If you have ever dabbled in woodturning, and specifically in bowl turning, you would have come across the problem of trying to refinish the bottom of your turned bowls after you have hollowed out the bowl itself. Because of the general process or procedure of bowl turning, where the back side and bowl foot/bottom is turned first, and then this foot is chucked up to hollow out the inside of the bowl, the chucking of the bowl's foot often leaves chuck marks or indentations that need to be smoothed out or re-turned to remove them. The problem is that it is very difficult to re-chuck a bowl using its top outer rim with conventional woodturning chucks.

Wood turning machine and chuck manufacturer, Teknatool, designed the Cole Jaws to solve this common problem...

The Nova Cole Jaws
The Cole Jaws are an accessory set of jaws designed to fit the Teknatool Nova, Supernova, Supernova2, Titan and G3 woodturning chucks. They are named "Cole Jaws" after one of Teknatool's woodturning demonstrators, Trevor Cole, who helped design and produce the jaws to solve that common problem of re-chucking bowls to finish the bottoms, or to remove the foot completely to producing a smooth bottomed bowl. The "Nova" part of the name comes from Teknatool's best selling line of Nova and SuperNova woodturning chucks.

The Cole Jaws comprise four separate, but identical metal plates. These plates attach directly to the chuck's jaw slides using threaded screws supplied. Each plate engages in the small radius groove found on these Teknatool jaw slides, and the screw mounts line up with the existing jaw slide tapped screw holes (which also allow fitting of a wide variety of other Teknatool jaws and accessories). All plates are machined to the same specs and design, so attaching the plates in a specific order or configuration is not required, hence simplifying the installation process.

Each plate has a further 14 additional tapped screw holes radiating out from the "center" of each plate. These holes are designed to accommodate the round rubber holders, of which two are attached to each plate, making a total of eight holders on the fully assembled Cole Jaw. The rubber holders are what hold the bowl in place via a friction grip.

You can move the holders to any of the screw locations on each plate but given that, in most cases, the rim of your bowl will form a perfect round shape, each stopper will be located in a screw hole the same distance from the center of the jaws. You should select a holder location that allows the bowl to fit within the diameter created by the eight rubber holders, so when you tighten the jaw slides on the chuck itself, a firm grip is attained on the outer edge of the bowl. Because of the rubber design, bowls hold very well once secured and the rubber surface creates virtually no problems with marking or marring your bowl's edge/rim.

Once a bowl is mounted in the Cole Jaws, you have free access to clean up the bottom of the bowl and its foot with your turning tools, to remove the foot altogether with further tooling, or to finish it appropriately with a woodturner's finishing product. There is no way to hold a decent sized bowl like this with a regular woodturning chuck without additional accessories like the Cole Jaws (unless you have a very small bowl!).

You can achieve a similar grip on a bowl using a specialized vacuum chuck, but these are generally much more expensive to purchase initially, and require much more setup time, plus a compressor and fittings to use it. The Cole Jaw is a much simpler and more cost-effective method for re-chucking bowls.

Now, there are certain considerations to using the Cole Jaws. First, the Cole Jaws we tested were model JSCOLE. These jaws, out of the box, allow chucking of a bowl up to 10 inches in diameter. They can be used on any lathe that has a 10 inch or greater swing over the bed. If you have a mini-lathe with less than a 10 inch swing, Teknatool also make Mini-Cole jaws to suit these smaller lathes.

If you need a diameter capacity greater than 10" for a larger bowl, you can actually make your own MDF segments to attach to the Cole Jaws. Full instructions for doing so are provided in the printed manual included with the product. The manual itself is well-written, but apart from the safety information included, I didn't really need to reference it to assemble the Cole Jaws. It all goes together easily and intuitively.

The other issue with using the Cole Jaws is that they have a maximum recommended speed of 600 RPM when in use. This didn't present a problem in use for me personally, but a lower lathe speed does mean you have to take any re-finishing cuts a little lighter, and take care in doing so. Naturally, a faster lathe speed, especially when working around the center point of a piece, makes cutting easier and a little smoother, but any re-finishing cuts will generally be very light or shallow anyway so 600 RPM seemed fine for me. Besides, you don't want an attachment that large spinning too fast! The individual plates seem very well balanced and there was no noticeable vibration caused when using the Cole Jaws at the recommended speed.

For re-finishing the base of a bowl, you do not really need to perfectly re-center the bowl in the Cole Jaws, although you can quite easily get it as close to perfect as it needs to be without too much problem. The very small margin of error (or degree the bowl is off-center when re-chucked) will hardly be noticeable on the finished piece.

Overall Use and Opinion
Using the Cole Jaws is child's play. It is very simple to use. Just position your rubber holders as required for the diameter of the bowl, place your bowl in the center of the ring of holders with its top rim flat against all four Cole Jaw plates, then use your chuck wrench to tighten the jaws of your chuck, and hence the rubber holders, around the edge of the bowl. Your bowl is now chucked up with the bottom exposed ready for final tuning, sanding and finishing. The most time is consumed actually attaching and removing the Cole Jaw plates from your existing Teknatool woodturning chuck. However, there is a solution to this as well which is well thought out. You can purchase another set of jaws from the Teknatool range or use the jaws that come with your chuck (if appropriate) and mount these onto the Cole Jaw plates. This then allows you to turn a bowl using regular jaws (for bowl shaping) without having to add and remove the Cole Jaws each time you wish to re-chuck a bowl for foot finishing. A nifty idea!

There is no point spending a good amount of time actually crafting your woodturned bowl only to have some annoying chuck marks on the foot of the bowl ruin the overall look. For the retail price of around AUD$99 / USD$79 the Nova Cole Jaws are an essential accessory for all woodturners who craft turned bowls on a regular basis.

Cole Jaws Photos
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One of the Cole Jaw plates

Cole Jaws mounted on a
SuperNova 2 chuck.

The reverse side of the Cole Jaw plates.

Rubber holders secure the bowl.

Note how this chucked bowl is only half finished from chucking via the foot and a normal woodturning chuck. Here you can see how I have access to the full base/bottom of the bowl to refine the foot and sand and finish the piece.

Smoothing out the foot of the
bowl with a shear cut.