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tenon broke

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Forum topic by Karda posted 03-09-2021 04:15 AM 543 views 0 times favorited 24 replies Add to Favorites Watch
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Karda

3052 posts in 1610 days


03-09-2021 04:15 AM

Hi, I am turning a large ash bowl blank the largest I have ever turned and the tenon broke off. I can put it between centers and return the tenon I think. I started turning out the bowl so I can’t go back to the face plate, do i have other options. My chuck is a G3 2” jaws


24 replies so far

View Nubsnstubs's profile

Nubsnstubs

1774 posts in 2786 days


#1 posted 03-09-2021 02:14 PM

Mike, you know that pictures are worth thousands of words. Let us see what you did, then maybe we can steer you in the right direction. ......... Jerry (in Tucson)

-- Jerry (in Tucson) www.woodturnerstools.com

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Lazyman

6936 posts in 2443 days


#2 posted 03-09-2021 02:30 PM

Pictures will help. Depending upon how deep you have gotten with your hollowing, one thing I have done is drill a hole on the hollowed side that is large enough for one of your jaws to sit in in expansion mode and use the tail stock for extra safety as you make a new tenon or recess. You can just put it between centers too but this approach may be a little more steady if you have a large enough Forstner bit or small enough jaws and you can find the center well enough to drill a well centered hole.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View Axis39's profile

Axis39

460 posts in 653 days


#3 posted 03-09-2021 02:57 PM

I am a new turner, so so far from being an expert, but I watched a YT video a few weeks ago and the person suggested that making a dovetail recess instead of a tenon.

The logic was that a tenon lines up the grain across it’s width. This creates a weak spot (like you’ve experienced). Whereas a recess allows pressure on the grain in different directions.

Made sense to me.

Think you could turn a recess on the bottom and remount it that way?

-- John F. SoCal transplant, chewer uppper of good wood

View Davevand's profile (online now)

Davevand

260 posts in 1892 days


#4 posted 03-09-2021 03:02 PM

Can you cut the rest of the tenon off and glue a block on it?

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OSU55

2774 posts in 3045 days


#5 posted 03-09-2021 04:36 PM

Sometimes it just happens. It is helpful to look at the pieces to try to determine the root cause, and learn something about tenon shape or wood. Can be a hidden defect, especially if its spalted wood. Depending on the shape you have and the wood, a new tenon may be the answer, or a glue block. I’ll use a glue block before I use a recess. I may rechuck a piece for various reasons and recesses are not as reliable for getting back to the exact same position. Recesses are far more difficult to redress for twice turned items also.

View MrUnix's profile

MrUnix

8515 posts in 3255 days


#6 posted 03-09-2021 06:47 PM

Just turn another tenon if you can. Glue block would also be a good move, and you know me, I’d thread it first so I wouldn’t have to use a chuck :)

BTW: Like others here, I prefer tenons over recesses… tenons are held in compression and you can only compress wood to a point. Recesses hold under expansion, and it is possible to over expand the wood grain apart if you are not careful. I also like to keep my tailstock engaged with the piece for as long as possible for additional support on larger stuff, regardless of how it’s mounted.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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drsurfrat

569 posts in 243 days


#7 posted 03-09-2021 06:59 PM

another less-easy option is to flatten and screw on a faceplate, then after turning, make the screw hole square and fill with a different wood. it looks kind of Arts & Crafts-ish. i did it with a flat bowl and it looked nice

-- Mike (near Boston) ... Laziness is the mother of invention, necessity is the mother of exhaustion - me

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Karda

3052 posts in 1610 days


#8 posted 03-09-2021 11:11 PM

here are the pics, it sheared clean and I don’t see any defects in the wood the tenon is about 2” my max is 2.5”
I uped the speed from 750 to 1100 that may have been to fast

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Woodmaster1

1706 posts in 3643 days


#9 posted 03-09-2021 11:36 PM

Here’s what I use to prevent bowls losing tenons the dowel keeps pressure on the bowl so there is not as much stress on the tenon
.

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Karda

3052 posts in 1610 days


#10 posted 03-10-2021 12:24 AM

thanks, I’ll turn a new tenon and keep the tail stock in place as long as I can i was wondering what other options there were

View Lazyman's profile

Lazyman

6936 posts in 2443 days


#11 posted 03-10-2021 03:18 AM

Karda, which part of the base was bottomed out against the chuck, the bottom of the tenon (in other words that part that broke off) or the bottom of the bowl around the tenon? The bottom of the tenon itself should not be against the chuck. If it was, that is probably why it broke off. Also, from the picture it looks to me that the area around the tenon that should be registered against the end of the jaws isn’t flat enough. The jaws need to make contact with the bottom of the bowl (not just the sides of the tenon) and it must be flush. Basically, it should fit like this:

It doesn’t have to have a step from the shoulder to the bowl like it shows, but the shoulder does need to be flat against the jaws and the tenon itself should not bottom out. Maybe yours was and it is just hard to tell from the picture.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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Karda

3052 posts in 1610 days


#12 posted 03-10-2021 04:13 AM

the chuck was installed properly I was looking at the broken tenon and it looks lop sided. I think one side of the tenon was too small

View Davevand's profile (online now)

Davevand

260 posts in 1892 days


#13 posted 03-10-2021 04:19 PM

I am a novice wood turner just starting out, I too have turned a few turning into frisbees from a broken tenon or a catch. Now if I am turning a larger plate or bowl I use a larger tenon with the larger jaws.

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Karda

3052 posts in 1610 days


#14 posted 03-10-2021 04:32 PM

I don’t have larger jaws

View Lazyman's profile

Lazyman

6936 posts in 2443 days


#15 posted 03-10-2021 05:49 PM

I am not sure what you mean by lopsided?

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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