[Mazalee]

May sound stupid but can an intergrex rigid tap or should a sprung holder be used

[MetalZilla]

If you have the Mazatrol 640 MT Control it can rigid tap. If you need some help with tapping formulas try here: Tapping and Threading Formulas

[Mazalee]

Machine is an intergrex e670

[psychomill]

Since you're UK, I'm not sure what's standard or option but there's a couple ways to check....

Look on your OPTIONS page in the control and see if it's lit up. Should be something like "SYNC MILL TAPPING" (I think it's option #28).

Other than that, you can test the machine. Write a simple tapping program and go through the motions on the machine using G84.2 for synch tapping right hand threads.
If the machine goes through it, you have the option. If you don't have it, you'll get an alarm for "option not installed" or something like that. If you don't have it, you'll need a spring head and use standard G84 code.