Thread: Dovetail bit rises in action

Hi Dengy,

I'll put my money on the collet reducer or the shank of the router bit. When the bit is being pushed along by the router, it is under considerably for stress and power than you have in your hand. I have recently encountered the same issue with a Leigh Jig. Turned out it was the collet, not the jig or the bit.

Regards,

Rob

Thanks for this info, Rob, very much appreciated. I am using the Gifkins reducing collett, supposed to be the Rolls Royce of them all.

How did you determine it was the collett?

Strange that it started rising halfway through the job. It did 20 pins and 5 dovetails perfectly before starting to rise, as well as another 40 or so test cuts setting up the jig ( shim thicknesses) and the router bit height

I agree with Rob, it's probably the bit or collet rising. There's a lot of load on a dovetail bit because you're cutting the full depth in one go. I've never used a Gifkins jig, but is it possible to rout out most of the waste with a smaller straight bit first? That will reduce the load.
The other thing you could try is to put a thin bit of foam at the bottom of the chuck, so the bit sits on it. This will damp any vibrations coming from the router. Some of the new routers have the foam there, don't know if the Triton does.

It can only be the lack of collet pressure causing the bit to rise, as suggested by LGS. The rack and pinion gearing on the router would not, in any way, account for such action. The cause will be a lack of tightening of the bit in the collet, with a couple of reasons, depending upon the collet chuck assembly fitted to your router.

If your collet nut looks like this:

triton14.jpg

then it's the original "Hitachi-style" assembly - a male, coarse-threaded nut, fitting into a sharply-sloping shoulder in the female chuck body. The problem with this design is that, due to the coarseness of the threads, the "gearing" of the nut is high and requires significant wrench pressure to tighten it effectively. Add a reduction sleeve into that mix and problems begin. You may get better results by aligning the reduction sleeve slit with that of the collet nut, then lean on the wrench.

The problem was removed by the introduction of the "self-releasing" design of collet assembly, the nuts of which look like this:

mof00112.jpg mof00113.jpg

Here, the collet nuts have a fine thread, very much "lower-geared" and requiring much less effort to effectively tighten. They work with a much shallower sloping shoulder, also allowing better control. I have successfully converted my old TRA001 to the new design and I could assist with instructions if you consider doing it.

Meantime, lean on the wrench after aligning the slits, mark the router shaft and run it in some scrap to see if that alleviates the problem.

Hope that helps, Dengy.

Ray

Yep reckon it's the reducing sleeve, damn dangerous things, much better getting the full size shank dia for the router proper.

Had it happen many years ago a couple of times always use the right size shaft since never had a problem after that.

Cheers

Steve

Many thanks for all these very helpful replies, I really appreciated them.

I am satisfied it was the collet and reducer too. Spoke with Col Hosie of Gifkin about it, and he advised that routine maintenance was necessary for the collets on table mounted routers as all the sawdust collects in them.

Yes, it has been a very long time since I cleaned the collet and the reducer, and there was some sawdust buildup in the slots of the reducer and in the threads of the collet, so first thing this morning I soaked them both with Ooomph (a citrus cleaning solution available in the paint section of Bunnies). I have found this to be the best product by far for removing build up of resin etc on sawblades and router bits.

I then used a fine needle to remove the softened gunk in the slots of the collet and reducer.

I cleaned the female part of the collet assembly on the router, and this had a lot of gunk in the threads, which was easily removed by a toothbrush.

I also found that it was possible to tighten the collet further than what I normally do, so I did that too

Have been using the same bits all day without any problems

Thanks again everyone