27 Aug. 1976|
Woodturning chucks scroll,make a lathe duplicator,wholesale woodworking power tools,how to build timber retaining wall nz - Try Out
Sometimes on budget chucks the scroll is pulled round using tommy bars to open and close the jaws. On better chucks there are small pinions or bevel gears which engage with gear teeth on the reverse of the scroll.
In the picture on the left of a Supernova scroll you can see the spiral on top and the gear teeth below. The other picture shows a Patriot chuck with one dovetail jaw removed to show the mounting jaw at A.
Scroll chucks designed for woodturning have four jaws (metal turning ones are generally three jaw) so it is possible to grip square section wood.
You might imagine that all that is necessary with any chuck is to push the piece of wood into the chuck jaws and tighten up.
The chuck jaws have a dovetail on the outside so that they can be expanded to grip the inside of a dovetail shape recess in the base of a bowl. The Record Power range of chucks offer exceptional value for money and professional performance, with probably the widest range of accessory jaws available. Wood is a weak, soft material compared to metal and, to grip it securely, the chuck jaws must clamp over a large surface area. When the scroll is rotated, all four jaws slide inwards or outwards in unison in their Tee slots so they are always concentric.
So for maximum grip you have to turn the spigot (a short tenon or projection) to the correct diameter and dovetail angle to suit the jaws of your chuck.