I had some bit slippage in my C3D router, so rather than spend $20 or so on new Makita Precision collets, I spent $60 for the ER-11 version of the router, with two ER collets. I’ve not had a problem since.
However, I just watched this video, which shows that over-tightening ER collets will often result in increased runout, and can damage the collet, maybe even the spindle shaft:
It recommends using a torque wrench. I have 3 torque wrenches (¼", ⅜" and ½" drive), so I could probably do this, except for the business end of needing an open wrench style. What do people with the VFD or ER router here do?
All you need is the applicable size crows foot for your existing torque wrench. Once you torque to the correct spec you will get a feel for what that is and probably not need to use the torque wrench anymore.
I do not use a torque wrench for tightening bits in any of my routers or my one spindle. In my youth I snapped a few bolts off and learned by feel on how tight is tight. This works for me.
Usual preface, I’m with PreciseBits so while I try to only post general information take everything I say with the understanding that I have a bias.
Saw their first but same reply might be useful to you:
That said. The Makita and it’s like have another issue. The only part of the collet that produces the clamping is the tapered section. It’s only 4mm… That makes it much easier to not have enough slip resistance depending on the router and collet matching.
Hope that’s useful. Let me know if there’s something I can help with.
Note that use of a crow’s foot on a torque wrench has to be done such that the center of the wrench opening is the same distance from the handle as the wrench’s drive square center. It is usually said that the crow’s foot has to be at a right angle to the handle.
I do like the idea of human calibration by getting a feel, but I think one would have to have a torque wrench that was about the same length as the regular wrench you’re going to use manually later for that to work.
After working on cars my whole life I’ve taken to using the German spec gudentite for most things that don’t have “head” in the name. It’s all about feels. If your collet is of decent quality, clean and well maintained you shouldn’t have to crank on it to hold the mills securely, just needs to be gudentite.