The No Jam Yarn List: The Best and Worst Yarns for Your Sentro and Addi Crochet Machines

If you own a circular knitting machine like the Sentro 48 or the Addi Express, you know the sound.

It’s that sickening crunch.

You are halfway through a beanie, cranking happily, when suddenly the handle locks up. The gears grind, the machine lifts off the table, and you hold your breath, hoping you haven't stripped the plastic teeth inside.

90% of the time, the machine isn't the problem, the yarn is.

While these machines are often advertised as compatible with "standard size 4 worsted weight yarn," the reality is much more nuanced. A thick worsted weight will break your machine, while a thin worsted weight will knit like butter.

To save your gears and your sanity, we’ve tested dozens of brands to compile the ultimate No Jam list. Here are the best and worst yarns for your knitting machine.

The Golden Rule: It’s All About the "Squish"

Before we list the brands, you need to understand the physics. Knitting machines do not like friction. They rely on the yarn stretching slightly to pop off the needle latch.

• You want: Yarn that is slick, shiny, and elastic (stretchy).

• You do not want: Yarn that is stiff, matte, or rigid.

The Best Yarns (The "Green Light" List)

These are the workhorses. They glide through the tension guide smoothly, rarely drop stitches, and produce a professional-looking fabric.

1. Caron Simply Soft

If there is a "Holy Grail" for machine knitting, this is it. Caron Simply Soft is technically a worsted weight (size 4), but it is slightly thinner than average. More importantly, it has a glossy, satin-like finish that drastically reduces friction.

• Why it works: It is incredibly slippery. It slides through the plastic feeders without catching.

• Best for: Beanies with a nice "drape" (slouchy hats) and scarves.

• Verdict: [Check Price on Amazon]

2. Lion Brand Heartland

If you want your projects to look expensive, skip the budget acrylics and grab this. Heartland is an acrylic yarn, but it is dyed to look like wool with beautiful, heathered dimension. It is incredibly soft and has excellent elasticity, which the machine loves.

• Why it works: It has the perfect amount of "bounce." It stretches when the needle pulls it down and snaps back into place when released.

• Best for: Gifts for adults who don't want "shiny" synthetic-looking hats.

• Verdict: [Check Price on Amazon]

3. Bernat Baby Sport

Don’t let the Baby label fool you. This lightweight yarn (often labeled as Size 3 or Light 4) creates a tighter, denser fabric on the Sentro 48 than you might expect. Because it is lighter, there is almost zero resistance on the crank.

• Why it works: You can crank fast with this yarn. It is ideal for double-layered hats where you want warmth without bulk.

• Best for: Double-stranded projects or lightweight spring beanies.

• Verdict: [Check Price on Amazon]

The "Caution" Yarns (The "Yellow Light" List)

Can you use these? Yes. But they require special attention.

Red Heart Super Saver

This is the most popular yarn in America because it is cheap and comes in every color imaginable. However, it is famous for being rough and scratchy right off the skein.

• The Problem: The rough texture creates drag against the plastic machine parts. This can cause loud clicking noises and uneven tension.

• The Fix: You must use the "Wax Method." Run the yarn through a block of beeswax or hold a dryer sheet around the yarn as it feeds into the machine. This lubricates the fibers and stops the grinding.

The Forbidden Yarns (The "Red Light" List)

Avoid these at all costs unless you want to buy a replacement machine.

1. 100% Cotton (e.g., Lily Sugar'n Cream)

Cotton has zero elasticity. It does not stretch. When the machine needle tries to pull the yarn down, the cotton fights back. This creates immense pressure on the plastic gears inside your Sentro.

• Result: You will likely snap the handle or strip the internal gear teeth within minutes.

2. "Thick & Quick" Yarns (Size 6 Super Bulky)

Any yarn labeled "Bulky" or "Super Bulky" (like Lion Brand Wool-Ease Thick & Quick) is too big for the needles. The hooks cannot physically grab the yarn, and it will jam instantly.

The Essential Accessory: Thread Conditioner

If you insist on using cheaper, rougher yarns (like Red Heart or store brands), you can cheat the system by using a thread conditioner.

• What it is: A small pot of wax or silicone lubricant.

• How to use it: simply touch a bit to your yarn guide, or let the yarn run over it. It makes even the scratchiest yarn behave like premium silk.

• Recommendation: [Sewers Aid or Beeswax on Amazon]

Final Thoughts

Your Sentro or Addi is a tool, and like any tool, it works best with the right materials. For a frustration-free experience, stick to Caron Simply Soft or Lion Brand Heartland. Your wrists—and your machine—will thank you.