Alternative to SawStop?
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I think if we used the blade guards and splitters when we should we wouldn't be having this thread. It appears that there is a prototype version of the Whirlwind which floats over the blade like the Biesemeyer blade guard and doesn't connect to a splitter. This will make it easy to use with a riving knife or a Shark splitter like I use.
I'm really interested in the dust collection ability of this because my current setup is the pits.
I'm really interested in the dust collection ability of this because my current setup is the pits.
This has been hawked around WW forums for awhile now. Here is a Sawmill Creek thread about it from last year this time.
I really wish this fellow inventor well, but I don't have a lot of hope, since he is following the same route Gass did originally- trying to license it to a major manufacturer. The recent lawsuits have increased his chances, however. Maybe Delta's new owners will look at it. The next lawsuit will now be able to claim there are two systems that will save your digits.
Ron already identified some of the problems-
Like he said the guard must be used in order for the system to work. It is a bit large and clunky, though not much different than a lot of guards and dust shrouds. In my mind those guards and this one are still too inconvenient to use.
It must either be attached to the side or back, so how do you cross cut or cut a dado across the middle of a 6' or 8' long sheet of ply?
It uses a "skin" sensing system similar to the Sawstop, except the sensor is mounted in a strip that runs along the lower edge of the shroud. I couldn't tell if it still uses electrical braking (reverse current, DC braking, etc.) or if he has switched to a separate mechanical brake (he mentions a brake sound in one video) to stop the motor, in any case it takes longer to stop the blade than a Sawstop. Of course, activation happens at the shroud, before your hands reach the blade, so it can afford to activate a little slower.
But what are you saying when you have this system AND a blade guard? That a blade guard is no good by itself??
The benefit is that you don't need a replacement brake cartridge and you don't trash your blade every time the brake is activated.
I am still convinced that a Sawstop can be made that has a resettable brake that does not destroy the blade- the problem is, that would require a major redesign of the trunion so it could handle the g-forces of a separate brake. The current Sawstop design works and since customers pay for cartridges and blades, there is no motivation for Sawstop to spend money to redesign the brake system and market a more expensive saw.
I really wish this fellow inventor well, but I don't have a lot of hope, since he is following the same route Gass did originally- trying to license it to a major manufacturer. The recent lawsuits have increased his chances, however. Maybe Delta's new owners will look at it. The next lawsuit will now be able to claim there are two systems that will save your digits.
Ron already identified some of the problems-
Like he said the guard must be used in order for the system to work. It is a bit large and clunky, though not much different than a lot of guards and dust shrouds. In my mind those guards and this one are still too inconvenient to use.
It must either be attached to the side or back, so how do you cross cut or cut a dado across the middle of a 6' or 8' long sheet of ply?
It uses a "skin" sensing system similar to the Sawstop, except the sensor is mounted in a strip that runs along the lower edge of the shroud. I couldn't tell if it still uses electrical braking (reverse current, DC braking, etc.) or if he has switched to a separate mechanical brake (he mentions a brake sound in one video) to stop the motor, in any case it takes longer to stop the blade than a Sawstop. Of course, activation happens at the shroud, before your hands reach the blade, so it can afford to activate a little slower.
But what are you saying when you have this system AND a blade guard? That a blade guard is no good by itself??
The benefit is that you don't need a replacement brake cartridge and you don't trash your blade every time the brake is activated.
I am still convinced that a Sawstop can be made that has a resettable brake that does not destroy the blade- the problem is, that would require a major redesign of the trunion so it could handle the g-forces of a separate brake. The current Sawstop design works and since customers pay for cartridges and blades, there is no motivation for Sawstop to spend money to redesign the brake system and market a more expensive saw.
My best guess for method of operation is that this inventor is probably implementing 2 methods of dynamic braking depending on whether the saw uses a universal or induction motor. For universal motors he is likely shorting the motor (after powering off), exploiting the fact that when power is interrupted the motor transforms into a generator, thus slowing the motor quickly. For induction motors, he is most likely injecting DC into the motor, which will cause the motor to slow quickly as the rotor tries to synchronize to the 'stationary' field created by the DC current injected into the motor. As stated by another poster, the inventor is likely using capacitive sensor strips along the edge of the guard to detect user proximity, which is similar to the method used by SawStop -- except that SawStop uses the blade as the sensor.
I really feel that SawStop got it right with respect to focusing on sensing physical proximity with the blade, since this method offers protection with or without a guard and regardless of the type of blade used (standard blade, dado blade, moulding head, etc.). Where I have always felt SawStop got it wrong was in their use of an expendable cartridge with an explosive charge that destroys the blade and cartridge -- which makes false trips (e.g. wet wood) very costly by the time you purchase a new blade and cartridge.
Personally, I feel that SawStop should have used a braked induction motor and a large solenoid-spring combination to swiftly retract the blade safely below the table. This would eliminate the costly cartridge, blade replacement, as well as the need to adjust the sensor/cartridge each time your blade diameter changes.
Where this invention really shines, IMHO, is in its ability to be trivially adapted and retrofitted to most any tablesaw currently in use -- past, present, and future -- even if it is limited almost exclusively to through-cuts. By comparison, the SawStop detection method requires a custom arbor assembly that is electrically insulated from the rest of the trunnion assembly, which complicates retrofitting since a custom arbor -- or insulated bearings -- and sensor mechanism must be developed for each saw model it is intended to upgrade, not to mention finding a mechanism by which to retract the blade and/or stop the motor quickly on such saws.
I have wondered, though, if a variation of the SawStop could not be engineered for retrofit that focused on replacing the OEM arbor bearings with insulated bearings, a bolt-on capacitive-RF sensor module, and a possibly a motor replacement that utilized either physical braking alone, or a combination of physical and dynamic braking (perhaps even reversing the motor momentarily to arrest rotation), that simply focused on stopping the blade quickly as opposed to retracting the blade (which you simply can not achieve practically in a retrofit). It might not be as effective as a SawStop (i.e. you may get more than just a scratch), but I suspect it would be nearly, if not as, effective at preventing a more serious laceration and detachment injury.
Just my $0.02 to add to the discussion.
I really feel that SawStop got it right with respect to focusing on sensing physical proximity with the blade, since this method offers protection with or without a guard and regardless of the type of blade used (standard blade, dado blade, moulding head, etc.). Where I have always felt SawStop got it wrong was in their use of an expendable cartridge with an explosive charge that destroys the blade and cartridge -- which makes false trips (e.g. wet wood) very costly by the time you purchase a new blade and cartridge.
Personally, I feel that SawStop should have used a braked induction motor and a large solenoid-spring combination to swiftly retract the blade safely below the table. This would eliminate the costly cartridge, blade replacement, as well as the need to adjust the sensor/cartridge each time your blade diameter changes.
Where this invention really shines, IMHO, is in its ability to be trivially adapted and retrofitted to most any tablesaw currently in use -- past, present, and future -- even if it is limited almost exclusively to through-cuts. By comparison, the SawStop detection method requires a custom arbor assembly that is electrically insulated from the rest of the trunnion assembly, which complicates retrofitting since a custom arbor -- or insulated bearings -- and sensor mechanism must be developed for each saw model it is intended to upgrade, not to mention finding a mechanism by which to retract the blade and/or stop the motor quickly on such saws.
I have wondered, though, if a variation of the SawStop could not be engineered for retrofit that focused on replacing the OEM arbor bearings with insulated bearings, a bolt-on capacitive-RF sensor module, and a possibly a motor replacement that utilized either physical braking alone, or a combination of physical and dynamic braking (perhaps even reversing the motor momentarily to arrest rotation), that simply focused on stopping the blade quickly as opposed to retracting the blade (which you simply can not achieve practically in a retrofit). It might not be as effective as a SawStop (i.e. you may get more than just a scratch), but I suspect it would be nearly, if not as, effective at preventing a more serious laceration and detachment injury.
Just my $0.02 to add to the discussion.
I would think that this only works if you don't have to remove the saw guard to make a narrow cut.
Pete
I'm not sure if the numbers on the Whirlwind site are accurate now but they are quoting a 2003 Consumer Product Safety Commision Hazard Screening Report http://www.whirlwindtool.com/GO-hazard_tools.pdf on power tools and workshop equipment:
Table Saw Dangers-
58 people per week suffer amputations
1,000 people per week injured in U.S.
Annual injury cost estimate $2 billion
All saw dust is now classified as carcinogenic
I don't know about you but I am blown away by this! Even if these numbers are half as much now (doubt it...probably much more), the problem is not trivial and the industry has done nothing other than providing blade guards and splitters which are not effective because we don't use them. Riving knives are a step in the right direction but much too late and too scarce. Their head is in the sand to the obvious pain and suffering their product is causing in their biggest market, the Consumer/non-Industrial market where the Idiot Pool runs very deep and gets deeper with every second. It's one thing to have a product sold to the Industrial market where there are controls and supervision, but when you sell a 10" saw to the average Joe on a Saturday at Lowe's who has a TV in his garage and drinks beer when he's using it and thinks because he's seen Norm on TV he's an expert...it doesn't take a Rocket Surgeon to figure out that bad things are gonna happen. They better get off their rearends and fix this problem. The Ryobi lawsuit is just spitting in the ocean. Class Action Lawyers in Mississippi are a 1-800 call away.
Table Saw Dangers-
58 people per week suffer amputations
1,000 people per week injured in U.S.
Annual injury cost estimate $2 billion
All saw dust is now classified as carcinogenic
I don't know about you but I am blown away by this! Even if these numbers are half as much now (doubt it...probably much more), the problem is not trivial and the industry has done nothing other than providing blade guards and splitters which are not effective because we don't use them. Riving knives are a step in the right direction but much too late and too scarce. Their head is in the sand to the obvious pain and suffering their product is causing in their biggest market, the Consumer/non-Industrial market where the Idiot Pool runs very deep and gets deeper with every second. It's one thing to have a product sold to the Industrial market where there are controls and supervision, but when you sell a 10" saw to the average Joe on a Saturday at Lowe's who has a TV in his garage and drinks beer when he's using it and thinks because he's seen Norm on TV he's an expert...it doesn't take a Rocket Surgeon to figure out that bad things are gonna happen. They better get off their rearends and fix this problem. The Ryobi lawsuit is just spitting in the ocean. Class Action Lawyers in Mississippi are a 1-800 call away.
Something doesn't add up:eusa_thin.
Using 3450 RPM as the usual speed of a running blade and assuming a general purpose blade with 40 teeth.
3450/ 60 = 57.5 rev/sec.
So with a 40 tooth blade,
57.5 x 40 = 2300 teeth moving past your fingertip in a sec. :elvis:
Sawstop says it takes them .005 sec to stop the blade. So
2300 x .005 = 11.5 teeth through your fingertip. (Still sounds like it hurts)
But with the Whirlwind's claimed time of 1/8 sec (.125) , so
2300 x .125 = 287.5 teeth on your finger tip:swoon::swoon::swoon:
:saw::gar-BiThat sounds like a lot more potential damage.
Actually just the fact that Whirlwind take 25 times longer than SawStop raises a big question:help::help:.
Ok, I wrote the above with tongue in cheek, but now looking at those numbers :eusa_thin:eusa_thin:eusa_thin:nah::nah::thumbs_do:thumbs_do
Somebody check my numbers, please??
Using 3450 RPM as the usual speed of a running blade and assuming a general purpose blade with 40 teeth.
3450/ 60 = 57.5 rev/sec.
So with a 40 tooth blade,
57.5 x 40 = 2300 teeth moving past your fingertip in a sec. :elvis:
Sawstop says it takes them .005 sec to stop the blade. So
2300 x .005 = 11.5 teeth through your fingertip. (Still sounds like it hurts)
But with the Whirlwind's claimed time of 1/8 sec (.125) , so
2300 x .125 = 287.5 teeth on your finger tip:swoon::swoon::swoon:
:saw::gar-BiThat sounds like a lot more potential damage.
Actually just the fact that Whirlwind take 25 times longer than SawStop raises a big question:help::help:.
Ok, I wrote the above with tongue in cheek, but now looking at those numbers :eusa_thin:eusa_thin:eusa_thin:nah::nah::thumbs_do:thumbs_do
Somebody check my numbers, please??
That was probably the noise mentioned, because I believe it was being used on a Unisaw in that video.
I believe during initial prototyping and testing Gass discovered that the sensing and stopping the blade worked well, but were still not as fast as wanted or needed, so he decided to add the drop away mechanism. From what I've read, that was the biggest design hurdle to overcome.
I think there may be other ways to achieve the same end result, but doubt it could be done as a retrofit. Those big induction motors have armatures with a lot more mass and therefore inertia than the blade. That makes it a tough nut to crack. If I had the money, time and interest, here is the direction I would go:
- Design an arbor system that fixes the blade to the flange and keeps it from slipping via pins/studs and alignment holes in the blade. This would require special blades or blades sent in to have holes laser cut, until the blade manufacturers got on board and made them available. If the system was successful they could add the holes to all blades to reduce duplication.
- Arbor directly connected to a separate, heavy-duty brake using a heavy duty disc and caliper or possibly a toothed disc and pawl system.
- Sensing system comparable to the Sawstop.
- Motor clutch
How about this for a retro-fit. A simpler and totally different approach-
- A moving curved blade shroud that mounts below the table. The leading edge and sides would actually be part of a zero clearance insert.
- It would be mounted separately but have a link to the arbor so the height would vary with the height of the blade
- When activated a gas spring cylinder would cause it to pop or pivot up to the current blade height, pushing the operators fingers/hand out of danger.
Anyone got a few $M in venture capital to lend me? :dontknow:
I think the idea behind the Whirlwind is to start the process when your flesh is in the danger zone before it has a chance to contact the blade. I've seen a Sawstop fire its stop mechanism. It's fast and scared the you know what out of me (and I knew it was getting ready to happen). Whatever the math says, the Sawstop results don't lie. Zero amputations.
Your numbers are correct, but don't accurately map to the problem. The more important number is the feed rate of your hand. The blade can spin at 1k RPM or 100k RPM and not make much of a difference if your hand only moves 1/4" in to the blade. Only the first few blades will actually cut you and the rest will move (mostly) through the already made gap. The faster sooner the blade stops spinning, the less distance you can feed your hand in to it.
It would be a nice safety feature to have a motor brake with the capacitance blade sensor. Having the blade stop in ~1/8th of second wouldn't prevent a wound like the SS, but it should significantly reduce the severity of it. This is something that could be cheaply retrofitted to every saw on the market. I would imagine that every woodworker would gladly pay another $100-200 for a lot more safety, even though many can't afford/justify the additional $1500 for a SS.
From the Inventor in an email to me:
My original design goal was to develop a user-controlled and multi-tiered hazard-avoidance system approach with a suitable balance of end-user cost vs. safety features benefit for the various table saw stakeholders ranging from the machinery manufacturers and retailers to the wide spectrum of table saw operators from the novice to the most advanced users. I hope also to curtail some of the table saw litigation that we see by establishing identifiable responsibility for most table saw related injuries, which I believe is to the benefit of all. To that end I now have five operational prototypes with additional models under development.
This particular table saw hazard avoidance concept is designed to offer hazard protection through a series of FIVE simple steps:
First, the operator must easily and conveniently make personal safety-related decisions prior to operation of the saw, by first choosing to use or to override the hazard avoidance system with the use of a keyed switch.
Second, if the saw is operated in safe-mode, the operator must quickly and simply acknowledge that safety checks have been completed before each and every start of the machine.
Third, through electronic flesh-sensing, an extra margin of safety is provided the saw operator by non-destructive blade braking if the operator’s hands enter the “danger zone” which should always be avoided.
Fourth, each emergency braking event serves as a learning experience and a warning to novice saw operators that they have crossed into dangerous proximity of the saw blade and must rethink their operating practices to insure their personal safety.
Fifth, if the blade-enclosure hazard avoidance system is used, the dangerous, long-feared, and unpredictable table saw “kick-back” phenomenon is virtually eliminated.
Each time the saw is stopped, either through a normal stop or a flesh sensing emergency stop, the saw will revert to the amber light safe condition. The emergency flesh sensing stop is completely non-destructive. Neither the blade, nor the circuitry, nor the saw are damaged during the stop and the operator may simply correct the dangerous condition, rearm the flesh sensing brake circuit and resume sawing.
Think safety twice, cut once.
Regards,
David
My original design goal was to develop a user-controlled and multi-tiered hazard-avoidance system approach with a suitable balance of end-user cost vs. safety features benefit for the various table saw stakeholders ranging from the machinery manufacturers and retailers to the wide spectrum of table saw operators from the novice to the most advanced users. I hope also to curtail some of the table saw litigation that we see by establishing identifiable responsibility for most table saw related injuries, which I believe is to the benefit of all. To that end I now have five operational prototypes with additional models under development.
This particular table saw hazard avoidance concept is designed to offer hazard protection through a series of FIVE simple steps:
First, the operator must easily and conveniently make personal safety-related decisions prior to operation of the saw, by first choosing to use or to override the hazard avoidance system with the use of a keyed switch.
Second, if the saw is operated in safe-mode, the operator must quickly and simply acknowledge that safety checks have been completed before each and every start of the machine.
Third, through electronic flesh-sensing, an extra margin of safety is provided the saw operator by non-destructive blade braking if the operator’s hands enter the “danger zone” which should always be avoided.
Fourth, each emergency braking event serves as a learning experience and a warning to novice saw operators that they have crossed into dangerous proximity of the saw blade and must rethink their operating practices to insure their personal safety.
Fifth, if the blade-enclosure hazard avoidance system is used, the dangerous, long-feared, and unpredictable table saw “kick-back” phenomenon is virtually eliminated.
Each time the saw is stopped, either through a normal stop or a flesh sensing emergency stop, the saw will revert to the amber light safe condition. The emergency flesh sensing stop is completely non-destructive. Neither the blade, nor the circuitry, nor the saw are damaged during the stop and the operator may simply correct the dangerous condition, rearm the flesh sensing brake circuit and resume sawing.
Think safety twice, cut once.
Regards,
David
From studying the videos (admittedly low res and designed not to show too much proprietary tech) it looks to me like there is a copper stip on the bottom of the blade enclosure. Differentiating between even wet wood and flesh should actually be fairly easy - I believe that like the SawStop he is using capacitance, and salt water (which is most of what we are) has very different electrical properties than even the wettest fresh cut timber.
If you paid close attention to the hot dog test, there is not even the nick that you get from the SawStop. This because he has accommodated the slower stopping mechanism by doing the flesh sensing on the blade guard, not on the blade itself. So, he only has to stop the blade before your hand can get from the sensor to the blade. The wood you are pushing into the blade is actually helping:
I assume that he is cutting power to the motor, so the bladed is then free wheeling. Then as you push the wood into the blade it is slowed by friction as each tooth's attempt to cut the wood steels a little bit more angular velocity from the blade. Try this experiment for yourself - Turn your saw, let it spin up to full speed and then cut the power. Immediately start pushing a block of wood into the blade with your miter gauge or sled, and look at how far you get before the blade stops. Then look at the size of his blade guard.
Now we have to assume that he is also applying some sort of braking force to the blade itself - I have not yet decided what I think he is doing but based on the "sound of a 22 shot" that he mentions in his videos, I'm wondering if it isn't some sort of solenoid driven clamp (caliper) on the blade (but how does he avoid blade damage?) or on a modified arbor (in which case how close are the tolerances on his replacement modified arbors?).
All in all, this looks like a good prototype and I would certainly shell out some money for one.
8
8-Ball
vvvvvvvvv
It is an interesting design...I wish him luck.
If I was willing to put up with the PITA blade guard that came with my saw, then I would have no concerns with my fingers getting into the danger zone...and hence have no need for this product. Since I'm not willing to put up with the blade guard in the way, even if I had that product, it would be off the saw most of the time. Just my opinion.
I've been doing a comprehensive TS safety improvement effort in my shop, including buying a Gripper and building a decent outfeed table. I've had a few close calls that were the result of not having good outfeed support. If I had stayed with my Delta CS, I would have been seriously looking at the BORK riving knife add-on. A riving knife would have prevented every one of the kickback incidents I've had. And unlike the above product, I'd use it, since it doesn't get in the way or slow me down.
Chris
If I was willing to put up with the PITA blade guard that came with my saw, then I would have no concerns with my fingers getting into the danger zone...and hence have no need for this product. Since I'm not willing to put up with the blade guard in the way, even if I had that product, it would be off the saw most of the time. Just my opinion.
I've been doing a comprehensive TS safety improvement effort in my shop, including buying a Gripper and building a decent outfeed table. I've had a few close calls that were the result of not having good outfeed support. If I had stayed with my Delta CS, I would have been seriously looking at the BORK riving knife add-on. A riving knife would have prevented every one of the kickback incidents I've had. And unlike the above product, I'd use it, since it doesn't get in the way or slow me down.
Chris
I have never "experienced an accident" on the tablesaw. I have had two kickbacks, and two finger cuts, one requiring stitches. They were not "accidents" however, but were, as we used to say in the Navy, "Delta Sierra's. No amount of safety devices will protect you if you are not careful or don't follow safety precautions, or don't used them. In each instance I "knew" the dangers involved- like the little kid whose mother says "don't touch the pot, it is hot," but does it anyway!
With the sensor turned off a Sawstop will dissect a hot dog quite nicely and with the guard removed and Whirlwind will do the same!
I wonder how much he has spent on developing and marketing his design?
With the sensor turned off a Sawstop will dissect a hot dog quite nicely and with the guard removed and Whirlwind will do the same!
I wonder how much he has spent on developing and marketing his design?
I must be mis-interpreting what you've said...because this seems like a silly thing to say. I can come up with dozens of examples of safety devices do exactly that - protect you when you are not careful (enough). Would you care to clarify this?
The only way to make a TS safe for a person who goes out of their way to hurt themselves is to lock them out of the workshop, but they could always smash a rock against their head.
I'm sure it's possible to forget to check the bypass on a SawStop before using it, but that would be deemed an accident. If it's knownly disabled when it doesn't need to be, then that is being negligent. That's how I think many would view any willful disregard for safety. There are people who cannot afford the money to buy jigs/tools to make their tasks safer, but I don't think that is what is being discussed.
That's why hot dog mode needs the key. They want to make it difficult (at least in the non-home shop environment).
The window is closing on tech like this and SawStop, IMO. I got one word for you - Kinect. No, the current one isn't good enough, but it will get there. There are already "dead keyboard" prototypes, where the user types on a keyboard that isn't connected or transmitting and by "watching" a computer can tell what you type. That requires accurate and fast tracking of where all your digits are. Industry will probably see it before hobbyists. Where Kinect plays into this is that having something mass marketed that uses the technology is bringing the parts cost down out of the stratosphere.
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