2013 - Volume #37, Issue #6, Page #39
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They Repair Cast Iron Cracks And More
“Whether you’ve got a cracked bolt hole, a cracked block, heat cracks, impact cracks or design failure, we offer a permanent fix,” says Gary Reed, Lock-N-Stitch. “We make the repaired surface stronger than before the fix.”
Lock-N-Stitch makes a variety of inserts, locks and other tools for metal repair. They also offer repair and training services.
“We are a manufacturing company making the insert pins, locks, thread repair inserts, kits and tooling for repair work,” he explains. “However, we are also a cast iron welding and stitching company, and 50 percent of the parts we manufacture are used by us. We have crews travelling all over the world to repair everything from heavy industry jobs down to the smallest jobs.”
Reed says company products and services are used by major OEM manufacturers like Detroit Diesel, Cat and Deere, as well as by the company’s competitors. The company is currently using their products on the dome of the U.S. Capital.
“We have a 10-man crew repairing 27,000 in. of cracks in the dome,” says Reed. “It will take them a year to do the stitching.”
When Reed talks about stitching, he means drilling a hole or a set of holes using special jigs. Once stitching holes are threaded, they are filled with special inserts, depending on the situation.
As the pins are tightened their heads break off above the surface. Protrusions are ground down, and then a second set of holes is drilled, slightly overlapping the first set of pins. Once these have been ground down, the repair is finished and a solid surface remains.
In some cases, a standard, tapered, threaded pin is used to create radial pressure. This works if the cast has enough integrity to contain the pressure. The solid cast pushes back against the filler pins.
A crack running along an edge of a casting or into a core plughole doesn’t have that integrity. Standard tapered pins will expand the crack due to what Reed describes as “cumulative spreading pressure”.
Lock-N-Stitch offers a special pin design called the Castmaster. The bottom of the fastener thread is 45°, but the top is a negative 20° and acts like a hook. The shoulder of the pin has a reverse angle on it and when tightened into a matching machined counter bore, pulls up on the thread. This draws the metal together.
"Castmaster pins add strength instead of spreading pressure," says Reed.
The Full-Torque hole repair system uses a similar thread pattern for bolt hole repair. Reed notes that freeze or impact cracks often result in cracked bolt holes as well. Stripped or damaged threads in spark plugs and other bolt holes can also be repaired with Full-Torque inserts.
"We can take a bolt hole split right down the middle, put an insert in and pull the metal back together," says Reed. "The more you torque it, the stronger it gets. If it’s repairable, we can come up with a way to do it."
Reed says Full-Torque inserts create a pressure-tight seal that can withstand 3,000 psi hydraulic pressure.
"We don't just do stitching," says Reed. "Damage to cast iron or other cast metals breaks into two categories. It’s either an accident or a design failure where it has cracked under normal operating conditions."
In the first case, Reed uses stitching to repair the problem and bring it back to 100 percent. In the case of design failure, Reed adds reinforcements or brackets to attach.
Reed points out that cast iron is preferred for its traits of staying straight under heat and not warping. However, that same trait makes it extremely hard to weld any place but edges. Welding works best with things that can stretch and bend.
"Attempting to weld cast iron produces massive amounts of confined expansion and contraction that leads to more cracks, especially if the welding is in the middle of the cast," explains Reed. "Stitching avoids the heat issue."
"That can't be done on site or in frame," he says. "That's where stitching with pins and our inserts come in. They let you repair on-site quickly and get back in use. We do lots of ag equipment."
Contact: FARM SHOW Followup, Lock-N-Stitch, Inc., 1015 S. Soderquist Rd., Turlock, Calif. 95380 (ph 209 632-2345 or 209-614-4114; toll free 800 736-8261; www.locknstitch.com; www.fulltorque.com).
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