Shop safety - got nailed with a broken bowl today

[David Brimm]

Just posting this as a safety reminder not to get complacent at our lathes.

I got off easy this afternoon when I had a white oak bowl come apart on me unexpectedly. It was actually my wifes bowl and she'd just finished sanding it and needed to wax it (carnauba/bees mix) but she's a little skittish about being up close to things on the lathe while they're spinning too fast so she stopped and asked if I'd wax it for her. No problem dear.

It didn't have any cracks or other visible damage/weakness and had been turned and sanded at a variety of high speeds for most of the morning but I always move out of the line of fire when bringing the speed up on these things. Today I didn't do that when I started and didn't think of it until about halfway thru bringing the speed up at which point I started to move my body to the side. I didn't quite make it before the bowl came apart and took a solid hit to the face.

Unfortunately I didn't have my face shield on since it's too hard to see fine detail thru while applying finish. Fortunately I always wear plastic safety glasses, even under a shield (when I'm wearing it) and those almost certainly saved my eye. The glasses took the brunt of the impact (it broke them in multiple places) right over the center of my eye. I suspect the bruising will be impressive over the next couple days and is a nice solid oval in the exact shape of my glasses. Then some abrasion from where some of the bowl deflected down and scraped across my face. Also a moderate amount of bleeding in my sinus on that side that stopped before long. No concussion thankfully.

Very lucky and very glad that it was me instead of my wife.

The bowl was white oak (air dried 5 years), 3" by 12" (ballpark) and was about 1/2" thick in most places so nice and heavy. Photo taken a few minutes after the fact.

http://i65.tinypic.com/20pbzu0.jpg

http://i64.tinypic.com/29ojt37.jpg

[Jay Mullins]

You are a lucky man, you coul have been very seriously injured.

Jay Mullins

[Steve Arnold]

Sorry about your mishap, but you may have saved a few of us in the process. All too often I only wear my safety glasses and forego the face shield. I may have to rethink that after reading your post.

Thanks.

[Brian Kent]

Wow. What a hit!
Can you help us with a couple of details? Is that mounted on a tenon or in a recess? How fast was it spinning when it broke?

Thank you.

[John Keeton]

David, I am glad you are OK. I do notice there are a couple of cracks - one in each of the two larger sections and it may be that the separation occurred in other existing cracks. Also, the bottom/floor appears to be considerably thinner than the side walls and spinning a piece like that puts considerable stress on the floor of the piece, particularly if there is any difference in the density of the wood - and there almost always is some.

[Glenn C Roberts]

Is it an end grain bowl? And is there a recess?

[Lamar Wright]

Glad you are ok David. Very lucky indeed.

[Steve Mathews]

David - First and foremost, I'm glad you're OK and thanks for the safety reminder.

While finishing my last bowl project I noticed that a lot of heat can be generated during the buffing process. Does this have any effect on the structure of the wood possibly contributing to the fibers breaking apart? I was using the Beall system so the bowl itself wasn't turning but wondered at the time about what effect the heat might have on the wood.

[Prashun Patel]

wow. Sobering experience. Thanks for the reminder.

[William C Rogers]

David, glad you are ok. I had one come apart on me. I was wearing a face shield and it didn't cause any injuries. Mine was due to too high speed and I did see a small crack that I super glued. I now think about that every time I have a piece on the lathe knowing it can happen.

[Thomas L Carpenter]

As I am slowly teaching myself to use my Homecraft lath (around 50-60 years old) with the goal of working up to turning bowls, posts like this one, although they scare the bejesus out of me, also make me hyper alert to the dangers of high speed spinning things. Thanks, David and and am glad you and your wife are both OK.

[John K Jordan]

Just posting this as a safety reminder not to get complacent at our lathes.


Thanks so much for posting that, David. Each of us needs reminders, over and over. I wonder how many never get mentioned.

I wonder if a sticky thread compilation for accidents and near misses would be a good thing, not necessarily diluted with public comments but a single edited message for each story with photos if available: what happened, why, what to do differently.

JKJ

[David Brimm]

Wow. What a hit!
Can you help us with a couple of details? Is that mounted on a tenon or in a recess? How fast was it spinning when it broke?

Thank you.

It was mounted by a dovetail recess on my SuperNova2. Not sure the exact speed but somewhere in the 1800-2000 range I suspect. I was bringing the speed up to put a little wax on it and hadn't touched it yet.

[David Brimm]

David, I am glad you are OK. I do notice there are a couple of cracks - one in each of the two larger sections and it may be that the separation occurred in other existing cracks. Also, the bottom/floor appears to be considerably thinner than the side walls and spinning a piece like that puts considerable stress on the floor of the piece, particularly if there is any difference in the density of the wood - and there almost always is some.

Thanks John. Yeah I noticed those cracks when I gathered the pieces afterwards.. they weren't there as far as the wife or I could see prior to it coming apart. Now the whole piece of wood is coming apart in strips like that so I suspect the entire piece was weak but looked good at the time. I also didn't realize until after the fact how (comparably) thin the wife had gotten the floor, it's more like 1/4" to 3/8" thickness. Both of us made poor decisions that led up to the accident.

[David Brimm]

Is it an end grain bowl? And is there a recess?

Not end grain unless I misunderstand your meaning and yes there was a recessed dovetail for the chuck.

[David Brimm]

Thanks so much for posting that, David. Each of us needs reminders, over and over. I wonder how many never get mentioned.

I wonder if a sticky thread compilation for accidents and near misses would be a good thing, not necessarily diluted with public comments but a single edited message for each story with photos if available: what happened, why, what to do differently.

JKJ

Thanks JKJ, I know I certainly need periodic reminders. I find myself slowly getting more and more comfortable doing things that might not be completely safe but I've gotten away with in the past otherwise.

[Matt Schrum]

....Not sure the exact speed but somewhere in the 1800-2000 range I suspect. I was bringing the speed up to put a little wax on it and hadn't touched it yet.

Full disclosure-- I don't use wax finishes and have not made myself all that familiar with their application. That being said, for turning, I've always followed the Bowl Diameter (in inches) X RPMs should be in the 6000-9000 range. That is, for a 12" bowl, I'd probably be in the 500 to 750 RPM range. For finishing, I generally don't stray from this range either.

Am I ultraconservative and off base or do any others have similar rules of thumb I should be aware of?

[Leo Van Der Loo]

Spinning a 12” bowl at near 2000RPM with splits in it, (seen or unseen, they were there) is asking for trouble, you are just lucky you did not end up in the ER or worse.

Quote :{ I find myself slowly getting more and more comfortable doing things that might not be completely safe} and that is another indication of unsafe behaviour, I would advice to change that for your own self interest.

There are several splits in that bowl, more than the lines indicate, though a little harder to see in a picture of Oak wood, but easier when held and swivelled in the light.

364037

[Robert Henrickson]

Full disclosure-- I don't use wax finishes and have not made myself all that familiar with their application. That being said, for turning, I've always followed the Bowl Diameter (in inches) X RPMs should be in the 6000-9000 range. That is, for a 12" bowl, I'd probably be in the 500 to 750 RPM range. For finishing, I generally don't stray from this range either.
Am I ultraconservative and off base or do any others have similar rules of thumb I should be aware of?

I use speeds similar to what you do. I've turned several hundred bowls up to 16". For bowls, I don't think I've ever used anything other than the low range speed setup (1200 rpm max), even for smaller ones, and never to that maximum. 10-12" bowls would probably be 600-700 max. And sanding much slower. I do most finishing off the lathe.

2000 rpm means that a point on the rim of a 12" bowl travels over 6000 feet per minute, or 100 feet per *second* -- over a mile per minute. That's highway speed -- 60+ mph.

An extensive discussion of turning speed and guidelines (uses the Diam x RPM = 6000-9000), complete with chart/graph:

http://www.docgreenwoodturner.com/lathespeed.html

[John Keeton]

I find myself slowly getting more and more comfortable doing things that might not be completely safe but I've gotten away with in the past otherwise.David, Bob and Leo have highlighted much of what I might say, but your statement could be described as complacency. From Merriam-Webster - "...self-satisfaction especially when accompanied by unawareness of actual dangers or deficiencies. When it comes to safety, complacency can be dangerous."

I would encourage you do to quite the opposite - the longer you turn, the more uncomfortable you should become doing things that are not completely safe. Most of us will sometimes engage in procedures that may have an inherent danger beyond the simple act of turning, itself inherently dangerous. Those procedures may have become
necessary to overcome a problem that has developed. But, it is the heightened sense of awareness one develops with experience that causes us to take extra precautions in those situations that are necessary to prevent injury.

[Michael Mills]

First, I am glad you did not receive any more serious injures.
One thing I did notice is that you said the lens broke.
There are safety glasses and there are safety glasses.
Look for the + rating (such as Z87.1+)

There are tons available; mine are the Dewalt bifocals (About $8 IIRC)
Similar to these but Dewalt makes many styles. Many other quality makers out there also.
https://www.amazon.com/DPG55-11C-Anti-Fog-Protective-Glasses-Dual-Injected/dp/B000RKS07I/ref=sr_1_2?ie=UTF8&qid=1500318897&sr=8-2&keywords=dewalt+safety+glasses

Short version:
Without the + they must withstand a 1" steel ball dropped fro 50". Test over. No cracks, good to sell.
With the + thy must withstand a heavier pointed object dropped from the same height. AND must withstand a 1/4" steel ball at about 100 ft per second (IIRC this is about the same as a 17 cal shot). Velocity test not required if they do not have the + rating.
The Dewalt lens and all frame parts are embossed with the + as required.

[Brian Kent]

Thank you, David, not only for writing about the event, but for allowing us to analyze this for everyone's sake - your sake, my sake, and everyone else's sake. If I have a lathe on for applying finish on a bowl, I never do that fast enough for a friction-wax finish. Slowest possible speed, wiping on and buffing off by hand. I do use friction polish on narrow spindles.

I hope that heals quickly.

[Mike Goetzke]

First - glad you weren't seriously injured. I'm a newer turner and I have a Beall buffing system with the Beall "buffs" and they are driven off the lathe mandrel. Is it common to buff with the piece turning (just curious)?

Thanks,

Mike

[Leo Van Der Loo]

First - glad you weren't seriously injured. I'm a newer turner and I have a Beall buffing system with the Beall "buffs" and they are driven off the lathe mandrel. Is it common to buff with the piece turning (just curious)?

Thanks,

Mike

Mike there is a good discussion in this thread but there are more if you type Buffing in the forum search location.

http://www.sawmillcreek.org/showthread.php?245667-Buffing-questions&p=2586405#post2586405

[Leo Van Der Loo]

Michael whatever glasses this turner was wearing doesn’t really matter, as they are not making him safe from heavy and fast moving pieces of wood, and for small splinters or loose pieces of bark, normal safety glasses should do, the real problem is, do you think one gets to be safe with safety glasses and or face shields ????

Have a look what it did to this turner, neither glasses or shield will make you safe.

364076






First, I am glad you did not receive any more serious injures.
One thing I did notice is that you said the lens broke.
There are safety glasses and there are safety glasses.
Look for the + rating (such as Z87.1+)

There are tons available; mine are the Dewalt bifocals (About $8 IIRC)
Similar to these but Dewalt makes many styles. Many other quality makers out there also.
https://www.amazon.com/DPG55-11C-Anti-Fog-Protective-Glasses-Dual-Injected/dp/B000RKS07I/ref=sr_1_2?ie=UTF8&qid=1500318897&sr=8-2&keywords=dewalt+safety+glasses

Short version:
Without the + they must withstand a 1" steel ball dropped fro 50". Test over. No cracks, good to sell.
With the + thy must withstand a heavier pointed object dropped from the same height. AND must withstand a 1/4" steel ball at about 100 ft per second (IIRC this is about the same as a 17 cal shot). Velocity test not required if they do not have the + rating.
The Dewalt lens and all frame parts are embossed with the + as required.

[Thomas Canfield]

One other danger that I did not see mentioned is that a chuck expanding in a recess can break a solid piece, and any crack or weak section is much more likely to fail. A good solid ring of wood is required for a recess to withstand the expanding chuck.

[John K Jordan]

One other danger that I did not see mentioned is that a chuck expanding in a recess can break a solid piece, and any crack or weak section is much more likely to fail. A good solid ring of wood is required for a recess to withstand the expanding chuck.

Not so popular these days, but I believe a face plate can be more secure than either a recess or tenon if there is enough wood in the base, or a glue block mounted on a faceplate. A face plate can act to hold a piece together rather than pry it apart.

But even with a faceplate and a face mask I don't think I would turn a 12" piece over about 500-600 rpm.

I have a friend who turns even larger pieces so full of voids they would certainly come apart when cutting the inside but he has never had one break. After turning the outside he cocoons it in reinforced strapping tape before removing material from the inside.

JKJ

[Dave Fritz]

Exactly what I'm experiencing. I have more respect now than I did when I started. Maybe it's posts like this or my own experience. Pay attention, if you're mind drifts quit and sweep the floor. Thanks for all these posts and thanks for sharing your accident. We can all learn.


David, Bob and Leo have highlighted much of what I might say, but your statement could be described as complacency. From Merriam-Webster - "...self-satisfaction especially when accompanied by unawareness of actual dangers or deficiencies. When it comes to safety, complacency can be dangerous."

I would encourage you do to quite the opposite - the longer you turn, the more uncomfortable you should become doing things that are not completely safe. Most of us will sometimes engage in procedures that may have an inherent danger beyond the simple act of turning, itself inherently dangerous. Those procedures may have become
necessary to overcome a problem that has developed. But, it is the heightened sense of awareness one develops with experience that causes us to take extra precautions in those situations that are necessary to prevent injury.

[Michael Mills]

Michael whatever glasses this turner was wearing doesn’t really matter, as they are not making him safe from heavy and fast moving pieces of wood, and for small splinters or loose pieces of bark, normal safety glasses should do, the real problem is, do you think one gets to be safe with safety glasses and or face shields ????


Leo, I did not intend that any safety glasses will protect from all injury. As you state "normal safety glasses should do" I somewhat disagree. Go ahead and wear your "normal" $1.50 safety glasses rather than ones with the + rating. I do think the ratings matter for lots of folks (those who don't want shards of broken lens in their eyes).
I agree that glasses and shields do not stop injury but I do think proper protection helps mitigate damage.
The soundness of the wood, speed, proper holding method and standing out of the line of fire, etc. are more important.

I have a shield rated V50 (IIRC), ballistic grade. I also have the Bionic which is very light and has the + rating; it may not break easily but the lens will flex enough for you to still receive major damage.

[David Brimm]

Thanks for the comments, concerns and questions everyone.. much appreciated.

You're all absolutely right for the most part. I did many things wrong, made many mistakes and got caught. Fortunately it didn't result in serious injury to myself or my wife. In retrospect I realize the speeds we were using were way too high for a bowl (let alone of that size). This was a bad mistake on my part and in part due to my inexperience turning bowls, I've turned a dozen or two over the course of 5 years or so but 95% of my turning is spindle work (think pool cues, etc). When doing this bowl (and ones in the past I now realize) I didn't use the full speed I would have with a spindle but I didn't cut the speed back nearly far enough for this kind of job. I spend 40-60 hours a week turning spindles commercially and was so comfortable and confident in my 'skills' that I forgot physics had a say in the matter. I won't make that mistake again.

Sometimes it's hard for us to admit failures and mistakes to ourselves, let alone others, at least it is for me. In this case though I made myself share because I wanted to take advantage of this mishap to remind/warn people of the dangers we sometimes overlook or downplay. It's a bit embarrassing but if it helps other people be a little safer going forward then it's worth it in my mind.



First, I am glad you did not receive any more serious injures.
One thing I did notice is that you said the lens broke.
There are safety glasses and there are safety glasses.
Look for the + rating (such as Z87.1+)

There are tons available; mine are the Dewalt bifocals (About $8 IIRC)
Similar to these but Dewalt makes many styles. Many other quality makers out there also.
https://www.amazon.com/DPG55-11C-Anti-Fog-Protective-Glasses-Dual-Injected/dp/B000RKS07I/ref=sr_1_2?ie=UTF8&qid=1500318897&sr=8-2&keywords=dewalt+safety+glasses

Short version:
Without the + they must withstand a 1" steel ball dropped fro 50". Test over. No cracks, good to sell.
With the + thy must withstand a heavier pointed object dropped from the same height. AND must withstand a 1/4" steel ball at about 100 ft per second (IIRC this is about the same as a 17 cal shot). Velocity test not required if they do not have the + rating.
The Dewalt lens and all frame parts are embossed with the + as required.

Hi Michael, thanks for the detailed post. Being a commercial shop we buy safety glasses by the case, all are appropriately rated but are not "+" rated. To clarify my earlier comment(s) about my glasses breaking, the arms broke off (one broke, the other just detached) and the bridge across the nose cracked thru but held the glasses together until I broke them upon removal. The lens took the brunt of the impact and didn't break though it did flex enough that the poly (or whatever) turned opaque. The glasses were actually pretty cool to look at since you could see how they stopped the impact and the effect it had on them, I really wish I'd been thinking clearly enough to have the wife take a picture of them. I credit still having both eyes to those glasses.. without them I definitely (in my mind) would have lost the eye. As it is I feel lucky to have avoided any fractures around the socket.

Anyways, again, I appreciate your post. Safety glasses are something I'm passionate about (weird right?) and no one comes into my shop without a pair on their face, even if they're just walking thru from one door to the next.



Thanks so much for posting that, David. Each of us needs reminders, over and over. I wonder how many never get mentioned.

I wonder if a sticky thread compilation for accidents and near misses would be a good thing, not necessarily diluted with public comments but a single edited message for each story with photos if available: what happened, why, what to do differently.

JKJ

I would imagine that most accidents/incidents don't get mentioned but I don't have any data to back that up. I figure a learning experience should be used as such so really wanted to share so other could benefit from my poor decisions.

[Steve Bistritz]

I am curious as to where the recess was compared to where the center piece split off. Wondering if the expansion of the chuck magnified the pressure where it split...had a close call with that once and now use tenons only since...

[David Brimm]

I am curious as to where the recess was compared to where the center piece split off. Wondering if the expansion of the chuck magnified the pressure where it split...had a close call with that once and now use tenons only since...

Yes I'm sure that was a significant part of the failure. The bottom of the bowl was considerably thinner than I'd expected and the main break happened about 3/4" off the center of the recess.

[Steve Bistritz]

Well, glad you are ok. I am no expert but i always keep an eye on the bottom making sure its 1. not too thick and clunky. and 2. it doesnt become a funnel...plus it just feels better when they are even. I use a Veritas Thickness Caliper...dont think a link is allowed but its on their website...i have the large one and use it all the time...hope this helps a little...no more surprises!!!! Get better soon!!!!!

[Ted Baxter]

Take It from someone with only one eye always wear a face shield and use a good one not the cheap flimsy ones. The loss can happen literly in the wink of an eye.