10 Things to Consider When Buying Thread Repairing

If you are just getting into mending or needlecraft, you have probably noticed that there are a lot of different types of thread and yarn.

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The good news is, there is a lot of overlap when it comes to what materials are used for which type of stitching. This also means that as a beginner, it might be confusing to know how to choose the type of thread or yarn to use for your specific project.

Today, I am hoping to demystify some of this for you. I’ll explain different types of thread, and also yarn (I think it’s fine to use these terms interchangeably), and the terms or numbers you might see when looking for materials to use for your project. Many of these types of thread are sold in my shop, which I will also link to. Sound good?

When you are just getting started, and the options are endless, my advice is to start simple. If you are mending, find yourself some embroidery thread or sashiko thread and you can complete almost any mend with that single type of thread.

The more you mend, the more comfortable you will become experimenting with different types of thread. As your experience grows, you’ll notice how different threads can affect the both the outcome and aesthetic of a mend. 

Sewing Thread

What is it? Sewing thread is a staple for every sewing kit. It comes in varying fibers from linen, silk, or cotton to polyester and blends of poly and natural fibers for added strength. 

What are the different sizes? Sewing thread is more or less a standard thickness. There are specialty sewing threads that are thicker for commercial and heavy duty purposes. 

How is it used for mending? Use sewing thread to sew a button back on, other fine hand sewn repairs, or for use in your sewing machine. Sewing thread is too thin to be of much use when it comes to hand stitching on thicker fabric like denim.

Pearl Cotton/ Perle Cotton

What is it? This type of thread is made up of tightly twisted, indivisible 100% cotton strands that have been mercerized. Mercerization is a chemical process that increases the ability of the thread to take dye, and also decreases its absorbency. This process also increases the strength of the thread. It is noticeably shiny in appearance. Pearl cotton is sold as skeins or balls. 

What are the different sizes? Pearl Cotton is available in different sizes (3, 5, 8, 12, 16). The thickest size is #3 and the thinnest size is #16.

How is it used for mending? For mending and embroidery, I use #8 in my mending. For most dense fabrics, #5 is a little too thick. I don't use pearl cotton in my darning, because it doesn't felt together nicely like yarn or un-mercerized thread. 

Sashiko Thread

What is it? Sashiko Thread is a specialty Japanese thread, suited for hand stitching. It is not mercerized, and has a softer feel and look.

What are the different sizes? Sashiko thread comes in a small variety of sizes, thin or thick. Daruma, a carded sashiko thread is sized with the term, 20/4 or 20/6. The thinner, or 20/4 means that there are 4 strands tightly woven together to create a single strand, and 20/6 is thicker, with 6 strands woven together. Olympus makes skeins of sashiko thread that is closer in size to the thicker Daruma thread.

How is it used for mending? I love the texture of sashiko thread, and use it often in visible mending for denim or wovens, for darning mid-weight socks, and occasionally when darning a sweater. 

Crochet Cotton

What is it? Crochet cotton is another type of thread that is similar to both pearl cotton and sashiko thread in thickness, and it is also cotton thread.  It is mercerized, though is much less shiny than pearl cotton. As the name implies, crochet cotton is used to crochet fine pieces, like lace.

What are the different sizes? There are 3 sizes of crochet cotton. Size 3, which is thicker, size 10, which is similar to a #8 pearl cotton and sashiko thread, and finer in size #20.

How is it used for mending? Crochet cotton can be used in the same projects as pearl cotton-mainly mending denim and other wovens, or used for hand embroidery. I love crochet cotton because it is easily found at secondhand shops, making it a good economical and better environmental choice. 

Embroidery Thread

What is it? Embroidery thread or floss is made from 6 strands of cotton thread, that can be easily separated for use in projects.

What are the different sizes? There is only 1 size of embroidery floss, though you can adjust the thickness by using more or fewer strands. 

How is it used for mending? Embroidery floss can be used in both darning and mending, though because it is stranded, and wants to be divided, it may not stay looking as tidy in projects.

Yarn

Yarn is less familiar to me. Often, when I’m thrifting I will find leftover yarn from projects without labels, or gleefully come across bags stuffed full of vintage needlepoint yarn at creative reuse shops.

Before I started teaching about darning, I didn’t give these different types of yarns much thought other than finding a thickness that worked for a particular project. But then the questions started coming in, so I put my research hat on, and combed through some explanations on yarn sizing. I have included a list of my sources at the end of this post.

What is it? Yarn and thread can be used interchangeably, but for use here, I'm referring to the material that a sweater or knit hat is made from. Yarn is spun, interlocking the fibers together. The fibers may be looser or very tight, and made from natural fibers such as wool, linen, cotton, bamboo, hemp, alpaca, even cat hair! Yarn can also be made from synthetic material, or a blend of natural and synthetic. 

What are the different sizes? Yarn sizing has to do with WPI, or wraps per inch, so however many times it takes the yarn to wrap around a ruler, laid side by side, to get to an inch.

First, let’s talk about the big skeins or balls of yarn you would find at a craft or yarn shop.

There is a standard measurement of yarn set by the Craft Yarn Council, ranging from size 0-7. Other terms used are in parenthesis.

0=Lace (fingering)

1=Super Fine (sock, fingering, baby)

2=Fine (sport, baby)

3=Light (DK, light worsted)

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4=Medium (worsted, afghan, aran)

5=Bulky (chunky, craft, rug)

6=Super Bulky (super bulky, roving)

7=Jumbo (roving)

How is it used for mending?  I typically use for darning sweaters is the 0-3 range. However, depending on the type of repair, you might match the type of yarn chosen for repair with that that the sweater was initially made from, particularly if a hand knit sweater. Yarn is not used for mending jeans and wovens.

Specialty Threads

There are also various types of specialty threads that may be upcycled from textiles, repurposed and overdyed, or even hand spun, which do not fit neatly into the categories above. One examples of these are Mend-It's, which are upcycled from sweaters, and then dyed and carded. 

Weaving yarn is in its own group, and is unwashed. Weaving yarn is sized by weight, calculated by how many yards of yarn is spun from 1 lb of fiber. If you see larger cones of more natural looking fibers, this is likely weaving yarn.

Crewel and more These small skeins (similar to the size of embroidery floss skeins) are made for needlepoint, tapestry, crewel or Persian yarn, and also great to use for darning. Some of these smaller skeins are made up of single strands, and some of multiple strands.

All of the the threads mentioned in this post can be found in almost every hue, tint and shade. Using variegated threads in your mending are also an easy way to mix color. Variegated thread colors change within the same thread, giving your mend a more complex appearance with no added skill or effort. I love using variegated thread in both darning and embroidery style stitched patterns. 

I hope this thread breakdown has given you more insight into the world of thread choices that await you. The more you work with different types of thread, the less intimidating it becomes to decide what will work for any particular project. 

Sources

craftyarncouncil.com/standards/yarnweightsystem

www.orimonoimports.com/thread

sarahmaker.com/yarn-weights-guide/

woolery.com/yarn-weights-helpful-explanation/

worldofneedlepoint.com/guide-to-needlepoint-yarns-and-threads/

A thread repair kit is typically made up of a drill bit, tapping tool, an insertion tool and a threaded insert. An air or electric powered drill and a tap wrench are also required but are not usually standard in the kit. Thread repair kits are a cost-effective means of making a repair in a tapped hole without removing the part or parts containing the damage.

TYPES OF INSERTS

One of the most popular types of inserts is the Helicoil® insert. This insert consists of a small opening that engages with the insertion tool for an insert to be screwed into a tapped hole. The Helicoil® has a design of a tightly wound spring with a diamond cross-section. Though this type of insert may be simple to install, and relatively low-cost, it may not be as secure for a screw or bolt that will be under constant load (dimensional changes of the material it is installed in), high temperatures or torqued to a high level.

One of the most popular types of inserts is the Helicoil® insert This insert consists of a small opening that engages with the insertion tool for an insert to be screwed into a tapped hole. The Helicoil® has a design of a tightly wound spring with a diamond cross-section. Though this type of insert may be simple to install, and relatively low-cost, it may not be as secure for a screw or bolt that will be under constant load (dimensional changes of the material it is installed in), high temperatures or torqued to a high level.

Best application: Helical wire inserts are the way to go when cutting costs and minimizing space are priorities. In softer materials such as aluminum, titanium and magnesium alloys, they are especially helpful for making permanent strong threads and are ideally suited to lower heat and lower torque environments.

The Time-Sert® is another example of a thread repair kit that comes with an oversize drill bit relative to the nominal size of the tapped hole. This style insert is designed and equipped with accessories to drill and remove the old existing threads. The kit consists of a tap to create new threads, a counterbore drill to accommodate an insert flange, the insert which creates the new threads, the driver that inserts the Time-Sert® and a thread locking fluid to ensure the insert stays in place. Time-Sert® is a complete sleeve with threads on the outside diameter to be threaded into the hole and a stop flange to keep the sleeve from spinning inside the hole.

Best application: best in heavy wear, high vibration and high heat conditions, and hole depth is minimal.

The Helicoil® and Time-Sert® are easily found across the market. Although more expensive, the Time-Sert® is a more robust fix compared to the Helicoil® and depending on the criticality of the repair, may offer the right solution for the application. Though there are many options on the market, choosing the right insert depends on the difficulty of the repair, the application, and the cost of a replacement part. Overall, the Helicoil® is a less expensive alternative but can be difficult to install in tight spaces.

ProMAXX Prosert™ Inserts

Th ProMAXX® blind hole insert is designed with a thick wall for durability and made from stainless steel or black oxide coating for corrosion resistance. This high-quality, precision-made insert can withstand extreme temperatures and high torque applications that are often seen in fleet heavy and light-duty trucks.

The advantage of the ProMAXX® engineered inserts is that they completely isolate the fastener from the parent material being machined. This isolation further reduces corrosion via chemical reaction (particularly in aluminum) and because they are steel, can be machined out and replaced if necessary, in the future. ProMAXX® ProSerts™ are high-quality precision tooling and when used with the ProMAXX® thread repair kit, can speed a repair with the results of stronger holding than the original factory hole tapped in aluminum.

Moreover, there are no additional steps required when machining to accommodate the ProSert™. Simply follow the included instructions to drill the hole, apply Loctite®, then twist in the insert with the included ProMAXX insert tool. No breaking of a tab or machining for a flange is required. Best application: The blind hole insert is particularly useful when fixing an exhaust manifold bolt that was over-drilled, drilled off-center, or worse, a punctured water jacket in the cylinder head.

Image caption - Nico ProSert for repairing damaged threads in the head

A Nico Prosert is a threaded insert for 6.7L cylinder head restoration. It offers a permanent repair solution for Power Stroke fuel injector hold-down bolts that break off due to compromised threads and excessive corrosion.

Nino Proserts are heavy-duty inserts made of stainless- or high-strength carbon steel that have two pins to lock them in or a liquid thread lock that provides a positive lock for a permanent repair that is stronger than the original fastener itself. The thick walls are durable and constructed for corrosion resistance. These high-quality precision-made inserts can withstand the high manifold temperatures and duty cycles of the Ford 6.7L Power Stroke diesel engine.

Best application: Nino & Nico 6.7L Power Stroke thread repair inserts were each engineered with a specific application in mind. They are not a universal solution but offer the highest quality thread repair for two frequent and troublesome locations where threads need to be repaired and strengthened.

WHEN TO USE A THREAD REPAIR KIT IN THE AUTOMOTIVE REPAIR INDUSTRY

The dogma of using inserts to make a repair with the advent of newer machining capabilities and material technologies are a thing of the past. Making a repair that is better than factory specs is a good thing! When you combine that with high-quality precision inserts such as ProMAXX® ProSerts™, you get one that looks better too. Aluminum is the predominant material of choice because of the weight-saving factors and environmentally sound practices. Transmissions, oil filter adapters, oil pans, intake manifolds and many other automobile parts can suffer from threads that have been pulled out or a stubborn bolt that has galled into the parent material. Machine shop precision is the key to success in this equation and not as simple as running the tap through the hole. A thread repair kit will not only save a repair but ensures that the problem will not reoccur the next time the area is serviced.

HOW TO USE MOST THREAD REPAIR KITS

• Use a drill bit and bushing of the correct size to drill out the damaged threads.
• Tap the hole with a special thread to accept a threaded insert. Use the tap that is included in your thread repair kit.
• Using the insertion tool, screw the threaded insert into the hole below the surface of the part.
• Unscrew the tool used for insertion.

ProMAXX™ Tools exhaust manifold thread repair kit brings machine shop capability to the engine bay. Our kit includes a hardened steel precision bushing, machine-grade tooling bit, super sharp tap, and four 8mm x 125 black oxide hardened solid steel inserts. The thread repair kit restores stripped or damaged exhaust manifold mounting threads for better than factory spec repair. This kit works perfectly with any 200 Series ProMAXX™ ProKit and should be a staple item in all technicians’ toolboxes.

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Essential Tools For Thread Repair