Looking For 8 mm Collet - Head Diameter ± 13.05 mm

Hello All

Just joined. I'm Tom, British but living in Northern France.

I've had a Ferm router for years which I've hardly ever used as it's a very awkward tool to handle and operate. Recently, in desperation, I bought a Chinese made trimmer (new) off of eBay UK. The listing said that the machine came with three collets, 6 mm, 6.35 mm (¼") and 8 mm. I actually received only the 6 mm and 6.35 mm collets together with a split cone with an internal diameter somewhat larger than 8 mm. I have no idea what the purpose of this part is; I've tried fitting it all ways imaginable but without success. It fits into the collet holder but it's far too large for an 8 mm shanked bit. I contacted the seller about the missing part and he was well-meaning and helpful - he refunded 15% of the total price without complaint - but he (and the so-called User's Manual) are next to useless when it comes down to details.

The 6 mm and 6.35 mm collets supplied work well with my few existing bits of that size but almost all the bits I own are 8 mm. I cannot be sure of finding the right part I need - there are hundreds of collet sellers on eBay but I am of the opinion that not one of them really knows what he is selling.

The head diameter of the collets that work is 13.05 mm (say 33/64") and I'm assuming that any suitable 8 mm collet would measure the same or very close. My existing 8 mm collet (for the Ferm) measures 12.20 mm or thereabouts and this sits too far down in the collet holder for the collet nut to be able to compress it sufficiently.

Does anyone know where I might find what I think I'm looking for? And anyone know to what use I might put the cone?

Thanks

Tom