does anyone have problem with this coupler?

[wetsleeves]

I also use shaft savers on my shafts just incase the coupler lets go. Good insurance policy for very little $$$$$

[Mel279]

this one is much better but expensive http://mbp-rc.de/collet-clutches-5-x-475-SZK

[AlanN]

I noticed on the kintec coupler, you can pull the flex shaft into the motor shaft. This can cause a nasty vibration. Back the flex cable out slightly and re-snug.