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Metal Stitching

Metal stitching or metalocking as it is called in some parts of the world, have become generic phrases that describe methods of repairing cracks in cast metals without welding.  Why metal stitching?  Well, primarily because of the need for an alternative to the difficulties encountered in welding.  Cast iron is the most difficult of all common cast metals to weld.   All electric welding methods for cast iron have proven to be less than satisfactory and in many cases can cause even more cracks.  Most electric welds with nickel rod on cast iron fail.  Most cause more damage than was present before the attempted weld. Proper cast iron welding techniques require complete disassembly and oven preheat at 900º F. to 1500° F.  And there is a lot of time and effort involved in the clean-up and machine work of any welded piece.

Many different concepts have been tried over the years and most have been called metal stitch or metalock. A main part of the process that replaces the crack itself is the stitching pins. Some of the items that have been and are still used are:  bolts (copper-and zinc-plated); tapered plugs (both threaded and non-threaded); threaded rods; screws; set screws; dowels; and just about anything else that could be stuffed, hammered or screwed into the space.  Over time, these items have been called 'plugs', 'pins' and 'stitching pins'. Modern CNC machining processes have made it possible to manufacture new patented thread and design technologies that have made very important improvements to the art of casting repair.  There are currently two styles and multiple thread lengths and diameters available from LNS L Series and C Series.

The other element of metal stitching or metalocking is the locks.  They are primarily used in industrial repairs although there are applications in smaller castings.  Locks require a flat spot for installation.  Locks have also evolved over the years and have been created in many shapes, sizes and strengths.  LNS has a wide range of locks for performing repairs. Our receiving hole patters are completely created by drilling unlike the old Metalock process that relies on drilling spaced out holes and then using crude chiseling procedures to connect the holes. This lack of precision and size limitation leaves the old process seriously lacking in strength and function.

Many repairs may require using only stitching pins such as in cracked cylinder head repairs and cracked engine block repairs. Often large industrial repairs with structural damage only that don't require sealing the crack can be repaired with Locks only

Here is a glimpse at the advantages of metal stitching now at the fingertips of repair craftsmen.

bulletSpeed.  Installing LNS products can be done quickly with pneumatic tools.  Up to one inch of repair can be done in 5 minutes in 1/4" thick cast iron.
bulletEase of use.  The pins are designed with a breakoff groove that causes each pin to break off at the same predetermined torque.
bulletFlawless finish.  All LNS pins have shoulders that set into the casting so the threads aren't exposed at the surface.  Perfect metal-to-metal finishes are easy to accomplish.
bulletHigh pressure seal.  Stress free, uniform repairs seal without the use of epoxies and coatings required by inferior stitching products.
bulletHolding power.  LNS pins and locks create strength and seal over every linear inch of the repair.
bulletComplex contours.  Inside and outside corners are now as easy as flat surfaces.  C Series (CASTMASTER™) stitching pins don't spread the crack, in fact they pull the sides of the crack together.

The products developed and patented over the old metalocking process by LOCK-N-STITCH Inc. have been used for hundreds of thousands of successful repairs in many industries.  These repairs have been performed by both LNS repair personnel and LNS product customers to parts used in oil & gas, automotive, power generation, mining, railroad, trucking, metal working, construction, agriculture, shipping, and other industries.  These products have been extensively tested, approved, and used by General Motors, Navistar, Caterpillar, Cummins Diesel, Mack Truck, Chrysler, Dresser Rand, Cooper Bessemer and many others.

Possibly the most prestigious repair to date performed using LNS products was done by the developer, Gary Reed.  He performed a repair on the US Capitol Dome in Washington, DC.  The dome itself weighs almost 9 million pounds and is made of cast iron.  This is an architectural icon, a monument to freedom and humanity that must stand forever.  Repairs done properly with LNS products do, indeed, endure.


We manufacture a complete line of stitching pins, locks, thread repair inserts, kits with tooling and accessories for you to use to create dependable, durable repairs.  These innovative products are possible because of advances in machinery technology and the ingenuity of our development team.  Metal stitching has become a true craft that can be learned and performed well.  

We manufacture and sell products covered under US Patent No. 5,379,505; 5,417,532; 5,499,892; 5,562,371; 5,944,303; 6,071,051; 6,126,367; 6,212,750; 6,261,039; 6,382,893; 6,435,788; 6,439,817; 6,572,315; 6,725,518;

Australian Patent No. 684525; Russian Patent No. 2137581.   Many additional international patents have issued and are pending.

L Series    C Series     Locks    Comparison to Older Methods    Cast Iron Welding

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