Riving Knives... I'm 'Confounded"....

[David DeCristoforo]

Why, can anyone tell me, is such a big thing being made out of incorporating this preposterously simple feature into even the lowest priced saws? It's just a five dollar (if that) piece of steel fer cryin' out loud. I can't believe that manufacturers are making such a huge issue out of this or trying to justify the typically outrageous "upcharges" for something so simple. I have seen the most useless "features" on some ridiculously low priced machines that had to have cost ten times what it would cost to add a riving knife which adds an extraordinary level of safety for next to no cost. What am I missing here?

[Howard Acheson]

The issue, as I understand it, is getting the riving knife to raise and lower at the blade is raised and lowered. It's a little more than a $5 piece of metal.

[David DeCristoforo]

"...getting the riving knife to raise and lower at the blade is raised and lowered..."

I get that part too. But really, how hard can it be?

[Jim O'Dell]

I'm so confused...just as I was getting used to calling you David...:p
On a new design from the ground up...not a big deal. But it does require a totally different casting for the trunnion to incorporate the device. Thus the 800.00 price tag being batted around for the upgrade for the General table saws. The new one with it isn't 800.00 more than the old design without it, but the new one is more to offset the tooling costs. After a while, that too may go away once they have recouped those costs. JMHO Jim.

[Ken Fitzgerald]

David,

It's probably the total redesigning of the device and retooling costs to manufacture them. A lot of the current castings used have probably been used for decades.

[Matt Ocel]

Riving Knife = Paper weight.

I can't use it with my zero clearance and it seems as long as I have a sharp blade I haven't had any problems.

With that said, I'll probably shoot a 2x4 into my groin!:o

[David DeCristoforo]

"...total redesigning of the device and retooling costs to manufacture them..."

Well... maybe. But these "upgrade" prices are huge. Like the eight bills Jim mentioned for the General "upgrade". Again, maybe it's just me but it seems like these machines are getting "redesigned" all the time. Maybe not all of them and I understand that some designs have not been significantly modified for many years. But for a company like General, once they have set everything up to accommodate a riving knife, it just does not seem like they would have to add that much to the price of every saw.

Signed: "Still David but confounded nevertheless....."

[Alan Schwabacher]

It has nothing to do with cost to manufacture, and everything to do with not wanting to change. Some inexpensive saws have had them for a long time, such as the Ryobi BT3000.

[David DeCristoforo]

"It has nothing to do with cost to manufacture, and everything to do with not wanting to change..."

That's how it seems to me too. Dies and molds are changed with impunity when it suits the manufacturer to do so.

[Ken Fitzgerald]

David,

Today businesses are being run by bean counters for the most part. In a lot of cases, changes, unless they will produce greater income, are directly effected by business administration and not by marketing or engineering. Even within engineering departments and concerning design changes to existing products out there in use, budget concerns will be a major factor. A lot of folks don't understand the difference between an administrator and a manager. You administer a business plan...you manage employees and situations. Too many administers these days and a lot fewer managers.

Changing the design of the trunions used...incorporating the use of a good riving knife....unless they can show a profit....why?

Remember....a dollar bill has no conscience and a lot of people who chase the dollar bill don't either.

[David DeCristoforo]

"Today businesses are being run by bean counters....unless they can show a profit....why?"

Probably the best explanation anyone's gonna get.....

[Paul Ryan]

I can tell you that before I boughy my steel city saw I looked at the models with and w/out riving knives. There is a considerable difference in how the saftey devices are attached to both saws. That said. The way I understand is that as of 2009 every new saw sold will be required to have a riving knife. If that is the case the change to riving knives should be a very small difference in prices. If there would be an option to buy with or w/out a riving knife. I can understand the extra cost to buy the saw with the knife(still not $800). But since it is going to be mandatory the costs will be made up soon enough because the extra $20 added to every saw would off set the cost of redesign. My brother works in a factory as an engineer he tells me the re tooling cost would be next to nothing. I think it is just the bean counters saying we have to requop the costs as soon as possible.

[Loren Hedahl]

Poor bean counters! Get all the blame! And does anyone think they will become one penny richer for all their profitable influence over the company they draw their wages from?

Now -- just think of a good opportunity to sell a bunch of saws today. Just tell your potential customers that if they wait until tomorrow, they will have to pay $800 more because of a Government mandated requirement for a silly little riving knife that will most likely be jerked off and tossed in the trash the first time it gets in the way of some real work.

So you better buy your new saw today. I think we have just three of the old models left. Wait, lem'me check our inventory on my computer. Oops, nope, just two left. Which one do you want? I can't guarantee we'll have one for you tomorrow.

[Ken Fitzgerald]

Loren,

Maybe I missed something. Where is the government mandated requirement for a riving knife.

I do know that I've been working for 2 of the largest corporations in the world for 32 years this year. Bean counters have a lot more influence and control of these companies than they did even 10 years ago...even 5 years ago and do, in fact, yield a major control on businesses today.

[Frank Drew]

Well, I had an expensive German saw with an effective riving knife bracket that was simplicity itself - if I remember correctly, just a flat bar attached to the trunion, riving knife attached to the flat bar. A couple of holes drilled and tapped and some cheap parts.

[Jesse Cloud]

Loren,

Maybe I missed something. Where is the government mandated requirement for a riving knife.

I do know that I've been working for 2 of the largest corporations in the world for 32 years this year. Bean counters have a lot more influence and control of these companies than they did even 10 years ago...even 5 years ago and do, in fact, yield a major control on businesses today.

Underwriters Laboratory (not exactly a 'government') mandated riving knives for all new table saw models in 2008, and all table saws sold beginning in 2010. I think you are right about the bean counters, nobody would do it until they had to.

Not to put down bean counters. I've seen things go terribly wrong when no one is counting the beans, but its a mistake to look to the accountants for leadership and strategic vision.

[David DeCristoforo]

"Poor bean counters! Get all the blame! And does anyone think they will become one penny richer...?"

Well maybe not but that's their job... to count the beans. Not our fault if they don't get a "big enough" salary....

"...just a flat bar attached to the trunion, riving knife attached to the flat bar. A couple of holes drilled and tapped and some cheap parts."

Again, that's how it seems to me. This should not be as big a deal as the manufacturers are making out of it.

[Andrew Derhammer]

I believe Paul is right in the sense that Underwriter's Laboratory is requiring all table saws from 2009 on to have riving knives

[Jim Becker]

David, it's a bit more involved to equip an "existing" machine design to accommodate a riving knife. Many don't have the internal clearances to allow things to work properly, etc. The redesign does upset the apple cart relative to tooling, etc., and with the business environment being what it is, manufacturers are not "happy" with any kind of requirement (mandated or market driven) to spend money on things like that.

That said, I really love having a true riving knife on my saw. It's on there 100% of the time, doesn't get in the way and makes me feel a lot more comfortable knowing that there is help for pinching and that the blade is so close to the knife that it's nearly impossible to catch material on the back of the blade and thus, throw it across the room or into my body. (Nothing is absolute, of course, but the chance of kick back is greatly reduced. "Splitters" in the sense of the "traditional" American design tables saw so often get left in the drawer or in a corner somewhere because they are unusable for so many cutting situations. At least with the riving knife, there's almost no excuse to take it off the machine, so it's there doing its work nearly all the time. That alone helps with saw safety.

[David DeCristoforo]

"...it's a bit more involved to equip an "existing" machine design...The redesign does upset the apple cart relative to tooling, etc..."

You are totally correct. I just wonder how long that tooling would stay in place if retooling would save a couple of bucks on each machine. But, hey... we're only talking about making them safer. There are a huge number of table saw accidents every year (I think it's around 30,000). A very large number of these could be prevented or at least have the severity of injury reduced if the machine was equipped with a riving knife. We are not talking about SS here where the technology is expensive. This is a simple feature. I'm sure there are a plethora of reasons why the industry is resisting but I just can't see where it would cost eight hundred bucks per machine. And those low priced saws are redesigned more often than GM redesigns cars.

[Jim Becker]

They are indeed redesigned frequently to generate excitement, but "inside", there is little or nothing changed, IMHO. There is significant re-used of parts and tooling because that keeps the cost down and margins are thin in our "got to have it cheapest" world these days...

Please note, I'm not in any way defending this practice. I'm disappointed in it, frankly, because as you say, safety should take a higher priority when there are so many accidents attributed to the tool.

[J. Greg Jones]

Just as a clarification on the dates, from what I have read all new saw designs submitted to the UL after 1/2008 must incorporate the riving knife. All current designs are grandfathered and can be manufactured as is until 1/2014. I would expect that most, if not all, manufacturers will switch designs far sooner than 1/2014, but if not they could still sell all inventory made prior to 1/2014 after the 1/2014 deadline.

[Howard Acheson]

Just as a clarification on the dates, from what I have read all new saw designs submitted to the UL after 1/2008 must incorporate the riving knife. All current designs are grandfathered and can be manufactured as is until 1/2014. I would expect that most, if not all, manufacturers will switch designs far sooner than 1/2014, but if not they could still sell all inventory made prior to 1/2014 after the 1/2014 deadline.


A key point I think, is the word "submitted". There is no requirement for saws to be submitted to UL or to have a US seal. Most do or will but it's not a requirement.

A few years ago, the company I ran decided to get a cabinet saw to make crates and shipping containers for the molds we made. We bought a Jet which, at the time, did not have a UL seal or a seal from safety organization in another recognized country. We ended up swapping it for a replacement when our insurance company refused to cover its use.

[Ellen Benkin]

For a reasonable price I, for one, would be delighted to add a riving knife to my existing saw. It would save lots of time that I spend putting the splitter on for through cuts and taking it off for non-through and "sled" cuts. Maybe I'll toss/sell the old saw and get a new one when they are equipped with the riving knife.

[Jacob Reverb]

Riving Knife = Paper weight.

I can't use it with my zero clearance and it seems as long as I have a sharp blade I haven't had any problems.

+1

Somehow I've gotten by so far without one...somehow, I'll continue to try.

[Chris Friesen]

A riving knife works best when the blade moves vertically up and down, not on a swing-arm the way it does on 99% of saws currently. That way, the relative height of the riving knife and the blade remains constant regardless of blade height. This allows the knife to be set just below the blade and so it can remain on the saw for almost all cuts.

Having the blade move vertically requires a total redesign of the trunnion mechanism, which means new castings, new tooling, etc.

[Alan Schaffter]

A riving knife works best when the blade moves vertically up and down, not on a swing-arm the way it does on 99% of saws currently. That way, the relative height of the riving knife and the blade remains constant regardless of blade height. This allows the knife to be set just below the blade and so it can remain on the saw for almost all cuts.

Having the blade move vertically requires a total redesign of the trunnion mechanism, which means new castings, new tooling, etc.

I disagree. A riving knife might be a little easier to make for a blade/trunnion that moves vertically, but one for the typical swinging trunnion would only need a pivot link to keep it at the same height as the blade, despite blade height. The link could be designed with multiple user selected settings to allow it to work with different blade diameters or not at all. We are not talking rocket science here, just a little mechanical engineering. Besides, a riving knife does not have to be some sort of heavy-duty, massive device. A riving knife is just moving splitter and can be a piece of metal or other material that will keep the saw kerf from closing behind the blade. There are little to no forces on it from any direction, except occasionally some pinching and rearward force. Look at some of the manufacturer supplied and after-market splitters out there. At least one brand is made out of plastic!!

[Ken Fitzgerald]

Alan,

While a simple pivot point might seem simple...then there's the linkage involved or some type of cam set up. All of this requires a redesigning and retooling.

Don't think this doesn't add increased cost. Even with building houses or buildings...change orders are where your pocket book takes the biggest hits.

Making these type of changes will effect the bottom line and those who worry about budgets and bottom lines .....especially with today's global economy where the market effected might be here in the US but the manufacturing plant is on some other continent. Getting changes done can be a real pain....I"ve seen that within the huge company I work for.....with parts manufactured overseas. Just the communications of getting something changed can be a real pain. Then, while some administrative people may not want to recoginize it, you do have to take into account the cultural differences......time differences.....what day of the week is it there......are they on a national holiday there and we aren't or visa versa....... It's really not as simple as some would like to sell it.

Take the riving knife....How many companies sell table saws? Not everybody in the world enjoys woodworking and thus there is a limited market. You have to spread these redesign costs and manufacturing retooling costs and in the case of the simple pivot..and linkages across a realitively small market. We are not talking tissue paper that has a huge market base and is a consumeable. My table saw was given to me by my wife. Now I could probably convince her to let me buy a SawStop based on safety but I'd have to save my pennies for a few years to get that. Otherwise since it was a gift from her, I'll will have to either win the lottery and buy the SawStop or wear it out in short order on something that is bringing in an income before she'll let me replace it. That's the economics of it. A good table saw......should last for a couple of generations and then...if it's designed and built properly IMHO, you could overhaul it and it'll last a couple of more generations.....

My point is the relatively small market is one of the things companies have to look at before making a change.

Changes or not making changes are often and especially in today's competitive market place just another business expense that has to be considered in making those types of decisions. And some companies resist making those types of decisions because it effects cost, profit and market share. I personally don't have to make those decisions but do have to live with the results and it bothers me. I'm not justifying that type of thinking and often resent it but do have to live with it.

[Byron Trantham]

How does it work? I have a unisaw and use the beismeyer splitter when ever possible. What's the difference between the two approaches? :confused:

[David DeCristoforo]

A "splitter" generally stays at a fixed position. A riving knife moves up and down with the blade so that the top of the knife is just a hair lower than the blade tangent. Also, the riving knife is (theoretically anyway) more or less the same width as the blade which makes it much better at minimizing kickbacks. Also, it's additional thickness provides some resistance to wood moving away from the fence during the cut which also helps resist kickbacks and binding.

[David DeCristoforo]

"How many companies sell table saws?...there is a limited market."

This is true "but"... With the ridiculously cheap saws being sold these days, there are a lot more table saws ending up in the hands of people who would otherwise probably own one. A large number of new saw sales are in this category. And most of these saws have very "rickety" fences, lose miter gauge bars, massive blade runout, etc. all of which contribute to the dangers of using them. And you have a lot more very inexperienced people who are mostly unaware of the dangers of using a table saw buying them. The manufacturer's way of answering this issue is to spend more money designing graphics of bloody severed body parts that get stuck on the side of the saw. Not the most conscientious way of dealing with it.... is it?

[Ken Fitzgerald]

David,

To expand market share, if folks can't afford a SawStop or a cabinet saw, companies are offering a cheaper model and they are selling. Again, it's a business decision by both the companies and the consumer.

No one participant is scott-free in this. If the companies build a cheap unsafe saw and put it on the market and nobody buys it, it will leave the market. I couldn't afford a cabinet saw when I bought my first Craftsman direct drive t/s. I was novice and didn't know any better. Even the Ridgid I have now. My wife bought it for me to replace the worn out Craftsman. It was definitely a step up from what I had before and yet, it's not a good quality cabinet saw, a Euro-machine or a SawStop and I remind myself of that everytime I flip the paddle switch on it.

[Nissim Avrahami]

I would like to show you my TS Riving knife...I hope that you can understand how it's working and the linkage involved.

On the 2nd drawing I marked all the parts involved by a red arrow

http://i208.photobucket.com/albums/bb151/matsukawa/RKadj.jpg


http://i208.photobucket.com/albums/bb151/matsukawa/EBParts.jpg


About the thickness of the riving knife....

http://i208.photobucket.com/albums/bb151/matsukawa/RivingKnifeD.jpg


Just a small note; In Europe they say that the riving knife can reduce the chances to get a kickback but they strongly recommend the usage of "Short fence" (like on the picture below) when ripping solid wood because you never know if it's "reaction wood" or not.

http://i208.photobucket.com/albums/bb151/matsukawa/01-2.jpg

Regards
niki

[David DeCristoforo]

"...it's a business decision by both the companies and the consumer..."

Again I have to agree but... The manufacturers know the difference. The buyer may not. Sure, you can say that it's incumbent on the "consumer" (man I hate that term!) to understand the dangers. And no one is ever going to make a "100% safe" table saw. But it seems to me that we would all be better off if the manufacturers would ask themselves "Are we selling a saw that is as safe as we can make it at a reasonable cost?" Is it a complete fantasy to imagine this? Well maybe no more so than to imagine a black man getting elected president!

[Mike Henderson]

I admit I haven't read every word of this thread so maybe I'm repeating something here.

It seems rational that the saw companies would put a significant premium on a saw with a riving knife. The company has a bunch of older saws in inventory and some models have not been upgraded to a riving knife yet.

The customers are educated and see the value of the riving knife.

If they priced the saws with the riving knife at the same price as the saws without a riving knife, no rational person would buy the older saw. So the question you (as an executive) have to ask yourself is, "What price difference will cause enough people to buy the non-riving knife saws?"

You can't drop the price of the old saws because there's a manufacturing cost to them - dropping the price means you lose money on each sale. So you raise the price on the saws with a riving knife. It has nothing to do with manufacturing costs of the riving knife saws.

Seems very rational to me.

After all the manufacturers transition their product lines to a riving knife, the saws with a riving knife will sell for about what the older line of saws sells for today.

But the customer who buys the older saw will be stuck with the less safe saw for a long time.

Mike

[If the difference in price really is $800 (for two otherwise equivalent saws) then that's the value that customers put on a riving knife. Otherwise, they'd ignore the saw with the riving knife and buy the one without. So, to me, it appears that woodworkers (in general) value safety.]

[Alan Schaffter]

As many posts have alluded- the riving knife issue is a complex cost-benefit issue. Cost vs need, vs engineering, vs reliability, vs product liability, vs market competition, vs ability to retro-fit, etc., etc.

For most operations, while more cumbersome, a standard splitter does exactly the same thing and works just as well. What you gain with a riving knife is that it can and usually is left on the saw all the time. An operator doesn't need to remember to "snap in on" like a splitter which must be removed for a number of operations. So, from a saw manufacturer's perspective, it is a convenience issue and why should they incorporate it. It only becomes something else when their bottom line is affected, then the other issues above come into play.

If I were a betting man, I would bet all tablesaw tool manufacturers have a riving knife design ready or almost ready to go. Unless the gov't mandates it sooner, it is just a matter of time before and if, after weighing all the issues, they decide to incorporate riving knives.

It took the Japaneses to sell even base model cars with power options (windows, door locks, adj. seats, etc. etc.) in the US before US car manufacturers followed suit.

[Thom Sturgill]

...they will have to pay $800 more because of a Government mandated requirement ...

Actually, I believe its United Laboratories (A.K.A. the insurance companies) that are mandating this. No equipment manufacturer will go to market without the UL sticker of approval lest they risk major liability lawsuits, nor will any commercial insurance company care for a business that runs non-UL approved equipment when equivalent UL-approved equipment is available.

[Brian Weick]

Alan,

While a simple pivot point might seem simple...then there's the linkage involved or some type of cam set up. All of this requires a redesigning and retooling.

Don't think this doesn't add increased cost. Even with building houses or buildings...change orders are where your pocket book takes the biggest hits.

Making these type of changes will effect the bottom line and those who worry about budgets and bottom lines .....especially with today's global economy where the market effected might be here in the US but the manufacturing plant is on some other continent. Getting changes done can be a real pain....I"ve seen that within the huge company I work for.....with parts manufactured overseas. Just the communications of getting something changed can be a real pain. Then, while some administrative people may not want to recoginize it, you do have to take into account the cultural differences......time differences.....what day of the week is it there......are they on a national holiday there and we aren't or visa versa....... It's really not as simple as some would like to sell it.

Take the riving knife....How many companies sell table saws? Not everybody in the world enjoys woodworking and thus there is a limited market. You have to spread these redesign costs and manufacturing retooling costs and in the case of the simple pivot..and linkages across a realitively small market. We are not talking tissue paper that has a huge market base and is a consumeable. My table saw was given to me by my wife. Now I could probably convince her to let me buy a SawStop based on safety but I'd have to save my pennies for a few years to get that. Otherwise since it was a gift from her, I'll will have to either win the lottery and buy the SawStop or wear it out in short order on something that is bringing in an income before she'll let me replace it. That's the economics of it. A good table saw......should last for a couple of generations and then...if it's designed and built properly IMHO, you could overhaul it and it'll last a couple of more generations.....

My point is the relatively small market is one of the things companies have to look at before making a change.

Changes or not making changes are often and especially in today's competitive market place just another business expense that has to be considered in making those types of decisions. And some companies resist making those types of decisions because it effects cost, profit and market share. I personally don't have to make those decisions but do have to live with the results and it bothers me. I'm not justifying that type of thinking and often resent it but do have to live with it.



Ken,
How you doing? long time since I spoke with you , Anyways ,
I want to ask you something, that Rigid saw you have, How well is it cutting your wood, Are the cuts strait, are you able to have square assembly when joining stock , and are you satisfied with the what it was designed to do, ????????? honestly~
I have a PM 64S contractors Saw bought it brand new and I have made several additions to the table to make it more versatile and better ease of operation when cutting stock - I often wondered what the "real" difference was between the Contractors saw and Cabinet saw , what separates the two , don't get me wrong the new PM cabinet saw is gorgeous and is just a spectacular saw , But I am not ready to shell out $2200.00 now on something that I already have that does what i want it to do ,a piece of shop equipment that has made good clean square edge cuts and more-accurately and smoothly ( and part of that credit goes to the blade) and that is what my current saw is doing for me write now and I couldn't be happier. Now when the PM64S dies or,,,A good deal happens to strike at the write time and the write place, then that new PM cabinet saw will be in my shop - My point being , don't you feel that the most important pieces of equipment we have in our shops are the ones that do what they were designed to do, and do just that , but do a good job! Not weather or not it looks great , or , it cost's XXXX amount of dollars, or it is the latest technology,,,, the bottom line is ,,,,,,," when you look at that piece of wood that just came of your saw ~ and you lay it flat on the bed,do you see daylight~ is it straight , , is the cut angles accurate from both ends with a smooth cut all the way down the stock - if you answered yes to all 3 ~ then you know your saw has done it's job ~and isn't that what is important ?, I think, sometimes we get lost with all these new fangled gizmo's and gadgets and forget why we actually bought the tool to begin with.
there is a good article about the 2 comparisons of contractors saws to cabinet saws by David write (http://www.woodcentral.com/bparticles/con_vs_table.shtml) , a, non biased interesting comparison.
Just my 2 cents.

PS: As far as that splitter/riving knife, Nothing but a problem as far as i am concerned- Zero clearance insert - now that's a smooth operation, say what you will , nothing but problems , just to many negatives with that thing, kept running out of alignment , a regular procedure to just change the blade, angled cuts bind up - nothing but a headache! poor engineering and just a royal pain in the kerf!:D

take care
Brian

[Glen Blanchard]

PS: As far as that riving knife , Nothing but a problem as far as i am concerned- Zero clearance insert - now that's a smooth operation, say what you will , nothing but problems , just to many negatives with that thing, kept running out of alignment , a regular procedure to just change the blade, angled cuts bind up - nothing but a headache! poor engineering and just a royal pain in the kerf!:D

take care
Brian

I don't think I understood a single thought in that paragraph. :confused:

[Brad Shipton]

Right now, I think North American Manufacturers see the riving knife as a higher end feature and price point accordingly. Eventually, they will become standard as with the European saws and then I think the price of this feature will be of no consequence. I will have to check my Felder tonight to see the riving knife connections. I dont think it is anywhere as complicated as the other post, but i really have not looked all that closely at it. I can say it is a wonderful safety device that I would not give up.

Brad

[Ken Fitzgerald]

I don't think I understood a single thought in that paragraph. :confused:

Glen,

That's my man Brian! He's trying to say he likes zero clearance inserts and found the riving knife to be a pain to use on a regular basis.

Brian,

My Ridgid TS3650 works okay. The dust collection on it lacks a little. I 'm stilll struggling trying to get it to where I'd like it to be. But ...my wife bought it for me and I"ll drive it I wear it out or can convince her to let me get something else...most likely a SawStop but.....in the meantime, it cuts fairly accurately. It's more accurate than I am with a cs.:D

[Glen Blanchard]

He's trying to say he likes zero clearance inserts and found the riving knife to be a pain to use on a regular basis.



One of the wonderful things about a properly adjusted riving knife is that it not only works great, but it does so invisibly. If I did not see it rising above the surface of my ZCI, I would not know it was even there.

[Ken Fitzgerald]

One of the wonderful things about a properly adjusted riving knife is that it not only works great, but it does so invisibly. If I did not see it rising above the surface of my ZCI, I would not know it was even there.

Glen....I wasn't arguing or discussing ....I was acting as a translator!:D

[Glen Blanchard]

Glen....I wasn't arguing or discussing ....I was acting as a translator!:D

No, I understand that totally Ken. Although I was quoting you, I was not attributing the thought to you (and thanks for the translation).

[Brian Weick]

, and it does what is most important, that's all that matters, ahhhh,,,,,,The dust collection issue~ yes, I designed something to alleviate that headache,,,I have created a constant air volume cycle. what Idid was I mounted EPDM roofing membrane (15m) on the back , also to allow for the trunnion carriage to move in accompanying the angle changes- I alloted an extra amount of the membrane on the back end of the motor housing,cut out where the fan on the motor housing fan is, mounted a seal sleeve there and around the 3 trunnion chamber walls and the top table bed- then created a button sleeve made from the same material to go around the angle adjustment shaft from 0-45 degrees forming better seal as far as air loss ~ this implementation of the cover in fact causes the air from the fan motor into the trunnion chamber, via, the fan on the motor, and the vacuum system picks up on the bottom end - hence the zero clearance comes into play again ~ it does an incredible job, it was a lot of work and time to get it write- trial and error ~ but it does what I intentionally designed and what more could I ask for ,,,,,~,,,,maybe a PM contractors saw with all the bells and whistles, and by the way, some car wax so i can buff her out ~ yeee haaa~~`!!! :D, Nice to hear from you Ken :)

[Brian Weick]

One of the wonderful things about a properly adjusted riving knife is that it not only works great, but it does so invisibly. If I did not see it rising above the surface of my ZCI, I would not know it was even there.


Let me clarify myself,
I do not have a Riving knife~ I have a "splitter" . now, to me they are the same ,but technically - I am incorrect, I understand ~ any how,, I didn't like it so I took the blasted thing off and turned it into a paper weight , took a sip of coffee, shut the door and called it a day~!

Glen ~my viewpoint has always been ~ to each his or her own~ if it works for you ~great! and hey , I might try that, and ,, hey ~ more power to you - :),, but currently , that would put me on the tenth floor of some building i really don't want to be in, do you catch my drift~ :D
You have your self a great day Glen ~ :) Seriously!
Brian

[Glen Blanchard]

but currently , that would put me on the tenth floor of some building i really don't want to be in, do you catch my drift~ :D


I catch your drift there Brian. ;)

[Ken Fitzgerald]

Brian....the next time you are at Starbuck's......ask the cute little lady there for decaf!:D

[Brian Weick]

Brian....the next time you are at Starbuck's......ask the cute little lady there for decaf!:D

Yes ,
the caffeine man is back in action ~:eek: but I also believe you have some ailments as well, does the "trigger happy finger" guy mean anything, not to mention , that lathe that "you turn on" are you sure you read the directions - all the way through, what manual came with that? that has got to be giving you some headaches~ you want me to send you some Dramamine~ ?:D hey ~we all have issues Ken,just depends on what side of the fence they fall into,,,:D:D:D:D I have my caffeine , and you , well I 'll have to get back to you on that one~:D
sincerely,
Brian

[Ken Fitzgerald]

Bro....we are both hooked on caffeine. Don't need dramamiene...They have prescribed Triam HCTZ.....Much more effective ....stopped my earth from spinning. Haven't had a vertigo attack since late November.

[Shane Sura]

This year I purchased the new Jet Xacta table saw with the riving knife. Before it I had my Grandfather's old Craftsman contractor style. I really like the riving knife and I actually feel much safe with it and the kickback pawls and blade guard. What I like about the riving knife more so than a splitter is it allows it to sit within 3/16 of the back of the blade. This makes it near impossible (notice the near) for something to get caught back there.

The other thing I like is that the guard, pawls, and Riving knife is stupid simple to put on and off. This means I will USE THEM!!!! The only time I have to take them off is when using my cross cut sled. I have already trained myself that no matter how simple the cut I do take the time to put them back on.

All in all it was well worth the purchase. I certainly would not have spent extra to upgrade unless it was reasonable. Since it came new with it then I can't complain. So far zero kickback or even a hint of a kickback. Keeping fingers crossed and at least 3 inches away from the blade :eek:

Shane

[Brian Weick]

Bro....we are both hooked on caffeine. Don't need dramamiene...They have prescribed Triam HCTZ.....Much more effective ....stopped my earth from spinning. Haven't had a vertigo attack since late November.


nice talking with you on a serious note , but back to business:
I have a question for you , how do you adjust the RPM on that PUPPY (http://www.sawmillcreek.org/showthread.php?t=66047&highlight=turning+lathe), and if so , I would like to be in charge of that responsibility at the next turners gathering ,the questions you have to ask yourself Ken is , do you trust somebody with 15 times the average nominal intake of caffeine with their hands on your VFD, that is the question you have to ask yourself Ken~ do you ya feel lucky ~ punk? :eek: (sound familiar) man this stinks of plagiarism , and it's splattered all over this thread ~ what a cluster (*^*&! ~ :D
sincerely,
Brian

[Paul Ryan]

I agree with shane. With the little I have used my saw, the riving knife does make me feel safter. As shane mentioned it is really easy to change to the blade guard or back to the knife when needed. The other thing I have noticed is how it holds the wood up against the fence once it has passed through the blade. This maybe due to the fact this is a much better saw than I was using before(jet jwts-10). Or the fact that the knife came adjusted perfectly from steel city. The splitter on the old saw did a horse @#$7 job of holding and splitting the wood. Anyway I would never buy another saw with out it. If you can't afford it now don't by a saw until you can.
Besides all of that. I have read all of the arguments trying to justify the added expense. But I still think it comes down to every manufacturer will need to have it on there saws in the real near future. If they want there machines to be sold in high volumes. And if that is the case then the extra costs will certainly be made up quickly with only a very modest increase in price.

[Brian Weick]

Man,
I totally agree with you ~ Hey, i wish I could have one , but I can't the 64s has a splitter and it really is a problem, no joke. I had wood binding and tough to finish the cut ~ just plain and simple , it wasn't working, so i solved the problem, I am looking at it write now holding down all my paper work, bills by the way, hey maybe I should take it off and watch all my bills go flying around out the window, along with all the money i am spending for gas which my truck is eating for a snack lately.
I am sure I will really like it when I bump up to a cabinet saw some day, but write now~ this economy is starting to freak me out-I watch the stock market, pay attention to the economy,the gas, prices going up, job security, yea- thats a thing of the past, not to mention the housing market melt down. yea ~ I don't think it's a good time to get my new PM cabinet saw at the present time.
But seriously, on a safety note ~ you guys are absolutely write- and I envy you , but some day i am personally going to submit a high glossy 5x8 photo of my shiny new Pm ,,hmmm,hmmm ~ with a "riving knife" thread,,,,,mind you. :)
sincerely,
Brian

[Ken Fitzgerald]

Okay Brian...back to earth

I think Alan was correct earlier. I think every manufacturer has probably got a t/s with a riving knife on the drawing board. Knowing marketing gurus, they probably added one or two other features just so they can move the price up a little more.

My Ridgid has a splitter and it works fairly well. The only time I have taken it off is to do dados.

Seriously, it's all about time and money. How much it'll cost to redesign, retool and the length of time it will take to recover the costs. And how long it will take the consumer to refuse to buy a less safe product.

It's sad to think the government has to step in or in this case, UL to try to get businesses to change their products. But even that could be driven by insurance companies who looking out for their dollars.

The dollar bill has no conscience and neither do those who worship it.

[Brian Weick]

No - wait, you guys have got me pegged on the wrong side of the bulletin board ~ seriously, I couldn't agree more , man, it's all about safety - I totally agree, as i said in an earlier thread ~ If I could have one on my PM 64S I would ~ seriously, I would , but like I said that is not possible with the PM 64S ~ I totally agree with you guys about the Riving knife, everyone jumps the bandwagon on me all the time~I know it's the way I explain things. sorry for my inability to expires myself properly ,as i so desire to do , however, in a , half hazard, dysfunctional manor , at best~ anyways ,,, my apologies ~ you guys are write- just wanted to clarify the issue. ~ OK :)
sincerely,
Bran

[Glen Blanchard]

everyone jumps the bandwagon on me all the time~I know it's the way I explain things. sorry for my inability to expires myself properly ,as i so desire to do , however, in a , half hazard, dysfunctional manor , at best~ anyways ,,, my apologies ~ you guys are write- just wanted to clarify the issue. ~ OK :)
sincerely,
Bran

Hey Brian. No worries man. We are all friends here. :D

[Shane Sura]

...., along with all the money i am spending for gas which my truck is eating for a snack lately.....
sincerely,
Brian



Thanks why I bought a Prius over a year ago :D

[Karl Brogger]

Thanks why I bought a Prius over a year ago :D


Save on gas, spend on batteries? :confused: I don't understand "Hybrids". Diesel VW's get 60 mpg, and the TDI option isn't nearly as expensive as a hybrid. My pickup gets 20-21 mpg, weighs 7300 lbs, 4wd, has around 300hp/675 ft.lbs of torque, and will pull anything I care to. Diesel rules.

Sorry, rant off.

[Chris Friesen]

Save on gas, spend on batteries? :confused: I don't understand "Hybrids". Diesel VW's get 60 mpg, and the TDI option isn't nearly as expensive as a hybrid. My pickup gets 20-21 mpg, weighs 7300 lbs, 4wd, has around 300hp/675 ft.lbs of torque, and will pull anything I care to. Diesel rules.

The real benefit of hybrids is improved city mileage, especially in stop-and-go traffic. Most hybrids get the same mileage in the city as they do on the highway, and some hybrid SUVs actually get better city mileage due to lower air resistance at city speeds.

One of the reasons diesel engines report better mpg is that the fuel itself has more energy per gallon. It also generally burns dirtier than gas. The last time I checked the VW TDI vehicles didn't do very well for repair history.

I own a Toyota Matrix. It can hold 8-foot long lumber with the hatch shut, although for sheet goods I have to cut it down at the store and hang it out the back. I get over 40mpg on the highway. It's pretty gutless, however.

[Steve Sawyer]

I recently purchased a new saw, and the riving knife was the one "must have" feature. I was willing to compromise on just about every other issue, including horsepower and configuration (contractor vs. cabinet vs. hybrid). I tried to get the new Grizzly G0661, but had I committed to that model, I'd still be waiting another two months to get it. As it is, I had to wait six weeks for the Jet I ended up buying.

Neither the Grizzly nor the Jet is priced exorbitantly IMO, but their scarcity tells me that there are probably other woodworkers that value this feature. If you look at how the riving knife is mounted and moves with the blade on both of these two saws (as well as the PowerMatic PM2000), you'll see the extent to which the entire trunnion needs to take the riving knife into consideration when it's designed. No, it isn't rocket science, but it's like designing a convertible vs. a sedan. You don't just cut the top off the sedan and throw a piece of canvas over the passengers. The convertible option has to be designed into the vehicle from the start. Are convertibles a lot more expensive than sedans? No, just as riving-knife-equipped saws aren't a lot more than non-RK saws. However, there are considerable design and manufacturing costs involved with introducing a new saw equipped with a riving knife, and manufacturers need to look carefully at how they spend their limited resources to introduce new models with these kinds of up-front product development costs.

[Vic Damone]

I disagree. A riving knife might be a little easier to make for a blade/trunnion that moves vertically, but one for the typical swinging trunnion would only need a pivot link to keep it at the same height as the blade, despite blade height. The link could be designed with multiple user selected settings to allow it to work with different blade diameters or not at all. We are not talking rocket science here, just a little mechanical engineering. Besides, a riving knife does not have to be some sort of heavy-duty, massive device. A riving knife is just moving splitter and can be a piece of metal or other material that will keep the saw kerf from closing behind the blade. There are little to no forces on it from any direction, except occasionally some pinching and rearward force. Look at some of the manufacturer supplied and after-market splitters out there. At least one brand is made out of plastic!!

Alan, I agree, your suggestion is possible but your looking at least two links for your mechanism. The cost of manufacturing and assembling two links with the minimum of runout needed to create the stiffness needed by the function of a riving knife might be quite high. The performance would certainly draw criticism when compared to solidly attached designs.



Poor bean counters! Get all the blame! And does anyone think they will become one penny richer for all their profitable influence over the company they draw their wages from?

Now -- just think of a good opportunity to sell a bunch of saws today. Just tell your potential customers that if they wait until tomorrow, they will have to pay $800 more because of a Government mandated requirement for a silly little riving knife that will most likely be jerked off and tossed in the trash the first time it gets in the way of some real work.

So you better buy your new saw today. I think we have just three of the old models left. Wait, lem'me check our inventory on my computer. Oops, nope, just two left. Which one do you want? I can't guarantee we'll have one for you tomorrow.

Interesting cost estimate, care to elaborate? Government mandate or simply an Underwriters Laboratory approval?


Vic

[Larry Conely]

I'm not sure I can add any more relevant information. I have an INCA 12" table saw with a riving knife. I've owned it for over 15 years. It is always perfectly positioned and I have not had a kickback in that many years of amateur use. The blade rises and falls in a straight line, not an arc. I doubt I will ever purchase another saw, but I would never own a saw without a riving knife.

[Steve Sawyer]

Loren,

Maybe I missed something. Where is the government mandated requirement for a riving knife.

Some people just like to speak in terms of hyperbolic absolutes, and if they can make a case against our government in the process, they will.

From what I understand, the situation is that as of this year (2008) UL (an independent, non-governmental testing service) will no longer certify a table saw of new design unless it's equipped with a riving knife. Existing designs are grandfathered for a few years (I've seen some quote until 2014). And it isn't costing anyone $800. The Grizzly G0661 is about $800 in total, the Jet I just bought was $1500, and the PM2000 goes for about $2200.

I think someone spoke of a cost of $800 to retrofit an existing saw with a riving knife, which means replacing the entire trunnion assembly. The point of THAT is to illustrate that it isn't practical to retrofit, that it requires a new design to do the job right.

[Ken Fitzgerald]

I couldn't understand why the existing trunions would have to be modified until Larry posted that picture of the riving knife and then it struck me ...........Most trunions tilt to raise or lower the blade.

For the riving knife to maintain it's position with respect to the postion of the blade, the trunion has to move vertically. If the trunion tilted instead of raising and lowering vertically, the knife would change and could be either higher or lower than the blade (depending on which way the trunion tilted w/respect to the riving knife) and could not only defeat it's designed purpose but actually become detrimental to the safe operation of the saw. Of course you could manufacture some type of lever action or cam action to offset this but................

In any case it would require redesigning and retooling and increased manufacturing costs.

I see the light! Fiatlux!

[Karl Brogger]

I know I ranted on this before, but riving knives give me the willies. So do blade guards. Don't put your hand in front of the blade and every thing is fine. Trust me I've ran some really stupid shit through a table saw.

In 10 years of doing woodworking at a professional level I've never worked at a shop that had a single riving knife, on a single saw. I can count the number of kickbacks I've had on my fully fingered hands. The only time we ran guards is when we got the phone call from another shop that OSHA was around town. The first table saw I bought both sat on a shelf for 3 years before I finally just pitched them in the trash. The last table saw I bought it went into the garbage as soon as I unloaded it.

Now air clamps always get me. I've gotten fingers caught in every single stupid pnuematic clamp at one place I worked at. Cope clamps, face frame tables, castle machines, and pnuematic door clamps, (Which was the worst one BTW), for some reason I have a mental block on air clamps.

Just because someone gets hurt doesn't mean we need legislative action. We've got too many laws already, and to many mindless civil servants trying to enforce them. If a-holes stop sueing everyone else everytime they do something to THEMSELVES the world would be a much shinier place.

[tim rowledge]

Same old story; "oh noes! woe is us! this will add a gazillion gold pieces to the the price of the widget!"
Seat belts in cars. Airbags. Catalytic converters. Fused plugs on appliances. Smoke alarms in houses.
Every time some feature is proposed the manufacturers scream and holler about the end of the world. I seem to recall UK car companies trying to scare customers with claims of adding a couple of thousand pounds to the cost of each car if the evil catalytic converters were mandated. Did actual prices go up? Nah. People will pay what they find acceptable and manufacturers have to live with that. Same old story.

[Steven Hardy]

I can tell you that before I boughy my steel city saw I looked at the models with and w/out riving knives. There is a considerable difference in how the saftey devices are attached to both saws. That said. The way I understand is that as of 2009 every new saw sold will be required to have a riving knife. If that is the case the change to riving knives should be a very small difference in prices. If there would be an option to buy with or w/out a riving knife. I can understand the extra cost to buy the saw with the knife(still not $800). But since it is going to be mandatory the costs will be made up soon enough because the extra $20 added to every saw would off set the cost of redesign. My brother works in a factory as an engineer he tells me the re tooling cost would be next to nothing. I think it is just the bean counters saying we have to requop the costs as soon as possible.

I think the story with most manufactureres is "Why include something and lose the opportunity to upsell the item?" I believe that: most accesories not included "in the box" are grossly overpriced (relative to manufacturing cost).

[Glen Blanchard]

I know I ranted on this before, but riving knives give me the willies. So do blade guards. Don't put your hand in front of the blade and every thing is fine.

Karl,

I would think that if it was just that simple, there would be more folks walking around with intact fingers than there are.

I'm trying to wrap my brain around why riving knives (JUST a riving knife - no blade guard) give you the willies. A properly adjusted riving knife never gets in the way. The only time I remove mine is if I change blades. Why would it cause any discontent?

[Peter Quinn]

I have the beis splitter on my PM66 and it works well for me. It is the same thickness with in thousands as my full kerf blades, set up easily. comes in and out easily, and those kick back pauls that some hate have saved my butt more than once. I have yet to cut any wood with so much tension that the difference between the 3/16" gap between to the blade that a riving knife would create and the gap my splitter creates made a hill of beans. As far as non through cuts it would be nice to have a riving knife there but thats not my highest likely hood kick back operation and iI've never felt lost without one!

As far as the previous suggestion that a ZCI helps prevent kick back, perhaps you could explain that theory again, cause us slow guys missed that the first time.:D It might stop small off cuts from becoming torpedos, but how does it affect a serious kick back?

I see the riving knife as a marginal improvement worth including on new models. Its not quite the emperor's new clothes, but its close. I for one would never pay to have my cabinet saw retrofitted with a riving knife. For what? More important would be some serious dust collection, now thats a retrofit I would throw down for.

[Karl Brogger]

It is just that simple though. I think the idea of a kickback has been somewhat inflated too. I've gotten hit by things catching and then whipping out of a saw, it doesn't feel nice, but its a good solid reminder of why you don't allow those things to happen. Most animals respond well to pain, including humans.

Whacking a finger off, or getting a kickback isn't an act of god. It's not lightning where it is out of your control. Its having your head elsewhere and not paying attention to the signs of the proverbial poop hitting the fan. I've been there, hung over or thinking about something else and "oops". Driving a car in poor weather, flying a plane, open heart surgery, being in the middle of a combat zone, there is all sorts of things that demand 100% attention to come out unscathed or not kill someone else unintentionally. Woodworking is no different if you want to count to ten with out removing your shoes. These things are sharp, powerful, and dangerous when not granted the proper amount of respect. I've seen alot of guys get mangled because they forgot that whatever they were doing could hurt them. Whether it was a saw, shaper, chisel, motorcycle, icy steps, whatever, life's dangerous, having your head up your butt makes it more so. I'm not saying I don't make mistakes either, but preventing such things requires more between the ears than a piece of metal or plastic.

While it can be said that a guard or a riving knife will thwart or prevent an accident I just don't like em'. I like a naked blade, I can see all the issues before they arise. It's probably more just because that is what I am used to. I'm not trying to convert anyone, but for me the hassle isn't worth it and with proper care isn't neccesary. I do everything I can to keep my digits out of harms way. I spent $800 on a clamp for the shaper for coping door rails. I worked at a place all we had was a T-square. That scared me everytime I used it.

[Steve Sawyer]

As far as non through cuts it would be nice to have a riving knife there but thats not my highest likely hood kick back

The advantage, Peter, isn't so much preventing kickbacks on non-through cuts (I agree that kickbacks are much less likely in that situation), as it is that you seldom, if ever, need to remove the riving knife. Splitters must be removed for most non-through cuts, and I know that I'd be careless enough (or lazy enough) to not put it back on afterwards. With the RK that's never an issue. I don't even need to remove it to change the blade.

I agree that the additional advantages of the RK over a good splitter (and I've heard nothing but good things about the Bies) - that gets used - makes it hard to justify the trouble and/or expense of figuring out how to retro-fit an RK.

[Peter Quinn]

The advantage, Peter, isn't so much preventing kickbacks on non-through cuts (I agree that kickbacks are much less likely in that situation), as it is that you seldom, if ever, need to remove the riving knife. Splitters must be removed for most non-through cuts, and I know that I'd be careless enough (or lazy enough) to not put it back on afterwards. With the RK that's never an issue. I don't even need to remove it to change the blade.

I agree that the additional advantages of the RK over a good splitter (and I've heard nothing but good things about the Bies) - that gets used - makes it hard to justify the trouble and/or expense of figuring out how to retro-fit an RK.

Guess that's what I'm saying Steve. I have the beis splitter. I use the bies splitter for every cut where it is applicable. It only come out when actually necessary as it takes only seconds to remove/install. That or a simple shop made version is the way to go on a traditional cabinet saw. Forget the $800 retrofit. The guard with build in splitter that came on my 66 was a joke, and I wish it had been optional. I'd love to send them back that POS for a refund.

If manufactures want to include a good riving knife or even just a splitter that is actually useable on new machines then more power to them and its about time. I sure would have bought a model that had one if they were available when I got my saw. I see the riving knife as a nice tweak that is just beginning to jump the pond, not a great leap forward or a must have. There out to be something in there keeping that kerf open when ripping off the fence. Riving knife? Splitter? Piece of frozen hot dog? Something.

I worked for years in a shop that had 4 cabinet saws (one was an SCMI that came with a riving knife) and a big slider. All had the guards/splitters removed. Every guy in there could count to ten. Long push blocks, feather boards, and power feeders were on each machine and got used all the time.

Before I'd make riving knives mandatory I'd require manufacturers tap the tables and offer a power feed bundle with each saw as well as hold regional educational seminars on safe saw use. That might prevent some accidents. Perhaps a wrench to tighten up the nut that holds the wood to the table and pushes?

[Steve Sawyer]

[quote=Peter Quinn;862395]Before I'd make riving knives mandatory/quote]

I don't think anyone (at least around here :D) is suggesting making anything mandatory. UL, an independent organization, has made a decision as to the importance of a riving knife as a safety enhancement, and the insurance industry seems to be paying attention to that.

Personally I believe in the value and for me it was a "must have" when making my recent purchase, especially as it didn't add noticeably to the cost, only limiting my range of choices. Others have found other (and equally good, for them) choices as to how they want to work safely. That's as it should be.

Splitters work, as do featherboards, power feeders, paying attention and not working "under the influence" ;). I lost the tip of my left thumb many years ago to my tablesaw (my fault, not the saw's), so I might be just a tad more paranoid than most.