Cracked or Damaged Casting Repair by Reynolds French

Recognized as the Leader
in repair of cracked or damaged castings.
We do field machining, alignment and
consultation for equipment problems,

Rich in experience----Eager to serve

Tulsa, OK, home of Reynolds French Equipment Repair
Providing outstanding service and products to  industry for over 60 years.
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Lock-N-Stitch Repairs

Pulse cavitation, pinholes and other small holes

Cracked Bolt Hole

Cracked accessory mounting hole.

Cracked head bolt hole.

Cracked bell housing bolt hole.

Cracked main bearing cap bolt hole.

Basic metal stitching

The four steps of metal stitching

  1. Drilling the lock hole pattern
  2. Installing the Lock
  3. Start installing stitching pins
  4. Completed repair is ground flush

Used in conjunction with each other, high strength, pressure-tight and durable repairs are easy to perform. Metal stitching is a simple concept wherein the crack or joint is removed and replaced with an overlapping series of stitching pins with Locks installed at intervals along the length of the repair for added strength. Cracked bolt holes, blow-out holes and severed sections can be repaired with confidence. Cast iron is not a mystery metal to be misunderstood or welded without preheating over 900 F. It has many advantages and desirable qualities. Millions of successful repairs on cast iron, steel and aluminum parts have been repaired over the years.

Castmaster or C-Series StitchingCASTMASTER or C Series stitching pins utilize a unique thread design that ads strength across the crack when installed. The patented hook threads work in opposition to the opposing hook angle of the shoulder when tightened. This creates a clamping action and radial drawing force that works to attach the opposite sides of the crack together.

C Series pins are installed in an overlapping fashion along the crack until the entire crack has been removed and replaced by interconnecting pins. They also have a break-off groove above the shoulder that allows the head of the pin to twist of when it reaches the proper torque. Excess pin metal is then ground flush to the surface of the casting.


L Series Stitching pins Utilize standard threads with an interference fit to the tapped hole. These pins do exert a spreading force when tightened that in some cases is important. They feature a preset break-off groove that causes them to always twist off at the same torque. They work very well in stitching in a patch or when the angle of installation to the surface exceeds 20. The tapered shoulder crushes into the surface and leave an invisible finish.

Locks are used to ad additional strength to the repair. The Locks are made of high strength 4130 steel and heat treated to 175,000 PSI tensile strength. The receiving hole-pattern is created with a set of precision drill jigs designed for use with a hand held drill. Locks are installed to a depth of 80% of the casting wall thickness.

The Locks induce a slight pulling action across the crack when installed. This prevents crack extension and keeps the repair tight. They are available in three styles and eight sizes to accommodate different applications.


Full-Torque thread repair inserts

This is a totally new concept in threaded hole repair.

Full Torque thread repair insertsAll bolts and studs produce a significant radial spreading force when torqued. In low strength metals such as cast iron, brass and aluminum, this spreading force often results in cracks. Threaded holes are the number one location for cracks found in castings during rebuilding and repair work.

Utilizing the same unique external threads as the CASTMASTER stitching pins, these inserts will contain the spreading force of the fastener and only transfer a radial drawing force to the surrounding metal. A hole repaired with Full-Torque inserts will become stronger than original. Inserts are available in through hole, blind hole, with shoulders and without shoulders. Solid plugs are available to repair a very badly damaged hole. After installing the plug, a new hole can be drilled and tapped in the proper location.

Understanding Lock placement

Locks need to be added to the repair when additional strength is required. It is advisable to always make the repair as strong as possible so that it will survive moments of extreme operating conditions. Try to use the largest size Lock that is practical to use for the application. Locks can be stacked on top of each other to reach a depth of 80% of the casting thickness. Stack the bottom Locks into the hole pattern followed by one surface Lock at the surface high enough to finish grind or machine off the excess leaving a flawless finish.

The minimum spacing between the Locks for maximum strength is equal to one half of the length of the locks being used. Spacing between Locks is measured from any point on one Lock to any closest point on an adjacent Lock. Locks should be used on all class C and D repairs and on all other types of structural repairs where possible.

LNS Plugs

FSP style solid plug is great for badly damaged bolt holes that have lost the original location or when plugging a miss-drilled hole. Simply install the plug and drill and tap the new hole in the right place.


LNS Pins Installation

3 crack in the crankcase sidewall of a block

The first series of precision spaced holes are drilled along the crack with the drill spacing fixture.

The drilled holes are spotfaced to accept the shoulders of the stitching pins.

The holes are tapped with the special tap.

The first series of CASTMASTER stitching pins are installed into the holes.

The second series of holes are drilled between the first series of installed pins.

After spotfacing and tapping, the second series of stitching pins are installed.

The third series of stitching pins are installed to make a continuous row of overlapping pins.

When all the pins are installed the crack is completely removed, and strength and seal are reestablished.

LNS Locks Installation

After the crack has been stitched with pins, Locks are installed across the repair to add more strength.

The first step is to place Drill Jig #1 on the casting and center it to the crack repair with the centering line on the side of the jig and drill both locating pin holes. Remove the jig and attach Jig #2 into the two locating pin holes

After drilling the four small locating pin holes, change the drill bit and drill the five large holes. Remove the Drill Jig,rotate it 180 and re-attach it to the casting with the same two locating pins and drill the five holes again.

Attach the third Jig and drill the four center connecting holes completing the lock hole pattern. The lock shown here is a L15, which uses 3/32 and 3/16 inch drill bits. The Lock length is 1.400 with 3,200 psi tensile strength.

The Lock hole patterns are spaced along the crack.

The Locks are driven in with press fit using a hammer and stitching pins are installed at the ends of the Locks to prevent them from backing out.

The repair is ground flush to the surface and inspected for gaps and to make sure the entire crack has been removed.

Use a needle scaler to texture the repair site to match the finish of the surrounding roughcast surface.

The completed repair is ready for paint. This 4 inch long repair can be completed in approximately one hour.

*LOCK-N-STITCH and Full-Torque are registered trademarks of

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Reynolds French & Co.
12525 E. 60th St.
Tulsa, OK  74146
Phone:  918-252-7545
Fax:  918-252-7540

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