I wouldn't buy one. One, the vendor is not a supplier I use anymore. Two, I don't see how the collet grips anything. Sure, at end nearest the taper, the collet will grip. But as you move away from the taper there's nothing compressing the collet fingers and making them grip. I'd imagine that a 25mm endmill would work loose in a very short time with any sort of cut.

Andrew

Only way thats going to hold anything against cutting forces is if you tap tight fitting sleeve, or better, shrink fit, over the extended part after you've put the cutter in.

A semi permanent job. Which might be worth it if you have a suitably hefty cutter, flycutter, boring head or whatever on a 25 mm shaft sitting around doing nowt.

Considerable risk of the collet snapping where the taper runs out into the extended part.

Better to get a sidelock (weldon) holder and grind a flat on the cutter. At least the holder is all solid.

Although I have full sets of R8 in both imperial and metric I'm rapidly coming to the conclusion that sidelock is the better way for plain shank cutters. But Clarkson is my general purpose go to as I have plenty of screwed shank cutters.

Clive

I have one of these as someone gave me several 50mm milling cutters i find if i clamp it in and also use a jublee clip at the end it works fine i have never tried to work the cutter hard though.

Bob

For me its a no ! When using larger cutters its far better to use a screwed shank cutter and a Clarkson [style] chuck. Better not to push beyond the design limits IMO.

However If you did choose to go there I would consider making a split collar that goes over the extended part of the collet and lock it in place with an allen screw thus supporting the thin walls and not allowing them to splay outwards. Still not the best option — use the right tool for the job !

John

At not more than £10 from most well known UK suppliers why would you?

I dont have or use R8, but this one looks the same as the one Arc have so what is oversized about it?

Ian P

If you also compare it to a standard R8 collet you will see that they grip in the tapered area but the oversize ones grip in the extended end so not as direct a closing force.

It's a bit like using a 5C step collet without the closing ring.

Edited By JasonB on 12/10/2019 17:14:31

For Crawford’s range of sizes, see p22 of this brochure: **LINK**

http://www.rotagriponline.com/datasheets/5C.pdf

[ ignore the file-name ]

MichaelG.

Using a big cutter [i.e. 25 mm / 1"] or above in an R8 spindled machine seems attractive but in practice you would get little or no benefit out of doing so.

Tony