NOVA Cole Jaws Review
Rubber buttons on an aluminium plate that grip a bowl rim so you can turn the foot off. One job, and nothing else does it as safely.
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Every bowl held in a chuck has a tenon or a recess on the bottom that the chuck gripped. Once the bowl is turned, that tenon has to come off, and the foot has to be finished. That is the whole reason Cole jaws exist.
They are large aluminium plates that bolt onto a scroll chuck in place of standard jaws, drilled with concentric hole patterns. Rubber buttons screw into the holes. Set four or eight buttons on a circle matching your bowl’s diameter, expand the chuck so the buttons press outwards against the inside of the rim — or contract it to grip the outside — and the bowl runs held only by friction on rubber.
The foot is then completely accessible.
The safety rules, which are not optional
Friction on eight rubber buttons is a fraction of the grip a chuck has on a tenon. Three things follow.
Run slow. Cole jaws are a low-speed accessory. The manufacturers’ warnings on this are not boilerplate — a bowl leaving the lathe at speed is a genuine hazard, and the plates themselves are heavy and out of balance at the best of times.
Take light cuts. You are removing a tenon and refining a foot, not hogging. If the tool needs pushing, the bowl will move.
Bring up the tailstock while you can. Turn the tenon down to a small nub with the tailstock supporting the bowl, then remove the tailstock and pare that nub away by hand or with a very light cut.
Getting it concentric
The buttons must sit on a true circle for the bowl to run centred, and it is easy to end up one hole out. Mount the bowl, spin it by hand, and watch the rim against a fixed point before the lathe is switched on. Adjust and check again. A bowl mounted 2 mm off centre will have a foot 2 mm off centre, which reads as a wobble every time the bowl is set down.
Alternatives worth knowing
A shop-made jam chuck — a waste block turned to fit the bowl’s opening — costs nothing and works well for a one-off. A vacuum chuck is faster and holds harder than Cole jaws, and costs considerably more once you have bought a pump and a rotary adapter. Cole jaws sit in between, which is why they are the usual answer.
What works
- Reverse-chucking a bowl to remove the tenon and finish the foot is the step that separates a finished bowl from an obviously unfinished one, and this is the safe way to do it
- The rubber buttons grip a finished surface without marking it, which a jam chuck or a vacuum chuck ring will not always manage
- The buttons reposition in multiple hole patterns, so one set covers a wide range of bowl diameters
What doesn't
- They are strictly a light-cut, low-speed accessory: the grip is friction on rubber, and an aggressive cut will throw the bowl
- Setting the buttons concentric takes patience, and a bowl mounted off-centre will wobble and then leave the foot off-centre too
- The jaw plates are large and vulnerable — a catch with a gouge against an aluminium plate spinning at speed does real damage to both