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The Glass Grinder is a trap from the Saw franchise appearing in Spiral.

Design and Function

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This trap consists of a large scrap shredder with two chutes cut out in the front and a set of fans at the back, with a conveyor to deliver bottles to the shredder. The victim has their hands restrained above their body with their back facing the chutes. When trap begins, many glass bottles are delivered via the conveyor belt into the shredder at regular intervals. Once the shards are small enough, they slip through the grinder into an area below the machine, where a set of fans blow the shards to the other side. The chutes in front of the shredder allows the glass shards to deflect out at high speeds, shredding the main test subject from the back, where they would quickly die of blood loss.

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The second test subject has to find the key in a trashcan using the hint in the tape ("...locked up, and thrown away the key"), and unlock the padlock in the victim, when the conveyor, shredder and fans finally stop. The second test subject is then given 20 seconds to find and use the key to free the first subject, escaping the trap. If they do not do this, the first subject dies of blood loss. (Spiral)


Hello, Detective Banks. I want to play a game. When Peter Dunleavy murdered an innocent man, your career was shattered like glass. Can you stand on the sidelines while justice is finally served? There is a way to save him, or you can keep him locked up and throw away the key. The decision is yours.
— Peter Dunleavy's Tape[src]

The trap was designed and built by William Emmerson, a homicide detective who targeted corrupt members of the Metropolitan Police Department to avenge his father, Charlie Emmerson, who was unfairly killed by Peter Dunleavy.

Ezekiel Banks Test

Pete in his trap

As Zeke navigates his escape, he encounters Peter Dunleavy, his former partner who Banks reported for murder, chained in place. Ezekiel Banks's second test is to save Pete, the victim of the Glass Grinder trap, a machine hurls crushed shards of glass at him. Banks is horrified to find a tape recorder that give him a choice to either save Dunleavy or let him die for his crimes. If Ezekiel seeks to release him, he must find the key to the chain. However, Ezekiel is supposed to not save him, in order for justice to be enacted. If he does not find the key, his ex-partner will die.

Pete's corpse

After Ezekiel played the tape, the machine began to start Zeke realizing what was going to happen to Pete ran over to grab the booby pin he had used earlier to escape. Zeke then tried to pick the lock but failed, the machine had then started shooting glass shards Zeke quickly got out of the way while Pete turned around and had shards of glass lacerate his back. The motor to the machine then stopped Zeke tried picking the lock again but was unsuccessful then the motor to the machine started back up. Zeke thought back to the tape about the clue he then realized what the clue meant and found the key, meanwhile Pete was being lacerated by shards of glass. Zeke shielding himself with a trash can attempted to save Pete but failed because Pete had already died from being lacerated by shards of glass. (Spiral)