Size Matters: The Importance of Balance Wheels

Item # X-HT-300331

The Sailrite® Ultrafeed® Sewing Machines have a long history helping both sailmakers and DIYers sew their dream projects. While there are many features of this machine series that make it exceptional, the Ultrafeed would not be the powerhouse it is today without the help of our revolutionary balance wheels.

The Power Plus® Flywheel on the Ultrafeed LS-1 (left) and the Monster® II Balance Wheel on the Ultrafeed LSZ-1 (right).

What Does a Balance Wheel Do?

A sewing machine’s balance wheel, also called a flywheel, rotates the upper drive shaft for machine operation, which causes the needle and hook to move in a manner that produces stitches. The transfer of power through a sewing machine is a key part of its operation. Essentially, the motor powers a belt which then turns the balance wheel, transferring power through the internal components to push the needle through fabric. Sailrite has developed proprietary mechanical technology to enhance the success of this power transfer in all Ultrafeed Sewing Machines

On the Ultrafeed, the power transfer flow is as follows: motor > belt > balance wheel > internal components > needle.

Sailrite Balance Wheels & Posi-Pin Technology

Sailrite carries two oversized balance wheels that are suitable for use with the Ultrafeed Sewing Machines: the Power Plus® Flywheel and Monster® II Balance Wheel. While traditional portable sewing machine balance wheel sizes vary, they are all significantly smaller than the Power Plus and Monster II. Typical balance wheels are about 2-1/2 inches in diameter as compared to Sailrite’s 5-1/4-inch diameter balance wheels. This larger diameter provides greater torque and more power. This is because of the basic laws of physics – more mass positioned further from a wheel’s center allows for more energy storage. A larger diameter balance wheel also provides a gear change which greatly enhances power. There is a mechanical advantage by having a larger gear size.

The Power Plus and Monster II Balance Wheels work in conjunction with a very important part of the Ultrafeed Sewing Machine: the clutch system. All other portable sewing machines have a standard friction clutch system where the drive shaft rotation relies solely on applying pressure, or friction, between two smooth surfaces – the balance wheel and bushing flange.

The problem with that system is that the friction often gives way and fails to transfer power through the machine when sewing heavy fabric or thick assemblies. If the clutch slips, the needle will not be able to penetrate the fabric. Sailrite Owner and Vice President, Matt Grant, saw this problem and set out for a solution. In 2007, he invented the patented Posi-Pin® Clutching system (Patent #7438009) which utilizes a more efficient and dependable system that is guaranteed to transfer 100% power from the motor to the machine’s upper drive shaft.

The Posi-Pin system works with a specially designed pin that is positioned through a hole in the balance wheel and into a matching hole in the shaft bushing to engage and disengage the drive. This creates a constant positive connection between the balance wheel, the bushing and the drive shaft making it impossible for it to slip. This strong connection ensures that there is no loss of power between the motor and the needle, enabling you to penetrate heavy fabric assemblies, even at slow speeds. The added torque and power that come from our oversized balance wheels are perfectly paired with our foolproof clutch system to create a machine with the reputation for sewing anything you can fit under the foot. The video below does a great job of explaining this system.

To learn more about the Ultrafeed’s unique clutch system, be sure to check out “The Ultrafeed & Posi-Pin®: The Perfect Power Couple” (300332XHT) blog.

Cogged Construction

In addition to their larger size and this innovative clutch system, the cogged construction of our Power Plus and Monster II Balance Wheels provides a slip-free transfer of power from the motor to the balance wheel when paired with a mating cogged belt. Many sewing machines use a friction belt-to-groove setup, which is simply a belt in a channel under tension to drive the balance wheel, meaning that there is a high probability of slipping and loss of power. You’ll never have to worry about this issue with Sailrite’s proprietary balance wheels.

The cogged construction of the Monster II and belt can clearly be seen on the left of the balance wheel.

Making History

At Sailrite, we pride ourselves on constant innovation. On the early version of the Ultrafeed, the balance wheel was much smaller and not nearly the powerhouse that we now know the Power Plus and Monster II to be today. The photo below illustrates this dramatic change in size. The Power Plus and Monster II wheels evolved over time. The original Monster Wheel was the first of our larger balance wheels to be created. It had a diameter of roughly 4 inches and had a V-groove for a smooth belt. Similar to other components on our Ultrafeed Sewing Machines, it went through many changes over the years until we ultimately built what we now call the Monster II Balance Wheel.

Following the Monster Wheel II came the Power Plus Flywheel. The Power Plus was created because the increased diameter of the Monster Wheel II proved to be so efficient for customers that having a smaller balance wheel became obsolete. The original version was created before our innovative Posi-Pin, but it has since gone through several updates. Once combined with the Posi-Pin, the Power Plus was transformed into the extraordinary addition we know today.

Notice the much smaller old balance wheel on this early Ultrafeed model (right of machine).

Improving the Wheel

The Monster II Balance Wheel is a top-tier upgrade that provides exceptional power and torque for greater slow speed control, and it comes with a detachable hand crank. It is made from 7 pounds of nickel-plated steel so its weight creates enough momentum that you can use the hand crank to sew heavy fabrics effortlessly without electricity. We highly recommend the Monster II for when slower, more precise sewing is necessary, such as on vinyl or leatherwork where every stitch hole is visible. Plus, it’s quick and easy to install on any LS-1 or LSZ-1 Ultrafeed Sewing Machine!

The lightweight Power Plus Flywheel is made from sturdy automotive-grade plastic and comes standard with all Ultrafeed Sewing Machine packages. It is injection-molded to produce a lower cost alternative to the impressive Monster II while still having the same power advantage, just without the hand crank. This remarkable balance wheel allows you to sew incredibly thick assemblies at slow, controlled speeds, something the Ultrafeed is known for.

The Power Plus Flywheel on the Ultrafeed LS-1.

Our Power Plus and Monster II Balance Wheels are just two examples of the many advanced features found on the Ultrafeed Sewing Machine series. Our commitment to our customers and mission to constantly improve has truly elevated the Ultrafeed Sewing Machines to best in class.