Troubleshooting Tips - Chuck & Bur

If you experience any one of the following symptoms, most likely causes are contamination and/or wear of the chuck.

- Bur drop-off - Hard-to-pull-off bur - Bur wobbling To Prevent Bur Drop-off

Most faulty chuck troubles are caused by contamination inside the chuck due to lack of proper maintenance. To minimize the wear of chucks, pay attention to the following point.

Selecting a Bur - Confirm the maximum rotation speed allowance specified by the bur manufacturer before selecting a bur. - Especially, if you intend to use the bur with a turbine and/or speed increasing contra-angle, be sure to select one with right rotation speed allowance. - Burs with wider blade such as carbide bur tend to come off easily when cutting load exceeds chuck’s holding force. - Bur also may come off easily when a long type bur is used with a mini head. - Bur with worn out shank or chipped blade, and crooked bur tend to come off easily and exert negative influence on bearing durability.

Locking a Bur - Wipe bur shank with clean cloth before inserting to chuck. Debris and other foreign articles remained inside may cause lower holding force. - When inserting a bur to turbine or speed increasing contra-angle, be sure to push it in all the way until the bur stops. Locking insufficient depth shank is extremely dangerous. - Make sure bur is tightly and securely locked by giving a pull-and-push test. NSK push-button type chuck used with air turbines and speed increase contra-angles is designed to increase the holding force as load increases. By giving a pull-and-push test prior to use, the chuck obtains stable holding force from the beginning.

	While Using
	- While using a carbide bur, bur coming off becomes more probable if the handpiece is used in pull motions. Further, when the bur’s full chucking depth is lost through vibration, the probability of bur’s coming off gets even higher if pulling force is applied on it.