When a end mill slips

1

When an end mill slips up into the collet two thirds of the way through a job, after tightening the bit for the third time, can I continue the job from a mid point with out having to start from the beginning

2

If there are multiple toolpaths you can disable them and restart after the last one which was successfully cut.

Restarting is a feature which may appear in a future version.

Until then you would need to edit the G-code in a text editor preserving the preamble, and restarting at a move down from safety height or some other suitable point in the code.

3

The real problem is your bit slipping 3 times. So to help address that here are some ideas about tightening your bits.

  1. Clean the router shaft and the collet and nut with something that will degrease it. I use spray break cleaner but use what ever you have. On the spindle be sure to lay out something to adsorb the excess spray so it does not damage your spoilboard. The collet/nut/router shaft should be dry and lubricant free.

  2. When inserting your bits the bit must be minimally inserted so the top of the bit is even with the top of the collet. To aid in this measure your collet and put a magic marker mark on your bit that distance so you have a visual reference on how deep to insert a bit. The reason this is so important is the collet has cuts made in it. The inside of the router shaft is an inclined plane. So when you insert a bit in your collet and tighten the nut the bit and collet is being driven up the inclined plane and the cuts in the collet are squeezing on the bit and making it tighter and tighter. So for the best grip on a bit it should be minimally at the top of the collet. You can insert a bit further up but do not bottom out a bit in t he top of the router shaft. The reason is the top of the shaft may be roughly cut and cause out of round condition of a router bit. More importantly is the bit is supposed to be moved up slightly in the inclined shaft when the bit is tightened and if it is already at the top of the shaft it has no where to go.

  3. If using a Makita/C3D router you can use the stop button and one wrench to get your bit tight enough not to drop out but use 2 wrenches for the final tightening. Using only the stop button and a single wrench is not recommended by C3D. They recommend the two wrench tightening to make sure you bit is tight in the collet. In step 1 I mentioned making a mark on your bit and the benefit of that is obviously a visual guide to insertion but anytime you want you can pause during a jog and have a visual confirmation your bit has not moved up/down.

So give my 3 steps a try to see if that fixes your bits coming loose. If the three steps above do not fix your issue then you would need to think about replacing your collet and nut. There are several companies that sell 3rd party collets but I like https://elairecorp.com/. Just make sure you have selected the proper model of your router. They come in metric and imperial sizes for the Makita C3D routers as well as the Dewalt.

5 Likes
4

Thanks. Good information

5

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