Felder's high-tech preventative contact system could eliminate all saw injuries | Woodworking Network
Felder has unveiled a patent-pending preventative contact system that could potentially one-up SawStop's legendary system.
Better than SawStop
- Thread starter Mike Davis
- Start date
I think it's great for others to offer an alternative. I hope SawStop doesn't block this technology with a patent suit too. I like my SawStop saw but I keep my old Ryobi functional so I can use it's 6 inch dado set (haven't purchased a 8 inch yet) and to cut wood that may have nails in it. The drawbacks I see to the SawStop technology is the possibility of triggering by wet wood, nails (or staples) in the wood, the cost of cartridges (including a unique one for dado blades), and the destruction of a blade if the cartridge triggers. The Felder technology seems to avoid the blade damage and probably the cartridge cost but I wonder about false triggering. If the only consequence of a false trigger to the Felder is you push a button, that wouldn't be as big a deal, however.
All saw stop has to do to stay competitive is be some cheaper than the other system. There isn't a good reason for there to not be competition here though. I would think less of saw stop if they continue to try to 'corner the market' here in the US for this technology.
Although possible, a wet wood trigger is accounted for in the SawStop software. I was cutting a piece of wood I thought was dry enough and it was not. The SawStop sensed this and merely stopped the blade turning - it did not trigger the brake. It flashed a code that said "wood too wet" and suggested that I use the override key to continue the cut. I did and all was well. Just trying to help relate that hyperbola is not fact and personal experience is just that.
I also welcome competition and the lowered price it brings. Perhaps all premium Table Saws and soon band saws will include flesh sensing technology. Kudos to SawStop for being first to implement it.
I applaud them for sure. Anything that makes our work safer is a good thing, don't care how it is achieved. I hope to see some advances like these on all spinning blades and mechanized cutting tools in the future - the technology is here so it is now clearly possible...
I have never put my SawStop in bypass mode. I have the instructions in the top drawer of a cabinet below the extension table just so I can do this operation but I still just go back to using the old Ryobi. I am pretty sure I am evidence of "old habits die hard". But my shop is so small I really cannot afford space for 3 table saws. I also have a little $100 Ryobi that was my ex-wife's under my assembly table. I can pull poles out to set it up at the height of the assembly table if I want to use it. I need to get rid of the BT3100 to gain the space in the shop and just use the cheapo when I need or want a second saw. Last time I used it was when I was doing a staircase and I put a 1/4 dado set in it for cutting a tongue on the back of the treads and a dado in the risers. Progress will happen but it happens slowly in my case. I may have a little time this weekend (doesn't look like the gas tubing I bought will show up) so maybe I will throw an old blade on the SawStop, put the saw in bypass, and cut a piece of wood with a nail in it. Probably not, however. I don't like dinging up even old blades unless there is a purpose... Maybe I should jut put it in bypass and cut a regular piece of wood for the practice.
Yeah, I've gotten the warning and used "hot dog" mode (as I call it) on subsequent cuts. Still the one false trip I have the SS people think was due to a conductive piece getting between the blade and the brake module. It was a surreal event. I'm almost through cutting a piece of plywood and the blade disappears. What? Then I realize the safety has fired. I stare at my hands (which were nowhere near the blade) to see if I missed something. The new brakes have a piece of tape over the surface to prevent this.
Still, the new design looks intriguing. I'll have to look into it more than what they show in the video. I've not been able to find any details yet.
Looks better than the Whirlwind kludge (and that "inventor" was a pip as when I expressed doubts about the system, he reamed me publicly in one of the other forums rather than just explaining what he was doing, which he never actually did explain).
Still, the new design looks intriguing. I'll have to look into it more than what they show in the video. I've not been able to find any details yet.
Looks better than the Whirlwind kludge (and that "inventor" was a pip as when I expressed doubts about the system, he reamed me publicly in one of the other forums rather than just explaining what he was doing, which he never actually did explain).
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OK, here's Felder's page on the subject: FELDER GROUP
First off, I was immediately cheesed off on the thing because they claim the saw blade retracts "at the speed of light." Absolutely impossible. They then say a few milliseconds. This is more like it. Not even quite the speed of sound.
I'd have liked some explanation of the proximity detector. I suspect that like the SawStop, it's using a tuned circuit that placing your hand near causes a disruption (ever watch the guys play a Theremin?).
Right now it's only on the Kappa 550. That's a little more saw than I can use in my shop.
First off, I was immediately cheesed off on the thing because they claim the saw blade retracts "at the speed of light." Absolutely impossible. They then say a few milliseconds. This is more like it. Not even quite the speed of sound.
I'd have liked some explanation of the proximity detector. I suspect that like the SawStop, it's using a tuned circuit that placing your hand near causes a disruption (ever watch the guys play a Theremin?).
Right now it's only on the Kappa 550. That's a little more saw than I can use in my shop.
Hey, I make cabinets! Not many, not professionally, and very slowly. But still
I must admit, even though I'm very happy with my Grizzly slider, if they put this feature on one of the Hammers I may decide to upgrade. The slider design keeps your hands away from the blade most of the time, but most of the time is not good enough most of the time.
BTW, I'm still surprised that a sliding table saw is still something that's considered to be only useful for processing sheet goods. Or that it takes up more space than a regular cabinet saw.
Actually it's the speed of magnetism minus mechanical resistance.
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I found the explanation interesting, it seems to clearly say that the only consequence of false triggering will be an interruption in the work - no consumables.
The speed with which it retracts will be determined by the amount of force that the retraction mechanism and the mass of the portion of the saw that retracts. The equation if F=MA - force equals mass times acceleration.
For SawStop, the force is applied by a tensioned spring. There is a little wire restraining the spring that is melted when the brake triggers. That thrusts an aluminum piece into the blade. The good sized arbor of my SawStop is actually a disadvantage in terms of how quickly it stops. But it seems to be fast enough.
Felder is saying they are doing it by magnitism. I presume they are talking about an elecromagnet. You could reverse the current to the motor - effectively throw it in reverse. That would use magnetism to stop the blade. The force in that case would be the maximum the motor can generate but the mass would also include the motor armature. It also seems like it would be transmitted through the belt which seems inconsistent with the blade dropping. So that probably is not it.
The speed with which it retracts will be determined by the amount of force that the retraction mechanism and the mass of the portion of the saw that retracts. The equation if F=MA - force equals mass times acceleration.
For SawStop, the force is applied by a tensioned spring. There is a little wire restraining the spring that is melted when the brake triggers. That thrusts an aluminum piece into the blade. The good sized arbor of my SawStop is actually a disadvantage in terms of how quickly it stops. But it seems to be fast enough.
Felder is saying they are doing it by magnitism. I presume they are talking about an elecromagnet. You could reverse the current to the motor - effectively throw it in reverse. That would use magnetism to stop the blade. The force in that case would be the maximum the motor can generate but the mass would also include the motor armature. It also seems like it would be transmitted through the belt which seems inconsistent with the blade dropping. So that probably is not it.
For me, the technical how and why it does what it does causes my eyes to glaze over. All I care about is that all my fingers are present if I screw up and get to close too the blade! I prefer the Felder over SawStop method if it saves me a few bucks or $100 when it triggers
I have owned a SawStop for over ten years and have triggered the safety break on two occasions. In both cases, metal came "accidentally" in contact with the turning blade. On those occasions, my feelings ran the gamut from surprise, confusion (what the heck is going on), irritation (discovered what was going on and realized it was my negligence), aggravation (cost of a new break cartridge and blade), and finally satisfaction (the machine works as advertised). If Felder's technology works as advertised and a blade retraction was triggered I am sure I would still be surprised and confused as well as satisfied...but if no consumables were lost (break cartridge/blade $$), I may avoid the experience of being irritated and aggravated!
My SawStop is an awesome saw, but I always knew it was only a matter of time before someone came up with better mousetrap...maybe Felder has!
My SawStop is an awesome saw, but I always knew it was only a matter of time before someone came up with better mousetrap...maybe Felder has!
see what I mean...
While the spring moves the brake block toward the blade, but once it starts to decelerate the blade, it's the momentum of the blade that provides the force necessary to jam the arbor down below the table.
You can indeed apply power to the blade to stop it. It's not even hard if you're using a VFD drive to run a three-phase motor at various speeds. However, I don't think that's a drastic enough braking. I suspect that they have something else that is moving the blade from harm's way. They get a few milliseconds of grace as their system appears to detect you just getting NEAR the blade, not actually in contact with it like the Sawstop.
Sorry to those who do not like the technology involved. It is interesting to me.
I guess it's just belt and suspenders but all these systems, including Bosch, seem to both retract and stop the blade. That seems redundant. If you drop the blade below the surface of the saw, it wouldn't make much difference if it is still running. If you stop it, it can still do a little damage but not a lot if it is sticking up. I guess if you are designing a system it probably isn't a huge deal to do both. I'm not sure how SawStop drops the blade and I have no clue what Felder is doing.
I guess it's just belt and suspenders but all these systems, including Bosch, seem to both retract and stop the blade. That seems redundant. If you drop the blade below the surface of the saw, it wouldn't make much difference if it is still running. If you stop it, it can still do a little damage but not a lot if it is sticking up. I guess if you are designing a system it probably isn't a huge deal to do both. I'm not sure how SawStop drops the blade and I have no clue what Felder is doing.
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