old colombo spindle

[petercolombo]

I bought a colombo spindle and with a Chinese VDF it works great at 12000 rpm
BUT the collet nut is not standard ER25 with M30 x 1, but M30 x 1.5mm. Also the hole for the collet is strange, only 22mm deep and first a 18mm cylinder and then a taper of +/- 40°
hope there is anybody that knows about this old spindle, and what type of collet I can use.
peter
ps type is RV130 -HP 4 -- 9.6A --200Hz en n=12000 GIORDANO COLOMBO