My preference for anything home based, would be BT30.
However, due to the strong anti-change US scene, there are a lot of options for R8 if you want to make tool changes easier.

The Coventry system is good, but I wouldn't use it on any kind of high speed or high HP spindle. The biggest machine I'd say it's good for is something Bridgeport sized, which is the original market it was aimed at. It's just that the educational CNC machine suppliers realised it was a good option to get consistent tool changes, without requiring a full blown ATC.


Quote Originally Posted by Muzzer View Post
I get the feeling that 40 taper is the most readily available and cheapest for medium sized machines. 30 taper costs more due to less industrial usage. HSK is for big and really high speed machines and big pockets - unless you are running >10krpm in a large, powerful spindle there's no advantage for the likes of us. R8 is a US activity and more readily available over there but it's only really suitable for small to medium machines - created by Bridgeport for their machines.

I can get a wide range of good quality ISO40 tooling for my Shizuoka for around £20-25 a pop. My Bridgeport has ISO30 and the holders are more difficult to find and cost a fair bit more. I don't get close to challenging either of those with the work I do.
BT30 tooling is cheaper than BT40.
ISO30 isn't that popular, and why it's generally more expensive. But if you want to save money, BT30 will fit with a slightly longer drawbar (I had various BT/ISO 30 holders for the Harrison mill I've just sold, and they all worked fine with a longer drawbar. The ISO ones just had a bit more thread engagement)

If you've not seen them, APT have spindle tooling at reasonable prices - https://www.shop-apt.co.uk/cnc-spindle-tooling.html