The expanding ring mandrel is made from stainless steel bar stock and is completely CNC-machined for a precision fit and almost zero runout.Our expanding mandrels come with hex keys. Simply chuck up the ring mandrel, slide on the ring core, and tighten the hex key to secure the core from spinning. Use minimum pressure to keep the ring core from rotating on the mandrel. This will also ensure the mandrel does not distort the ring when clamped. The expanding ring mandrel will significantly reduce runout/concentricity issues between the wood band and metal core, which you would encounter when using wood jam chucks or expanding rubber sleeves (sanding sleeves). It can be used for turning, sanding, and finishing your ring creations. For those who make all-wood rings, this is the perfect addition to your tool collection. Use care not to overexpand the mandrel, which can cause a permanent set in the diameter. If the mandrel does become 'over-expanded,' simply remove the screw, compress the stepped segments together using a hose clamp to restore the original size. Option A has an 18mm circumference on the bottom handle. Option B has a 15mm circumference on the bottom handle.
