Why no riving knife on American saws?
I don’t understand why American tablesaw makers have taken so long to realize that a riving knife is perhaps the safest and most flexible anti kickback device for a tablesaw.
We have all heard the extollations ( a new word?) of its benefits. And I would venture to guess that it is a device that would not impede the use of other fixtures we use on our tablesaws, i.e. crosscut sleds.
Also, I can’t for the life of me understand why someone hasn’t come up with an after market solution? Why should we woodworkers have to stick dowels into the zero clearance throat plates we woodworkers make in order to make our tabesaws safer. It seems to me that here is a chance for someone to really make some money and benefit a lot of folks in the process.
It just seems to me that a riving knife is quite simple and would be a benefit to all tablesaw users.
Regards,
Regards,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Edited 7/20/2007 8:36 pm ET by KiddervilleAcres
Replies
Bob-
I'll treat your question as stated, although I suspect you already know that a riving knife cannot simply be stuck on the inner workings of a Delta-style table saw. The Unisaw blade-raising mechanism follows a circular path, so a riving knife, being farther from the axis of rotation than the center of the blade, would rise above the top of the blade as the blade is raised.
European table saws use a linear blade-height adjustment mechanism, so the riving knife remains at the same height relative to the top of the saw blade throughout the adjustment range. Equally important is the fact that the riving knife can be located very close to the saw blade. That means that the riving knife will keep the kerf open no matter that stresses in the timber might cause the the kerf to close the gap. A "splitter", located maybe a foot farther back from the blade, does essentially nothing for safety.
The Delta Unisaw was first sold at about the time that the DC-3 was the latest in airline transportation. One would suspect that development costs for Delta and its imitators had been recouped many decades ago. Why the manufacturers are reluctant to design a new model that incorporates a riving knife is beyond me. But I suspect that they have counted their beans to indicate that their sales do not justify a redesign.
As an aside, the straight up-and-down motion of the European riving knife has another safety benefit that is not often mentioned. A blade guard that is attached to the riving knife also follows the blade, so it can be left in place through all cutting adjustments. I am excluding dado-blade operations in this discussion.
Donald,
So, am I to understand that the almighty dollar has struck once again.
I don't mean to diminish or cast disregard on your response but if so, that is a sad reflection on our manufacturers concern, or lack thereof for the safety of their customers, in my humble opinion.
Kinda like Bush trying to eliminate funding for PBS. No I don't want to turn this discussion into a political Cafe! Sorry, I got carried away I guess.
It just irks me that there is a safer way to use tablesaws and with all the technology available.............
I'll be honest. I have a Delta contractors saw and the splitter has a half a$$sed attempt at a splitter/riving knife that is basically junk with respect to alignment to the blade.
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Edited 7/20/2007 10:22 pm ET by KiddervilleAcres
Edited 7/20/2007 10:27 pm ET by KiddervilleAcres
Bob-"So, am I to understand that the almighty dollar has struck once again." Why yes. From both the buyers' and the sellers' side. A Unisaw or its imitators is incredibly inexpensive in today's market."...if so, that is a sad reflection on our manufacturers concern, or lack thereof for the safety of their customers, in my humble opinion."What about the partner of the manufacturer in this transaction, the consumer? Every time a safety feature (e.g., the Sawstop blade rotation arrester or even a Euro-style riving knife) is brought up in this forum, how many responders tout personal working habits as the only worthwhile safety device? Consider all the discussion about riving knives and such on this forum: Do you really believe that the manufacturers are cynically conning the table saw buyers? Or are fully-informed buyers opting for the remarkably inexpensive table saws without riving knifes and other routine safety features?It's hardly a cartel of Delta-like saw vendors out there. There is now a sizable number of alternative suppliers: Mini-Max, Felder, Hammerer, Rojek, Laguna, all offer a variety of saws and combo machines that meet European Community safety standards. Sadly,most consumers choose affordability over built-in safety.
Don:"…how many responders tout personal working habits as the only worthwhile safety device?"Anyone who has experience in working with things that kill, knows that safety goes beyond the technology that makes an inherently dangerous activity somewhat safer. Safety starts with the right mindset, but while that is necessary, it is insufficient by itself.It's like saying I don't need a seat belt because I always obey speed limits and drive very carefully.Unfortunately, we in the USA have to pay a premium for all of the "euro" safety features. As Lataxe pointed out in another post, there are many more choices and price points there, only the high-end stuff finds it way here. It's not helped by the weakness of the dollar.Regards,HastingsPS My experience with things that kill was as a gunnery officer in a tank regiment. An entire turret crew was killed next to me during practice firing.
So... if manufacturers add a riving knife to the saw as the Euro's, do we rejoice and declare ourselves......
Safe.. Safe.. Safe at Last?
I personally don't think so. A riving knife is only one stop on the road to safety. It keeps the stock from pinching the back of the blade when reactionary stock is encountered that has the tendency to close on the back of the rear teeth.
What does it do to combat stock from binding and twisting when that same reactionary stock has a tendency to open toward the fence that extends beyond the cut... then rebound back toward the rear teeth of the blade? So.. you put a riving knife on the saw and you still leave 50% of that particular problem of reactionary wood un-covered and deem it safe?
If your stock does bind on the dangerous rear teeth and rise up, is the plastic substantial enough to stop the launch. The riving knife won't stop an up movement. Is the thin plastic on top substantial enough to do so? Was that considered when the riving knife was designed for a particular saw by the manufacturer?
If you are working with long, thick stock and it gets squirrelly and out of hand due to it's mass of weight distribution, will a riving knife eliminate that problem? Or perhaps we should consider full support (under.. over.. around.. in every direction to counter that from happening?
And don't get me wrong, I fully support riving knives. And as Steve stated, there will come a point that we will see them on all saws when the manufacturers agree to do it together to keep prices fair with the engineering design changes.
I have a TS with a riving knife.. I have one without. If we all just bought Euro saws with riving knives, 80% of current WW hobbyist would have to find a new hobby as they are economically ruled out of having a TS.
What can the current hobbyist do to be able to afford safety. Do they have to wait till the manufacturers make the switch to purchase or hope their lotto ticket comes in and get the current Euro at their lofty prices?
And what about those millions that already have a U.S. saw with the standard fare on-board. Should they declare it totally worth-less and sell it for scrap metal? And then go Euro or wait till changes are made here in the U.S. so they can afford a riving knife and be safe?
I say neither.... I say understand what causes kick-back and eliminate those factors and you can do it with what you currently have. It will require a little thought and field expediency. Or have we lost the knack that our fore-fathers had to take what you got and make it work?
A riving knife is only part of the answer to safety with a TS. If you only consider a riving knife without considering the other elements, you have over-looked other key elements and are not safe!
I run a re-conditioned Uni-saw I got rather cheap. I also rip 10'-14' lengths and wide stock very frequently. But... I consider my operation as safe if not safer than if I had a Euro saw with a riving knife. I added a substantial crown guard over-head.. a short fence to the right and springboard to the left. Extensions to accommodate long stock fore and aft. A plastic shield in front of the substantial crown guard that not only won't allow my hand to get near the blade, but give excellent protection from fine dust which is just as important in the long run to safety as keeping fingers today.
My splitter won't ride up and down with the blade, but it does tilt and the crown guard I added will ride up and down with the blade in a matter of a few seconds adjustment as I made it do so with field expediency. The guard or splitter can come off the saw in under 30 seconds. Let's not say "quick release", we will say semi-quick release. All done with what I had, scrap and a $25 purchase of a dust shield.
So... I am not waiting for the manufacturer to bring safety to me... It is my responsibility as I see it and I attacked the problems with "hot pursuit" before they did with their hesitancy to address the matter. And all in a nicely wrapped package of what I had.. scrap.. a $25 dust shield purchase.. thought and field expediency. And so can you.
Safety is much more complicated on a TS than just a riving knife!
So... "What-cha waiting on".. Xmas or the manufacturer? :>)
Sarge.. john thompson
Edited 7/21/2007 12:18 pm ET by SARGEgrinder47
Sarge,
You make many relevant points and it is true that a riving knife is just the begining of what might be considered a safe saw (read "foolproof").
Hold-downs integral to the fence are a great help, as is a guard that moves with riving knife. In essence, it should be possible to fall over the tablesaw without contacting the blade; to shove your fingers at the blade with something to stop them (but not the wood) and to have any amount of reaction wood without the kickback occuring
I believe my saw achieves this condition except for the possibility of forcing fingers under the guard and around the hold-downs (although I would have to try very hard). For this reason I would also like a sawstop mechanism in the saw - not yet available to we Europeans (so you Americans are ahead there).
The blade following riving knife is set to the shape of the back of the blade and 3mm from the teeth tips. The riving knife is a mere 0.2mm thinner than the blade kerf. When the wood closes up at the back, it nips the riving knife (on both sides) not the blade teeth. The saw merely labours a bit to tell you it is hard going as the kerf closes up. Out comes the wedge and the cuting is resumed.
Even were the blade to grab the back of the wood in the 3mm between the teeth and the start of the riving knife, the hold downs will prevent the wood kicking up, as will the guard, which is attached to and moves with the riving knife.
In short, the saw I have (a Scheppach, but typical of European saws) comes with a good riving knife and guard. It's fence and tabletop has T-slots to mount hold downs, which Scheppach sell as an extra (greedy men). I have devised my own from Lee Valley kit (a lot cheaper and more usuable).
Believe me, the saw is foolproof (except for that sawstop thang). I am a fool and here I am still fully digited.
Lataxe
Good day Lataxe...
I believe that your saw meets safety requirement also. I have seen your saw and many more of the English and Euro's advertised in Furniture & Cabinetmaking (your countries version of FWW) which Richard Jones made me aware of. For that matter RJ made me aware of riving knifes, crown guards, short fences and proper extension supports which I adhere to and added with what I had and scrap.
I am familiar with the clearance from the front (and up and over) of a true riving knife to the back of blade. My splitter does have about 1" gap there currently in the 6/4 position which I use a lot. It narrows as 8/4.. 10/4.. and 12/4 gets the call. But... I can remedy that simply with a small modification in about 30 minutes and I may go down and do it now as I have it on my agenda along with a million other things. And I can do it so the top of the saw teeth actually sit inside the crown guard and ride un-obstructed.
I have a Uni-saw that I could afford and it is as safe as safe can be without going to power feed. And it was not by a miracle of God or Delta Machinery that it got that way as that is not how it arrived in my shop on a crate. ha.. ha... ha... ha..ha..ha..
BTW.. from what I've seen of that Scheppach.. pretty nice saw!
Regards...
Sarge.. the tinkerer
"Sarge.. the tinkerer"
But Sarge, I thought I was the tinkerer. Ha Ha! I started out being Tinkerer but when we had that change of the forum a couple years ago, I lost that status and finally became Tinkerer 2 to get back in the forum.
Paul
Evening Paul...
You may hide under that tinkerer2 handle in an attempt to be formal, but you are and will always be "Tink" to me. ha.. ha...
I used to post under just SARGE before the change, but it got taken also so what you see is what ya gonna get I suppose.
Regards...
Sarge.. john thompson
Edited 7/24/2007 12:02 am ET by SARGEgrinder47
"You are and always will be "Tink" to me."
Tink, I like that. Someone, some time ago, referred to me by that name and I always liked that. By the way, what does "SARGEgrinder" come from? I see you sing "john thompson." Now that name sounds kinda Swedish.
Your humor and your keen evaluation of machinery always hit a special spot.
Morning Tink..
After SARGE was taken during my absense and stay at the local convent during the Taunton switch-over, I had to add to SARGE with something. Grinder was a name given to me with my style of poker play as I prefer to take a nibble of the cheese and run rather than go for the larger chunk and increase the risk of getting caught in the trap.
47 is nothing more than date of birth. Not sure about any tie to Sweden? But just in case I am declaring it was obviously "southern" Sweden they came from. ha.. ha... ha..ha..ha..
Regards...
Sarge.. john thompson
Edited 7/26/2007 12:28 am ET by SARGEgrinder47
While I respect all the views here I think Sarge sums up the whole issue regarding safety.
Safety has to rest with the user, and unfortunately safety does not appear to be cool or trendy.
Originally from the UK, but living in Canada for the last twenty seven years I don't suppose the European designs would have much impact on safety when I see almost all users remove the safety guards on North American or European tools as soon as they attempt a task that the safety equipment causes slight inconvenience.
Safety appears to be low on most peoples priority list - until after the accident, and even then some people assume it wont happen twice and continue as before.
As a student in the UK I was taken to an industrial accident wax works museum where actual accidents are remodeled as they happened in all the gory details, the severed hands, injured eyes and torn off scalps due to long hair and drill press use without the guard, thirty five years later I remember that day and the wax models of the people in it.
Tradition is another reason we have the tools we do, they are familiar old friends and we like them, like the ones we used at school and the ones our fathers had.
Price of the tools also determines availability, and we have far higher availability than our European friends do, are we prepared to have less to be safer?
Manufactures are building what they believe we want, when we start wanting something else than we currently have I am sure they will build it, until then we could all try using the safety features we all have right now.
Sorry this is lengthy but on a closing note; I don't believe any industry world wide cares about safety at all but they do care about insurance costs, stock value and public image.
Safety is up to us.
Blackbird
From your comments, I'll assume that you haven't read the many threads on table saws, safety for TS, Saw Stop vs everything else, European saws vs American saws, etc. This isn't a new topic and nobody is impressed with the half-assed splitter/guard that comes on saws. Yes, the dollar wins out again. No, not everyone will jump up and replace what they have. No, the companies don't have any mandates that require them to build their saws with a riving knife and they aren't willing to be proactive in designing new saws when they can continue to sell the same ones that have been their bread and butter.We, as buyers and users of machinery and tools with cutters, knives and rotating blades, must accept a certain amount of the responsibility for what happens when we use these machines and tools. We can't just claim that the manufacturer didn't do enough when we are injured by being distracted, clumsy, ignorant of safe habits and inattentive. I narfed my left index finger with my brand new, shiny T&G router bit. It was my fault. I screwed up. I accept that. I didn't make any claims against the router or bit manufacturer, nor will I. We choose to use these machines and tools. It's up to us to use them safely. We should want the manufacturers to make them as safe as possible but we do need to be dilligent. Maybe we could have a class action suit based on the fact that the supplied splitter/guard is such crap, that everyone removes them and makes their saw inherently more dangerous. No, better not- the only ones who will make any money are the lawyers.
"I cut this piece four times and it's still too short."
Edited 7/21/2007 10:13 am by highfigh
You are correct highfigh. Bob has brought up an old topic that's been going around on this and other forums for years- a decade or more that I know of. And of course you are correct to say that users of powerful machinery have a responsibility for their own safety. That self responsibility won't ever change.
I remember getting involved in those saw safety discussions here away back in the late 1990's, and on one or two other forums. I find it interesting that after all this time there are hesitant moves on the part of American saw suppliers to incorporate a riving knife on their machines. Some of these suppliers, like Bosch are European based, so they shouldn't have much trouble with European style machinery. And DeWalt has a history of owning Elu, another European company that Black and Decker swallowed up. So again, another business fully au fait with European regs and standards.
I also find it interesting that the change in the stance on table saw safety in the US has been like watching a super tanker the size of the earth change direction, ha, ha. After all, just how hard can it be for a decent engineer to study the rise and fall mechanisms that are normal on European saws that have been standard for decades, and come up with something similar? So, it's definitely not the engineering nous then.
The change is coming from some other angle, and who knows what that might be. Health and safety issues? Pressure from the buying public?
The saw safety topic's certainly not new as you say, but there again I can't recall seeing a topic truly new to me raised on a woodworking forum for many a year now. The old questions mostly just go round and round, and what makes the old topics interesting to me is perhaps a wee wrinkle in the question, or a bit of personality in either the questioner or in the posters that respond.
I guess it just shows how many people are either new to woodworking, or woodworker's with some to long experience that are new to woodworking forums in general, or perhaps new to this woodworking forum in particular. I've probably missed a category or two there, but that'll have to do for now. Slainte. Richard Jones Furniture
highfigh & ALL,
This isn't a new topic and nobody is impressed with the half-assed splitter/guard that comes on saws.
My point exactly. We have been forced/expected to rely on these poor excuses for safety devices that in my opinion are border line insanity at best. To the point of most users completely removing them, thus making the TS even more dangerous!
In the manuals, at least in mine, it says that under all circumstances the user should/must have the splitter/guard installed. And then they have the audacity to provide a device that could never have been tested or they would have found that it doesn't line up with the blade and is so flimsy that it actually makes the TS more dangerous.
The board gets caught on the splitter unless you bend the arm to align it with the blade. You see pictures that say, "Splitter/guard removed for clarity" or some such nonsense when the reality is, "Splitter/guard removed cause it's useless!"
Now they are mandated to provide a riving knife that's been available on Euro saws for nearly a ¼ of a century! HELLO!
Perhaps we should give Mr. G a standing O.
Regards,
P.S. Yes, I did take a dunk in the lake this past weekend!
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
I just read and responded to the following thread on the PM2000 saw, but it's worth repeating here. It appears from the owners of these saws that Powermatic has left off their braking type motor, which in my opinion is very much a safety feature. Doesn't it seem kind of ironic that they would add a riving knife, then leave out a braking type motor? Once again the almighty profit's of capitalism are still very much a motivating factor at the expense of our safety. Go figure!
Danny
Newly designed saws are going to be required to have riving knives quite soon in order to be UL listed. There is a longer phase in period before older designs have to be redesigned or replaced in the model lines. Since long experience has shown that safety doesn't sell there hasn't been a competitive reason to change the long standing designs that work well in other respects, and which are quite safe if the existing safety devises, splitters, hold downs and blade guards, are used. Riving knives make it a lot easier to use the devise with fewer reasons to remove for particular cuts.
Steve,
You have always had my respect. If you don't mind I will respond:
Since long experience has shown that safety doesn't sell there hasn't been a competitive reason to change the long standing designs that work well in other respects,
Wow, The bean counters strike again?
and which are quite safe if the existing safety devises, splitters, hold downs and blade guards, are used. What safety devises? The ones we woodworkers devise to make up for the manufacturers shortcomings; such as crosscut sleds, zero clearance inserts, dowel pins behind the blade to act as splitters? I get quesy thinking about those pins longevity.
Riving knives make it a lot easier to use the devise with fewer reasons to remove for particular cuts.
My point, exactly!
Please don't take me as critical to your words. Maybe I should get off this rant and go up to the lake and dunk myself in the water to cool down!
In my mind a riving knife in and of itself should be an integral part of a tablesaw.
Regards,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Edited 7/20/2007 10:58 pm ET by KiddervilleAcres
Edited 7/20/2007 11:01 pm ET by KiddervilleAcres
How else can a company respond, in a (mostly) market economy? Companies that don't consider what sells go out of business, or find themselves relegated to small niche markets like Saw Stop. "Bean counting" isn't an option, it is vital, for companies that must make a profit to survive.
Yes, I think the riving knive is a good feature, but good as it is it will only arrive because there is an agreement among all the manufacturers (given the UL consensus rule making process, I think that is pretty close to being right) to require them. Any manufacturer trying to go it alone incurs extra costs that are not likely to sell many more saws and puts itself at financial risk. It's a very expensive thing to completely redesign and retool. Requiring everyone to do it levels the playing field, at least among companies that have the resources to create new designs instead of copy patent expired machines.
But, now that the UL rule is in place we can expect just about every new table saw introduction to come with a riving knife.
You don't have to make a thing to operate safely. Beisemeyer splitters work well even if they aren't quite as close to the blade. Good blade guards are in the market to buy--Brett is one. You can buy all sorts of devises. Mostly the riving knife adds convenience for the user it's not the only way to skin that cat. The fact that most don't chose to spend the money just illustrates the proposition that safety doesn't sell.
>> But, now that the UL rule is in place we can expect just about every new table saw introduction to come with a riving knife. What I don't understand is how a saw with a european style riving knife is going to work when a dado or moulding cutter is installed. Dados have been outlawed in Europe for a number of years. The arbor on the saw is only long enough to install a blade.If the riving knife is easily removed, then it will be no more useful than the blade guards currently supplied with table saws.Howie.........
I do think there will be a big difference in that there will be a lot less need to remove the riving knive for other cuts. Splitters have to be removed for any non-through cut, including cut-off tables, while the riving knife doesn't. But, you are right about having to remove them for dados and moulding head cutters, unless there is some sort of "adjustment" that keeps them in place while a smaller diameter cutter is employed.
Blade guards currently supplied with saws are pretty disasterous. I wonder where the one originally supplied with my Unisaw is? Probably in its second or third reincarnation as a automobile fender, since it was likely replaced with a Brett when they became available.
But I do use my Beisemeyer splitter, especially since it is quite easy to install.
Steve and Howard,
I can imagine (for I do not have one to actually test) that if the dado cutter's right-hand blade remains in line with the right-hand edge of the riving knife (as you would expect if the dado blade abuts to arbour flange in the same way as an ordinary blade) then the riving knife can stay on; and it will keep the workpiece in line with the fence.
If the fence is also on the right, the workpiece will have the area of the workpiece that is to the right of the dado groove wedged between the fence and the riving knife. The workpiece cannot move left (the riving knife stops agin' the wall of the dado) nor right (the fence stops it). It matters not that there is no riving knife in line with the left-hand wall of the dado groove.
Of course, this assumes a riving knife that lies below the height of the blade, so the dado groove can pass over it. Mine is a subsatntial riving knife that is always below the height of the blade (moving with it) despite having enough meat to attach the large blade guard. I can make cuts over the top of the blade with the riving knife in place (indeed I would not dare to do so without it). This is not unusual in European TS.
I don't know about dado cutters (banned in Europe - dangerous you know) but I assume they are the same diameter as a normal sawblade (eg 10 inches)? If so, the above scenario should work.
Not so with groovers, I suppose, as the wall of the groove will be profiled and so interfere with the riving knife.....?
I am sure you will correct me if I have made a wrong assumption or drawn an illogical conclusion.
Lataxe
"I assume they are the same diameter as a normal sawblade (eg 10 inches)"
"I am sure you will correct me if I have made a wrong assumption or drawn an illogical conclusion."Most dado blades are 6" or 8" in diameter for use on 10" saws. Probably more to do with the mass of the rotating blades and the ability of the arbors and bearings to handle them. As well as the fact that they are not intended to cut through the wood, just groove it. That said I do have a 10" set and your comments about the riving knife with it would apply.Dadoing on the wild side.
Wow, I've been reading this thread and what you fine folks have wrote about TS safety, here I'm fixin to upgrade from my little 10" portable to a 35 yr old Sears Craftsman 3hp that has none of anything mentioned. The guy only wants $100 and the saw does purr like a kitten. But caution will rule the day that I get it and put it to work.
Chris.
Chris, you can add a splitter and blade guard to that saw, and (IMHO) you should. You can make a wedge or pin splitter that inserts into a shop-made throat insert. You an buy an overhead blade guard, or make one yourself. Representative links below.....
Shop-made overhead blade guard
Penn State overhead blade guard
One splitter and a plan for a similar oneAnother splitterAnd a commercial aftermarket splitter
Although the splitter is rather insignificant looking, it is arguably the more important of the two devices in terms of the preventative protection it provides, but personally I won't work without either of them. You'll find plenty of die-hards who poo-poo the use of these safety devices, if you want to you can let them convince you otherwise.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Heyyy,
Thank you for the info, very interesting.
Chris.
Any time, Chris. Here's one of the entertaining things that can happen when things don't go well on a table saw. In this particular instance, there was a splitter installed, but the stock was too small and not being fed right (by your's truly). But lack of a splitter can create a similar problem, and of course the more prevalent stock-closing-on-blade thing.
You don't want your hand following the stock, for sure!
View Imageforestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Nice burn-out ya did there...glad you did not get hurt.
My little portable has the splitter, the gripper teeth and blade guard, they are nice things to have for sure. I was musing in my post that everybody was talkin about all the new and different safety items that can be had for a TS, and here I am contemplating buying a 35 yr old saw that has none of the stuff...kinda along the lines of 'my how things change over time'.
By reading the posts by our trusty ol' friend Sarge, I figured I could modify it to make it safe, if I wanted to. I thank you again for the links you posted, I made a folder in favorites for them, when I have a spare moment I'll stick them in a file on my PC for later use.
I basically was thinkin of getting the saw for a dedicated dado machine, I'm just not sure I want to pay $100 for it.
Have a good day out there on the left coast,
Chris.
"I basically was thinkin of getting the saw for a dedicated dado machine...." A great idea, and easily worth $100 in saved time as long as you have room for it. "I wanna new shop!" she cries.
Those "gripper teeth" are anti-kickback pawls. Some guys don't like them, because occasionally they can fall between the stock and the splitter. I tie mine up with a Acco binder clip if I think they might get in the way.
My step-son picked up an old Craftsman saw at the fundraiser where I got the little Inca a couple weeks ago. His doesn't have the guard either, but I have a couple junked ones, one of which we're hoping will fit.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
The ole tell tale quarter round. Cross cutting with the fence? Take your eye off the fence and...Or have the fence too close on the outfeed end, or have a dado cut out in the fence where the piece may hang up. Technique and set up are just as important as any devices. Those kickbacks take to the air and will lift off small kerf splitters. They can shatter a guard or toss the splitter assembly. It's great to have some safety devices but they are easily defeated if technique is incorrect. The reason I say this is from watching many students who watch the blade and not the fence. It's one of those accidents that happens too frequently and can result in injury. Glad you were not hurt.Beat it to fit / Paint it to match
Amen to technique and usage. Perhaps the most important safety device in the shop is your mind, not to mention its keen edge!
Off to take a look at a real old set of Stanley chisels.
Regards,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Edited 7/28/2007 9:21 am ET by KiddervilleAcres
Of course y'all could use a power feeder, provided the saw will stand the weight.
As was mentioned, they on this side of the pond they are usually smaller than the 10" blade. There is another reason, I think, for the banning of dado blades. If I understand correctly, European standards call for a pretty rapid blade brake. An American style Dado blade could easily spin off the arbor given it's mass if the arbor stops and the blade doesn't. So the blade brake makes dados dangerous and generates things like arbors with pins. Even the most impatient of us must be safe.
Personally, I don't find the dado blade all that dangerous, especially since they are almost never used for through cuts, which I suspect is the major cause of kickback. This is especially true since the alternative would have to be a router, which in my mind is too loud and which can have too much of a mind of its own. I own one, I use it, but I go pretty far to avoid it if I can. (I do have an excuse, being interested in 18th c. reproductions where I can, if need be, find a quiet alternative.
Lataxe and Steve
Dado heads aren't banned in Europe - I have mine set-up on a radial arm saw in a commercial shop and it is legal - but as you say our requirements for pinned arbors on 12 in and above saws, motor braking on all saws (except some types of overhead crosscut saw), limited arbor length on saws and adequate guarding makes usage of the stacked saw dado set on a table saw difficult here (and all but impossible in a work-place environment). Some manufacturers (notably Scheppach, Kity, Felder and deWalt) do have a solution - they offer a 2-piece "safety" cutterhead not unlike the 2-piece rebating heads we use on spindle moulders (shapers). This design of head has cutter limitation and will tend to eject a hand or fingers pushed into it, although that's still no excuse for attempting to insert one in the first place.
What I still find hard to fathom is why woodworking machinery engineers in the UK introduced the riving knife on our equivalents to the Unisaw and PM66 (the Multico and Startrite saw benches) in the late 1950s/early 1960s, some 25 plus years or so before mandatory legislation here. Maybe our firms were not sufficiently profit-motivated to fight the court cases.....
Scrit
Edited 7/23/2007 5:24 am by Scrit
Scrit,
It certainly is the case that Scheppach sell a kind of dado for the saw I have, which is more like a moulding head in that it has a diameter a lot smaller than the 10 inches of the normal blades, has only 4 cutters and cannot cut a dado wider than 1.5cm (just over 1/2 inch) in one pass.
Also, they want a ridiculous amount of money (hundreds of pounds sterling) for this silly little thing, whilst insisting you need to spend yet more money on their great SUVA guard that incorporates hold-downs, for safety.
I do make dado cuts with the saw but using a normal 10 inch blade with 80 tooth flat-top grind. Although I have to make multiple cuts at 3.2mm per cut (the blade width). This is easy to do using the sliding table and carriage. In fact, the use of the sliding table with its 0.05mm accurate micro-adjuster on the crosscut fence makes very,very accurate dados - they fit like a chicken's top lip!
I can leave the riving knife in place with this blade as it's top is just below the top of the blade. I use two Veritas hold-downs on the T-track of the fence to ensure the workpiece cannot be kicked up (although the riving knife still works to prevent this anyway).
However, for best speed making housing joints of a set width (eg for veneer-faced blockboard, laminboard or plywood) I use, agin' a straight edge, a router with a cutter having the exact dimension needed - 18.2mm as often as not.
In this way, I do not feel deprived by the lack of an arbour big enough to take a "normal" dado blade in the TS - especially as I can then keep the riving knife in place at all times and enjoy the benefits of that blade brake.
I wish we could have a sawstop trigger though. It only takes one careless moment in a lifetime of woodworking and there you are, unable to waggle a reprimandory finger at the grandchild slurping their soup........
Lataxe
There's the difference - I'm in the trade and if you make your living out of it you are supposed to ensure that your tooling is the safest possible, th guarding is adequate and that you've done a risk assessment......... If you don't and you have an accident then your insurance payout will be much reduced. So like almost everyone else I now rebate on the spindle moulder (shaper) and housings (dados) are cut either with a radial arem saw and a dado head or more often than not using a router and jig - which I find faster and more accurate (having figured out a jig which auto-adjusts to the width of the material).
I agree that Scheppach's prices look a tad high, but when you compare it with what a split vari-width groover with disposable tips for a spindle moulder costs (a very similar design of tool) they're not that far out of the ball park. Maybe you should buy a spindle - then you'll get used to the high price of production tooling <G>
Scrit
Hi All,
I wonder. Do Alaskan crab fishermen use a riving knife :)
I applaud any new practical safety features for woodworking tools. But , we do work with a natural material that is often unpredictable in many ways. The only way it will be completely safe is if we're on our couches watching Norm.
Do your best to stay safe
Paul
A properly designed riving knife works well and isn't in the way so you won't be tempted to remove it. You are right that a riving knife would be removed for dadoing and using a moulding head, but a well designed knife would be easy to remove and replace.
John W.
"Maybe I should get off this rant and go up to the lake and dunk myself in the water to cool down"!
Or over to Europe where we are all sensible folk and take out fingers seriously, even in Britain where they sew them back on for free should one be careless enough to use an American TS (although the sew-ons are never the same and probably only good for making rude gestures; even nose-picking is hazardous because the nerves are shot and you can overpick, or so I hear).
You would also have the joys of planer/thicknessers and biscuit joiners that work. However, you mut call your shop your shed, otherwise housewifes will come expecting to be able to buy bags of sugar, yoghurt and the latest issue of Hello magazine.
Lataxe the 8-fingered and also still fully-be-thumbed
Lataxe,
Would I also have to refrain from making those scuttle legs with the clawed balls on the end?
Bob, and she'll have fun fun fun till her daddy takes the T-Bird away............... Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Just give it time Bob and soon they all will. First Saw Stop, now the new Powermatic has one. Only a matter of time.
Edited 7/20/2007 11:44 pm ET by mvflaim
FYI. A number of US makers are rolling out riving knives this years;
http://blogs.taunton.com/n/blogs/blog.aspx?nav=main&webtag=fw-editorsblog&entry=209
- MB
Matt,
Well I'll be dipped! That's great news!
I've already started the savings account for a new saw. Besides, I haven't bought any significantly expensive tools for nearly a year now.
Feeling a bit guilty about depriving the economy..................
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Those Dewalt and Bosch guards look an awful lot like the Shark guard guy's guards. I like that design, I guess they did too.
donkey
That is wonderful news. But, I'll tell you what..I will be buying the SawStop because they had the guts to be first to include it in their product (I am talking about North American products here) instead of HAVING to toe the line due to the UL regs.Cheers,Peter
Actually, I think the designer of the sawstop knew what he was doing when he was adding a riving knife to his saws.
He was rocking the boat, so to speak. Once one manufacturer added a safety device that was not limited to others; i.e. required paying royalties, or was new untested technology - then fear of lawsuits would FORCE the other manufacturers to add a riving knife to their saws. (example: air bags, court held Ford liable for a crash to a car that did NOT have airbags, at the time of purchase an expensive option, BECAUSE they were available, the manufacturer should have used them, irrespective of the fact that the purchaser CHOSE not to have them - the plaintiff, in court, testified that they did not order the airbags because they were too expensive)
During this addition of the riving knife, the mechanisms for raising and tilting the blade would have to be redesigned. The stated reason why they were not interested in the "sawstop" mechanism to begin with.
By forcing the other manufacturers to go to this exercise, the hope was that they would then add the "sawstop" or similar device to their saws at the same time.
This genie is out of the bottle, both riving knives and the "sawstop" type mechanisms are here to stay, and will only proliferate.
My opinon, YMMV
Mike
QUOTE: I don't understand why American tablesaw makers have taken so long to realize that a riving knife is perhaps the safest and most flexible anti kickback device for a tablesaw.
Arrogance and the fear of lawsuits. First of all American companies think they have the best designers and anything designed elsewhere isn't as "good." Second, their lawyers have convinced them, and perhaps rightfully so, that if they started putting riving knives on saws before it was announced that there was a deadline for them to be placed on table saws, that the companies would be open to lawsuits from people claiming that they were injured because there was no riving knofe and that the company realized that their product wasn't safe even before the riving knives were added to them. Now that it's clear that a riving knife will be required on table saws, the companies can blame the switch on someone else, whomever is requiring the change, and not admit that it makes saws safer. If you delve deeply into the reason that these companies wouldn't put the stopping brake now in the SawStop, you'll find a speech that was given to the "big wigs" of the companies laying out just this legal "problem." What's safe isn't important. In our society, lawsuits or the fear of lawsuits, more times than not, determinies what is done.
ALL,
Just ran across an ad for a Merlin splitter @ Woodcraft. $59.99!
Seems like a good price?
http://www.woodcraft.com/family.aspx?familyid=4578
Regards,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Let me tell you why I don't like the Merlin Splitter. As said in the add, the splitter is made 0.075" thick. The blade tip thickness of a standard carbide blade is 0.125" (1/8") or, it it's a thin kerf blade, the blade tip is about 0.095" - 0.100 thick. One important safety factors for a proper splitter is preventing the closing up of the kerf and pinching of the rear of the blade. This splitter will not perform this function. The most effective and safest splitter is one that is the same thickness as the width of the kerf or, at most, one that is only a couple of thousandths thinner.Howie.........
Howie,
So that explains why my stock splitter/guard doesn't/didn't work, i.e. it too is too thin. I might be reading too much into this but IMHO the manufacturer supplied a safety device that simply doesn't work. It amazes me that Delta (manufacturer of my saw) hasn't had the pants sued off them!
Well now, that $60 for the Merlin you just saved me should provide me with a lifetime supply of shopmade splitter material or a double my cost and go with the Bies splitter.............
Thanks for the info.,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Bob
European saw makers supply splitters to suit the blades - typically a 3.2mm (1/8in or 0.125in) kerf blade will have a 2.7 or 2.8mm (0.106 or 0.110in) riving knife supplied as standard - the riving knife matches the thickness of the saw plate or body. Generally thinner kerf blades are around 2.5mm kerf/2.1mm body (0.098/0.83in). My smaller table saw came with a second riving knife of that thickness.
Maybe when Delta have to produce machines with riving knives (around 2014?) they might just get it right. One hopes they'll get their act together soomer
Scrit
>> So that explains why my stock splitter/guard doesn't/didn't work, i.e. it too is too thin.If you are referring to the thin metal device where the blade guard and pawls are attached, it was not designed to be a splitter. It was designed to hold the blade guard and pawls and be thin enough to fit into the kerf generated by the old, pre-carbide saw blades which were much thinner. Remember, Delta is the originator of almost everything that relates to cabinet saws and contractor saws. The designs go back to the 30's and 40's. No carbide blades then.The Merlin "Splitter" is nothing more than the standard blade guard assembly without the plastic shroud. So if you want the Merlin, simply remove the plastic blade guard and you've got a real cheap "splitter".Howie.........
Howie,
Thanks for all your insights. My neighbor who oh by the way has basically "donated" some real fine tools to the woodshop, has taken on a keen interest to my issue. He's a machinist and stopped by the woodshop earlier tonight.
I printed out some of the posts in this discussion for him to take a look at and he's going to machine a riving knife for me.
I'll keep everyone posted as to our progress.
Thanks,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Beyond all of the excuses about the cost to retool their production process for a riving knife? I suspect that to offer any improvements or changes now may be tantamount to admission that their old "safety set-up" was less then adequate.
BigK,
improvements or changes now may be tantamount to admission that their old "safety set-up" was less then adequate.
My take on it is that the major manufacturers don't give a damn as long as they can keep pumping iron out the door. I doubt that Delta, Powermatic, Jet, Grizzly et al, see Steel City, SawStop, etc as significant competition.
Also if they, in the case of Delta anyway, see fit to offer their clunky splitter as standard equipment on their TS, why not at least offer a decent replacement riving knife as an option? Beisemeyer has certainly done OK from their lack safety offerings as have others with aftermarket products that are superior to the original manufacturers.
It's just my current pet pieve. Maybe the next one will be safety guards for planes and chisels!
Maybe my perception is wrong but when I see innovation seemingly basing its aim on safety, they get my attention in a hurry!
Regards, Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
FYI; Delta has owned Biesmeyer for 12 years now. The nice removeable splitter was introduced after Delta aqquired the company.------------------------------------
It would indeed be a tragedy if the history of the human race proved to be nothing more than the story of an ape playing with a box of matches on a petrol dump. ~David Ormsby Gore
Retro-fitting a true riving knife to a Unisaw just doesn't work the way the lift mechanism is designed--adding a riving knife requires a new design. A new design isn't likely to recover its extra cost unless the competition also has to raise prices to cover their new designs.
But the Beisemeyer splitter, while not as desirable as a good riving knife, is still a sustantial advance over the factory equipment. It pops in instantly, and removes with only a little more difficulty. (And Beisemier is Delta after all.)
As far as the standard splitter/blade guard shipped with the saw, OSHA shops don't want it--they have to use more substantial guards, such as the Brett or Uniguard. Many one man shops won't use a guard because it is less safe and slows work flow. Consequently, raising the price for a better standard guard doesn't make sense, since anyone needing more can obtain it and those that don't haven't paid a higher price for something that will end in the local land fill.
That's why the UL regulation requiring riving knives makes sense. The manufacturers have "conspired", through the UL process, to require riving knives so no one faces a competive price disadvantage by introducing the new design.
"Retro-fitting a true riving knife to a Unisaw just doesn't work the way the lift mechanism is designed--adding a riving knife requires a new design. A new design isn't likely to recover its extra cost unless the competition also has to raise prices to cover their new designs"
I find that to be one of the saddest things about this whole saga. Delta have been building the Unisaw since the 1930s and yet they've never changed the design? They've long since amortized the original tooling costs and could quite easily change if they wanted to - it's much easier and less costly to change sand castings and CNC machining than die casting after all. The fact that the Europeans all changed years back and in most cases well before legislation my indicate something about US manufactuirer's regard of their customer's safety.
"That's why the UL regulation requiring riving knives makes sense. The manufacturers have "conspired", through the UL process, to require riving knives so no one faces a competive price disadvantage by introducing the new design."
It also gives them a fighting chance of getting a toehold in the European markets should they so desire...... At present their saws and many other machines don't meet our regs
Scrit
Changes in the design of the Unisaw have been very small. I have been able to get parts from Delta for my 1945 vintage saw. Basically there seems to have been one small arbor change, and various changes to the cabinet. (My saw has a cast iron "plinth" at the base of the cabinet, not the rolled sheet steel of later vintage, for example.) (Both Delta and Powermatic have mirrored their designs to offer tilts of either direction).
Whether or not a design is "fully amortized" or not is entirely irrelevant to the economic decision to spend money to develop a new design. Sunk costs should always be ignored, with decisions made solely on the added costs and benefits going forward.
Of course, European manufacturers didn't have much machine tooling left after WWII, so all started with a tabula rasa. And, though I don't know the history I wouldn't be surprised to learn that European manufacturers worked hard to get safety regulations enacted that were designed primarily to keep the US manufacturers out of Europe.
"Of course, European manufacturers didn't have much machine tooling left after WWII, so all started with a tabula rasa. And, though I don't know the history I wouldn't be surprised to learn that European manufacturers worked hard to get safety regulations enacted that were designed primarily to keep the US manufacturers out of Europe."
Steve
That certainly isn't true of three out of four of the major woodworking machinery manufacturing nations - The French industry was relatively unaffected by bombing during WWII, neither was the British industry whilst most of the Italian firms, including the world's largest, SCM, post-date WWII. Only the German firms were badly damaged. Against that no American firm was damaged at all by the conflict.
Your snide comment about EU manufacturers "working hard to keep US manufacturers out" bears no relationship to the truth at all. Delta Unisaws (made in Canada and sold in the UK as the Beaver) were available here into the 1970s, although sales were poor from at least the mid-1960s in the teeth of competition from the locally produced Startrites, Multicos, Sedwicks and Wadkin Bursgreen offerings and the emergent Italian brands, some of whom were selling re-engineered and improved versions of American machines (just klike the Japanese). By 1970 the Unisaw couldn't compete on either price or performance or safety. As for Powermatic they couldn't be bothered to export to us at all. Incidentally riving knives become standard on British-made table saws by about 1960, pre-dating legislation by more than 14 years. I'd like to ask this question in reverse - why should we in Europe be forced to reduce our safety standards to the pitifully low standards adopted by Delta et al at the cost of more personal risk and injury amongst woodworkers here?
What we have in Europe is actually a form of (uneasy) concensus between the government safety bodies, the trades unions and the insurers on safety issues. Why is it so hard to accept that? This concensus has led to many safety features here which are often unwillingly adopted by US manufacturers when we choose to mandate them for the well-being of our own working population. That is common across many areas of European manufacturing and includes "pointless" devices such as seat belts, heated rear windows, anti-skid braking, etc in cars all of which came to you from us over here. US manufacturers bellyaching about anti-competitive behaviour are often just underlining their unwillingness to invest in the development of their products or the safety of their clients. If you want proof of that just go and look in any woodworking factory in the USA. You'll see lots of European panel saws, spindle moulders (shapers), CNC routers, etc. On the other hand you'll see virtually no American-manufactured equipment in an equivalent plant in the EU or in almost any other country in the world save very old stuff. There are exceptions to this, however, with one or two firms such as Ritter and Kreg making a name for themselves, however they are the exception
The costs of incorporating many of the safety features taken for granted in Euro saws is piffling compared to the overall cost of the machine. The unwillingness of US manufacturers to invest in primary safety has allowed the Europeans, with their more modern and more safety oriented designs to gain a foothold in your market. Trade protectionism has nothing to do with that.
Scrit
Edited 8/3/2007 7:16 am by Scrit
Edited 8/3/2007 7:19 am by Scrit
Well put. Still, too bad you cannot put a dado set in them to this day. I will be going for the SawStop which to me seems to incorporate the best of both worlds.Cheers,Peter
Steve,
European manufacturers worked hard to get safety regulations enacted that were designed primarily to keep the US manufacturers out of Europe.
Come on, that's utter nonsense!
Noone will ever convince me that our domestic tablesaw providers can't come up with at least a reasonable splitter/guard mechanism and remain competitive! With all their resources to bring to bear as compared to the third party companies filling in the safety gap, it's a joke.
I too think that the recent changes are nothing more than a provision for US manufacturers to expand their penetration into foreign markets. I would bet that through all the shenanigans and legal bopping around that they saw the UL as a chance to cover their collective butts.
We're talking safety here, not accessories! And if you go to their WEB site in search of safety devices, where do you typically find the?
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Edited 8/3/2007 10:32 am ET by KiddervilleAcres
There is no absolute thing called "safety"--there is always a balancing of risks and I believe most American consumers want to choose their own balance. Why shouldn't consumers have choice as to whether they buy a good splitter and guard? The OEM's make them. It makes no difference whether it is called accessory or not--that's just a meaningless semantic difference, unless one believes we are all children.
It would take a lot more than riving knives for American manufacturer's to return to Europe, so that motivation doesn't make much sense, and there are almost no signs that products are being pointed that way.
For example, an OSHA shop may want to spend $380 for a overarm Brett guard. If so, it doesn't want to spend much for an "improved" standard guard just to replace it with the better one.
In my personal shop, I'm going to put the guard in a remote place and forget about it. I sure don't want to be required to pay a lot for it. I'll keep and use my Beisemeyer splitter. (I've got a Brett guard (actually two of them) buried somewhere that was included with my Unisaw.)
Either way, that adds up to a large segment of the market that will not want to buy a basic improved splitter and guard--those that want to go even higher, and those that don't want them at all. Manufacturers just work for the market they have. It's not the role of manufacturing corporations to save the world.
I have stuck one of my fingers into the tablesaw blade once. I felt that the saw was safer without their joke of a blade guard that would not stay adjusted no matter what. I was real lucky, still have the finger and it works normally, but nerve sensation in the tip is still not right. I have since installed the uniguard and the removable splitter that comes with it, use them religously. I contacted Delta and asked them if they would consider selling a tablesaw/uniguard package. The answer was an immediate no; told me that they were worried about the price point. My arguments for a safer saw fell on deaf ears.All hail the almighty dollar. And Delta can kiss my a--!
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