Bowls Breaking Out of my Stronghold

Re: Bowls Breaking Out of my Stronghold

Fog Tanner

>Depends on your definition of decent size. A good rule of thumb is 40% of the diameter. You can reverse chuck it later and the foot down to a more pleasing 33%. A bigger question is how are you cutting the tenion or foot. Are you leaving a square shoulder for the chuck jaws to register against. Is the tenon or foot bottoming out in the chuck. If you are only getting support from the side of the foot/tenon, it will most likely fail - unless of course you are Richard Raffin.

You can use less than the 40%, but you will need to take lighter cuts on larger bowls. There is considerably more leverage on the rim and when a heavy cut is applied, this places a lot of stress on the tenon/foot.

Another thing to look at is the contact points on your foot. The standard jaws will only be making contact with eight points when they are at the end of their travel. That's the reason for the larger jaw sets. I have both the standard and #3. I use the number #3 for 10 inch and up, a 40% tenon and return the foot when I am through.

All this is good for us mere mortals. I was watching the Richard Raffin video on making a bowl. He was using his 4 step jaws, which I have a set of, to make a 10 inch bowl. The depth of the steps on these jaws is only 3/16" compared to the 7/16" on the standard stronghold. Richard turned a finished foot about 33% of the diamter and it appeared that he mounted the bowl flush on the chuck face and gripped by the foot on the side. He proceded to hollow and finish the bowl. This looked good, so I tried the same thing on a smaller bowl, ripped it from the chuck and went back to the other jaws. Just shows the difference in touch that 20,000+ bowls and 30+ years can make....

Re: Bowls Breaking Out of my Stronghold

Brian

>Thanks, I was making the spigot too small. I increased the diameter on a couple of bowls and it worked like a champ.

Re: Bowls Breaking Out of my Stronghold

Bill Hale

>Brian

I see that you changed size and have had sucess.

My question is what you mean by breaking out.

Is the tennon breaking off or are the edges of the tennon breaking.

I make my tennon almost to the bottom of the bowl and just a little larger than the closed position of the jaws. Be sure the tennon of the foot is the same angle of the tennon of the jaw.

If the wood is a little soft it does not hurt to run a little thin CA on the tennon of the bowl and re true prior to reversing.

Good turning and be safe

Bill