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The spindle/engraving motor on the Wizzard engravers is a 115 volt, 1/15 HP, 5000 RPM, operating at 60HZ, 1.2 amps. Although a similar motor has been available from Grainger in the past, is should not be used as additional modifications are added to this model by Dahlgren. These modifications prevent static discharge which can cause cursor loss, and other software problems. (Note: The motor is no longer listed in the Grainger catalog.)
While I have checked with the motor manufacturer and several other sources, I have not found an exact answer as when to replace motor brushes. Some types of engraving require replacement more often. Dahlgren recommends to replace after 500-600 hours of rotary engraving. I have measured many sets of brushes and have found that a carbon brush less than .375 (3/8 of inch) in length should be replaced.
Symptoms Of Bad Motors or Brushes
Here are a few of the symptoms that a bad engraving motor, or a worn engraving brush can cause:
- Snow across the CRT (screen) when you first turn on spindle motor, caused by electro-magnetic force or interference.
- Motor emits so much static/interference that the stepper motors wouldn't slew.
- Most common problem is incorrectly installing the motor brushes. The small metal tabs or `wings' that are part of the brush assembly need to go on the inside of the square housing.
- Replacing only one brush, causing uneven rotation, which can eventually damage motor armature.
- Possible to get a soft set of brushes, but quick wear is usually result of not blowing out the motor from excessive carbon buildup.
- Cracked or chipped brushes
- Motor speeds up/down; inconsistent speed, or stops while running.
Removing the Motor
- Unplug the 3-prong connector (from the engraving motor) that plugs into the AC Power Distribution Board. Also disconnect the green ground wire of the engraving motor that connects to the engraving frame (near the Y-axis stepper motor).
- Using a 1/16 Allen wrench remove the 6/32 x 3/16 Allen screw holding the spindle belt motor pulley to the spindle motor shaft. You may have to push the flexible engraving frame down to get to the Allen screw. Note the position of the pulley on the shaft before removing so you can replace it for proper belt alignment.
- With a 1/8 Allen wrench, unscrew the two 10-32 x 1/4 button head screws that hold the spindle motor to the engraving frame. Only back up the screws far enough to release the motor. The screws don't have to be removed from the engraving frame.
Removing the Brushes
When removing the brushes, note the rotation curve and groove of each carbon brush as it is removed. Here are steps in removing each brush:
- Unscrew the black brush cap(s) that hold the brushes in place
- Remove both motor brushes. Blow out the motor. This is the most common detail overlooked by most engravers. The buildup of carbon dust can cause premature wear on new brushes, and prevent new brushes from seating properly. Carbon dust can also short circuit the power supply and other electronic components.
Replacing the Brushes
Scratch the inside curvature of new Brushes on Wizzard before installing
I've always had problems replacing motor brushes. It was almost impossible to hold down and keep the motor brushes in place while trying to replace the caps. Usually the brushes would pop out, or if I did get the cap on, the brushes would pop out inside the motor.
I made a special `tool' for holding the motor brush in place while I reposition the cap. I made it from a piece of coat hanger. After bending (see illustration below), I took a hammer and flattened both ends similar to a screw driver. The flat ends help me when I'm pushing the brush into the square housing.
Your special tool may have to be adjusted slightly (more angle on the bends) to accommodate the variations in some of the motors.
(Note: My tool was designed for use on the gray engraving motors. It will not work as well with the older, black motors.)
Replace both brushes, not just one. If one is more worn , you may need to replace the motor.
Before replacing brushes , make sure you blow out the motor of excessive carbon buildup.
Make sure the two small wings fit inside the square housing when inserting the brush assemblies. If the wings cause the brush to stay in place (finger or tool not required) after you press them into the square housing, make sure you free them up after you install the caps. Reach inside the motor housing with your tool and make sure the metal part of the brush assembly is touching the plastic brush cap).
Also make sure the groove of the brush matches the groove in the housing (groove is usually to the opposite side of the shaft which holds the pulley.
Some of the motor brush caps I have seen have been mis-threaded or will no longer fit securely. You can use a piece of reinforced shipping tape to make sure the cap stays in place until the motor or caps can be replaced.
Remounting The Motor
Note the bare area (not painted) around the bottom screw that holds the motor in place. It is a ground point for the engraving motor to the Wizzard frame. Use sandpaper to remove rust and corrosion before remounting the spindle motor.
Over tightening the mounting screws can strip out the threads in the engraving motor housing. And be sure to use the same length screws as the originals. Longer screws can damage the internal parts of the motor.
Replace the green ground wire to the engraving frame.
Notes
- Some replacement motors distributed by other vendors do not have the black caps for replacing the motor brushes. They have to the disassembled to replace the brushes.
- Some replacement motors do not use the `winged' one piece motor brushes. Their brushes and springs are separated, and are a different size. Check your brushes before ordering.
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