Are dado blades safe?

[Susumu Mori]

It just occurred to me and I'd appreciate it if you could shed some light.

When I use a table saw, I always use a blade guard and a riving knife.
However, that is not the case for dado blades.
I can imagine kickback can happen, especially when rabetting along a long stock if it is pinched between the blade and the rip fence.
Maybe it is safe for crosscut, like making tenon. Am I correct?

But then how about making dado in sheet goods?

Should I strictly avoid using the rip fence?

Your advises would be greatly appreciated.

[Matt Day]

Yes they're safe. Keep pressure against the fence, and pressure downward to keep the depth of cut consistent.

The blade is generally covered with material that acts like a guard.

[Cody Colston]

Use push blocks and don't place your hands directly over the blade, even though it is covered by the stock. Don't EVER try a thru cut with a dado stack.

[Doug Landphair]

Yes, a dado blade is potentially hazardous. Heck, most woodworking tools can be hazardous. It's how you use the equipment that reduces the potential for injury. In regards to making a dado at the end of a piece, it would be better to use a sacrificial fence with the dado blade slightly buried. Then butt the piece against the fence and move it through the blade. That way none of your wood is pinched between the fence and the blade. If I need to make a dado in the middle of a board, I may use the miter gauge if the board is small enough. Otherwise, I'll use the fence and firmly hold down on the board as I move it through the blade.

That's not much of an explanation so you may want to take a look at youtube videos to get a better idea of how to safely make dados on a table saw. There are also numerous magazine articles and books available showing how to make dados.

[Tom M King]

Since you're not going all the way through the piece, it's not likely to release enough inner stress to put anything in a bind.

[Mel Fulks]

I like the way the question is worded. Dados are not safe in a commercial shop. Even though they are expensive and unsafe when damaged they get clanked around, set down on hard damaging surfaces, and new and old sets get co-mingled so that the first sharpening of a divided new set .....makes two almost worn out leveled sets. I've had to tediously make them into color coded boxed sets. I say tediously because after a mess has been made you have to carefully look at the piece sizes before marking them or you are just part of the problem. If you meant are your fingers safe I answer that is up to you. Certainly beginners with short attention spans should not be allowed or required to do any repetitive work with dados ;things like those hideous strip dentils. A guy I worked for let a childish worker cut a pile of those things. I told him the kid had no ability to concentrate and should be moved to something else. He refused . Few minutes later the kid gave himself life altering serious damage to a hand. Had to have it sewed to his stomach for a while and subsequently operated a number of times.

[Rod Sheridan]

Hi Susumu. yes when using a dado blade you need a guard, either a home made bridge guard or an overhead guard.

Keep control of the workpiece to avoid kickback by using feather boards, push blocks or a power feeder.

Regards, Rod,

[Martin Wasner]

Nothing is safe. In a woodshop, out of a woodshop.

[Grant Wilkinson]

I've seen nasty kickbacks using dado set to cut dados, especially in the middle of large gables for shelves. I believe that you will find that dado sets are illegal in most of Europe because of the safety issues with them. That said, I use one frequently. However, when running dados, I use a sled that that the rip fence cannot become a lever to launch the piece back at me.

[Cary Falk]

Nothing is safe. In a woodshop, out of a woodshop.


This whole thread reminded me of this quote from Days of Thunder
"Control is an illusion, you infantile egomaniac. Nobody knows what's gonna happen next: not on a freeway, not in an airplane, not inside our own bodies and certainly not on a racetrack with 40 other infantile egomaniacs."

Nothing is safe in a woodshop, just safer.

[Jerome Stanek]

I have a nice scar from kick back using a dado blade. I was running some oak and caught a small knot that came loose and caused the kick back

[Tom Ewell]

When using a table saw, the primary safety concerns are kickback and mutilation caused by the blade.

Guards, pawls, pushers, riving knives, etc are a good start. For additional safety adding an after market hold down/anti-kickback device (board buddies and the like) not only add to safety but also aids with precision.

Using one of these devices allows for dado cuts (grooving the stock) to be done in relative safety without the guards, splitters, riving knives in place.

Below is what I use, don't recall the brand, RipStraight maybe
331842
Board buddies below, readily available near as I can tell.
331843
Jessem Clear cuts below, nice but expensive.
331844

All of the above hold down, direct the stock into the fence and are anti kickback.

I'm sure other options are out there, point being that these things add functionality to a table saw (and other fenced gear) along with increased safety.

[Erik Loza]

...I believe that you will find that dado sets are illegal in most of Europe because of the safety issues with them...

Yep! Blind cuts on the table saw are forbidden over there. You would do it with the shaper, instead.

Erik

[Scott Dorrer]

I have a nice scar from kick back using a dado blade. I was running some oak and caught a small knot that came loose and caused the kick back


Yup same here. Back in '84 and I was using a push block. The whole thing kicked out and my palm went all the way to the stack. I still own a dado set but avoid using it like the plague.


http://i5.photobucket.com/albums/y165/boatrman/Stuff/20160216_110757_zpsp0omurge.jpg (http://s5.photobucket.com/user/boatrman/media/Stuff/20160216_110757_zpsp0omurge.jpg.html)

[john lawson]

Nothing about a table saw is safe.

All the safety equipment and techniques are to mitigate the risk.

The fact that you phrased your question the way you did indicates a need for some training, which is a good thing. There are some good videos on youtube that show things like "kickback". You need to watch those videos so you get a good understanding of the physics and how quickly things happen if you lose control of the wood or put yourself in a bad position safety wise. One of the most important and least understood things about woodworking is keeping a firm grip and complete control of the wood (as someone posted earlier this may be an illusion).

[Susumu Mori]

guys, thank you for all the inputs.

I thought the non-through cuts are not as dangerous as through cuts and thus dado blades are less dangerous.
But then, dado operations usually remove all the safe guards (splitter, riving knife, blade guards, anti-kickback pawls).

I started this thread because I read a Japanese article from a woodworking school, that strictly prohibits dado blade operations by students because of kickback incidents, that blew operators away several times. It is interesting to hear it is prohibited in Europe too.

Eric, your suggestion about the shaper is well taken, but it can't be really used for a wide sheet goods, I guess.

For rabetting, what Doug said make sense. I don't see additional danger due to dado blades in that way. However, the sacrificial fence would require additional setting and routers/shapers would be easier options.

For dado, it seems what Rod and Tom suggested are good options, although I'm not sure how effective it would be for wide sheets, in which dado locations would be quite far away from the rip fence where hold-downs are operating.

I'm fortunate to have a slider table saw. So, dado operations can be done using the rip fence or a crosscut fence. From what Grant said, would it be safer to use the crosscut fence because there is no "pinching" zone? Slider is considered as safer in terms of kickback because we are not in the line of the cut-off pieces but for the dado operation without the riving knife, the entire sheet can be launched. I guess there are reasons why dado blades are not allowed in Europe even with sliders...

In any case, it is always very informative to discuss about experiences and approaches to reduce the risk.
After all, knowing "how things can happen" is the best way to protect ourselves.

[Rod Sheridan]

Yep! Blind cuts on the table saw are forbidden over there. You would do it with the shaper, instead.

Erik

Are you sure of that Erik?

My understanding of the issue is that the machine has to have adequate guards and be able to stop the dado cutter in the specified time of 10 seconds or less.

That's why the smaller machines have short arbours, they can't provide enough braking to stop the cutter, and there isn't a suitable guard available.

regards, Rod.

P.S. here's a link to the UK HSE site showing proper use of the saw for rebates and grooving. http://www.hse.gov.uk/pubns/wis16.pdf

The groovers that Felder sell look like a shaper cutter, they meet the MAN requirements for hand fed machines in the EU. I presume the stacked dado cutter would not receive a MAN rating.

[Erik Loza]

Rod, no blind cuts is always what I have been told. In fact, it was a Felder engineer who told me that. Maybe they do it in the UK but as far as mainland Germany, Italy, etc., nope.

That Felder cutter they sell for their dado machines is just a slotting cutter for the shaper, turned on its side. It's not that it's not MAN approved. The tool might be MAN-approved but the cut, itself, is still a blind cut and thus, verboten (LOL).

Erik

edit: Oh, and for the record, I have no issue with dado, just explaining the EU criteria. Like anything, it's as dangerous as you let it be.

[Rod Sheridan]

Rod, no blind cuts is always what I have been told. In fact, it was a Felder engineer who told me that. Maybe they do it in the UK but as far as mainland Germany, Italy, etc., nope.

That Felder cutter they sell for their dado machines is just a slotting cutter for the shaper, turned on its side. It's not that it's not MAN approved. The tool might be MAN-approved but the cut, itself, is still a blind cut and thus, verboten (LOL).

Erik

edit: Oh, and for the record, I have no issue with dado, just explaining the EU criteria. Like anything, it's as dangerous as you let it be.

Eric, that doesn't agree with Felder written procedures which list their machines with groovers as CE compliant, and their groovers as being CE compliant........Regards, Rod.

[Erik Loza]

Rod, that might be right but you still won't find any EU mfr. that makes dado saws for domestic use. At least not in mainland Europe. Only for export. Maybe the UK buys machines that way, though. I was with Felder when they first introduced dado in 2003. It was only in response to US demand. At the time, it was the dot-com boom and rich hobbyists were buying $25K+ CF741's left and right so naturally, their machines "had to have everything". Prior to that, dado never existed on any Felder or Hammer machine and ditto for Minimax. For Minimax, it still exists pretty much only for the North American market.

Erik

[roger wiegand]

OK, I'm at a loss to understand how you can cut dados with a shaper. In thin stock sure, but say you are cutting dados for shelves every foot along a 6 ft long board. With my shaper the highest I can raise the cutter is about 5- 6", I don't see how you'd get to the middle of a 6' board.

[Erik Loza]

OK, I'm at a loss to understand how you can cut dados with a shaper. In thin stock sure, but say you are cutting dados for shelves every foot along a 6 ft long board. With my shaper the highest I can raise the cutter is about 5- 6", I don't see how you'd get to the middle of a 6' board.

Well, they really don't do dados in Europe for cabinet construction. It's primarily frameless cabinetry on the 32mm system.

Erik

[Susumu Mori]

Thanks Rod and Erik for clarifications.

Well, about a month ago, I started a thread when I injured my finger badly with the most unexpected operation; handsaw.
And then I was amazed to see how many creekers shared the same experience with exactly the same way.

The biggest culprit was the very notion "unexpected".

From what I heard in this thread, I think kickback by dado blades is real and existing risk, just like a hasty motion of a handsaw can make it jump out of the kerf and land on our fingers!

I guess just knowing how things can go wrong could reduce the risk significantly, even if we keep doing the operations. Once the board somehow rides on the dado blades, there is nothing to stop the board from flying.....

[Peter Kelly]

American-type stacked dado sets aren't permitted for sale in Germany. Not sure how the Felder one-piece table saw groovers fit into that though.

[Erik Loza]

Susumu, my feeling is that it's like anything on a table saw: The machine can hurt you if you let it, so work smartly. I would definitely use a featherboard, board buddies, or something like that if I was going to make a non-though-cut.

Folks may find this interesting: There is only one sliding table saw in the US Minimax lineup that does not dado. All the rest do and most of the combos do, as well. So, most owners have a Minimax machine that will dado. Funny enough, as I talk to owners over time, guess how many actually use the dado feature? Almost none. Guys ask about it prior to the sale but I talk to them six months, a year, several years down the road. "You ever use a dado head?". Probably 75% of them tell me no. And pro shops are similar. In fact, lots of pro shops hang onto the cabinet saw and keep the dado stack on that. "Too much work to reset the crosscut fence, adjust the riving knife, etc. Just easier to do it on that saw over there". So, it makes you wonder how much of the all this is just marketing and perception?

Erik

[Martin Wasner]

I've always wanted to try running dados on a slider for box work. I'm not sure it'd work for the way I do things though. I do a lot of climb cuts in veneered materia to score the face, and plunge cuts for stopped dados for the nailers and stretchers. Plus rabbets to recess backs.

I think if most people on here saw how I machine box parts they would straight up vomit. lol All that gadgetry on a saw and I'd never get anything done.

[Susumu Mori]

Eric, you are right.

When the rip blade is on the saw, I find myself using a miter saw for crosscut. When a crosscut blade is in the saw, I use the bandsaw for ripping....

Dado stack is certainly much more pain for set up.

For 1/4 grooves, I have thickness-matched router cutters and that are the go-to options. I am certainly one of those customers who rarely use the dado. Knowing the potential risk, maybe my TS won't see them for a while.

[Chris Padilla]

I use a Domino. The dado stack is gathering dust with the Domino around.