Carving out custom workholding

Aug. 1, 1999
A vise doesn't always become a dedicated workholding system just because a shop carves the jaws.

A vise doesn't always become a dedicated workholding system just because a shop carves the jaws.

CarvLock and FixtureVise are the foundation of Kurt's workholding system that can include jaw blocks with four machinable sides.

The two dotted circles represent the pocket on the underside of the moveable, carvable jaws.

An angular nose engages or hooks into the movable jaw's surface to hold it down.

Rounded or arced surfaces contact the inside radius surface in the underside of the movable jaws.

Kurt Manufacturing incorporates both quick-change jaw plates and machinable jaw blocks into one workholding system. Called CarvLock, it provides flexibility by offering various jaw plate options that make one vise seem like four. Shops can set up the system using either a standard jaw package, Kurt's EZLock jaws, or carvable jaws offered in two material types. All of which interchange on a single vise base for workholding flexibility.

Kurt's carvable, stationary, and moveable jaw blocks have four machinable faces, as opposed to two. "Each block is the equivalent of four fixtures," says Ingo Wolfe, company vice-president. The blocks are 90° indexable, made of ductile iron or aluminum, and come in three heights.

The vise's machined body rail fully supports nuts that have the manufacturer's special conical hook. It is similar to Kurt's Anglelock configuration but was redesigned for quick change. Movable jaws have an angular, circular bottom surface that contacts the nut, which has a matching surface. This allows jaws to be put on and taken off quickly, while self-aligning up to 10° on removable keys.

Operators simply pry up in the rear keyway with a suitable tool (screwdriver) to remove the moveable jaw blocks. Engaging the rear surface of the vise nut while pushing forward on the block will quickly snap the jaw block back onto the vise body. Jaws repeat to within ±0.001 in. when removed and reinstalled. Stationary center jaws have the same features as the moveable jaws except they are fastened to the vise body with four cap screws.

When carved to a specific part shape, this jaw block will contain the datum reference features of the part being held.

When carving jaws, the movables are brought toward the stationary jaw only as far as necessary for adequate support. With spacer blocks clamped tightly between both jaw openings, users can then machine the contour for a specific part. For the greatest holding rigidity, says Wolfe, remove only as much material as needed to clamp the part. However, if users need to carve deep, a low hook area lets them do so without vise damage.

The hook is located more forward, close to the front edge of the clamping location, to eliminate lift. "Vises with hooks in the center," says Wolfe, "will not give the same results."

As a multiple-part workholding system, CarvLock reduces machine travel from part-to-part and toolchange times. Its locator key system speeds setups and locates on a 40-mm, 50-mm, or 2-in. grid pattern. Made of 80,000 psi ductile iron, the vise body, along with other steel components, absorbs and dampens cutting vibration.

All the CarvLock jaw options not only apply to CarvLock double vises but are also inter-changeable with Kurt's single-vise system, called FixtureVise. In addition to these, the company offers its EZLock system, consisting of moveable and stationary jaw blocks with a new lock/un-lock mechanism.

What makes the system special is that the vise does not have to be opened wide enough to get an Allen wrench in for changing the blocks. Two hex-head fasteners, accessed from the top, draw the jaw plate in with a half turn. Another half turn in the opposite direction releases the jaw plate, which is then removed vertically.

A split locating pin forces the jaw to one reference side, ensuring accurate remounting. With conventional jaw plates, users loosen four bolts in 180° turns, then repeat the process to reinstall new plates. The whole procedure can take over four min, says Wolfe. "It's done in under a minute with the EZLock system."

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