Deltana CC78 Corner Chisel for Squaring Radius Corners 7/8" Depth

A corner chisel squares off the rounded corners left by a router or hinge template so a square corner hinge will sit flat in the mortise. The Deltana CC78 is made for exactly that job, preparing the door (or frame) mortise for square corner hinges. If your hinges have radius corners, you don't need it; radius hinges drop straight into a routed pocket.

The CC78 cuts to 7/8 inch depth, which is the length of the cutting legs. That depth covers standard butt hinge mortises on a wood door or jamb. For a deeper pocket you would have to chase the remainder by hand.

A corner chisel is a struck cutting tool for paring wood fibers, so use the CC78 on wood doors and wood jambs. Hollow metal frames come factory prepped for hinges and are not chiseled in the field. If you're working a hollow metal opening and need strike prep instead, a template ASA strike such as the Cal-Royal ASA478 is the part that drops into the standard frame cutout.

Only if the hinges are square corner. Routers leave a radius at each corner of the pocket; the CC78 removes that radius so the square leaf seats fully and the hinge doesn't rock or stand proud. With radius corner hinges the routed pocket is already the right shape.

No. The Deltana CC78 is a corner chisel used to prepare the door for square corner hinges, cutting a 7/8 inch deep square out of a radius hinge mortise. The Cal-Royal PDL-200 is a privacy door latch disengage tool in steel construction, used to release a privacy bed or bath latch from outside the room. One is a door prep tool for the installer, the other is an access tool for a locked privacy set, so they do not substitute for each other.

For the hinge mortise itself you want the Deltana CC78 corner chisel, which squares the rounded corners of an existing radius mortise to 7/8 inch depth so a square corner hinge will seat. The Cal-Royal ASA478 is a template ASA strike for commercial doors, a strike component that goes in the frame on the latch side. They address opposite edges of the opening and a hinge changeover does not involve the strike unless you are also changing the lock.

Deltana lists the CC78 as commercial grade hardware, and it's used the same way on either job: squaring hinge mortise corners on wood doors and frames. Locksmiths and door installers use one chisel across a whole building's worth of openings.

The CC78 is sold each, one chisel per unit. A single chisel squares all four corners of a mortise, so one tool handles the job; buy multiples only if you want a second on another truck or a spare.

It squares any routed pocket corner up to 7/8 inch deep, which includes face plate and strike plate mortises with square corners as well as hinge pockets. Deltana's stated purpose for the CC78 is square corner hinge prep, so treat other square-corner paring as the same cut, not a different tool.