help needed holding green wood for turning

[starr]

I have been trying to turn green wood. The first bowl I turned a tenon on the end to hold in my Nova chuck but a small dig in caused the whole tenon to rip off.

The next bowl I held with a faceplate, but found that the screws loosen quickly and the piece starts wobbling on the lathe. I tried longer screws and it was better, but it still wobbled after a little turning and I have to keep tightening the screws and they seem to lose their holding power in the wet wood.

What is the secret I am missing?

[Tomislav]

Hi
I have found the more agressive jaws useful. I ahve the 75mm spigot jaws and they have a lot of grip. Perhaps the wood is a tad too green. But I am a newbie, and still learning..

[Skew ChiDAMN!!]

It sounds like you may be using the wrong screws. If the screws are working loose in the timber then either your screws are too short or they have too fine a thread. Try using shanked particle-board screws and see if they're any better. I heartily recommend drilling pilot holes for them though... they're not the strongest screw in the world. :wink: (Do make sure they're a nice fit in your faceplate, too! ie. no "side slop" in the hole!)

Another possibility is to glue a sacrificial piece to the end of your blank to screw into instead, something that will hold the screws well. I've used both Hot-melt or PVA glue with success. Turn the inside of your bowl, reverse mount and remove the sacrificial piece when you turn the foot. Easy.

Depending on just how green the timber is, as well as the type of timber, you may need to wash down the surface to be glued in a solvent first, so the glue can adhere.

Yet another method: have you had any experience with making Jam Chucks?

[ss_11000]

Turn the inside of your bowl, reverse mount and remove the sacrificial piece when you turn the foot. Easy.

an older thread on the same subject
http://www.woodworkforums.ubeaut.com.au/showthread.php?t=308.

hey skew..do you mean that you turn the outside last on a green bowl???
or just the foot (as usual).

cheers

[Skew ChiDAMN!!]

hey skew..do you mean that you turn the outside last on a green bowl??? or just the foot (as usual).

I turn enough of the outside to define the shape I want... then I start hollowing. Once I'm happy with the shape of the inside, I finish the inside and top half of the outside (I find it's easier to get nice thin walls that way. :D) then reverse mount and finish the lower half and foot.

Everyone finds their own way of doing it.

[ss_11000]

fair enough:)

[joe greiner]

Sheet metal screws are somewhat superior to wood screws for faceplate attachment. Hex head also allows easier fastening, i.e. with a wrench or socket. Predrill about the same diameter as the root diameter of the screw, or slightly less. Also, you may be taking too aggressive cuts; slicing cut also produces less tearout. Assuming poor purchase of the screw in the turning blank, owing to softness of the wood, waste piece gives good attachment of the screws and lots of contact surface for glue to workpiece itself.

Joe

[rsser]

Starr if you're ripping a bowl out of a chuck the first thing to attend to is whether your tenon is big enough and your grip tight enough.

And with green wood you need to keep checking the grip.

Then review the size of your cuts ... bigger than around a third the flute depth? If so it's too much.

... btw, Tomislav, I get less grip out of the 75mm bowl jaws than from the Vicmarc 50mm standard jaws. The reason is the rounding over of the top face of the Nova's. That reduces the capacity of the jaws to dig into the wood.

[rodent]

Who's chuck are you using and i find the square drive screws the best.

[Tomislav]

Thanks Ern, I will look at how well the 75mm holds.. long way to learn yet..