Replies

1. 
   WmGalloway | Dec 29, 2008 03:41am | #1

   A four jaw chuck both is difficult to turn wood with. You clamp down on the wood and it compresses relieving the pressure. A three jaw chuck is somewhat more forgiving and easier to center. For bowls you would be better to look at mounting on a face plate.

2. 
   Thorvald | Dec 29, 2008 04:06am | #2

   I'd say the amount of force required will vary with the size of the bowl, and it would be pretty hard to explain without quantifying in terms of torque, etc.  You'll probably have to just experiment until you develop a feel for it. 

   I've turned a lot of samll pieces -- up to 10-12" -- and I gave up on fancy chucks a long time ago.  I turn the base first and make sure I have it nice and flat.  Then I mark a circle on the bottom the same diameter as a round block that is already drilled and threaded to fit a home built screw chuck.  I glue the block on to the blank with super glue and it's ready to go -- just thread it on to the screw.  When you're done, a single tap on a chisel in the joint will usually pop the bowl off with nothing but a thin layer of glue left to scrape off.  (I just put a basket with a cloth underneath to catch the bowl.)  The size of the waste block varies with the size of the blank, so the greater force applied by a larger piece is accomodated by a larger glue joint. 

   If you're working with large blanks or bowls with relatively small bottoms for their overall diameter, you'll probably need to use something like the Nova.

   Happy turning,

   Verne

3. 
   oatman | Dec 29, 2008 07:04am | #3

   Millions of turners have turned bowls safely with a four jaw chuck. Larger blanks should be mounted in compression mode, not expansion mode, and don't feel shy about cranking down the pressure on the tenon. You'll be turning it off anyway. If you are turning green wood, retighten the chuck once in a while to make sure it stays mounted. Take light cuts, keep the speed down on large pieces, and have fun.

   Dennis

4. 
   Napie | Dec 29, 2008 08:31am | #4

   Do you have a scroll chuck?  That is what Nova makes; it is not the same as a four jaw chuck, even though it has four “jaws” and it is self centering. I use them all the time to turn bowls and platters.  I will tighten it down as much as needed either in the compression or expansion mode.  You can really reef on them, they are very well made and can take it don’t be afraid to jump on it.  I have turned platters up to 30” with no problems with my Nova chucks.  I almost never use a faceplate anymore.

    

   It also a good idea to take the chuck apart once a year or so and give it a good cleaning and lubrication.

5. 
   bigfootnampa | Dec 29, 2008 04:42pm | #5

   Nova makes several types of jaws for their chucks... I am wondering if you have the proper type/size for what you are trying to do.  Mine works very well when I have it set up properly... at the extremes of the jaws adjustments they tend to hold less securely.

1. 
   Biscardi | Dec 29, 2008 07:14pm | #6

   All,

    

   Thanks for the advice. I will try retightening periodically- the compression concept makes sense. I have glued bowl onto faceplates in the past and will consider that again.

    

   Thanks

   Frank