[deanq]

Can CAT40 tools be run without keys and not slip? Does anyone know if there is a maximum horsepower that they can/should be run without keys (assuming you can safely)?
I don't want to ruin my spindle.
Thanks
Dean

[Geof]

I would not try even if someone says you can drive a certain horsepower.

The reason is that I have had cutters pull down in holders due to the action of the helix in heavy cutting. Obviously they were putting a strong downforce on the toolholder. This would reduce the grip on the taper and in the absence of keys could cause it to slip. And I think any slipping is very likely to cause serious damage to the spindle taper.

[underthetire]

Not worth it. A std CT40 drawbar pulls the holder in to the taper with ~1800lbs of force. At that point, you would be hoping for full contact along the entire taper, however this is not usually the case. Some spindles make contact top and bottom only, some holders aren't ground right, ETC. One slip and the spindle is pretty much done and will need re-grind.

[gridley51]

This has been discussed at length before.Matchmaker sold machines with toolchanger and power drawbar with no keys on the flange.Slippage was not a problem according to several service guys I have spoken to,and I have a machine which I bought to break and the spindle is perfect.
Admittedly they are not high horsepower machines.

[Geof]

I don't recall any discussion about Cat40 toolholders without keys. I do remember discussions about R8 and C5 both of which do not depend on a key and get all their drive from the friction in the taper. But these have a tighter taper and in the case of the R8 are commonly held in with a rigid drawbar; no spring washers to compress. Sometimes C5 collets are led in by springs or air pressure but the recommended drawbar force is somewhat higher than a Cat40 at around 2200lbs if my memory is reliable.

If a Cat40 was held in with a rigid drawbar exerting a force greater than a typical Belleville washer drawbar then I would be happy to use it without keys.

[deanq]

I guess it's not worth the chance of damaging the spindle taper.
Thanks
Dean