To Sawstop or not to Sawstop

[redknife]

Motorcycle crash statistics tell a very different story. And unlike saw injuries, there are a lot of statistics to to compare when it comes to motorcycle crashes. It is troubling how easy it is for people to convince themselves that something is factual without having any real proof. I think that we are all guilty, more of less of accepting that something is true, when it isn't.
Pete

Pete, firstly congrats on working to your new saw. You’ve put a lot of thought on this and gained advice from most every quarter to steer your final decision. Nothing that follows is meant to argue a point, but rather to add some of the known data.

While there is more and better data on motorcycle crashes, there is reasonable data on table saw injuries. As in medicine, I think it is good for the serious woodworker to have a handle on the available data. Research, databases, analysis, and conclusions always have limitations. Nonetheless, understanding what is actual known is important in my opinion. We make decisions in medicine all of the time using a combination of data (with all its warts), experience, and judgement. I would pose that this no different.

Here is a link to a review article
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4154236/#!po=28.9474
This peer reviewed publication appeared in the Journal of Plastic and Reconstructive Surgery, a respected journal. The publication is a review of existing literature and databases and the work was funded by the National Institutes of Health. There is discussion of Sawstop technology, but again the article and work were not funded by Sawstop. The references at the end provide links to other related studies.

Some of the highlights:
Estimated 30,000 table saw hand injuries per year, ranging from lacerations to amputations
Vast majority of TS injuries involve skin to blade contact (minority from kickback/other that does not induce skin-blade contact)
mean age 50 yo
30 some percent of injured with 10+ yr experience
Many had the blade guard removed
No significant change in the incidence of TS hand injuries after the 2005 riving knife requirement.
There is much more, but a formal literature review is beyond the scope of a forum post.

This study is older but notable because it looks at all non-occupational finger amputations:
http://www.sciencedirect.com/science/article/pii/S0196064404015513?via=ihub
Of note, power saws were responsible for 20% of all non-occupational finger amputations

From a different perspective, the main risks to us in everyday life are the much more common heart disease, cancer, debilitating chronic illness,etc. My impression from participating in the forum over time is that these non-woodworking risks, as expected, show up more frequently as life events in our group. For most of us, Woodworking is a choice, and we generally know the risks. Injuries can affect others (family, workplace, health $), but predominately you are making risk decisions that impact you.

i can post more studies or list some of the databases used as injury sources, but I posted this to increase awareness of available data (good or bad) and facilitate some exploration of the data for those interested.

 

[nn4jw]

Some of the highlights:
Estimated 30,000 table saw hand injuries per year, ranging from lacerations to amputations
Vast majority of TS injuries involve skin to blade contact (minority from kickback/other that does not induce skin-blade contact)
mean age 50 yo
30 some percent of injured with 10+ yr experience
Many had the blade guard removed
No significant change in the incidence of TS hand injuries after the 2005 riving knife requirement.
There is much more, but a formal literature review is beyond the scope of a forum post.

I'm not diagreeing with anything Chris said in the quoted post, but before I can relate my situation and experiences to those statistics I'd need some additional info from the study that likely isn't there.

I'd like to see the data classified into professional versus amateurs, on the job versus off the job, job site versus home, etc. Was the saw actually running or does the data include injuring yourself handling the blade, e.g. during blade changes and such? It's interesting that 70% of the injuries were to people with less than 10 years of experience. I'd want to see a distribution of the data across years of experience.

My point is NOT to dispute the data, just to say than IMO there's not really enough detail there to get a better feel for whether better safety device would have prevented a significant number of those injuries at this point. It's too easy to jump to conclusions prematurely. It's interesting that the riving knife requirement hasn't made any significant differences. And yes, my TS has a riving knife and I use it.

As a hobbiest I don't have time constraints and I take the time to plan and make deliberate table saw cuts. I work alone without distractions. I'm not too worried about the TS. Jointer, that's another matter.

 

[tarheelz]

Jim,

You make fair points, however, we should not overlook that you are still making a decision , in part, based upon this data. You are deciding this data is insufficient for you to abandon your current beliefs (even if those beliefs are themselves constructed off of far more scanty data points).

Decision-making by the human brain is brilliantly interesting.

 

[nn4jw]

Jim,

You make fair points, however, we should not overlook that you are still making a decision, in part, based upon this data. You are deciding this data is insufficient for you to abandon your current beliefs (even if those beliefs are themselves constructed off of far more scanty data points).

Decision-making by the human brain is brilliantly interesting.

It's not quite like that. It's not about abandoning a belief as such. It's about becoming convinced that that at my age and remaining years to use equipment, my usage levels, techniques, etc. that the benefits of replacing my current table saw outweigh the cost and effort. Scare tactics are almost always suspect in my mind. In my experience those tactics are almost always employed as emotional sales techniques when supporting data is insufficient alone. By scare tactic reasoning I shouldn't even own a table saw. Then there would be 0% chance of injury by one.

How data is presented also says a lot about the point of view of the presenter. In this instance they were presented as 30% of the injured had 10+ years of experience. It could just as easily been presented as 70% of of the uninjured had 10+ years experience. I'd say those statements imply different things.

There was a book I read a long ago that I believe is still in print called "How to Lie With Statistics". It should be required reading.

Now, all that said, if I was just buying my first good table saw I "believe", if could afford it, that I just might buy a Sawstop. Looking back I also believe that having one at that stage of my experience just might have given me a false sense of security and even some bad habits.

Decisions, we all make them.

 

[redknife]

Jim, good points. It should be clear that I selected certain information to include in the post, with a goal of including data relevant to points made in the discussion. I have a sawstop but don’t hold a belief that others should as well. I do believe that as practitioners of the craft, we should be aware of available information. All scientific medical literature has inherent biases. The available data on table saw injuries is no different, but perhaps we can add to our understanding.

I think it is important to point out that most literature on table saw injuries is based on the National Electronic Injury Surveillance Sustem (NEISS), https://www.cpsc.gov/Research--Statistics/NEISS-Injury-Data, a product of the US product safety commission. The NEISS samples a subgroup of hospitals, extrapolates those numbers for population estimates, and then reports those numbers based on stated rules. Statisticians limit reporting of extrapolated data where it would not be reasonable statistically to present the extrapolation (i.e. you can’t multiply small numbers x one million and present that as representative of the population). In medical research, we use similar databases for research all of the time. We also routinely evalute smaller cohorts of patients and then attempt to make population inferences, under statistical scrutiny. It can be very frustrating working with these national hospital sample databases, because you really need to understand the minutia of how the data is gathered and presented. Often, the questions you want answered can’t be queried because the of the way the data were collected (i.e. Jim’s example).
There are a few table saw injury papers based on woodworker survey including some administered by Woodworking magazines and some surveys of Woodworking groups like ours, Those surveys have their own quirks and warts when trying to generalize the results.

For balance, here is a critical view of the NEISS data https://www.popularwoodworking.com/article/table-saw-injury-numbers-in-perspective. I don’t personally agree with the slant of the points in the PW article but I wanted to present a skeptic’s view. In fairness, the editorial was in response to a USA Today article.

 

[petebucy4638]

The reports that you cited, especially the first one were an eye-opener. I never realized that there were that many table saw injuries every year. It was especially noteworthy that neither experience, nor safety training had any impact on the number of injuries. Motorcycle injuries fall off considerably with experience and training. I was amazed at how many blade contact injuries occurred with the blade guard installed.

Based on the data, the only technology that can stop the vast majority of table saw injuries is available on on brand of saw - Sawstop.

Thanks present some hard fact to this discussion.

Pete

Pete, firstly congrats on working to your new saw. You’ve put a lot of thought on this and gained advice from most every quarter to steer your final decision. Nothing that follows is meant to argue a point, but rather to add some of the known data.

While there is more and better data on motorcycle crashes, there is reasonable data on table saw injuries. As in medicine, I think it is good for the serious woodworker to have a handle on the available data. Research, databases, analysis, and conclusions always have limitations. Nonetheless, understanding what is actual known is important in my opinion. We make decisions in medicine all of the time using a combination of data (with all its warts), experience, and judgement. I would pose that this no different.

Here is a link to a review article
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4154236/#!po=28.9474
This peer reviewed publication appeared in the Journal of Plastic and Reconstructive Surgery, a respected journal. The publication is a review of existing literature and databases and the work was funded by the National Institutes of Health. There is discussion of Sawstop technology, but again the article and work were not funded by Sawstop. The references at the end provide links to other related studies.

Some of the highlights:
Estimated 30,000 table saw hand injuries per year, ranging from lacerations to amputations
Vast majority of TS injuries involve skin to blade contact (minority from kickback/other that does not induce skin-blade contact)
mean age 50 yo
30 some percent of injured with 10+ yr experience
Many had the blade guard removed
No significant change in the incidence of TS hand injuries after the 2005 riving knife requirement.
There is much more, but a formal literature review is beyond the scope of a forum post.

This study is older but notable because it looks at all non-occupational finger amputations:
http://www.sciencedirect.com/science/article/pii/S0196064404015513?via=ihub
Of note, power saws were responsible for 20% of all non-occupational finger amputations

From a different perspective, the main risks to us in everyday life are the much more common heart disease, cancer, debilitating chronic illness,etc. My impression from participating in the forum over time is that these non-woodworking risks, as expected, show up more frequently as life events in our group. For most of us, Woodworking is a choice, and we generally know the risks. Injuries can affect others (family, workplace, health $), but predominately you are making risk decisions that impact you.

i can post more studies or list some of the databases used as injury sources, but I posted this to increase awareness of available data (good or bad) and facilitate some exploration of the data for those interested.

 

[petebucy4638]

Gentlemen, and ladies, if any ladies are present. After reading Chris' very informative post, I realized that my belief, not based on any statistics or facts, that having a riving knife and a modern blade guard would make using a table saw considerably safer. I also assumed that a lifetime of experience with construction tools and table saws somehow conferred me with some protection. Chris' post showed that I was very wrong.

I can't think of any other activity that I have been around where experience and safety training accounted for no substantial reduction in injuries. In my world of dangerous activities, from scuba diving when I was young to motorcycle riding for most of my life, the vast majority of injuries and death occurred to people with the least amount of experience and little or no safety training.

The data in the reports are clear - the only technology that has factually reduced table saw injuries is the Sawstop saw brake. Statistically, there is no safety advantage in me trading in my Grizzly 1023 without a riving knife for one with a riving knife and a more modern blade guard - none! It is particularly discouraging that statistically the training that I will give to my nephew will do much, if anything, to make his use of a table saw safer, nor will him gaining experience using a table saw make him less likely to be injured.

Safety wise, my two options are to keep my Grizzly 1023 or to buy a Sawstop table saw. I stand by the old saying that intelligence allows for a change of mind, and I have changed my mind. I am going to buy a Sawstop saw when my Grizzly sells.

Again, thanks to Chris for his input.

Pete