Archive for Wednesday, October 21, 2009

Shawnee inventor’s advice to stop burglaries is simple: Zip it

Door-locking system awaiting patent, customers

Stan Demster invented and has begun to produce and market the Doorzipper, a device, he says, “turns anybody’s door into a bank vault.”

Stan Demster invented and has begun to produce and market the Doorzipper, a device, he says, “turns anybody’s door into a bank vault.”

October 21, 2009

A new locking system promises to thwart thieves, and its developer says it will be made in Shawnee.

Stan Demster has begun to produce and market the Doorzipper, a new device that “turns anybody’s door into a bank vault,” Demster says.

“We do our testing on the cheapest door you can buy at Lowe’s, and you cannot beat it in,” he said.

The Doorzipper is more than 15 years in the making, and Demster says he hopes to ramp up production and marketing of his invention once his company is better established.

Doorzipper engages 24 interlocking stainless steel tabs along the edge of any door when a key or latch, just like a deadbolt, is used to twist them into place. The first Doorzippers were installed last year, Demster says, and the product’s patent has been pending for about nine months.

Demster said he was inspired to create a better locking system in his youth. When he was growing up in the late 1950s in Shawnee, attending St. Joseph’s School, he remembers people trying to break into the house he shared with his mother one night. He said he scared the would-be robbers off by yelling that he had a gun and would shoot if they kicked the door in, but the experience taught him how little typical door locks can really do.

“Door locks and deadbolts and all these things people put on their houses are only capable of keeping the good guys out,” he said. “They don’t do anything to keep the bad guys out. … So I decided I was going to find a way to lock a door to keep the bad guys out.”

When he went to Kansas University, Demster majored in mechanical and electrical engineering. After years of tinkering, he got his first patent on a locking mechanism in 1982. He said he also hold 11 other patents for other items related to heating, ventilation and cooling systems.

Demster said he quickly realized his first locking mechanism had several flaws.

“Being a young man, I didn’t realize it was a great lock, they couldn’t pick the lock or anything, but they could just kick the door in,” he said. “I realized the issue was making the door force proof.”

It then took another 15 years to develop a lock that would reinforce the doorjamb and the door itself, and even stay hidden from sight: the Doorzipper.

Similar to putting several locks down the side of a door, as often seen in popular culture images of New York City apartments, the Doorzipper reinforces the door along its length. But because one strip of upward-facing steel tabs is put on the inside of the door, and one strip of downward-facing tabs is put on the inside of the doorframe, it is invisible when the door is closed.

The strip on the doorframe is nailed into the studs of a home, further reinforcing it, whereas many deadbolts are only nailed into a flimsier wooden support inside the doorframe, Demster said.

Other benefits of the lock: it is easy to rekey; it is unable to be broken into with “bump keys,” keys that will work for all locks of the same type, or “key bumping,” a way of picking locks; and it more forcefully pulls the door up against weather sealing, saving energy.

Demster said he wants to ensure the product is made in the United States — Demster’s company, KJD Services, set up in its Shawnee digs in mid-June at 6936 Martindale — and uses only parts made here, as well. The economic downturn has slowed down the company’s growth so far, but Demster said he’d like to add 30 jobs to the company to further produce and market the Doorzipper.

“Hopefully not too far in the future, we’ll become a household word, like ‘Kleenex,’” he said.

For more about the Doorzipper, visit


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