a table saw 101 refresher for some of the suggestions made. I'm 77 and have used table saws almost daily since I was 12 and began at 8 with no kick backs and no blade contact injuries. Learn to operate it safely or the next time you won't be as lucky.
> 
> Charley


That was not OP. BTW.


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## ORBlackFZ1 (Dec 25, 2013)

Sorry, but a hand saw and a bench vise would have avoided all of this...in my shop, it would have been faster and safer....

Pick the safest tool for the job at hand. Just because you have a table saw doesn't mean you should use it for every cut...

I am glad that you have learned from your mistake. Please don't do it again...

Eric


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## Tool Agnostic (Aug 13, 2017)

Just because you are not injured when you do something does not make it safe. 

I read a lot of shockingly bad advice in this thread. 

I hope that @nckheinrich takes the time to thoroughly study and internalize the basics of table saw safety, plus the same for any other power tools he/she may own. The truth is that nearly everyone who posted in this thread would benefit from it, and I do not exclude myself.


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