The last cut and bang!

[BillPappas]

I was taking a final light trim cut on the inside of the bowl to just smooth it out before sanding and it went bang! I know I did not cut through the side and the tool was not removing much wood. I was using a Ci0 Easy Finisher when this happened and I did not feel it catch. Any thoughts on what would cause this? This particular bowl blank did fly off the lathe one time a few weeks ago when my son was visiting and wanted to try turning...since I am a newbie at this it was the blind leading the blind. I did not make a very good lip for the chuck and he had a minor catch while removing material and the bowl flew off and bounced around. Luckily neither of these incidents caused and bodily injuries:embaresse:embaresse

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[Bas]

Bill, I feel your pain. That was one pretty bowl, way too pretty to turn into abstract art like that! I hope you figure out the problem soon. Wood is still an unpredictable substance.

 

[Ken Massingale]

Ouch! That was a beauty.

 

[DaveO]

You made the last cut...never make the last cut :gar-La;:gar-La;
Were you near the rim of the bowl when you took this last cut? I find that sometimes bowl when closed to be finished will get slightly out of round near the rim in response to heat drying or wood movement. That combined with the leverage of making even a light cut near the rim can easily dislodge the bowl from the chuck.
How are you chucking the bowl? I find that chucking with a tenon gives you little mechanical attachment should the wood fibers get crushed. Chucking in a recess, especially a dove-tailed recess gives you that mechanical advantage should the chuck become a little loose.

Dave

 

[Mark Stewart]

I feel your pain there has been a lot of this around here this weel Rob me and some one else besides you. Shame that looked beautiful..

Thanks Mark

 

[BillPappas]

I had the chuck clamping down on a dovetail tenon and the bowl stayed in the chuck when it blew out....it was still tight after the blow out. I think DaveO is onto what happened though. I inspected the bowl after I made the post and it shows a deeper cut out at the rim than I thought I was taking or at least intended to take. Possibly as DaveO indicates it was getting a bit warped at the rim and the pressure of the cut caused the stress resulting in the blow out. I sure plan on being a bit more careful the next time I get a bowl this close to being finished.

Regards,

Bill

 

[PChristy]

I don't know that much about this but it looks like the thickness of the bowl is to thick for it to start warping -Does dry wood warp that much:dontknow: I thought you need to worry about the warping with the green wood from the heat = I could understand that theory if it where where thinner on the walls - How hard did it hit when it came out of the chuck with your son - Could it have hit hard enough to crack it enough to cause this but not enough to see with the eye? Like I said I don't know that much - just throwing my 2CW in

 

[erasmussen]

Looks like the top is PH, every time I get a catch its a piece of PH:elvis:
But I thought that was just me:eusa_thin

 

[BillPappas]

I don't know that much about this but it looks like the thickness of the bowl is to thick for it to start warping -Does dry wood warp that much:dontknow: I thought you need to worry about the warping with the green wood from the heat = I could understand that theory if it where where thinner on the walls - How hard did it hit when it came out of the chuck with your son - Could it have hit hard enough to crack it enough to cause this but not enough to see with the eye? Like I said I don't know that much - just throwing my 2CW in

The blank seems real dry but I don't have a moister meter so I do not have a way to test. I agree if it is truly dry you would not think it would not warp but wood does what it wants...truth is it seemed to be spinning very true at the time.

When my son was turning the blank and it came out of the chuck it did not hit that hard, it bounced off his foot then rolled around on the ground. I guess it could have cracked when it hit...you never know. When it came out of the chuck my son had only cut out the first inch of the inside so the blank was still fairly solid. I put it back on the screw chuck and recut the outside, cut a new tenon then started on the inside again. I did not see a crack when I recut the outside. Maybe it really was just a catch in the purpleheart or another wood working mystery:rotflm::rotflm::rotflm: More than likely just a newbie wood turner mistake...:BangHead::BangHead::BangHead: