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#1
Posted to rec.woodworking,rec.crafts.metalworking,alt.home.repair
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Ping Leon: Design Q on SawStop
There seems to be two mechanical strategies at work in the SawStop, of translation, and of rotation, ie, retracting the blade, and stopping the rotation. It seems to me one would be sufficient, with retraction having the advantage of being non-destructive. Not sure if the blade is direct drive or belt drive, but if it was belt drive, the retraction could all the more rapid, since you would not have to retract the mass of a relatively heavy motor. In fact, if designed properly, you could proly have only the blade and its bearing retract, along grooved guides of some sort, allowing for a very rapid acceleration from whatever force is applied -- presumably springs? But could also be pneumatic or hydraulic, or solenoidal. Unless the deceleration of rotation is just an inherently faster process than the retraction process. But, from what I see, it seems the retraction is occurring FIRST, anyway, to initiate the destructive crash, so mebbe the rotational issue is irrelevant?? Now, if rotation is still an issue, wouldn't a caliper/rotor brake type deal be as fast as his collision process, AND be non-destructive? Mebbe multiple calipers. Oh, oh, but then he wouldn't be able to sell new crumple ditties at $70/pop..... Mebbe you could run this by (G)ass, ask him to send me $5 if he likes the idears. Or mebbe just invite me to one of them 'spensive luncheons, where he's twisting CONgress's arms on safety'n'****, you know, for all the li'l children.... -- EA |
#2
Posted to rec.woodworking,rec.crafts.metalworking,alt.home.repair
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Ping Leon: Design Q on SawStop
On Dec 8, 8:36*am, "Existential Angst" wrote:
There seems to be two mechanical strategies at work in the SawStop, of translation, and of rotation, ie, retracting the blade, and stopping the rotation. It seems to me one would be sufficient, with retraction having the advantage of being non-destructive. *Not sure if the blade is direct drive or belt drive, but if it was belt drive, the retraction could all the more rapid, since you would not have to retract the mass of a relatively heavy motor. In fact, if designed properly, you could proly have only the blade and its bearing retract, along grooved guides of some sort, allowing for a very rapid acceleration from whatever force is applied -- presumably springs? But could also be pneumatic or hydraulic, or solenoidal. Unless the deceleration of rotation is just an inherently faster process than the retraction process. But, from what I see, it seems the retraction is occurring FIRST, anyway, to initiate the destructive crash, so mebbe the rotational issue is irrelevant?? In the videos I've seen the blade is fully stopped, while the retraction is only partial, more like the retraction has only started. And I think one problem with relying only on retraction would be that it's not going to be fast enough to get all or enough of the blade out of the way. You could do the math and find the force necessary to move a given mass several inches in 1ms. A side question is why have the retraction at all. I guess if you're flopping a whole arm down on the saw, it would prevent injury from just hitting a stopped blade. Now, if rotation is still an issue, wouldn't a caliper/rotor brake type deal be as fast as his collision process, AND be non-destructive? *Mebbe multiple calipers. It would have to be one hell of a caliper brake to stop that spinning saw in 1ms. With the way it's implemented now, at first contact of the jamb the saw is stopped dead. Oh, oh, but then he wouldn't be able to sell new crumple ditties at $70/pop..... Mebbe you could run this by (G)ass, ask him to send me $5 if he likes the idears. You really think he didn't think of a simple brake, like they have on say lawn mowers, first? *Or mebbe just invite me to one of them 'spensive luncheons, where he's twisting CONgress's arms on safety'n'****, you know, for all the li'l children.... -- EA Or better yet that anyone involved in this is interested in answering your questions, given all the insults and names you've called them? |
#3
Posted to rec.woodworking,rec.crafts.metalworking,alt.home.repair
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Ping Leon: Design Q on SawStop
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#4
Posted to rec.woodworking,rec.crafts.metalworking,alt.home.repair
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Ping Leon: Design Q on SawStop
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#5
Posted to rec.woodworking,rec.crafts.metalworking,alt.home.repair
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Ping Leon: Design Q on SawStop
On Dec 8, 10:35*am, tiredofspam nospam.nospam.com wrote:
On 12/8/2012 9:56 AM, wrote: On Dec 8, 8:36 am, "Existential Angst" wrote: There seems to be two mechanical strategies at work in the SawStop, of translation, and of rotation, ie, retracting the blade, and stopping the rotation. It seems to me one would be sufficient, with retraction having the advantage of being non-destructive. *Not sure if the blade is direct drive or belt drive, but if it was belt drive, the retraction could all the more rapid, since you would not have to retract the mass of a relatively heavy motor. In fact, if designed properly, you could proly have only the blade and its bearing retract, along grooved guides of some sort, allowing for a very rapid acceleration from whatever force is applied -- presumably springs? But could also be pneumatic or hydraulic, or solenoidal. Unless the deceleration of rotation is just an inherently faster process than the retraction process. But, from what I see, it seems the retraction is occurring FIRST, anyway, to initiate the destructive crash, so mebbe the rotational issue is irrelevant?? In the videos I've seen the blade is fully stopped, while the retraction is only partial, more like the retraction has only started. *And I think one problem with relying only on retraction would be that it's not going to be fast enough to get all or enough of the blade out of the way. You could do the math and find the force necessary to move a given mass several inches in 1ms. A side question is why have the retraction at all. I guess if you're flopping a whole arm down on the saw, it would prevent injury from just hitting a stopped blade. Now, if rotation is still an issue, wouldn't a caliper/rotor brake type deal be as fast as his collision process, AND be non-destructive? *Mebbe multiple calipers. It would have to be one hell of a caliper brake to stop that spinning saw in 1ms. *With the way it's implemented now, at first contact of the jamb the saw is stopped dead. Oh, oh, but then he wouldn't be able to sell new crumple ditties at $70/pop..... Mebbe you could run this by (G)ass, ask him to send me $5 if he likes the idears. You really think he didn't think of a simple brake, like they have on say lawn mowers, first? * *Or mebbe just invite me to one of them 'spensive luncheons, where he's twisting CONgress's arms on safety'n'****, you know, for all the li'l children.... -- EA Or better yet that anyone involved in this is interested in answering your questions, given all the insults and names you've called them? Maybe if you two watched the video you'd understand. I did watch the video. Nothing in the video shows exactly how the blade retracts, what it's attached to beneath the saw, etc. And there isn't just one video, so how would you know what videos anyone did or did not see. The blade is stopped, and that is actually part of the retraction mechanism. The inertia is dissipated by retracting. The retracting saves the finger as well since it is pulling away from the finger. OK, using the momentum of the saw to retract the blade makes sense. Is that all that causes the retraction or is there something else, eg spring involved? The design as it stands is very good, your ideas are not. BTW this is a top notch saw, so no it is not direct drive. The workmanship on all of these saws exceeds what we now currently have from the standard non-euro options.- Hide quoted text - - Show quoted text - I think you're confused. You replied to my post. I did not propose changing the SawStop. I'm fine with it. It was EA that was proposing the new ideas and simply pointed out some of the obvious issues. |
#6
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Ping Leon: Design Q on SawStop
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#8
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Ping Leon: Design Q on SawStop
Alls I know is, having cut my finger nearly in half (still got it,
though) is that I'll be buying a Sawstop saw as soon as I get a 240V circuit added to my garage. The electrical guy comes next Tuesday. |
#9
Posted to rec.woodworking,rec.crafts.metalworking,alt.home.repair
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Ping Leon: Design Q on SawStop
"tiredofspam" nospam.nospam.com wrote in message ... On 12/8/2012 9:56 AM, wrote: On Dec 8, 8:36 am, "Existential Angst" wrote: There seems to be two mechanical strategies at work in the SawStop, of translation, and of rotation, ie, retracting the blade, and stopping the rotation. It seems to me one would be sufficient, with retraction having the advantage of being non-destructive. Not sure if the blade is direct drive or belt drive, but if it was belt drive, the retraction could all the more rapid, since you would not have to retract the mass of a relatively heavy motor. In fact, if designed properly, you could proly have only the blade and its bearing retract, along grooved guides of some sort, allowing for a very rapid acceleration from whatever force is applied -- presumably springs? But could also be pneumatic or hydraulic, or solenoidal. Unless the deceleration of rotation is just an inherently faster process than the retraction process. But, from what I see, it seems the retraction is occurring FIRST, anyway, to initiate the destructive crash, so mebbe the rotational issue is irrelevant?? In the videos I've seen the blade is fully stopped, while the retraction is only partial, more like the retraction has only started. And I think one problem with relying only on retraction would be that it's not going to be fast enough to get all or enough of the blade out of the way. You could do the math and find the force necessary to move a given mass several inches in 1ms. A side question is why have the retraction at all. I guess if you're flopping a whole arm down on the saw, it would prevent injury from just hitting a stopped blade. Now, if rotation is still an issue, wouldn't a caliper/rotor brake type deal be as fast as his collision process, AND be non-destructive? Mebbe multiple calipers. It would have to be one hell of a caliper brake to stop that spinning saw in 1ms. With the way it's implemented now, at first contact of the jamb the saw is stopped dead. Oh, oh, but then he wouldn't be able to sell new crumple ditties at $70/pop..... Mebbe you could run this by (G)ass, ask him to send me $5 if he likes the idears. You really think he didn't think of a simple brake, like they have on say lawn mowers, first? Or mebbe just invite me to one of them 'spensive luncheons, where he's twisting CONgress's arms on safety'n'****, you know, for all the li'l children.... -- EA Or better yet that anyone involved in this is interested in answering your questions, given all the insults and names you've called them? Maybe if you two watched the video you'd understand. The blade is stopped, and that is actually part of the retraction mechanism. The inertia is dissipated by retracting. The retracting saves the finger as well since it is pulling away from the finger. I've seen the actual patent, IIRC... I can't remember the details about the sensing mechanism...but... A block of aluminum acts as a brake, effectively stopping the blade dead in it's tracks by more or less directly engaging six teeth or more all at the same time (depending on blade pitch) which equates to maybe 10 degrees of rotation... --if you do the math, what you'll find is that you'd have to be moving your finger into the blade at speeds that are simply not humanly possible in order to do anything more than to draw a very slight amount of blood. Kind of like the bullet that you never heard... The design as it stands is very good, your ideas are not. BTW this is a top notch saw, so no it is not direct drive. The workmanship on all of these saws exceeds what we now currently have from the standard non-euro options. |
#11
Posted to rec.woodworking
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Ping Leon: Design Q on SawStop
On Sun, 9 Dec 2012 00:03:49 -0800, "Lew Hodgett"
wrote: So, what now? Total senility in operation? |
#12
Posted to rec.woodworking
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Ping Leon: Design Q on SawStop
yep, last 5 empty.
On 12/9/2012 3:03 AM, Lew Hodgett wrote: |
#13
Posted to rec.woodworking,rec.crafts.metalworking,alt.home.repair
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Ping Leon: Design Q on SawStop
wrote in message
... On Dec 8, 8:36 am, "Existential Angst" wrote: There seems to be two mechanical strategies at work in the SawStop, of translation, and of rotation, ie, retracting the blade, and stopping the rotation. It seems to me one would be sufficient, with retraction having the advantage of being non-destructive. Not sure if the blade is direct drive or belt drive, but if it was belt drive, the retraction could all the more rapid, since you would not have to retract the mass of a relatively heavy motor. In fact, if designed properly, you could proly have only the blade and its bearing retract, along grooved guides of some sort, allowing for a very rapid acceleration from whatever force is applied -- presumably springs? But could also be pneumatic or hydraulic, or solenoidal. Unless the deceleration of rotation is just an inherently faster process than the retraction process. But, from what I see, it seems the retraction is occurring FIRST, anyway, to initiate the destructive crash, so mebbe the rotational issue is irrelevant?? In the videos I've seen the blade is fully stopped, while the retraction is only partial, more like the retraction has only started. ======================================== http://www.youtube.com/watch?v=eiYoB...endscreen&NR=1 1:45 the retraction looks pretty complete to me. BUT, at 2:50, which shows the whole process, it appears that the retraction occurs AFTER the collision thingy engages. Yet, at 1:45, the retraction seem instantaneous, upon touching the hot dog.... Go figger. And I think one problem with relying only on retraction would be that it's not going to be fast enough to get all or enough of the blade out of the way. You could do the math and find the force necessary to move a given mass several inches in 1ms. ================================================= 10,000 newtons per cm of retraction for a 1 kg (2.2#) mass, or about 4x the weight of a 200# guy. If 1/2 cm was suff, and the unit to be accelerated was only 1/2 kg, then it would only be 200# of force, a lot more manageable. 800# is actually not a cosmically large force, given that some people can lift 800#, but it's perhaps a bit to apply in a very small area. And mebbe too expensive to implement. A side question is why have the retraction at all. I guess if you're flopping a whole arm down on the saw, it would prevent injury from just hitting a stopped blade. ================================================== I suspect the retraction is not for retraction's sake but as a kind of force reaction to the stopped blade, preventing more damage than is already occurring. Now, if rotation is still an issue, wouldn't a caliper/rotor brake type deal be as fast as his collision process, AND be non-destructive? Mebbe multiple calipers. It would have to be one hell of a caliper brake to stop that spinning saw in 1ms. With the way it's implemented now, at first contact of the jamb the saw is stopped dead. ================================================== === Here's a way to do it: If a quick retraction occurs over a relatively small distance, AND a caliper-applied deceleration then occured (non-destructive), you'd have a more time to stop the blade rotation, ie less demanding braking, no trashed blade. To wit: Suppose the retraction was about 1/2" (roughly 1 cm). Wood is fed into a saw somewhere around .25-1 ft/sec, wo we'll use 12"/sec. Now, upon the 1/2" retraction, the hand won't contact the blade for another 50 milliseconds, giving the blade 50x longer to stop, before the hand has another chance to contact the blade -- a whole lot easier to accomplish than a 1 millisecond stop. I suspect the most feasible way to accomplish this kind of retraction is with bigazz spring (proly two, on either side of the blade, moving two bearings), triggered much the way the spring of his jamb-ditty is applied, with the calipers simultaneously engaging. Heh, and these calipers can act as a brake on the saw during normal use, as well, instead of electric motor braking. Lathes often have a frictional stop system, using a drum-like squeeze brake, very handy. Oh, oh, but then he wouldn't be able to sell new crumple ditties at $70/pop..... Mebbe you could run this by (G)ass, ask him to send me $5 if he likes the idears. You really think he didn't think of a simple brake, like they have on say lawn mowers, first? ================================================ Mebbe he dudn't drive, or mow his lawn. Or mebbe just invite me to one of them 'spensive luncheons, where he's twisting CONgress's arms on safety'n'****, you know, for all the li'l children.... -- EA Or better yet that anyone involved in this is interested in answering your questions, given all the insults and names you've called them? =============================================== Like they don't warrant it, right? These corrupt assholes couldn't give a goddamm about you'n'me, but they are surefire quick to up the regulational ante, and then **** the public for the slightest transgression. Municipal penalty pricing, donchaknow. With high enough penalties, they could eliminate taxes, and still remain in the black. -- EA |
#14
Posted to rec.woodworking,rec.crafts.metalworking,alt.home.repair
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Ping Leon: Design Q on SawStop
On Dec 8, 10:55*am, "Existential Angst" wrote:
wrote in message ... On Dec 8, 8:36 am, "Existential Angst" wrote: There seems to be two mechanical strategies at work in the SawStop, of translation, and of rotation, ie, retracting the blade, and stopping the rotation. It seems to me one would be sufficient, with retraction having the advantage of being non-destructive. Not sure if the blade is direct drive or belt drive, but if it was belt drive, the retraction could all the more rapid, since you would not have to retract the mass of a relatively heavy motor. |
#15
Posted to rec.woodworking,rec.crafts.metalworking,alt.home.repair
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Ping Leon: Design Q on SawStop
wrote in message
... On Dec 8, 10:55 am, "Existential Angst" wrote: wrote in message ... On Dec 8, 8:36 am, "Existential Angst" wrote: There seems to be two mechanical strategies at work in the SawStop, of translation, and of rotation, ie, retracting the blade, and stopping the rotation. It seems to me one would be sufficient, with retraction having the advantage of being non-destructive. Not sure if the blade is direct drive or belt drive, but if it was belt drive, the retraction could all the more rapid, since you would not have to retract the mass of a relatively heavy motor. In fact, if designed properly, you could proly have only the blade and its bearing retract, along grooved guides of some sort, allowing for a very rapid acceleration from whatever force is applied -- presumably springs? But could also be pneumatic or hydraulic, or solenoidal. Unless the deceleration of rotation is just an inherently faster process than the retraction process. But, from what I see, it seems the retraction is occurring FIRST, anyway, to initiate the destructive crash, so mebbe the rotational issue is irrelevant?? In the videos I've seen the blade is fully stopped, while the retraction is only partial, more like the retraction has only started. ======================================== http://www.youtube.com/watch?v=eiYoB...endscreen&NR=1 1:45 the retraction looks pretty complete to me. BUT, at 2:50, which shows the whole process, it appears that the retraction occurs AFTER the collision thingy engages. Yet, at 1:45, the retraction seem instantaneous, upon touching the hot dog.... Go figger. Well, one is normal speed video, the other is high-speed photography that is slowed down so you can actually see what is happening. At the 1:45 normal speed spot all you see is the top of the saw and it's impossible to determine any sequence of events. At the 2:50 area it's clear that a substantial amount of the movement is ocurring after the saw blade has stopped spinning. Also, what "tired" just posted makes sense. The saw has momentum that has to go somewhere. One place to dissipate it is to allow the blade to go down in a controlled fashion. It could be that is all they use. If so, the sequence would be that the pawl engages first and as it stops the saw, the momentum then causes the retraction. And I think one problem with relying only on retraction would be that it's not going to be fast enough to get all or enough of the blade out of the way. You could do the math and find the force necessary to move a given mass several inches in 1ms. ================================================= 10,000 newtons per cm of retraction for a 1 kg (2.2#) mass, or about 4x the weight of a 200# guy. If 1/2 cm was suff, and the unit to be accelerated was only 1/2 kg, then it would only be 200# of force, a lot more manageable. 800# is actually not a cosmically large force, given that some people can lift 800#, but it's perhaps a bit to apply in a very small area. And mebbe too expensive to implement. I would expect the mass is more than 2.2 lbs. And not clear how you'd apply such a large force. If you used a spring for example, the mass of the spring also has to be accounted for because you're also accelerating that. ============================================= Depends how you design it. I could see a strong magnesium housing to a belt-driven blade being pretty lite. And actually, a large spring IS the force-provider. Basically you'd have a mouse-trap type situation, where a very small/fast actuator trips the spring, which then applies the accelerating force -- one on each side of the blade could supply wicked fast accelerations. For example, Lee Spring in NYC has dies springs with spring constants of over 2,000 # per inch.... and that's just one spring. So these forces are easily obtainable in very small spaces, more than adequate for even multi-kg blade housings. Heh, resetting the blade, tho, would require crowbar.... LOL But actually, could be done with fine-thread "resetting screw", might take a cupla minutes. A side question is why have the retraction at all. I guess if you're flopping a whole arm down on the saw, it would prevent injury from just hitting a stopped blade. ================================================== I suspect the retraction is not for retraction's sake but as a kind of force reaction to the stopped blade, preventing more damage than is already occurring. From "tired"'s reply it is indeed the saw momentum. But he seems to imply that it also prevents the injury by pulling the blade away. We'd have to see a very high-speed close up of the hot dog video to see the exact sequence and if the saw stopping alone isn't sufficient. Now, if rotation is still an issue, wouldn't a caliper/rotor brake type deal be as fast as his collision process, AND be non-destructive? Mebbe multiple calipers. It would have to be one hell of a caliper brake to stop that spinning saw in 1ms. With the way it's implemented now, at first contact of the jamb the saw is stopped dead. ================================================== === Here's a way to do it: If a quick retraction occurs over a relatively small distance, AND a caliper-applied deceleration then occured (non-destructive), you'd have a more time to stop the blade rotation, ie less demanding braking, no trashed blade. Yes, IF you could retract it quicker than a finger can advance for as long as it takes to stop the saw. To wit: Suppose the retraction was about 1/2" (roughly 1 cm). Wood is fed into a saw somewhere around .25-1 ft/sec, wo we'll use 12"/sec. Now, upon the 1/2" retraction, the hand won't contact the blade for another 50 milliseconds, giving the blade 50x longer to stop, before the hand has another chance to contact the blade -- a whole lot easier to accomplish than a 1 millisecond stop. I suspect the most feasible way to accomplish this kind of retraction is with bigazz spring (proly two, on either side of the blade, moving two bearings), triggered much the way the spring of his jamb-ditty is applied, with the calipers simultaneously engaging. Heh, and these calipers can act as a brake on the saw during normal use, as well, instead of electric motor braking. Lathes often have a frictional stop system, using a drum-like squeeze brake, very handy. Oh, oh, but then he wouldn't be able to sell new crumple ditties at $70/pop..... Mebbe you could run this by (G)ass, ask him to send me $5 if he likes the idears. You really think he didn't think of a simple brake, like they have on say lawn mowers, first? ================================================ Mebbe he dudn't drive, or mow his lawn. Or mebbe just invite me to one of them 'spensive luncheons, where he's twisting CONgress's arms on safety'n'****, you know, for all the li'l children.... -- EA Or better yet that anyone involved in this is interested in answering your questions, given all the insults and names you've called them? =============================================== Like they don't warrant it, right? These corrupt assholes couldn't give a goddamm about you'n'me, but they are surefire quick to up the regulational ante, and then **** the public for the slightest transgression. Municipal penalty pricing, donchaknow. With high enough penalties, they could eliminate taxes, and still remain in the black. -- EA- Hide quoted text - - Show quoted text - I've only looked into the SS itself a bit. I haven't looked into what the inventor is or isn't doing regarding politicians, making it mandatory, etc. ================================================== Well, a few replies in the previous thread addressed this, and some forums have discussed this at length. The almost universal consensus so far is that his tactics/lobbying, altho legal, are manipulative and greed-driven. (G)ass is quite at home with the lobbyists.. All's you gotta do is scream Safety loud enough, or " ....the li'l children...". and BAM, everyfuknthing stops, sense goes out the window, and you can rip off the system to yer heart's content. Ergo, Crawling Helmets. I think that whiney asshole TiredofSpam has color-coordinated crawling helmets, to match his diapers and Superman cape. -- EA |
#16
Posted to rec.woodworking,rec.crafts.metalworking,alt.home.repair
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Ping Leon: Design Q on SawStop
On 12/8/2012 12:06 PM, Existential Angst wrote:
wrote in message ... On Dec 8, 10:55 am, "Existential Angst" wrote: wrote in message ... On Dec 8, 8:36 am, "Existential Angst" wrote: There seems to be two mechanical strategies at work in the SawStop, of translation, and of rotation, ie, retracting the blade, and stopping the rotation. It seems to me one would be sufficient, with retraction having the advantage of being non-destructive. Not sure if the blade is direct drive or belt drive, but if it was belt drive, the retraction could all the more rapid, since you would not have to retract the mass of a relatively heavy motor. In fact, if designed properly, you could proly have only the blade and its bearing retract, along grooved guides of some sort, allowing for a very rapid acceleration from whatever force is applied -- presumably springs? But could also be pneumatic or hydraulic, or solenoidal. Unless the deceleration of rotation is just an inherently faster process than the retraction process. But, from what I see, it seems the retraction is occurring FIRST, anyway, to initiate the destructive crash, so mebbe the rotational issue is irrelevant?? In the videos I've seen the blade is fully stopped, while the retraction is only partial, more like the retraction has only started. ======================================== http://www.youtube.com/watch?v=eiYoB...endscreen&NR=1 1:45 the retraction looks pretty complete to me. BUT, at 2:50, which shows the whole process, it appears that the retraction occurs AFTER the collision thingy engages. Yet, at 1:45, the retraction seem instantaneous, upon touching the hot dog.... Go figger. Well, one is normal speed video, the other is high-speed photography that is slowed down so you can actually see what is happening. At the 1:45 normal speed spot all you see is the top of the saw and it's impossible to determine any sequence of events. At the 2:50 area it's clear that a substantial amount of the movement is ocurring after the saw blade has stopped spinning. Also, what "tired" just posted makes sense. The saw has momentum that has to go somewhere. One place to dissipate it is to allow the blade to go down in a controlled fashion. It could be that is all they use. If so, the sequence would be that the pawl engages first and as it stops the saw, the momentum then causes the retraction. And I think one problem with relying only on retraction would be that it's not going to be fast enough to get all or enough of the blade out of the way. You could do the math and find the force necessary to move a given mass several inches in 1ms. ================================================= 10,000 newtons per cm of retraction for a 1 kg (2.2#) mass, or about 4x the weight of a 200# guy. If 1/2 cm was suff, and the unit to be accelerated was only 1/2 kg, then it would only be 200# of force, a lot more manageable. 800# is actually not a cosmically large force, given that some people can lift 800#, but it's perhaps a bit to apply in a very small area. And mebbe too expensive to implement. I would expect the mass is more than 2.2 lbs. And not clear how you'd apply such a large force. If you used a spring for example, the mass of the spring also has to be accounted for because you're also accelerating that. ============================================= Depends how you design it. I could see a strong magnesium housing to a belt-driven blade being pretty lite. And actually, a large spring IS the force-provider. Basically you'd have a mouse-trap type situation, where a very small/fast actuator trips the spring, which then applies the accelerating force -- one on each side of the blade could supply wicked fast accelerations. For example, Lee Spring in NYC has dies springs with spring constants of over 2,000 # per inch.... and that's just one spring. So these forces are easily obtainable in very small spaces, more than adequate for even multi-kg blade housings. Heh, resetting the blade, tho, would require crowbar.... LOL But actually, could be done with fine-thread "resetting screw", might take a cupla minutes. A side question is why have the retraction at all. I guess if you're flopping a whole arm down on the saw, it would prevent injury from just hitting a stopped blade. ================================================== I suspect the retraction is not for retraction's sake but as a kind of force reaction to the stopped blade, preventing more damage than is already occurring. From "tired"'s reply it is indeed the saw momentum. But he seems to imply that it also prevents the injury by pulling the blade away. We'd have to see a very high-speed close up of the hot dog video to see the exact sequence and if the saw stopping alone isn't sufficient. Now, if rotation is still an issue, wouldn't a caliper/rotor brake type deal be as fast as his collision process, AND be non-destructive? Mebbe multiple calipers. It would have to be one hell of a caliper brake to stop that spinning saw in 1ms. With the way it's implemented now, at first contact of the jamb the saw is stopped dead. ================================================== === Here's a way to do it: If a quick retraction occurs over a relatively small distance, AND a caliper-applied deceleration then occured (non-destructive), you'd have a more time to stop the blade rotation, ie less demanding braking, no trashed blade. Yes, IF you could retract it quicker than a finger can advance for as long as it takes to stop the saw. To wit: Suppose the retraction was about 1/2" (roughly 1 cm). Wood is fed into a saw somewhere around .25-1 ft/sec, wo we'll use 12"/sec. Now, upon the 1/2" retraction, the hand won't contact the blade for another 50 milliseconds, giving the blade 50x longer to stop, before the hand has another chance to contact the blade -- a whole lot easier to accomplish than a 1 millisecond stop. I suspect the most feasible way to accomplish this kind of retraction is with bigazz spring (proly two, on either side of the blade, moving two bearings), triggered much the way the spring of his jamb-ditty is applied, with the calipers simultaneously engaging. Heh, and these calipers can act as a brake on the saw during normal use, as well, instead of electric motor braking. Lathes often have a frictional stop system, using a drum-like squeeze brake, very handy. Oh, oh, but then he wouldn't be able to sell new crumple ditties at $70/pop..... Mebbe you could run this by (G)ass, ask him to send me $5 if he likes the idears. You really think he didn't think of a simple brake, like they have on say lawn mowers, first? ================================================ Mebbe he dudn't drive, or mow his lawn. Or mebbe just invite me to one of them 'spensive luncheons, where he's twisting CONgress's arms on safety'n'****, you know, for all the li'l children.... -- EA Or better yet that anyone involved in this is interested in answering your questions, given all the insults and names you've called them? =============================================== Like they don't warrant it, right? These corrupt assholes couldn't give a goddamm about you'n'me, but they are surefire quick to up the regulational ante, and then **** the public for the slightest transgression. Municipal penalty pricing, donchaknow. With high enough penalties, they could eliminate taxes, and still remain in the black. -- EA- Hide quoted text - - Show quoted text - I've only looked into the SS itself a bit. I haven't looked into what the inventor is or isn't doing regarding politicians, making it mandatory, etc. ================================================== Well, a few replies in the previous thread addressed this, and some forums have discussed this at length. The almost universal consensus so far is that his tactics/lobbying, altho legal, are manipulative and greed-driven. (G)ass is quite at home with the lobbyists.. All's you gotta do is scream Safety loud enough, or " ....the li'l children...". and BAM, everyfuknthing stops, sense goes out the window, and you can rip off the system to yer heart's content. Ergo, Crawling Helmets. I think that whiney asshole TiredofSpam has color-coordinated crawling helmets, to match his diapers and Superman cape. Why don't you go back to the little hole you crawled out of. We really don't need low lifes like you lurking around here. pretty much the only thing coming out of you is some foul ****, and lots of it. If you ever had something useful to offer I haven't seen it. And as for whiney you sack of ****.... all you do is complain... so take a look in the mirror you penis membrane. |
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