Sean previously covered the Veritas twin screw vise with a chain drive here at TM. Evidently Lie-Nielsen thought it was such a good idea they produced their own chain drive vise. The concept behind both vises is simple: make sure the large jaw closes parallel by turning both screws the same amount.
The 1-1/8″ x 5tpi screws are made from rolled thread acme rod and are designed to give you a maximum opening of 8-1/4″. You can choose to set the screws 8″, 12″, 18″, or 24″ apart depending on your needs. Four bronze bushings and four needle bearing and washer assemblies reduce wear and make the vise operate smoothly.
The hardware to make the vise will run you $285 with $18 shipping. You can either buy a pre-made jaw with 12″ screw spacing for $70 plus $12 shipping or “borrow” an installation kit for a $45 deposit. The vise handle, which can be mounted on either the right or left screw, is sold separately for $35.
Chain Drive Vise [Lie-Nielsen]