Subscribe Search

Search form

Junkyard approach to demining

Junkyard approach to demining

Inventor Gary Christ left Siem Reap this month to trawl Chicago’s scrap yards for the raw materials needed to build the second prototype of his innovative demining machine

Photo Supplied

Gary Christ’s first demining machine detonated land mines by dropping a weight on them with an electromagnet.

An ASPIRING inventor has created a machine that he thinks will speed up Cambodia's demining program, if he can persuade the organisations in charge of ridding the country of the deadly devices to help fund and develop it.

Gary Christ, a regular volunteer worker in Siem Reap, cobbled together his own demining machine two years ago in a workshop at his Chicago home  and, after receiving feedback from the Mines Advisory Group, he returned to the United States this week to start work on a second version.

Christ's demining machine was welded together from a 60-year-old tractor, scrap metal, old tyres, wooden boards, a 450-kilogram weight and a giant electromagnet. It looked like something built to track down and flatten the Roadrunner, but Christ believes his design can clear a field of land mines for less money and with greater speed than the professionally manufactured alternatives.

The genesis of the machine lies in Christ's work with the Angkor Association for the Disabled, which provides assistance to land mine victims. Christ and the association have been struggling to establish a farm in Cambodia, so that land mine victims can support themselves instead of relying on begging. Christ was raised on a farm in the US, and joined the association as an agricultural adviser. But working the fields in Cambodia brings an entirely new set of challenges.

"When we farm in America we take out trees and rocks," said Christ. "Here, it's land mines."


Gary Christ.

The association had to abandon its first fledgling farm in Battambang province last year because the area was rife with mines. But the setback only cemented Christ's longstanding desire to take action against Cambodia's mine infestation.

"Cambodia is 10 years behind their demining schedule," said Christ. "The 2010 proposed deadline is not going to be met. But I believe I have a machine that will speed the process."

The starting point of the US$40,000 machine was the 60-year-old tractor that Christ learned to drive on, which he armoured against shrapnel with old tyres and wooden boards. The tractor was the driving vehicle for Christ's land mine detonator, which operated on a very straightforward principle.

"When you think of how a land mine is activated, it's by a footstep. So that's what this machine does." Christ's machine replicated a human footfall by using an electromagnet to drop a 450-kilogram metal slab, which stomped on land mines with enough force to absorb the brunt of the explosion. In its testing phase, the prototype tractor crawled through fields, periodically dropping the weight on mines. The bottom of the metal block was formed by a series of free-hanging pegs, which allowed the weight to effectively cover uneven ground.

Christ's electromagnetic stomper is competing against the mechanical flail method, a World War II-era design that involves continually whipping a series of chains into the ground in front of the driving vehicle. The flail technique is a leading method for demining, but Christ sees it as inefficient. "I was raised on a farm and we used flails for various applications. But it's a lot of weight, and it takes a lot of power, and it gets tangled up in the brush. With a flail, gravity wants to go one way, but you're making it go another way instead. It's a lot of energy being wasted, really. I wanted to make something simpler that uses less power and doesn't get tangled."

Christ is building his new demining machine in the same way he built his last one: by himself, in his own time and with a small amount of money. "It would be nice to have a big budget," said Christ. "But doing it with just a little money, you get to see if your heart is in it. You can't just go down to a shop and buy parts for it. That's what creates innovation. That's how I've always built things."

The budget for the new machine is $20,000, and to complete it for half of what he spent on the first version, Christ has hammered out a shoestring construction strategy. "How will I start? In prayer. Then I'll go to the scrap yard. In Chicago we have so much industrial scrap. You can buy the pieces for one-tenth the cost. I'll load up my truck with stuff and cut, weld and fabricate it in my workshop."

If all goes to plan, the new machine will be two-and-a-half metres long by one-and-a-half metres wide, far smaller than its burly predecessor. It will also be remote-controlled, making it safer to operate. Instead of dropping a weight with an electromagnet, it will have a 600-kilogram weight attached to a hammer system. Finally, it will be powered by compressed air.

"The machine will work on compressed air instead of really high-powered motors and hydraulic systems," said Christ. "It'll keep the costs down because when the engine's running it stores the energy."

Christ hopes to finish the new machine in December and will present it to the Cambodian Mine Action Centre. His ultimate goal is to work with Aki Ra, curator of the land mine museum, and start producing the machine in Cambodia, providing manufacturing and demining jobs for disabled Cambodians.


  • Australians protest Asean summit visit by PM Hun Sen

    Hundreds of protesters gathered in Sydney’s Hyde Park on Friday to protest against Cambodian strongman Hun Sen, who claimed to have been gifted millions of dollars by the Australian government ahead of a special Asean summit this weekend. An estimated 300 protesters, the majority of

  • American ‘fugitive’ arrested in Cambodia outside of US Embassy

    An American citizen was arrested on request by the US Embassy in Phnom Penh on Tuesday, according to Cambodian police. Major General Uk Hei Sela, chief of investigations at the Department of Immigration, identified the man as American Jan Sterling Hagen, and said he was

  • One Australian, one Cambodian killed in explosion at military base

    Updated: 5:20pm, Friday 16 March 2018 An Australian tourist and a Cambodian soldier were killed in an explosion on Thursday afternoon at an army base in Cambodia’s Kampong Speu province. The Australian, whom the government initially identified as a technical demining expert in his 40s, and

  • Peeling back layers of prehistory in Battambang

    When the man passed away, he had not yet reached 50. He belonged to a tribe that had settled near the Sangker River in Battambang province, likely cultivating the fields and raising animals. On the side, they hunted for boars, and even turtles, one of which