# Sounded like a shotgun blast



## oldmacnut (Dec 27, 2010)

I just had a 12" wide 7" deep Maple Stave Bowl explode, and I mean explode like a Micheal Bay movie.

Had it rough shaped, so it was balanced, was turning the outside when BAM, it just disintegrated. 

Now I was on the tail stock side, so nothing came close to me, I have only found bits and pieces, maybe 30% of the bowl, some pieces are stuck in the ceiling. Looks to be the glue joint at base failed as the base is still on the lathe in one piece.

I didnt really like turning Maple as it was, such a pain to turn, now I really dont like it.

I do know from quick inspection, one of my belt pulleys is now bent on the lathe, after I change my drawers I will have to inspect my tools now, including the planer and Bandsaw as they were in the line of fire.

Blah. 

Yup, had on my full face mask, glasses, and other gear, though if I was in the line of fire I dont think they would have helped very much.


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## knika (Jan 15, 2012)

That has happened to me twice and I won't have it happen again. That is why I will never turn a bowl again.

Jack


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## RusDemka (Jun 9, 2012)




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## john lucas (Sep 18, 2007)

I'm guessing it was joint failure since you didn't say anything about a a catch. Almost every segmented vessel I've turned has had some maple in it. I don't think it was the wood unless the wood had a defect. Did you let the glue dry long enough. I let yellow glue dry overnight. In a mad rush I've turned pieces within 2 hours but that's really pushing it. 
You also didn't mention how fast you were turning. I generally don't turn segmented pieces as fast but that's not always the case. Sometimes it just needs more speed and sharp tool to cut cleanly. 
The good news is you weren't hurt. I try as much as I can to stay out of the line of fire when turning but sometimes you don have to stand over the bowl to properly judge it's shape while your cutting. That is the dangerous time.
I jokingly said that turning bowls is what causes all accidents on the lathe. Seriously anything can hurt you but bowls and hollow vessels are the most likely so use sound wood, good glue joints, and take care when turning those.


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## oldmacnut (Dec 27, 2010)

Pics.

Some pieces










I don't think shaft is bent, could be the handle.









It is apparent the glue joint failed. This was one of 4 bowls I used polyurethane glue to secure bottoms.









Got a knick in shaft, can't see the carbide edge is a little jacked up now









Sent from my Galaxy S2 using Woodworking Talk


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## Dave Paine (May 30, 2012)

Wow, glad you did not get hit by those large pieces. :thumbsup:

Talk about a brown trouser incident. Definitely one to get the ticker going at full speed.

In a recent thread someone posted a FWW article which compared the strength of various glues. Polyurethane was the weakest.

+1 with John Lucas that it looks like joint failure at the base, then likely the spinning carcase hit something which caused it to break.

Edit added link
http://www.woodworkingtalk.com/f5/glue-joint-44950/


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## oldmacnut (Dec 27, 2010)

john lucas said:


> I'm guessing it was joint failure since you didn't say anything about a a catch. Almost every segmented vessel I've turned has had some maple in it. I don't think it was the wood unless the wood had a defect. Did you let the glue dry long enough. I let yellow glue dry overnight. In a mad rush I've turned pieces within 2 hours but that's really pushing it.
> You also didn't mention how fast you were turning. I generally don't turn segmented pieces as fast but that's not always the case. Sometimes it just needs more speed and sharp tool to cut cleanly.
> The good news is you weren't hurt. I try as much as I can to stay out of the line of fire when turning but sometimes you don have to stand over the bowl to properly judge it's shape while your cutting. That is the dangerous time.
> I jokingly said that turning bowls is what causes all accidents on the lathe. Seriously anything can hurt you but bowls and hollow vessels are the most likely so use sound wood, good glue joints, and take care when turning those.


Yeah John my guess is joint failure.
Wasn't going fast, second speed on my lathe could be 1200 for all I know, highest I ever go is 3rd for super sanding.

Honestly, it was just a matter of time, as it is. Turning is in my eyes the most dangerous thing to do in the shop. However, thanks to RusDemka's big a$$ tools in my 22" handles, I wasn't that close to the bowl.

Only sucks cause I see it as a waste of material, if my heafstock shaft is indeed bent like the pully, bonus for me as I can now push to upgrade the lathe, even if it is just to the harbor freight one for now. I'd then just convert this one to a disc sander.

I'm not going to turn this week, ill just start making grunt call, bottle stopper, handle and other segmented blanks to sell to help fund a new tool, and do some flat work for upcoming shows next month. Yeah, I have a big pile of bowls ready to turn, but I think they can find new homes for now. I need to really inspect that lathe before I use it again.

And to think, I just made a nice new walnut base for it this weekend, polished the tube, new belt, relocated the motor. Was actually running very nice, smooth.

Sent from my Galaxy S2 using Woodworking Talk


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## RusDemka (Jun 9, 2012)

oldmacnut said:


> Pics.
> 
> Some pieces
> 
> ...


Oh man, that's scary... Glad your ok. 
Did the tool rest survive? U sure did get a surprise test for durability LOL


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## Shop Dad (May 3, 2011)

Wow, glad you're safe. Interesting you tried Poly glue. Here is the article that Dave mentioned.

http://www.titebond.com/Libraries/News_Articles/HowStrongisYourGlue_FWW.sflb.ashx


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## oldmacnut (Dec 27, 2010)

RusDemka said:


> Did the tool rest survive? U sure did get a surprise test for durability LOL


Like a Boss.

LOL.

Sent from my Galaxy S2 using Woodworking Talk


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## RusDemka (Jun 9, 2012)

oldmacnut said:


> Like a Boss.
> 
> LOL.
> 
> Sent from my Galaxy S2 using Woodworking Talk


Hope yur tool is fine, you just got them yesterday...


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## john lucas (Sep 18, 2007)

The problem is the end grain joints. End grain to end grain is the weakest glue joint. You can sometimes make it a little stronger by using a thinned glue to wipe on the joint. let it sit for minute or so and then wipe it off. Then apply full strength glue. Still when I ran a glue experiment it did not strengthen the joint very much at all. 
I glued 3/4" square end grain to end grain joints using a bunch of different glues. Then I clamped one end in a vise and used a 2 1/2lb weight to slide out the piece starting at the glue joint. CA glue broke when I move the weight only an inch past the joint. That's horrible. Gorilla glue was next and only a little stronger. Yellow woodworkers glue with the thinned glue applied first (we call this sizing) and then full strength held up until the weight was about 5" out. Epoxy on slightly more than that. Now remember we are only talking about a 2 1/2lb weight. With a side grain joint the weight was increased to 10 lbs and went out about a foot before breaking the wood. The glue did not break.
Doing a staved bowl like that I cut the wood so the grain runs from top to bottom. This way you have a side grain glue joint. If you really need to make an end grain joint for appearance sake then find a way to make the joint in such a way that it will have some long grain glue surface. Perhaps a birds mouth bit or a fancier joint. You might try adding a spline but if you plan to turn the wood afterwords you have to leave the wood thick enough the spline won't show.


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## TomC (Oct 27, 2008)

Glad your OK. Accidents can happen in a heart beat. The hobby we practice is dangerous as we all know. I believe when individuals post accidents or near misses it helps us remember to wear our safety gear and always work as safely as we can.
Tom


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## duncsuss (Aug 21, 2009)

TomC said:


> Glad your OK. Accidents can happen in a heart beat. The hobby we practice is dangerous as we all know. I believe when individuals post accidents or near misses it helps us remember to wear our safety gear and always work as safely as we can.
> Tom


My thoughts exactly, on all points ... but especially that you're OK.


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## duncsuss (Aug 21, 2009)

john lucas said:


> The problem is the end grain joints. End grain to end grain is the weakest glue joint ... Doing a staved bowl like that I cut the wood so the grain runs from top to bottom.


I had to think about this for a while, but I finally got what you're saying.

Segmented bowls made with multiple layers have the same end grain joints between the segments.

But that's just in a single layer -- since each ring is usually offset with respect to its neighbours, the end grain joint has at least one face grain joint supporting it at the side (like splints round a broken bone).


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## Dave Paine (May 30, 2012)

duncsuss said:


> I had to think about this for a while, but I finally got what you're saying.
> 
> Segmented bowls made with multiple layers have the same end grain joints between the segments.
> 
> But that's just in a single layer -- since each ring is usually offset with respect to its neighbours, the end grain joint has at least one face grain joint supporting it at the side (like splints round a broken bone).


You are correct for a ringed segmented bowl. This was a stave construction. I think since the base was glued on without a recess, it was relying on an end grain in the stave glued to face grain on the base.

A 12in bowl is rather large and the polyurethane is not the strongest glue. I think the bowl came free of the base and then shattered when it hit something.

I have made only 1 segmented bowl, but it was ring construction and a solid bottom with face grain to face grain joint.

Based on Jim's close call, I think if I did a stave construction I would include a recess for the bottom and glue the two halves around the base in the recess.


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## duncsuss (Aug 21, 2009)

Dave Paine said:


> ... This was a stave construction. I think since the base was glued on without a recess, it was relying on an end grain in the stave glued to face grain on the base...


Look at Jim's first photo again -- I think the grain is running across (not up and down) the staves.


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## Dave Paine (May 30, 2012)

duncsuss said:


> Look at Jim's first photo again -- I think the grain is running across (not up and down) the staves.


Sorry, I did not look at the details of the picture. You are right the staves have the grain running side to side on this bowl, so this would have had a portion of the joint face grain to face grain.


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## BassBlaster (Nov 21, 2010)

WOW, thas scary, glad you wernt hurt!!

Another issue I see is you were using a square cutter. That cutter is for roughing only and is intended to be pushed straight into the work only. When finishing, you should switch to the round cutter or a sqaure with a radiused edge. That sqaure is very difficult to keep perfectly aligned with the work and just the slightest offset will cause a catch when working it sideways on the face.


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## PhilipCollier (Jan 2, 2012)

Glad no personal injury occurred. Sorry about damage to the lathe but against personal health glad it was the machine that got nailed.

PCollier -the forever rookie-


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## john lucas (Sep 18, 2007)

One solution to the problem is to put regular segmented rings on the top and bottom. You are correct in that if you do regular segmented rings with end grain only joints you should overlap each ring so that each joint is covered with a solid piece of wood from the next ring up. This gives you long grain glue joints above each end grain joint. 
I made a lot of small bowls with the grain running sideways around the main part of the bowl. These succeeded because the bottom was a solid piece (which is also not good due to wood movement but I'll answer that in a minute) The top was 3- 1/4" layers of segmented rings with the joints overlapping. 
Now to discuss the solid bottom. ON these bowls the bottom was solid wood, walnut and was about 5 1/2" in diameter. These bowls have been kept in a home with a relatively stable environment so the wood movement is minimal. If you subjected the bowl to any extremes of moisture the wood movement of the bottom won't match the movement of the segmented rings and you could get a broken glue joint. The segmented rings on the top move with the ones below. 
What I do now to eliminate this problem is to make the bottom a staked layer of thin wood so it is in effect homemade plywood. The top and bottom layers are always of the same wood as the piece so you don't reallly know it's plywood. It looks like solid wood. This wood won't move much at all and matches the segmented rings above.


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## oldmacnut (Dec 27, 2010)

There is an awful lot to quote, so I wont, but will do my best to answer questions.

I had a few hours to think, and look and this is what I came up with.

The Maple Stave I was turning was #50 in stave bowls I have done, and who really knows how many were indeed Maple, I never cared for turning maple, finicky.
This bowl was 1 of 6 bowls I tried something different.....I used Polyurathane glue to glue the bowl to the base, this was the only solid maple one, the rest were either solid cherry, or both.

While it is apparent the glue line failed, until I cant locate every piece, it is still very possible that I had a catch. I will rule nothing out yet, including operator error.

Glue Age...I glued these up weeks ago, and they have been in the shop the whole time. Temps have gone down to freezing, and up to 80. I usually do a run of bowls and do have a rack that looks very similar to someone who rough turns solid, then goes back later, right now I have 30 to choose from to turn.

End grain gluing, great info there, I will use that for future projects.

Cutting...I was "plunging" the cutter down the side, basically using the corner of the cutter to rough out the side. Lite cut, done it 100 times before.

Safety, I had a 3M full face sealed respirator and safety glasses on underneath, plus I was standing closer to the tailstock, regardless of what gear I had on, i am pretty sure it would have shattered my face plate if it came my way. I got into the habit of never standing over anything turning on the lathe.

Yeah, the solid base method is well documented "it works/doesnt work" I have read so much about the solid base thing.

Damage......

Headstock pulley is warped, headstock spindle was sheared from the pulley retaining screw, and the shaft is bent.
Tool is fine, you wont believe this, the cherry handle cracked.....
Tool rest is fine, not a scratch.

What does this mean.....no more turning until I get a new lathe. While I have done alot of maintenance, cleaning and otherwise put alot of time into this old Mono Tube lathe, which with the big motor I put on it, solid base, lack of vibration it actually is a decent lathe, save for the fact I hate the banjo, however it is new lathe time. And new lathe time does not mean Nova as I cant afford it, it means Harbor Freight if I want to keep turning.

I took nothing personal anyone said, the idea of trying to figure out where I might have gone wrong is in my opinion, a really good idea, because the info posted in this thread might help others from getting seriously hurt.

It's still pretty early in the "what happened" game, as I am still trying to find the rest of the bowl, and I just broke the news to my wife that the shaft is bent.

Now, time to do some glue ups for various types of blanks for other people. Man I love glue ups, and man....I am not using Poly glue for that again.....lol
Oh, also going to cut the bottoms off any bowls I used Poly on, and use proper PVA glue.

Keep in mind, I love doing stave bowls, and I am pretty much all Stave type bowls, this is the first time this has ever happened. I have thrown bowls, I have gone to thin and had them come apart, but never had one explode like this.


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## john lucas (Sep 18, 2007)

Another possibility is using a scraper for this. when your on the upper portions of a bowl a scraper can create more vibration and it can try to pull the tool into the wood. Of course this can happen with a bowl gouge as well but it's less likely if you are doing a bevel rubbing cut.


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## oldmacnut (Dec 27, 2010)

john lucas said:


> Another possibility is using a scraper for this. when your on the upper portions of a bowl a scraper can create more vibration and it can try to pull the tool into the wood. Of course this can happen with a bowl gouge as well but it's less likely if you are doing a bevel rubbing cut.


Yeah I have experienced tool pull in, infact that is how the original cast iron tool rest broke, my gouge got pulled in, hit the tool rest and it broke, well the bowl came off and hit the rest, but the bowl was fine.

so, wife aint to happy about this, im just happy it didnt hit me. Plus, the positive side is of course the need for as new lathe now as this one is not worth hunting down parts.


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## duncsuss (Aug 21, 2009)

I'll go through all my magazines to see if there are any coupons for the HF lathe to get the price down for you.

_Edit ... 

No luck, just the 20% coupons that I'm sure you already have. If you can wait a month, there might be a 25% coupon valid only on New Years Day (there have been the last couple of years.)

_


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## Shop Dad (May 3, 2011)

Be sure to check CL too and even ebay. You never know what will turn up.


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## oldmacnut (Dec 27, 2010)

duncsuss said:


> I'll go through all my magazines to see if there are any coupons for the HF lathe to get the price down for you.
> 
> _Edit ...
> 
> ...





Shop Dad said:


> Be sure to check CL too and even ebay. You never know what will turn up.


It's 269.00 right now, toss in a 20% off it does bring it down.

Yeah, I check local and DFW CL everyday, sometimes just for a good laugh......


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## Handplane (Nov 28, 2012)

Some noob input for what it is worth:

The endgrain advice is dead on, especially Hard Maple.

Things I would do different is first use a floating base, as the wood movement on a base that size will slightly warp due to constraints. Second is to make the segments shorter and use two rows, staggering the layers. That way you are not relying on end grain to keep the piece together and it will be pretty strong.


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## oldmacnut (Dec 27, 2010)

Handplane said:


> Some noob input for what it is worth:
> 
> The endgrain advice is dead on, especially Hard Maple.
> 
> Things I would do different is first use a floating base, as the wood movement on a base that size will slightly warp due to constraints. Second is to make the segments shorter and use two rows, staggering the layers. That way you are not relying on end grain to keep the piece together and it will be pretty strong.



I haven’t had a chance to do a multi layered "stave" bowl yet, it is actually on my list of must do's.


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