VEVOR 4-Jaw Lathe Chuck, 10 in (250 mm), Lathe Chuck, 0.6-9.84 in (15-250 mm) Clamping Range with T-key Fixing Screws Reversible Jaws, HT300 Cast Iron Material, Internal External for Wood Metal Lathe

Establishing a spigot on a backplate for a 250mm 4-jaw independent chuck is a critical task for ensuring the chuck runs true. On an English lathe with a "00 nose" (typically a threaded spindle nose), the backplate must be machined while mounted on the lathe's own spindle to guarantee alignment. Please refer to the video in the link below. https://www.youtube.com/watch?v=90YE2zdjlaw

For installation, it uses a flat-back (short cylindrical) rear pallet connection. The chuck has a 206 mm diameter recessed locating ring groove on the back. You will need to precisely mate it with a flange with a 206 mm outer diameter flange (Spigot/Boss), either by yourself or by purchasing one. Then, use three M12 bolts to lock it in place from behind the flange via the threaded ring on the back (thread engagement circle diameter 226 mm).

This is a genuine K12 series self-centering (interlocking) chuck. Turning the key in any position will cause all four jaws to move simultaneously towards the center or outwards (if you need individual adjustment for each jaw to clamp irregularly shaped parts, you should choose the K72 series independent chuck).