Thread: annoying problem -- router bit climbs out of the collet in the router table

Are you using the correct sized collet? Does the bit come out when you give it a good pull?
Does the bit actually come out or is the plunge mechanism lifting?

I'm using the 1/2" collet and shaft - trying to mix and match 1/2" and 10mm just doesn't work. Same
goes for 1/4" and 6mm. The bit would not even turn, never mind get half way through the job.

No, I cannot pull the bit out, the collet was really torqued up, and I was using the fixed router base in the table, no plunge mechanism
involved.

It's exactly as I said, the bit climbs out of the collet. It actually left some mark on the shaft, like a part
spiral climbing up to the business end of the bit.

hrmm... sounds like you might have a faulty collet on your hands. If its a new machine take it back to the seller

Check that it's not a 12 mm collet.

Sorry meant to say 12 mm shaft cutter.

Assume you are leaving a small gap between the end of the router shaft and the bottom of the collet recess so that the collet can compress around the shaft properly.

yes, usually leave 2-3 mm

I found putting a small "O" ring in the bottom of the collet shaft, keeps it far enough up and allows for compression.
Kryn

I would check the router bit shaft diameter. One man's half inch is another mans conical 12.2-12.8mm

I have no idea what an Evercut insert router bit is, but if there is a up shear on the inserts, it will want to pull the bit out of the collet. Look at industrial CNC tables and you will see tracks cut into the surface which clearly shouldn't be there (I've never done this, but I've heard stories )

{unfortunately} the shaft diameter is 12.700 mm - so we're not nearer to the root of the problem.
Evercut - or is it Evacut - is a brand of router bits sold by Bunnings and Mitre 10 here in NZ.

The sharpening marks on the cutters seem to indicate that an upward force could possibly happen.
They are so fine I can not really see them with the naked eye though.

So, I went and cleaned and reassembled all, the router (and spindle) is cool, put the bit into the collet
in the technically correct fashion (i.e. shaft through the full length of the collet, but leaving space between
the nut and the cutting head. Tightened.

Now, yesterday, when the bit had climbed out, I could tap it back into the collet with a piece of softwood,
despite the collet being really torqued up...

Today, with everything cold, I cannot do that. It's held solidly.

Scratching my head, still. (or again)

Perhaps you have tapped the answer on the head.
As you work the bit heats up and transfers it to the collet. The collet expands at a slightly higher rate than the bit so it slips out. When everything cools down all appears tight.

How much use has the collet had. Perhaps you could try a replacement.

The only time I've ever had a bit climb out at me was when I'd been using a 1/2" - 1/4" inch collet "reducer" or sleeve. Never used one since. Too dangerous.

The others have given you all the appropriate suggestions. You've checked that it's not a 12mm shanked bit. You haven't bottomed out the shank in the collet, thus allowing the conical collet to tighten appropriately. Presumably the bit's shank is actually parallel sided, not slightly conical. The only other suggestions that I'd make is to clean the collet gripping surface with an ear bud dipped in kero & wipe the bit's shank with a well-soaked rag, drying both thoroughly. DON'T try scoring the bit's shank: all you'll achieve is a minute further narrowing of the bit's shank, & risk damaging the collet's mating surface.

Just a couple of final suggestions: both long shots! Are you sure that the bit's shank is inserted sufficiently into the collet, & that the collet itself is correctly inserted/clipped into its tightening nut (assuming it's of the Elu type)?

Yours doesn't have any problem like this one does it. Seems a fairly common problem by the comments below the video.

I have had it happen on occasion when using the full width of a bit. It felt like I found what I can only describe as the resonance frequency of the router, bit and timber system; the cut became too easy, almost like it was self-feeding and the whole thing was vibrating like crazy.

Be careful with over tightening to compensate, you can damage both the collet and the spindle/nut threads.

Yes, I hope like hell that I have not overtightened trying to compensate.

I am considering getting a musclechuck for it ... I have an 'extreme extender' in my Hitachi TR12 that works on the same principle as the musclechuck and it works very well indeed.
Of course, that may introduce a new problem if it isn't perfectly balanced, not to mention: pricey.