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Discussion Starter · #1 ·
Hi all, new to this place, I felt inspired to join up because I've recently acquired a nice Bosch GOF 1600 CE router and bought the fixed base
for this router from Amazon.

The fixed base I installed into my homebrew router table.

Currently I am building a new kitchen and I'm using Blum hardware that requires me to rout a 38mmx8mm rebate (rabbet I think in American?)
into the drawer bottoms.

Put an 18mm router bit with a 1/2" shaft into the fixed router base that's sitting in the table. Started making some cuts, around 16mm wide by
8mm deep. It worked fine for a while, when, suddenly, the router bit emerged from the top surface of the work!
Imagine my surprise. Just glad I didn't have my hand anywhere near.

This is not the first time it's behaved like that. The first time it happened I assumed I might not have tightened the collet sufficiently. I also
cleaned collet and router bit shaft with acetone, in case of oil or other lubricants. That time I was able to finish the job.

But twice? That is no longer an accident. I checked, the collet was really tightly torqued up.
I'd made about 8 or 9 cuts without a problem, when suddenly the bit started climbing, and it climbed 8mm (3/8") over a stretch of 200mm (8").
That's rapid!

It still was as tight as I can get it when I dropped the motor out of the table and checked the collet. But, having said that, I was able to gently
tap the bit back into the motor with a piece of 4x3 that I had lying on the workbench.

I simply don't know what's going on with this. Is it the collet? Is it my technique of using nearly the full width of the router bit (I was cutting with
the end-face of the router, and not with the side, running the sheet of mdf over the table)?

(please don't ask if I was using a 10mm router bit in a 1/2" collet -- I am not THAT clueless :grin:).
 

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a little reading on collets..

..
 

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Discussion Starter · #3 ·
Thank you for the links. Unfortunately, nothing in there that would be new to me - and I do keep things clean, and I know not to insert the bit all the way to the cutter head.
Don't forget that the router is very new; it's maybe clocked up 1-2 hours of running time all-up. Wear and tear and buildup of crud is unlikely to be the culprit.

One of those files mentioned resin leaving discoloration ... and I had some discoloration ... but, realistically, no resin or dust should be able to get between the collet and the bit
during operation (without a bit change). Some dust may have got into the slots and then smeared across the shaft when the bit started to slip. Which is the thing that should NOT
have happened.

Heat - is it possible that the spindle could expand from the heat of frequent cutting? The nut should hold things together one would assume.

-Peter
 

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I Peter and welcome. I have a Chinese bit that I can hardly get in my collect and I can hardly get it out. So like Stick said that might be a problem. You could also take the router back or call the manufacturer.
 
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David - Machinist in wood
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Welcome to the forum, Peter! I have never had that happen so not much help from me on this one. I do hope you get it resolved - could be dangerous! You can post photos if they're on your computer, btw.

David
 

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I too, suspect it's the bit. Try other bits and see if they slip too.
 
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Can you put a caliper on that bit and measure the shank...?
 

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Discussion Starter · #9 ·
Thanks, going to put the calipers on the shank tomorrow. Maybe that will give me a clue.
Doesn't really explain why it would work just fine for a while and then suddenly start shifting out.

But yes - the collet was very tight after the incident, yet I could tap the bit back into the collet with a piece of softwood,
so it was NOT firmly held in the vertical.
 

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Could it be possible that you might have had some "new-bit-goop" on it when you started...? Or some goop in the collet from a previously used new bit...?
 

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time to clean everything..
if the collet is ''very tight'' it may be broken now..
 

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I have to say that I, too, suspect the collet. It may be new to you, but do you know how it has been treated prior to you acquiring it? TBH I'd think in terms of buying a new, industrial quality cutter (in the UK that would be Titman or Leitz as the best, maybe Trend, Freud, CMT, etc as good trade quality), cleaning everything thoroughly, then adding a very small amount of a dry lubricant (to the collet and collet nut) and trying the cut again. If it still climbs out then you need to throw the collect away and start again - it has probably been over tightened and is now permanently distorted.

BTW did you ensure that the collet wasn't completely bottomed out (so the end of the cutter was hard against the top of the recess in the router's shank)? And that the fillet (radiused transition) between the cutter shank and cutter body wasn't inside the collet? And that the cutter wasn't extended so far that the collet body wasn't completely filled with cutter shank? All of those promote the type of behaviour you are experiencing

As an aside I find it interesting that NZ gets the same model numbers we have here - GMF1600 instead of MR23 as in the USA
 
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John
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Another thing is the collet nut and collet Snapped Together sometimes You’ll find this on a new router
 

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Discussion Starter · #14 ·
So, first up, thanks for all the responses.
I tried earlier to reply from the computer in my shop, but a picture upload failed and then I must've accidentally closed the browser ... so, here goes again.

I put the calipers on the shaft of the bit in question, and it's 12.7 mm dia as it should be. Even with a 12mm shaft like someone suggested, I think there's
no way you could tighten the collet on it if you were to try that, it would just wobble around. But no, this one is bang on the mark for a 1/2" bit.

With the router cool (ha, heatwave, it was over 30C in my shop today) I cleaned everything, yet again, put the bit in the router and tightened it, and even
without over-tightening I got the result that gentle tapping with a softwood mallet the bit would not slip further down into the collet, the way it did
immediately after the climbing episode.

Maybe I should look for another collet ... does anybody have a source for quickchange collets for the Bosch routers? I have a quickchange type extender
on my Hitachi TR12 and that one works just beautifully. Much better than messing about with spanners ...
 

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John
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MUSCLECHUCK TYPE 4
Easy install
Great piece equipment
Runs about 70.00
1/4” turn it is tight
I would highly recommend
 
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Semipro's recommendation for the Musclechuck is definitely a plus.

I had a spiral bit climb out of the chuck once. Turned out that the adapter collet (/2 down to 1/4) was defective.
 

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I had a spiral bit climb out of the chuck once. Turned out that the adapter collet (/2 down to 1/4) was defective.
I've always regarded reducers as a sort of "sticking plaster/get you out of a hole/one time only" solution that may, or may not work. Maybe OK for a short pass of a few feet, but that's about all. A good 1/2in router collet has 6 or more slotted segments, a good 1/4in one has 3 or 4 slotted segments - a reducer has often just one slot which means that it won't conform fully to the shape of the cutter shank when compressed with maybe only 2 actual points of contact between the reducer and the cutter and possibly only 3 or so points between the reducer and the main collet. Any pull exerted on the cutter during the cut (as you'd experience with a spiral up-cut) and the cutter will simply pull itself out of the reducer.

Personally I try to avoid them as they are a sure fire way to risk damaging expensive work - and there are enough opportunities for me to damage it when I'm installing the stuff without a bit of tight-fisted behaviour on my part making it more likely. BTW it's the need to use reducers on every 1/2in Japanese router I've ever seen when using 8mm cutters (because Hitachi, Makita and Ryobi don't sell 8mm collets for their 1/2in routers) which means that I avoid them
 

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Discussion Starter · #19 ·
So Eric's post opens a new angle on the discussion for me:

If I get a Musclechuck 4 for my router, I'd be using a reducer for my 1/4" bits, I expect. ( try to always buy 1/2" shafts, but sometimes you just can't get
what you want in that size).

However, for more or less the same money I can get a PreciseBits chuck with separate 1/2" and 1/4" collets that work with the same chuck-nut.

small difference for the PreciseBits is that it needs a special spanner instead of the more convenient allen key, but that is really not a big factor.

Has anyone had the opportunity to compare the two in Real Life(tm)? Would you recommend one over the other?
 
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