Page 3 of 4 FirstFirst 1234 LastLast
Results 31 to 45 of 52

Thread: Something I don't understand about the Sawstop design

  1. #31
    Join Date
    Dec 2006
    Location
    Webster Groves, MO
    Posts
    655
    Blog Entries
    10
    Wow Larry. I am so glad to see you are okay.

    This is exactly why I want a Sawstop. I consider myself a very safe woodworker, but there are some events that I just cannot control. For instance, one of my biggest fears is ripping a piece of wood and suddenly coughing or sneezing unexpectantly, causing my hand to move right into the blade.

  2. #32
    Quote Originally Posted by Rob Lee View Post
    Hi -

    Well, I think safety sells...

    We got rid of every table saw we had (15-20?) and replaced them all with Sawstop saws... it's the only reasonable choice for a business, other than buying a panel saw...

    Why? It takes the operator right out of the equation.

    From a liabilty standpoint - there is a "duty to use" argument which is somewhat compelling, even if you don't agree with the cost....

    Cheers -

    Rob
    In this same vein, the local Austin Hardwood store will cut lumber to rough size for you. They used to have a radial arm saw but a few years ago put in a saw where the wood is placed in position, a clamp/guard is in place over the cut, and the blade comes upward to make the cut (it's a fairly large blade, maybe 12-14" so it can cut wide lumber). The operator's hands are not touching the wood when the cut is made and the blade is never exposed.

    It's much safer than a radial arm saw so I can see why they installed it.

    The situation is similar to what Rob pointed out. If a much safer tool is available, it's tough for a company to justify using the older technology.

    Mike

    [I don't remember what those kind of saws are called. I've seen them advertised but just don't remember the name. They weren't all that expensive for commercial, production type equipment. Anybody know what they're called?]
    Go into the world and do well. But more importantly, go into the world and do good.

  3. #33
    Jump saws


    (asdfasdfasdfa)

  4. #34
    Join Date
    Sep 2007
    Location
    Western NY
    Posts
    225
    Quote Originally Posted by Brian D Anderson View Post
    ..........
    So they came up with a design that not only stopped the blade faster than the Saw Stop, it also didn't destroy the blade either. He said their recharge "kit" was going to be fairly cheap, like a $20 CO2 type of cartridge. ............
    There's usually quite a bit of time and money between a prototype and robust, close-to-foolproof day-in-and-day-out production unit that will withstand years of abuse, vibration, dust, etc. So that $20 cost would translate to something quite a bit more, I suspect, by the time it made it into a vendor's saw.

  5. #35
    Quote Originally Posted by Ken Fitzgerald View Post
    Folks,

    I don't own a SS and will never buy one. I don't have a dog in this fight.


    That being said,

    I don't think the sale of a $65 block of aluminum is the reason.

    I suspect that neither the brake block engagement or the retraction of the retraction of the blade will do it fast enough to produce the desire results or.................

    Say one fails....say the blade block fails to fire.....yup...if the blade drops...you have a backup system.....and visa versa.

    Either way.......I don't think the $65 aluminum block has anything to do with it.
    I'm with Ken on this one. I don't have a SS, won't have one unless someone decides to give me a really nice gift and I think that selling a $65 chunk of aluminum is among the least of the manufacturer's concerns.
    Stephen Edwards
    Hilham, TN 38568

    "Build for the joy of it!"

  6. #36
    Join Date
    Jun 2007
    Location
    Clinton Township, MI, United States
    Posts
    1,551
    Once upon a time, I attended a convention where they tracked the cost of a $100 dollar list price back to the initial cost. At no step on the way was anyone gouging or inflating the price - and the initial cost was about $13 dollars!
    It was an eye opener.
    We all want to get paid for our labor and investments, so your $20 dollar CO2 cartridge would be about $125 to be added to the list price.

    Of course, try and buy a mid range saw today, the 300-500 dollar field only has jobsite saws, the basic table saws are gone.

    Mike
    From the workshop under the staircase, Clinton Township, MI
    Semper Audere!

  7. #37
    Join Date
    Mar 2009
    Location
    Ogden, UT
    Posts
    947
    Quote Originally Posted by Greg Pavlov View Post
    There's usually quite a bit of time and money between a prototype and robust, close-to-foolproof day-in-and-day-out production unit that will withstand years of abuse, vibration, dust, etc. So that $20 cost would translate to something quite a bit more, I suspect, by the time it made it into a vendor's saw.
    Additionally why sell the replacement for $20 when you can get $50 and still be cheaper than sawstop.

  8. #38
    Join Date
    Dec 2005
    Location
    London, Ont., Canada
    Posts
    2,200
    Quote Originally Posted by larry cronkite View Post
    The timing of this post couldn't be better. ...
    The only injury that I sustained was a slight groove (that didn't even bleed) on the end of my left forefinger and a nick on my fingernail that can be repaired with a nail file.
    Glad you're okay Larry! (probably not as glad as you are, but I expect that... )

    I do find your photos to be too small, though. Any chance you can post larger photos?
    "It's Not About You."

  9. 1. IF you are worried enough about cutting yourself, there is only one option right now. I certainly have come close before so I understand. I am probably not going to buy a SS unless my wife finds out they exist

    2. They came up with a simple straight forward easy to implement, easy to replace system that functions very well. It's easy to monday morning quarterback someone else' design.

    3. A spinning blade and motor contain a significant amount of kinetic energy that must be dissipated in milliseconds to keep someone from getting cut. They Needed the blade/ arbor to move to help absorb the force generated that would otherwise make the table jump or break something else. Besides, doesn't hurt to get the blade out of the way. There may be a little kickback in the blade which could still do damage.

    4. Who cares about an 80 dollar blade when their fingers are on the floor? Any idea what it costs for the repair? I've repaired way too many table saw/ hand injuries. Done my share of replants and amputations. While the insurance company may put a price on your fingers/ hand, I bet you can't, they're priceless.

    5. Life has risk, deal with it. Personally, I am appalled by the lawsuit, but not surprised, it's the way we have developed our current society. Sad.

    Off the soapbox now..

  10. #40

    Energy Absorbtion

    I am certainly no expert on how this mechanism works. Wouldn't it make some sense that the blade going under the table also be a form of energy absorbtion? When you think about all that energy being directed into the cartridge, wouldn't it stress the arbor and the motor and the mounts etc. This perhaps aleviated the whole slamming stress by using it to lower the whole works rather than just slam it into the saw. If you all get what I am saying?

    Chris
    "I have worked myself up from nothing to extreme poverty." Groucho Marx
    http://www.youtube.com/user/TheChrisPineWorkshop

  11. #41
    Join Date
    Feb 2003
    Location
    Washington, NC
    Posts
    2,372
    To achieve the short response time they wanted, they needed both the blade break and the blade drop. If you look at the arc of the blade and the path it follows- the movement of the blade is AWAY from the the leading edge (away from the hot dog). So the response time relies on both actions. A nice bit engineering without the use of explosives.

    Edit: I just found an email exchange I had with Dr. Gass about my bristle, soft-sided, overblade dust shroud (which is safe for use on a SawStop by the way) he said:

    "On the retraction/braking issue - the retraction is a passive byproduct of the braking torque, so unfortunately without the braking action, you don't get any retraction. Although it is in theory possible to just have retraction and get the same protection you'd get with braking, in practice the force required to move the blade away from the user fast enough is huge and it is very difficult to find anything short of an explosive actuator that could apply enough force fast enough."

    I hope he doesn't mind me quoting him.

    As a serious tinkerer and designer, I am convinced however, there is a way to achieve the same or faster response time, WITHOUT destroying the blade, using a combination of drop away and a brake that contacts a companion gear instead of the blade. It will still require a sacrificial brake cartridge and special trunnion.

    There is no new ground-breaking technology, engineering, or electronics in the SawStop. They were just the first to put it all together in this manner and make it work. They took a chance and bet that safety might sell- as far as I can see they won the bet!

    I don't own a Sawstop and unless my retirement income is significantly increased, I probably won't replace my 12 year-old Uni.

    Has anyone filmed a Sawstop "hot dog test" where the dog was moved into the blade very quickly, instead of at a snails pace? What amount of damage was done?
    Last edited by Alan Schaffter; 04-04-2010 at 11:32 PM.

  12. #42
    Join Date
    Apr 2008
    Location
    Edmonton, Canada
    Posts
    2,262
    Quote Originally Posted by Alan Schaffter View Post
    If you read the SawStop literature, website, etc, somewhere (maybe in an email I got from Dr. Gass?) it says to get the short response time they wanted, they needed both the blade break and the blade drop. If you look at the arc of the blade and the path it follows- the movement of the blade is AWAY from the the leading edge (away from the hot dog). So the response time relies on both actions. A nice bit engineering without the use of explosives.

    As a serious tinkerer and designer, I am convinced however, there is a way to achieve the same or faster response time, WITHOUT destroying the blade, using a combination of drop away and a brake that contacts a companion gear instead of the blade. It will still require a sacrificial brake cartridge and special trunnion.

    There is no new ground-breaking technology, engineering, or electronics in the SawStop. They were just the first to put it all together in this manner and make it work. They took a chance and bet that safety might sell- as far as I can see they won the bet!

    I don't own a Sawstop and unless my retirement income is significantly increased, I probably won't replace my 12 year-old Uni.

    Has anyone filmed a Sawstop "hot dog test" where the dog was moved into the blade very quickly, instead of at a snails pace? What amount of damage was done?
    two comments:

    1- The trouble with having a sacrificial "blade" thing so the brake bites into (instead of the real blade) has the problem that the arbor nut will probably come loose and will cause the blade to rotate. Perhaps a secondary brake is needed for that but makes the whole thing more complicated and perhaps slow.

    2- I remember seeing a video in which they slash a hot dog (at a very fast speed) into the running blade. The damage was a more than a nick but was nowhere close to a cut half-way the thickness or something like that.
    Unfortunately, I cannot find the link.

  13. #43

    Funny

    "I have worked myself up from nothing to extreme poverty." Groucho Marx
    http://www.youtube.com/user/TheChrisPineWorkshop

  14. #44
    Join Date
    Feb 2003
    Location
    Washington, NC
    Posts
    2,372
    Quote Originally Posted by mreza Salav View Post
    two comments:

    1- The trouble with having a sacrificial "blade" thing so the brake bites into (instead of the real blade) has the problem that the arbor nut will probably come loose and will cause the blade to rotate. Perhaps a secondary brake is needed for that but makes the whole thing more complicated and perhaps slow.
    In reality the arbor nut would not be an issue since you would likely need to use special blades that have two or more "alignment" holes in the disc to couple it securely to the "sacrificial" blade. You don't want the real blade to continue to rotate, so both "blades" must stop at the same time. The saw manufacturer could offer drilled blades until the major blade manufacturers started selling them.

    The big problem is the amount of inertia generated by the dual "blade" assembly and the force it applies to the brake- an incredible amount of instantaneous 'G' force required to stop that blade cold. Also, the sacrificial blade would need to be smaller in diameter to allow the regular blade to extend above the table. Its "teeth" would need to be hefty enough to handle the stopping force without breaking to avoid replacing it after each activation. The brake cartridge would need to absorb/dissipate increased force and the trunnion would need to be really tough. The drop-away action might need to absorb much more energy, especially if the brake cartridge was designed so it didn't need to absorb/dissipate energy, to save money. In the SawStop, crushing the aluminum brake absorbs a lot of energy.

    Any increased cost to the consumer would be easily offset when you no longer need to replace a $100 blade each time you have an activation and possibly using a less expensive brake cartridge. Only testing (or some serious computer modeling) will tell if this approach is possible.

    I suspect SawStop is already working on SS v2.0
    Last edited by Alan Schaffter; 04-05-2010 at 12:37 AM.

  15. #45
    Join Date
    Apr 2008
    Location
    Edmonton, Canada
    Posts
    2,262
    My comment about arbor nut was with the assumption of using regular blades. But your points are good and make sense too.
    One other thing is that the blade is not necessarily junk after brake activation. Once I had my Freud Fusion blade in an activation. Got it fixed by replacing 3-4 teeth and sharpened all, for a total cost of $34. So typically the blade is salvageable.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •