LaymarCrafts Woodturning Techniques

 

Aluminum Spigot for Accurate Re-Chucking

When Turning Vessels I often prefer to use a Spigot at the Base as the means of holding the Piece in the Chuck, this is generally 30mm by 25 / 30mm long when using the 38mm (1") O'Donnell Jaws in the APTC Chuck.

The problem that I have experienced is that if it is necessary to remove the Piece from the Chuck before the Vessel is completed then when Re-Chucking, the Vessel will not always run true.

This is caused by the Wood being deformed by the pressure exerted by the Jaws when first placed in the Jaws, then when removed from the Chuck this deformity can swell back to almost, but not totally, its original shape. This makes accurate Re-Chucking difficult, if not impossible, to achieve. 

This situation is often worse for those Woods with variations in Density, i.e. Burrs, Spalted Woods, Open Grain Woods etc and also with the less dense Woods such as Chestnut, Birch etc.

To overcome this I obtained a length of Aluminum Tube (The Ink Transfer Drum from an Old Fax M/C) this is quite a Hard Aluminum  and at 32mm externally and 26mm internally was ideal for my requirements, I cut this into 6 lengths of approximately 40mm giving me six potential Re-usable Aluminum Spigot Tubes.

The Picture shows four of the Spigot Tubes, the one on the right has the remains of a Beech Vessel I had previously Turned and by boring a suitable sized hole with a slight taper this was used as a Jam Chuck for finishing some Shaker Pegs I was making for a local Kitchen Unit Manufacturer.

Being Aluminum it is an easy task to true the ends up on the Lathe using a Medium Cut File. The dimensions  of the Tube required  will of course differ from Chuck / Jaw make and size.

In use I mount the Piece of Wood I want to Turn between Centers or mount it on a Screw Chuck and Turn it to a Round and then carefully Turn a Spigot to give a good interference fit in the Aluminum Tube once this is done I mount the Tube in the Chuck and then with a few drops of Superglue on the Turned Spigot push the two together.

Set Up and ready to go, the piece of Wood is held between centers and the Aluminum Spigot Tube is placed over the Tailstock Barrel.
Closer view showing the Aluminum Spigot Tube on the Tailstock Barrel.
Spigot turned to Size and a length, not necessarily the same length as the Tube, to suit the overhang of the piece you will be Turning  and the type of Wood you will be using.
Aluminum Spigot Tube should have a firm push fit on the Spigot.

Once you have the correct Spigot Size add a few drops of Medium density Super Glue around the Spigot and using a twisting motion push the Aluminum Spigot Tube into place.

The Piece of Horse Chestnut in the Chuck and ready for Turning.

Aluminum Spigot Tube sits out from the Chuck allowing easy access to the rear of the piece being Turned.

This particular Vessel was Dyed and Re-Chucked 3 Times before being Fully Finished.

 

Now if at any time you want to remove the Work from the Chuck you will be ensured of a Firm and Positive Spigot when you come to remounting the Piece which will always run True.

Parting off is carried out as normal and I true up the Wooden End of the retained portion of the Spigot as I often also turn smaller items that require a smaller diameter spigot and it is therefore easy to mount the Tube + Wood Insert and bore this out to suit the size of spigot.

Once the Tube is finished with it is a simple task to mount it in the Chuck and carefully Turn out the old Wood Core and the Tube is then, again, ready for your next Project.



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Last update 17 July 2007
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