If it saves your thumb, sure. If you're ripping a wet piece of wood, no thumb risk at all, then, yeah, not so great.

Realistically, I don't like the tech or the methodology at all. Battle bots had saws that would drop into the floor without damage, and pop back up even, also without damage, and that was decades ago. That's the right model, not "fuck up the saw".

>Battle bots had saws that would drop into the floor without damage, and pop back up even, also without damage, and that was decades ago. That's the right model, not "fuck up the saw".

Might be wrong, but my own amateur reasoning has me believe that a table saw has far more kinetic energy than a battery powered battle bot, and that the SawStop must likely move the saw in microseconds, vs a battle bot which may comparatively have all the time in the world.

No, I mean they had table saw rigs that would bring the saw up/down into the floor with an actuator as a 'ring hazard', ie, your robot could be subject to sawing at any moment if they happened to be there.

The question is, how fast does it need to be? Likely not that fast really, certainly not microseconds, and an actuator could easily yank the saw down without damaging it if it detected you were about to lose a finger.

There's also no reason you couldn't use the same actuator to do fancy things, like vary cut depth on the fly, or precisely set the cut depth in the first place. Can't do any of that with a soft aluminum pad that gets yeeted into the sawblade when it detects a problem.

Basically, SawStop exists to sell saws. Those saws happen to be safer, but that's a marketing point, it's not what ultimately makes them money. Look at the incentives, you'll find the truth.

>The question is, how fast does it need to be?

I don't know - the marketing material actually says 5 milliseconds. That's the crux of the problem and I don't believe you can actually move the saw fast enough to not cause serious damage to the human without damaging the saw. The problem, as I understand it, is stopping the saw. The saw actuator only makes sense if it moves fast enough and given the saw stop works on detection, I'm not convinced you have that much time.

I'm considering the physical reality here - if the saw must be yanked down quickly, how much force must be applied to the saw to move it, and then can that equal and opposite force be applied to stop it without damaging the saw?

>Look at the incentives, you'll find the truth.

This is true of any safety device? The SawStop inventor created his company after trying to license it and eventually won in the marketplace after nearly 30 years. Surely his competitors would have released an actuator based solution if it is was possible rather than ceding marketshare of high end saws?

Bosch did release an actuator-based solution. They got sued by SawStop for patent violations and lost and pulled it from the market. SawStop's main patent just covers the concept of a blade brake, not a specific implementation.

The actual contention isn't whether an actuator-based solution would work, its if an actuator-based solution could stop the saw without damaging it (and therefore not give credence to the claim that SawStop is intentionally designing a poor solution in order to sell more blades).

As far as I can tell, REAXX also damages the blade.

REAXX retracts the blade inside the table and lets it coast to a stop. It does not damage the blade.

>and therefore not give credence to the claim that SawStop is intentionally designing a poor solution in order to sell more blades

This is the most asinine argument I’ve heard yet, and I am not a fan of this regulation.

Blades are typically cheap and the ones that aren’t are often repairable after an activation. Also, Sawstop barely sells any blades - I don’t know a single woodworker or cabinet shop that runs their blades.

I think the speed that things can go wrong when using a table saw (or most power tools) is faster than some people, including some woodworkers, might expect. There's a good example video here (warning, shows a very minor injury):

https://www.reddit.com/r/Carpentry/comments/11s6zlr/cutting_...

While we're still not talking microseconds, I think it highlights that moving the blade out of the way needs to happen very quickly in some cases to avoid serious injury.

Sounds like you're perfectly positioned to start a SawStop competitor!

"Protect your equipment AND your fingers."

With the government potentially mandating these types of devices, you could be makin' the big bucks!

These incentives are clear, where's the truth?

(This is only somewhat facetious. I'm skeptical of your claims, but not enough to discount them out-of-hand. The industry honestly does seem ripe for disruption.)

> The question is, how fast does it need to be?

According to my calculations, on a 10in/ 30tpi blade you have a teeth passing every 8.3uS.

I think the other key variable is how fast is your finger being advanced towards the saw blade and how much total depth of contact are you willing to accept and claim a victory. In an aggressive ripping the material you're holding towards the blade that might be 10 mph (~15 feet per second), if you're willing to tolerate a 1/16" depth of injury, you have about a half a millisecond.

If the rate of advancement is much slower (like a normal pace of feeding the stock into the saw accident), you have several milliseconds before reaching a 1/16" depth of injury from first contact to last contact.

Bosch used to have a system called Reaxx that could pull the saw out of the way without damaging it.

Sawblades are consumables and cheap enough (some are ~10-12 bucks) that it's probably a worthwhile cost.

An entry-level Dado blade can run about $100. The $10-12 sawblades can't make finish cuts that are worth a damn, because they chew through the work and tear splinters out rather than making precise nips at the front and back of each grain of the wood. For a saw blade an entry level blade that doesn't do this to your work can run you more like $60.

I know this because I've had to buy a table saw blade to replace a $10-12 one on my wife's table saw that someone threw on there because they were doing framing work.

I'm sorry, but this is a bizarre take to me. I don't care what happens to a saw if it would have otherwise cut my finger off.

SawStop works by detecting electrical conductance, and there are many reports of it misfiring when attempting to cut wood that isn't fully dry (i.e., there is moisture inside the wood, increasing its electrical conductance).

I'm aware. I'm not buying that a new saw blade and a replaced brake is too much of a cost over the peace of mind that you're at a significantly reduced chance of losing a finger.

And they're pointing out it's not just those two replaceable components - it's the _entire saw_ that they're risking destroying off a false positive that some woodworkers will hit frequently.

That just means the tech is not ideal, not that I want table saws without it.

They are suggesting the blade retracted, broke the saw, in a situation in which there was no risk to the finger. Maybe there was a literally hotdog in the wood.

> If you're ripping a wet piece of wood, no thumb risk at all

How many expensive false alarms are you willing to accept, per serious injury avoided?

I'm no expert in this, but I'd say 'definitely way more than one'.

And many people have experienced those ratios.

Many older woodworkers lost fingers often multiple fingers in multiple accidents.

So, the risk is really quite high here.

The guys I've seen lose fingers were all sleep-deprived and working flat out. The biggest risk to site safety is sleep deprivation and physical exhaustion.

Most people would rather go bankrupt than lose a finger. Fingers are kind of important. If I can choose to keep my house or my finger, I’m definitely choosing the finger.

So just divide the average net worth of a saw operator by the cost of a saw to get how many saws a finger is worth.

Really? I would definitely rather lose a finger than go homeless. Homeless people have far, far worse life outcomes than people with missing fingers.

A specific person isn’t the average homeless person who tend to be dealing with addiction, physical or mental illness, past incarceration, etc.

So talking about the average outcomes of a random homeless person doesn’t really apply here.

Exactly, homeless people living on the street should really be called familyless.

If I went bankrupt and lost everything I have a social safety net of family members who would put a roof over my head until I got on my feet again. Only people without that safety net end up on the streets. Or they have addictions that mean their family can’t take care of them anymore.

StopSaw makes these. The saws, tables, and fasteners are beefy enough to survive.

It works on conduction and capacitance. It's not immune from false positives.

I do it so seldom and am so careful not to put my fingers within 3 inches of the blade that this is a non-issue for me. This is another one of those "let's put 6 extra buttons that all need to be pressed to start the saw!" kinda situations that doesn't do anything to improve safety because the stop is the first thing you disconnect if it throws a false positive.

If we're concerned about job site injuries then let's address the real problem, which is that a lot of people using these things do so as fast as humanly possible with little regard for set up, site safety, or body positioning because the amount of money they will lose by doing that eats so much margin out of their piecework that it's not worth it. As usual we don't want to solve the hard problem of reducing throughput to improve safety, but we're perfectly happy to throw a part that is as expensive as the sawblade on the unit just to say we're doing something.

"If we're concerned about job site injuries then let's address the real problem, which is that a lot of people using these things do so as fast as humanly possible with little regard for set up, site safety, or body positioning"

Solving that sounds a lot harder to me than legislating that saws have safety features.

How often do you use a saw? At $3500 a saw I care. I saw a lot of wood and inadvertently hit at least one staple/nail/screw per year. Over the last 20 years of using my saw that would be tens of thousands of dollars if even a portion of them damaged the saw. It would essentially price me out of doing woodworking.

Frankly, the biggest problem is that this makes it impractical to test the brake. How do I know the brake even works, if testing it is not practical?

The point is that there's a (>1) cheaper solution that still saves your thumb, but it's (they're) being regulated out of the competition.

I tend to agree, assuming there are no false positives. Admittedly, I’m not sure how often that occurs, nor if we even can know that based on all the various work environments the cheap table saws are being used in today.