Chuck or jaws?

[Joe S.]

I'm looking into making some small and large-small bowls. To do that I need some way to keep a bowl blank on my midi lathe. I already have an old psi chuck (a gift from a friend) with alligator jaws and small step jaws. I would rather use dovetail jaws and jumbo jaws, so here is my list of questions:

1.) what are the advantages to a more expensive chuck (onway, nova)? As I see it right now, Chinese chucks from psi will still hold the wood.

2.) I see how it would be nice to have 2 chucks, but how much is it worth? It would be cheaper to just get extra jaws. (I am on a VERY tight budget, so cheaper is good.)

3.) what is your recommend combination to make smallish bowls? Dovetail jaws and a dedicated jumbo jaw chuck? A nice(er) chuck and still use the older psi chuck? New jaws and no new chuck?

While I would like to go all out and get the best, this needs to be under $200 and that is pushing it.

Thanks for your time.

 

[qballizhere]

I have the barracuda set from psi and I have not had a problem with them. I would recommend them. I dont do anything bigger than 8 inches.

 

[monophoto]

Joe -

I have the PSI "Utility" chuck - it's inexpensive, Chinese, and it works just fine.

There are basically three steps in doing bowls:
1. Mount the blank, and turn the bottom, leaving either a tenon or recess for mounting on the chuck.
2. Reverse the blank, and turn the top.
3. Reverse the blank again on either cole jaws, a vacuum chuck, or a jam chuck, and clean the bottom. In my opinion, this step is optional if you opted for a recess in step one, but it is usually necessary to clean up if you used a tenon.

So the question is what is the easiest/least-expensive path to get to that point from where you are.

You mentioned step jaws. That may be clue to a simple solution. Can you drill a hole in what will be the top with a forstner bit? If so, size the hole to allow you to mount the blank on your step jaws using a hole as a recess. Turn a recess in the bottom, but make the bottom as clean and finished as possible. Make sure that the area surrounding the recess is about 1/4" thick - you need the thickness to provide strength when you later remount the blank, again using step jaws, on that recess and turn the top.

If drilling the hole with a forstner bit is a problem, you can glue the blank to a waste block to turn the bottom with its recess, and then part it off and flip it around to do the top.

You might also want to check out Ernie Conover's book "The Frugal Woodturner". He devotes an entire chapter to ways to mount blanks, and suggests that buying a scroll chuck is something you should do only if you have exhausted all other possibilities.

Also, Mike Peace has an excellent video on mounting options that is available via YouTube.

 

[Joe S.]

Im not sure the step jaws are big enough to hold a bowl... But that could be just me. Thanks for your advice!

 

[phillywood]

You already have step Jaws and psi chuck what you need is to go online and look around for mounting the blank on the lathe and you'll find how to make your own chucks form wood and attach it to your already chucks and that will be least expensive way. Fancier chucks won't make you a better turner.

 

[John Den]

My pennyworth

Hello Joe,

I have an Axminster 4 jaw combination chuck. and the jaws I use most are the straight outside jaws for Square timber. Followed by the dovetail Jaws for Bowls.

If there is nothing wrong with your old PSI chuck and the modern PSI dovetail jaws will fit it - save your money, give it a clean up, a squirt of oil and spend 25$ on the dovetail jaws.

Dovetail jaws hold the work very securely and if you mark the bowl, when you take it off with the jaw position, you can put the bowl back very accurately and the bowl will spin true. That's about all you want from a wood chuck accuracy, runout etc is not an issue, all of these you turn out.

Using the Dovetail Jaws

1. Measure the minimum diameter the Dovetail Jaws need to enter the Dovetail you will make on the bottom of the Bowl
2. Mount the bowl blank on the Faceplate or Screw Chuck (inside of the tree to inside of the bowl stops rocking developing later)
3. Finish the outside of your bowl curves etc. Turning from the bottom of the bowl towards the Lip of the bowl.
4. Flatten the bottom of your bowl with your bowl gauge followed by a large round scraper angled down at the front on the Toolrest. Checking with a ruler/straight edge. You want it flat and slightly concave so that it sits nicely on the table.
5. Set your dividers to this diameter you measured previously plus 1/8" or so.
6. With the dividers pointed slightly down on the Toolrest approach the bottom of the bowl with ONLY ONE POINT touching and adjust its position so that both points and the scratched circle coincide DON,T LET THE SECOND POINT TOUCH THE BOWL
7. Using your parting Tool groove the bowl blank inside and touching your scribed circle on its base Plunging the tool straight in.
8. Still using the Parting Tool extend this groove to the center of the bottom of the bowl.
9. Flatten this central undercut using a round scraper tilted down over the toolrest.
10. Pick up your Skew Chisel.
11. Don't Panic!!!
12. Use the Skew Long Point as a scarper to smooth into the corner of the recess where the Round scarper didn't reach and then undercut the dovetail outwards from the scribed circle still in scarping mode.
13. Add a 2 scraped shallow grooves with the Skew Point used as a scraper for decoration.
14. Sandpaper the the outside well including the bottom.
15. Mount the Chuck and Dovetail jaws and as long as they fit and tighten your off turning the inside of the bowl this time hollowing from the outside of the bowl inwards.

Kind Regards
John

 

[KenV]

Joe -- the step jaws I have are designed for small objects and are marginal for all but the smaller end of the bowl scale.

Safety from flying objects requires using the tail stock whenever possible.

"Alligator Jaws" are serrated and do grip tenons well, but the tenon should be close to the "full circle" diameter of the jaws to get best hold. The full circle is near the smallest size.

I learned to start bowls between centers or mounted on the "woodworm screw" that locks into the chuck jaws.


I have had mixed success with the "Value Priced" chucks such as the PSI ones. They can be good or they can develop problems holding.

An excellent reference is Doc Green's book "Fixtures and Chucks for Wood Turning".

Be cautious with the Cole Jaws (button jaws) with chucks as they can produce flying objects are even the very low speeds where they are intended to be used. Keep the tail stock up there.

Unbalanced objects can fly and hurt things!! Turn carefully and stay out of the line of fire.


P.S. The Axminister chucks are outstanding quality -- and are sold on the left side of the big pond by Lee Valley.