Scoring plywood and veneered material

[Karl Brogger]

This was quite a while ago, but I finally remembered to take some video of how I score plywood when going across the grain to limit the amount of tearout.

The saw is a Delta 3hp with a Forrest Dado head. "Dado King" I think.

The audio sucks, I did it with my phone.

http://www.youtube.com/watch?v=u0I2GoVWGwI

[David Prince]

Did you minimize tear out or eliminate it with the process and did you have any precision loss when it dangles against the fence backcutting?

[Karl Brogger]

Did you minimize tear out or eliminate it with the process and did you have any precision loss when it dangles against the fence backcutting?

Usually zero tear out.

If its not tight to the fence it won't be accurate. Long narrow pieces with a dado near the middle can be tough. Both the fence and table have to be very slippery to make this work well.

[Josiah Bartlett]

Interesting technique- it looks incredibly dangerous to me. How do you keep the saw from launching the plywood across the room or pinching your fingers between the table edge and the piece?

[Jason Raksnis]

No offense but this has got to be the dumbest thing i have ever seen. NOTE TO PEOPLE WHO WANT TO TRY THIS: DONT! To avoid tearout when dadoing across the grain on plywood, use a slow feed rate and a quality, sharp dado set. Never attempt what is seen in this video!

[Maik Tobin]

Not sure I understand what the hub bub is. This video certainly makes an easy task pretty dangerous. I simply lower my blade (or dado) so it is only high enough to break through one layer of the veneer. Then repeat with the blade raised. Never have any tearout.

[Karl Brogger]

Just out of curiosity what comes across as dangerous?

I've probably done this ten thousand times in my career. Also common practice at multiple places I have worked at in the past.

[Karl Brogger]

Interesting technique- it looks incredibly dangerous to me.

Why? I'm not standing in the path of the material, my hands are no where near anything sharp and spinning during the back cut.


How do you keep the saw from launching the plywood across the room or pinching your fingers between the table edge and the piece?

You're remove less than a 1/16" of material, and the momentum of the piece moving backwards keeps it from digging in and actually getting a grip. Basically unless you are working it to slow it down and stop it, it really can't going flying out.

[Jay Allen]

That would get a flaming disciplinary "write-up" in the shop where I work.

[Peter Quinn]

Well, I've never seen the need personally with the forest dado and a decent ZCI to climb cut anything. Even the most paper thin veneers cut clean until the dado is dull. What I'm seeing you do there Karl is probably not for everybody. A seasoned pro with a deft touch, makes it look easy and quick. Replace Karl with a clumsy part time hobbiest (which is not to say that all hobbyists are clumsy nor that all pro's are coordinated) And you could have a trip to the emergency room or some flying plywood projectiles. At the very least that falls under "Advanced techniques".

You could easily make up some gauge boards that raise the work off the table so the climb part is only taking off a light 1/16" or so which limits any self feed tendency, then pull these and go forward. You could also just skip the climb and use the gauge boards for the first pass going forward and take the second pass full depth. Slower but safer.

The issue I see with raising and lowering the saw blade depth as others suggested is accuracy, which is not notoriously good or easy to set on the TS. In a given book case I sure wouldn't want to go about resetting the height that many times and then having to fix each shelf length if I got it wrong. Karl's method would allow one depth setting for all the work, change the fence for the other dimension, keep things consistent. You could also just get a euro saw or one of those Laguna hybrid Euro saws with a dado and scoring unit, end of problem! One pass, not tear out, minimal danger.

[Karl Brogger]

Well, I've never seen the need personally with the forest dado and a decent ZCI to climb cut anything.

And here we come to part two.:D

Its also faster and a bit easier than picking up the piece and lifting it over the blade. Also, if you get really good at this, you can take a fair amount of material off making the second cut that much faster, and easier to get a consistent dado depth.

Honestly, you guys are making this sound waaaaayyyyy harder than it is.

(edit)- Also, I do stop dado's where I plunge the head into the material, then push it out, typically for stretchers for drawer openings. Allows me to keep the fence at one setting and do an entire pile or cabinet worth of partitions, or ends. In the case of a partition, you can't run the dado all the way through on both sides when doing a 3/8" dado in 3/4" material. Well, you can..... it just isn't real strong.:p

[David Werkheiser]

In theory, this is how a scoring saw works, but thats with a 1/8"x 3" blade, not a dado blade. It might be safe with a correctly set up power feeder, but is very dangerous the way its shown in video. I agree with Jay, in 30 years most shops I've worked in, you would of been written up for unsafe work. Karl if you keep putting your hands that close to the blade using a dado, you will end up in a world of hurt someday.
David Werkheiser

[Stephen Cherry]

Why? I'm not standing in the path of the material, my hands are no where near anything sharp and spinning during the back cut.



You're remove less than a 1/16" of material, and the momentum of the piece moving backwards keeps it from digging in and actually getting a grip. Basically unless you are working it to slow it down and stop it, it really can't going flying out.


Karl, it looks like you have great skill in running the saw.

I wouldn't just dismiss the safety concerns that have brought up. Safety practice, generally, is about what happens when things go wrong. For example, if everything is working OK, then you really do not need fuses or circuit breakers in a house. But, given just a minor upset, for example plugging in the toaster and microwave at the same time, instead of toasting two slices of bread, you've toasted the whole loaf.

So in this case, what happens when your movement speed is not what it needs to be and the blade does dig in and get a grip? The human body is not a machine, and does not move perfectly every time, particularly as you get older. Personally, I wouldn't take that kind of a chance for a kitchen cabinet.

All just my opinion though.

[Craig Carpenter]

Got to chime in with Karl on this one. If you're Safety concious enough to hold the stock as needed, I see nothing wrong with the method. I've been working with wood for over 40 years and have had to come up with many different techniques in certain situations. The method Karl demonstrates is along the same lines as taking a route backwards for a couple of passes to avoid chipping and not have to reset a fence 4 times when doing a deep route.

Those who do woodwork as hobbyists are well honed in your safety methods as you should be. Those who work in the field and on site are there to make a living and speed is everything sometimes while still taking the time needed to give the customer a quality few out there care about.

Woodworkers that wind up with nicknames like "Stubby" concentrate more on maintaining their grip on their material when using the table saw. The hit a knot, or anything that causes the material to shift abruptly and try to hold it in position. I personally would rather completly let go pulling my hands back a.s.a.p. and let the kickback begin. I'd rather deal with a bruise on my chest or stomach vs. keeping a newly created stub soaked in hydrogen peroxide.

Albiet, Karls method goes against all training, I can see it as being a time saving boon on site.

Safe? To most no, to others more comfortable with their tools, I'd say yes in a heartbeat. Nice tip Karl and thanks!

[Ted Wong]

+1, I'm with Maik.

[Greg Roberts]

I would say that the technique shown could work fine if the person doing the job has the skil to pull it off. But it's very unconventional and cannot be accepted by a commercial shop for liability reasons alone. Not everyone is able to do something like this consistently and safely.

The real safety problem I see in the video is the speed with which the operator is working and how close his hands are to the dado blade. I wouldn't work with a person like that, and back when I had a crew working in the house building business, a person like that didn't make it til lunchtime before he was asked to leave.

Greg

[fRED mCnEILL]

"The real safety problem I see in the video is the speed with which the operator is working and how close his hands are to the dado blade"

Actually, in the process that most feel is unsafe (guiding the sheet backwards over the blade) his hands are VERY far away from the blade. His hands are at the outer edge of the table. Its only when he completes the cut in the forward direction that his hands get close to the blade and because the blade doesn't come through the wood there is little danger of his hands contacting the blade.

[Chris Fournier]

I pay the bills with my woodworking efforts and I can tell you that speed is way down on my list of "what it's all about". A good job quote will account for "speed" and you'll get paid for operating your equipment safely and gettting a high quality, repeatable product.

Climb cutting with a dado head as shown is not a safe shop practice. You may be incident free to date and I hope that you stay that way for the rest of your days but I'd say that cleaning a loaded gun also is a real time saver - I don't recommend that either.

The video is a bit rough as you mention so I can't say for sure but the sheet good is not flat on the table for the scoring cut so I can only imagine that the dado is scored poorly at various placed. To my thinking the feed rate is way too fast as well.

Sharp blade, steady feedrate and control - clean dado cuts.

How many sheets can you afford to do a poor job of before your time savings have been negated?

[Greg Roberts]

"The real safety problem I see in the video is the speed with which the operator is working and how close his hands are to the dado blade"

Actually, in the process that most feel is unsafe (guiding the sheet backwards over the blade) his hands are VERY far away from the blade. His hands are at the outer edge of the table. Its only when he completes the cut in the forward direction that his hands get close to the blade and because the blade doesn't come through the wood there is little danger of his hands contacting the blade.

As he's making the dado cut, look at the angle of his body and how hard he's pushing. His hand is just inches away from the blade. If his hand slips off the wood, it will go right into the blade. This is very bad ergonomics and very bad practice in my opinion.

Greg

[Richard Wolf]

Karl, that's an interesting technique. I have heard of people raising the blade 1/16" above the table and running it through backwards to act as a scoring blade, but not full height dado blade. How do you insure that the ply stays against the fence?

Richard

[Craig Carpenter]

[QUOTE=Chris Fournier;1560623]I pay the bills with my woodworking efforts and I can tell you that speed is way down on my list of "what it's all about". A good job quote will account for "speed" and you'll get paid for operating your equipment safely and getting a high quality, repeatable product.

QUOTE]

I have to agree with the speed being not that important vs. quality. However, as the competition gets tougher in todays economy, and more and more jobs are being lost to illegal aliens, undocumented workers, call them what you want, trying to stay busy enough is a lot tougher than it was 2 years ago. I've had 3 builders just retire and give up. I'd never allow something like this to be done on one of my jobs, but I could see myself trying it sometime. Looks as if the trick is to keep the stock tight to the fence to avoid a crooked beginning. As for the comments made to wards his hands proximity to the blade, it's set a good 3/8'' below the top and the man is just making sure the stock is down to get a good even dado on his work. You can't be afraid of your tools, yet you can be fully aware of any and all situations. How many out there have downplayed Karls method as unsafe, yet have had their own mishaps from not paying close enough attention to what they're doing. I personally have my entire set of digits and plan to keep them. Now if the man was doing this method with a small piece of material, that's another thing. Then I'd have to call it down right ignorant.

[Karl Brogger]

I pay the bills with my woodworking efforts and I can tell you that speed is way down on my list of "what it's all about". A good job quote will account for "speed" and you'll get paid for operating your equipment safely and gettting a high quality, repeatable product.

Hmmm. I guess in list of priorites. Quality would be number one, through workmanship and material. After that what else is there? I don't like wasting anymore of my time there than I absolutely have to, I don't produce garbage, and I try like hell to stay out of cheap homes. The average new home that I work on is around a million, so its not like I'm doing this stuff in the $150k starter homes. There's always deadlines too. Even if there isn't a pressing time issue, I still want that job done, and ready to roll early if I can. Stuff always pops up, and its nice to be ahead of the ball. Besides, every minute I don't have to spend in the shop is one more I get to spend with my boat.



Climb cutting with a dado head as shown is not a safe shop practice. You may be incident free to date and I hope that you stay that way for the rest of your days but I'd say that cleaning a loaded gun also is a real time saver - I don't recommend that either.

I worked for a pretty large custom shop before going on my own. Worst place in the world to work, but the place was a absolute machine. I hated every second I was there, but I wouldn't trade the experience for anything. On average we cranked out five houses a day with about 45-50 guys. The record while I worked there was nine houses in one day. The one year we did $25.7 million in business. We were banging out a lot of product! Sadly, the quality control was also excellent, even though they were of mediocre quality, if that makes sense.... Cheap material, cheap hardware, most jobs the boxes had no backs, etc/

The point is, there were two guys, on a couple of dado saws, doing this all day long. Granted that shop used melamine, but there was still plenty of veneered material on every job, and this was all handled in this manner. They have a CNC for machining and a beam saw ripping lengths for parts, the CNC was incapable of keeping up with three guys doing cutout. Not one accident that I can think of on a dado saw in the three years I was there working 60hrs a week the entire time. Plenty of others though. Some dumbass managed to remove a finger tip on a moulder that we used for putting the profile on door edges. He got it caught in between the conveyor and a door he was feeding in.


The video is a bit rough as you mention so I can't say for sure but the sheet good is not flat on the table for the scoring cut so I can only imagine that the dado is scored poorly at various placed. To my thinking the feed rate is way too fast as well.

So what if it is not parallel to the deck of the saw? What if I held it at a greater angle, how would that effect things? It would make the cut narrower, that's what it would do. I definitely do not have the math skills necessary to do the figurin's:D, but I'm sure its in the thousandths for how much the width is effected by the very slight angle that is there. And as far as a change in depth goes, so long as it is through the face layer, the task is completed, anything past that is a bonus that you don't have to hog out on the final pass.

I'd agree I was a bit aggressive in my feed rate on the final pass. But with out finding the part, (I think it was an island deck), I do know that its clean.


Sharp blade, steady feedrate and control - clean dado cuts.

Definitely. This just allows me to work faster.


How many sheets can you afford to do a poor job of before your time savings have been negated?

But I'm not doing a poor job. You are the Yoda of cabinetry if you can pick out that out from a cellphone video taken 10' away.



As he's making the dado cut, look at the angle of his body and how hard he's pushing. His hand is just inches away from the blade. If his hand slips off the wood, it will go right into the blade. This is very bad ergonomics and very bad practice in my opinion.

Greg

Front hand pushes for the most part in one direction. Down and into the fence. and that is to keep it tight to the table & fence. Back, (right), hand handles the forward, and also into the fence, and some down when finishing the cut.

Left hand won't slip unless I manage to push through the plywood. Back hand can't slip as the heal of my hand is right on the corner of the material. Digs into my hand nicely. Another thing that I don't think is in the video, but I commonly do, is straddle the front rail on the saw. Should the material try to come out of the saw, it can't on average sized piece as my leg will stop it. I'll get a sore thigh, and a pair of soiled drawers but thats it.


Karl, that's an interesting technique. I have heard of people raising the blade 1/16" above the table and running it through backwards to act as a scoring blade, but not full height dado blade. How do you insure that the ply stays against the fence?

Richard

Push it into the fence. Same as any other table saw operation.





I'm not trying to be a dick. I'm not new to this. I do think that this particular technique may be for the more advanced crowd. But to be perfectly honest this is no different than the operation of anything else sharp and spinning as far as the "danger" level goes. You can cover it in warning labels, and widgets, but if you've got your head up your rear end, (or in some cases just plain stupid) you're going to hurt yourself doing anything, whether its hurling 5k pounds of steel down the road, or just crossing the street. I've been doing this crap for 13 years now, and while certainly do not know it all, I've done what I do know a lot. I don't enjoy pain. I have a lot of scars from this business, but I also have scars from snowboarding, racing motocross, from firearms (true), from sailboats, and the list goes on. So please don't think that I'm just buying my time until I have a bloody stump of a hand. If that happens its because I was doing something that I do every other day, but not with a clear head. I think carefully about every movement I make in the shop to both keep my ability to count to ten, and to maximize my productivity. I tried whacking my thumb off last year in a tablesaw cutting far too small a piece in an attempt get a job ready to ship the next day, and after having worked 80hrs a week for close to a month and a half to get that job done. If you think this job sucks normally, trying wrapping things up, and delivering a job with one thumb bandaged up.

[Robert Reece]

I have to admit I was a little taken back by the video. It seemed like you were moving fast and the technique could fall apart quick.

But I decided to give it a try this weekend since I had some cherry ply to dado cross grain. I tried on a piece of prefinished ply that I had had a lot of chip out on before. The technique works awesome! It's not really that scary once you try it and get a feel for the ply feels on the blade.

So thanks Karl, you saved me a good bit of time this weekend!