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BROWSE SCHOOLHOUSE

Featherweight Motor Brush Replacement Tutorial

Today, we are going to be learning about Motor Brush Replacement. Although they are frequently overlooked, carbon brushes are a critical element of an electric motor. Not only is it important to be aware of the motor brushes in a Featherweight motor, but knowing what to look for in a replacement can help with your motor's longevity, too.  So, let's dive in!

NEWSFLASH!  We now have the exclusive Motor Brush for your Singer Featherweight 221 or 222: perfectly sized, shaped and with proper carbon density for optimum motor performance... just like the vintage originals!

CARBON MOTOR BRUSHES 

The carbon brush, also known as a motor brush, is a small carbon block that conducts the electrical current between the stationary wires, Stator (image A, below), and the Rotating Wires (image B) which is the Armature (image C).

 

Image A

Image B (screwdriver tip pointing to the rotating wires)


Image C

Image D

A spring is used to push the brush down from the underside of the motor cap screw to the Commutator (Image D, above).  A simple explanation is that the electrical current is going through a cycle between the Stator and the Armature, causing the motor to spin.

The carbon motor brushes are found underneath the motor cap screws. There is one motor cap screw located on the top and another on bottom of the motor.

The motor cap screw on the bottom of the motor is accessed through a hole on the underside of the machine.


The motor does not need to be removed to replace the bottom motor brush if these steps are followed:

1. Turn the machine on its side.
2. Locate the motor cap screw on the bottom of the motor inside the hole on the underside of the Featherweight machine.

 

NOTE:  When replacing motor brushes, both motor brushes will need to be replaced at the same time to maintain proper contact balance with the commutator.

When checking the motor brushes, remove the motor cap screw on both the top and bottom of the motor using the Safety Vera Screwdriver.  Be very careful when unscrewing the original motor caps.  They are made of Bakelite and can be very brittle with age. If you have a motor where the Bakelite cap has broken off, we do have another tutorial on how to remove it and we offer replacement caps as well. You can find the motor brush cap screw tutorial here.

Reproduction caps are only available for the 3/8" cap (measured across the threads).  This size is common on American Featherweight motors. For motors manufactured in the UK, the large 1/2" size is required and replacements are limited to vintage original stock.  (Click here for availability or to sign up for the in-stock notification for the larger sized motor cap screws.) 

Once the brush cap is off, gently pull the brush out of the motor using the attached spring. Occasionally, the carbon block will come off the spring and remain inside the motor. This is pretty common if there is oil, lubricant or carbon build up on the brush. If this happens, use a pair of fine tweezers to grab the end of the carbon block and pull it out.  If the carbon brush is in the shaft so tight and cannot be removed, even with tweezers, then we suggest sending your motor to us for a tune-up and service. The motor will need to be completely opened up to get those brushes out. Due to all the vintage and delicate wiring inside the motor, we do not recommend opening up a Featherweight motor without prior electrical motor experience. 

Upon removal of the motor brushes, check their size and condition.  They should be between 1/4" to 1/2" long and free from any oily residue.

With the brushes removed, clean out the brush tubes and any carbon build-up on the commutator.  To do this, dab a very, very small amount of rubbing alcohol on the tip of a cotton swab and clean out the tube, rubbing the sides and pressing all the way down against the commutator.

This would be the only time we would suggest using rubbing alcohol near the Featherweight because it can be detrimental to the clear coat on the machine. Keep alcohol away from all the painted surfaces while performing this task.

Turn the motor pulley while pressing on the commutator as this will clean a good portion of any build up of carbon residue.

Previous replacement carbon motor brushes were inconsistent in size, density, curvature and actually varied from batch to batch from the manufacturer.  Having an improperly sized brush results in loose or inconsistent contact with the commutator.  A soft density carbon brush causes premature wear and will not provide an efficient transfer of electrical current.  Incorrect brush curvature causes uneven contact with the commutator, often resulting in a loud, rattly motor. 

Good News!  High quality Featherweight motor brushes are now being manufactured and can be distinguished from any others by locating the FWS on the side.

These new Featherweight Shop (FWS) replacement motor brushes are designed with Featherweight motor longevity and care in mind. 

Features of FWS Carbon Motor Brushes:

  1. Correct carbon density
  2. Exact sizing (just like the original carbon motor brushes when Featherweights were new)
  3. Curvature is mathematically precise to the commutator curve, maintaining consistent and proper contact.
All of these features will provide a smoother, faster, more efficient running Featherweight motor, giving you peace of mind that your motor will have the best care and longevity as you sew into the next generation.


Here is a side by side comparison of The Featherweight Shop Motor Brush (top), an original motor brush (middle), and an older, poorer quality replacement brush (bottom).  Motor brushes will last years, or even decades, if the motor is properly maintained.

If the motor brush in your Featherweight is too short, oily or there is carbon build-up, then it is a good time to change it out. 

Motor Brushes are always sold as a set because both must be replaced at the same time for proper balance. Just be sure to insert the brush with the curvature on the bottom of the brush correlating to the curvature on the top and bottom of the motor, and then screw the brush cap back in place.

 

Thank you for joining us for the Motor Brush Replacement tutorial. If you have any questions, please feel free to contact us here.