How to Grease and Replace the Inner Shaft on Your Flex Shaft

How to Grease and Replace the Inner Shaft on Your Flex Shaft
The flex shaft is one of the most important and versatile tools you use at your bench. Keep your flex shaft running smoothly for years to come by performing basic maintenance on it. Learn how to lubricate or replace the inner shaft of your flex shaft to ensure a long service life, as well as how to reassemble the shaft and sheath after performing maintenance. 

 

Understanding When Flex Shaft Maintenance is Needed

The inner shaft on a flex shaft should be lubricated after every 50 hours of use. If you are having problems with the handpiece not moving, it may be time to replace the inner shaft. Both of these tasks are easy to perform. You can learn the proper steps below.

Rio Grande offers a variety of maintenance kits and replacement parts that make performing flex shaft maintenance quick and easy, as well as Foredom flex shaft lubrication for lubricating the inner shaft. 

To Lubricate the Inner Shaft

 1. Before performing any maintenance on your flex shaft, unplug the unit and remove the hand piece. Place the unit on a flat surface.

2. Using a 1" crescent wrench, unscrew and remove the motor coupling, which is the plastic housing at the base of the motor. Note that the motor coupling is a left-handed threading, not the standard right-handed threading.

3. Slide the sheath down and remove it completely, exposing the inner shaft. Using a rag or shop towel, wipe the inner shaft to remove any existing, old grease.

4. Squeeze a small bead of grease (about 1/16" dia.) from the tube, then starting at the top of the shaft (closest to the motor) run the grease along the length of the shaft, stopping approximately 6" from the key end of the shaft.

5.  Replace the sheath and motor coupling. Make sure the end of the shaft does not extend more than 3/4" past the end of the sheath with the shaft and the sheath fully extended. Adjust the placement of the shaft so that 3/4" of the shaft emerges from the end of the sheath. If the shaft extends too far from the sheath, the handpiece will overheat and wear prematurely, and the shaft also could easily overheat or be damaged. However, if the shaft doesn't extend far enough, it will not drive the handpiece properly. Once you have the sheath placement correct, tighten the set-screw to secure the sheath in place.

6. Hook the motor back onto the hanger and plug it in. Do not attach the handpiece before hanging up and plugging in the motor.

7. Place a trash can under the shaft to catch any excess grease. Then run the motor at high speed for 10-15 minutes. Running the motor heats up the grease, allowing it to redistribute down and throughout the shaft (the excess grease will drip out of the end of the shaft and into the trash can). It's important to allow that excess grease to drip off, otherwise the grease left in the handpiece may cause the handpiece to overheat. Re-attach the handpiece for use.

 

To Replace the Inner Shaft

1. Before performing any maintenance on your flex shaft, unplug the unit and remove the hand piece. Place the unit on a flat surface.

2. Using a 1" crescent wrench, unscrew and remove the motor coupling, which is the plastic housing at the base of the motor. The motor coupling is a left-handed threading, not the standard right-handed threading. There's no need to remove the sheath from the motor coupling, unless the sheath will also be replaced.

3. Use a screwdriver to unscrew the set screw on the shaft coupling connecting it to the motor. Dispose of the old shaft.

4. Place the new motor shaft onto the motor coupling. Align the flat side of the motor coupling with the set screws on the motor shaft. With a flat-head screwdriver, tighten the set-screw to secure the motor shaft in place.

5. Slide the sheath down and remove it completely, exposing the inner shaft. Using a rag or shop towel, wipe the inner shaft to remove any existing, old grease.

6. Squeeze a small bead of grease (about 1/16" dia.) from the tube, then starting at the top of the shaft (closest to the motor) run the grease along the length of the shaft, stopping approximately 6" from the key end of the shaft.

7. Replace the sheath and motor coupling. Make sure the end of the shaft does not extend more than 3/4" past the end of the sheath with the shaft and the sheath fully extended. Adjust the placement of the shaft so that 3/4" of the shaft emerges from the end of the sheath. If the shaft extends too far from the sheath, the handpiece will overheat and wear prematurely, and the shaft also could easily overheat or be damaged. However, if the shaft doesn't extend far enough, it will not drive the handpiece properly. Once you have the sheath placement correct, tighten the set-screw to secure the sheath in place.

8. Hook the motor back onto the hanger and plug it in. Do not attach the handpiece before hanging up and plugging in the motor.

9. Place a trash can under the shaft to catch any excess grease. Then run the motor at high speed for 10-15 minutes. Running the motor heats up the grease, allowing it to redistribute down and throughout the shaft (the excess grease will drip out of the end of the shaft and into the trash can. It's important to allow that excess grease to drip off, other wise the grease left in the handpiece may cause the handpiece to overheat. Re-attach the handpiece for use.