# Bowl slipping out of chuck



## Novice turner (Jan 5, 2016)

So I'm attempting to hollow out the bowl shown in the attached but it has slipped out of the chuck 3 times. Can anyone point out where I'm going wrong. I've turned bigger heavier bowls using the same method


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## knika (Jan 15, 2012)

No picture.


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## sawdustfactory (Jan 30, 2011)

Bowls slipping in chuck are usually due to incorrect size of tenon (too big or small for jaws to grab proper, or too deep and bottoming out in chuck), or not having a good shoulder to register the face of the jaws against. Any of the above factors compounded if you're trying to remove too much material at a time.


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## Bill Boehme (Feb 9, 2014)

Post a couple pictures -- one to show what the tenon looks like and another to show it mounted in the chuck. Also elaborate on what you mean when you say that the bowl is "slipping" out of the chuck. What are the circumstances when this happens?

The picture of the tenon needs to show the length, angle if dovetailed, and shoulder. The picture of the bowl mounted in the chuck needs to be a close-up that shows how well the tenon seats in the chuck jaws.


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## Novice turner (Jan 5, 2016)

Novice turner said:


> So I'm attempting to hollow out the bowl shown in the attached but it has slipped out of the chuck 3 times. Can anyone point out where I'm going wrong. I've turned bigger heavier bowls using the same method


Sorry guys I was having some IT issues and it wouldn't let me upload the photographs. There are a couple attached now


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## Novice turner (Jan 5, 2016)

Photo 2


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## hwebb99 (Nov 27, 2012)

Your recess might be cut improperly, but it is hard to tell from the picture. I think your biggest problem is the chuck jaws are too small for the job at hand. I used to have the same chuck. I made good use of the Woodcraft 90 day return policy, and bought a Oneway stronghold instead. Much happier. It would help to shorten the depth of the bowl because it has less leverage that way. Making the bowl would IMO improve the appearance of it.


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## 9thousandfeet (Dec 28, 2014)

So you're gripping that piece by the foot with the chuck in expansion mode, is that right?
And then the work just flies off the chuck while you're turning?

The first thing that jumps out at me is that the amount of material you have surrounding the chuck jaws when the work is mounted is insufficient to withstand the forces necessary for a secure hold. If you were to tighten the jaws inside that foot with enough force to hold the work really securely, you would likely split the work itself. It could also be that the recess you have is not a perfect fit for the outside profile of your chuck jaws. As hwebb says, it's hard to tell in the photos. 
A poor fit, combined with an inability to exert enough force without splitting the work will give you problems every time.

An inside hold like that, on a piece that "tall", with such a small amount of material surrounding the chuck jaws, is kinda asking for trouble. With a piece of those proportions I'd keep a tenon on the bottom and hold the piece in compression mode while I finished the inside, then contrive a way to reverse the piece (a jam chuck, say) to remove that tenon and finish the foot to my liking.

Of course it's always possible that the chuck mechanism itself is creeping for some reason, but since you've turned other work without problems that might be unlikely. The chuck is plenty big enough, so I don't agree that a bigger chuck would resolve this problem.


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## hwebb99 (Nov 27, 2012)

The chuck might be big enough, but the jaws are pretty small. A tennon correctly sized to the jaws will usually snap off on a piece that size. I have launched a few bowls and every one was caused be the tennon breaking off.


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## 44260 (Aug 29, 2013)

I see on the bowl towards the bottom there is a big void, are you turning the bowl with this void in it causing a bad catch or is the void a result of the bowl flying out of the chuck?


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## Novice turner (Jan 5, 2016)

No it's just a defect in the wood. It's not a result of the piece coming off the chuck


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## Novice turner (Jan 5, 2016)

9thousandfeet said:


> So you're gripping that piece by the foot with the chuck in expansion mode, is that right?
> And then the work just flies off the chuck while you're turning?
> 
> The first thing that jumps out at me is that the amount of material you have surrounding the chuck jaws when the work is mounted is insufficient to withstand the forces necessary for a secure hold. If you were to tighten the jaws inside that foot with enough force to hold the work really securely, you would likely split the work itself. It could also be that the recess you have is not a perfect fit for the outside profile of your chuck jaws. As hwebb says, it's hard to tell in the photos.
> ...



Thanks mate. Yes that's the set up that I'm using. I have expanded the jaws until they are very tight without the piece splitting so I assumed it would hold. The other points you have raised are consistent with what I was thinking. Appreciate the input. Cheers


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## Novice turner (Jan 5, 2016)

Bill Boehme said:


> Post a couple pictures -- one to show what the tenon looks like and another to show it mounted in the chuck. Also elaborate on what you mean when you say that the bowl is "slipping" out of the chuck. What are the circumstances when this happens?
> 
> The picture of the tenon needs to show the length, angle if dovetailed, and shoulder. The picture of the bowl mounted in the chuck needs to be a close-up that shows how well the tenon seats in the chuck jaws.


Thanks bill. Unfortunately I'm away from home at the moment so I could only use the couple of photographs I had on file.

By slipping I meant the piece comes flying off the chuck and scares the s#*t out of me!


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## NCPaladin (Aug 7, 2010)

I agree with most all the other said.
It appears to be a Nova G3?
Other observations... the item is very tall for the G3 with 50mm jaws (I am assuming they are the 50 mm). 
Suggestions can be pushed but Nova suggest up to 12" diameter and 4" depth with those jaws. The depth looks to be the problem because of leverage.
I use a recess most of the time vs a tenon. Nova suggest 1" of wood surrounding the recess. With 1" around a 2" area there is 3X the amount of wood around the area as there is within the area.
Nova suggest a max 1/4" depth for a tenon with those jaws. Difficult to tell but may well be over by quite a bit and could even prevent the top of the jaws from contacting the wood.
There should be a dovetail for the jaws to seat into and it appears to me the wall are straight. If it is straight there may not be enough meat on the bone to add a dovetail now.
It does appears the area the top of the jaws seat against are flat as it should be.
This is fairly old but here is a link to a Teknatool jaw manual. The 50mm are on page 20.
http://www.teknatool.com/products/Chuck_Accessories/General/downloads/Accessory Jaw Manual_Nov07.pdf
Note, by spigot mount Nova is referring to endgrain mount in their size suggestions. With a spigot mount they suggest up to 6" length but only 4" diameter.


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## NCPaladin (Aug 7, 2010)

Here are links to some videos by Stuart Batty on Vimeo.
He gives an excellent, and persnickety presentation. Persnickety is very good being extremely clear and exact.


https://vimeo.com/68649130


https://vimeo.com/68649135


https://vimeo.com/69018287


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