LumberJocks

Segment Bowl Explosion

  • Advertise with us

« back to Woodturning forum

Forum topic by John Choponis posted 01-09-2013 01:58 AM 1113 views 0 times favorited 16 replies Add to Favorites Watch
View John Choponis's profile

John Choponis

117 posts in 1448 days


01-09-2013 01:58 AM

Here is what a segment bowl looks like when it explodes. I was sanding the bowl when it happened, luckily I was standing beside the head of the lathe and not in front of the bowl. Still not sure why it made it through the turning process and exploded during the sanding process. I have made several segments in the past with no issues at all. It put a hole in the 1/2 OSB behind the lathe and one piece went threw the celling in the shop. This happened about 8 months ago and it took until now to work up the courage to try another one.

John


16 replies so far

View TCCcabinetmaker's profile

TCCcabinetmaker

925 posts in 1109 days


#1 posted 01-09-2013 02:02 AM

my guess woulod be a glue joint failure. Maybe something to do with the heat from sanding? Just guessing, but usually when glued pieces fail on the lathe it has something to do with either the wood itself, or the glue.

-- The mark of a good carpenter is not how few mistakes he makes, but rather how well he fixes them.

View Jimbo4's profile

Jimbo4

1183 posts in 1517 days


#2 posted 01-09-2013 03:16 AM

What was the RPM while sanding ? I found out the hard way not to exceed 500rpm while sanding – heat buildup will delaminate the glue.

-- *Arachnoleptic Fit*: The frantic dance performed just after you've accidently walked through a spider web.

View tamboti's profile

tamboti

207 posts in 1896 days


#3 posted 01-09-2013 04:59 AM

Glue joint failure, seems from the pictures there is a lot of end grain joints,not good if not sized before glue up. Speed should be 500 or less. You do not say with what grit you were sanding/ The lower the grits more heat and if you were trying to remove tool marks you applied to much pressure. Regards Tamboiti

-- Africa is not for sissies

View rance's profile

rance

4149 posts in 1915 days


#4 posted 01-09-2013 05:17 AM

John, anything I could add would be pure speculation. Please tell us more about RPM’s, glue type, glue process, etc. The more we know, the better we can hypothosize.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

View AddeCrom's profile

AddeCrom

9 posts in 757 days


#5 posted 01-09-2013 11:37 AM

John, thank God you’re not hit.
The exact cause is not clear, may be the use of old wood glue, not enough glue, not waited long enough??
Try it for yourself to analyze!

View Knothead62's profile

Knothead62

2364 posts in 1716 days


#6 posted 01-09-2013 06:42 PM

Glad you are OK. I find myself standing off to the side when turning.

View Marcus's profile

Marcus

1081 posts in 774 days


#7 posted 01-09-2013 06:47 PM

Yikes. Images like this terrify and have kept me away from lathes to this point. Glad the walls and ceiling took the brunt of the hits and not you.

View MonteCristo's profile

MonteCristo

2098 posts in 943 days


#8 posted 01-09-2013 07:31 PM

My guess is also higher RPMs during sanding, combined with a joint(s) that was ready to let go. It’s happened to me too.

-- Dwight - "Free legal advice available - contact Dewey, Cheetam & Howe""

View SCOTSMAN's profile

SCOTSMAN

5594 posts in 2340 days


#9 posted 01-09-2013 07:35 PM

I nearly lost my thumb when a piece I was sanding after it was turned exploded and whacked right down on my thumb .Ten days in hospital and two operations later all is well but it also took a while for me to work up the nerve to turn again.It is worth it though don’t give up.Just be extra careful. Alistair

-- excuse my typing as I have a form of parkinsons disease

View Kreegan's profile

Kreegan

1452 posts in 901 days


#10 posted 01-09-2013 07:41 PM

That’s a strong argument in favor of those lathes that have a cage that comes down over the work. If a piece exploded like that on my lathe, I’d have glass raining down on me when it hit the fluorescent lights on the ceiling. Glad you’re ok.

View John Choponis's profile

John Choponis

117 posts in 1448 days


#11 posted 01-10-2013 01:25 AM

Sanding speed was 550-600 rpm. This was glued up as a traditional cutting board, left to dry for a week, cut into angle strips on the table saw and then glued back together, dried for another week, then cut into rings on the scroll saw then glued the rings together. After all of this the bowl set for another month before I got back to it. Tight Bond II is the glue I use.

View ldl's profile

ldl

1135 posts in 1120 days


#12 posted 01-10-2013 02:41 AM

Sometimes things just happen with no explanation. Maybe all the cutting and reglueing was a factor.

-- Dewayne in Bainbridge, Ga. - - No one can make you mad. Only you decide when you get mad - -

View Monte Pittman's profile (online now)

Monte Pittman

15538 posts in 1093 days


#13 posted 01-10-2013 04:11 AM

Glad you’re not hurt. Always a scary situation.

-- Mother Nature created it, I just assemble it.

View Brandon's profile

Brandon

4145 posts in 1706 days


#14 posted 01-10-2013 04:23 AM

glad you’re safe! I still think you should finish it, it has a very cool look to it in its broken stage.

-- "hold fast to that which is good"

View rance's profile

rance

4149 posts in 1915 days


#15 posted 01-10-2013 06:12 AM

My guess would be internal wood stress. I’m guessing that less time sitting may have made a difference.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

showing 1 through 15 of 16 replies

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com

Latest Projects | Latest Blog Entries | Latest Forum Topics

GardenTenders.com :: gardening showcase