double locking on router collet.

[Fred Page]

Is there an engineer/mechanic on this forum? I’m in trouble with my Dexter Tools Router, the fairly big one, 1/2inch, 1,900W etc . The trouble lies in removing the cutter after use. It has this double lock thread business - which I don’t understand other than I realise it’s a safety device. Well, the first stage of unlocking is fine BUT for the second stage I have to use a massive amount of force on the spanner. At first I thought the thread was twisted, crossed, or whatever the term is, but no. The thread looks okay but my experience today has made me reluctant to try the process out again until I’ve taken advice from somebody. What’s gone wrong? It’s never behaved like this before. Clearly there’s something wrong judging by the amount of force I had to use to slacken off the collet. Could it be because I’m using a ¼ inch collet in an 1/2inch machine? I don’t think so, but would welcome some opinions.
Fred

 

[Steve Maskery]

Hi Fred
The "double lock" you are experiencing is normal, although perhaps not the strength of it. It happens because three pieces are being tightened and then loosened. You don't notice it when you tighten, but the cutter tightens on the collet and the collet tightens in the shaft. When you unlock, the collet has to come off the shaft (1) and the cutter has to come off the collet (2). They happen separately and you feel it.

That's what is happening, I'm sorry I can't explain why it is so hard in your particular case.

HTH
Steve

 

[OLD]

Is everything clean no resin sawdust etc clogging any of the threads, housings or expansion slots is the bit in to far so the radius where it flares out is expanding the adapter sleave. are the threads worn allowing them to ride over each other all worth a clean up and check .

 

[Raggy]

As OLD says make sure the collet is nice and clean.

 

[dickm]

Luckily, I've not yet had that problem on my Elu routers, but I'd be interested if someone could explain how the double locking system works. It's obvious how the nut <closes> the collet, but how does it open it :??

 

[DaveL]

I'd be interested if someone could explain how the double locking system works. It's obvious how the nut <closes> the collet, but how does it open it :??

I will try.

There is a ridge inside the nut, and another on the out side of the collet. Without a cutter shank in the collet, it will close and let it's ridge go past one in the nut, it then sits in a recess, behind the front face of the nut.
When the cutter shank is clamped in the collet, the collet jams in the taper in the end of the shaft.
When the nut is undone, the first stiff bit takes the clamping force off the collet and then ~ one turn later the two ridges touch and the nut gets stiff again. The two ridges cannot pass as the shank of the cutter stops the collet from collapsing though the smaller hole and when you apply the spanner for the second time, you are pulling on the collect, which should spring out of the taper in the shaft.

There, clear as mud. :roll:

 

[johnjin]

Hi Dave

Spot on. I have been wondering just how to explain it, but you got it just right. After using this type of collet for forty years or so I still find it difficult to explain. It is so much easier when you have the collet and nut in your hand and the person standing next to you.

Best wishes

John

 

[johnjin]

Just to add to what Dave has said.
There is no double locking as it has been called. The first tight bit is the nut coming free after pushing the collet into the taper the second tight bit is the nut forcing the collet out of the taper. I hope nobody is even more confused than before.

Best wishes

John

 

[9fingers]

A trace of grease on the thread should help.
When loosening the nut, wait till it becomes stiff then tap the cutter sideway gently with an offcut of wood. Then continue to undo the nut.
hth
Bob

 

[dickm]

Thanks for the explanation, guys. I'd seen the ridge you mention, but hadn't worked out its significance. Was assuming that something must actually force the collet open, rather than just freeing it a small amount from the taper.
But not sure if understanding that helps to solve Fred's problem !

 

[Fred Page]

Thanks to everybody above. The problem has been solved - simply cleaning and applying a trace of oil worked wonders. Nevertheless, with all the information above I'll be better prepared should the problem ever arise again. Smoothing the cutter shaft also greatly helped. Thanks everybody.
Fred