Advice on toolholders

[Rabs]

Hi everyone,
I have a mill which, frustratingly, does not have a drawbar. At present it uses the colchester easychange system:

(not to scale)
Dark Green=Mill body, Blue=spindle, Light Green = easychange chuck, Grey = clamping bolt, Red=toolholder

The problems with this setup are:

• Not very stiff - the height of the easychange chuck means that the tools end up very long way out from the spindle nose
• The easychange chuck I've got is either poor quality, damaged or worn and there is noticeable play between all the toolholders and the chuck
• The length restricts the working height of the mill
• It would be hard to implement automatic tool changes (not a high priority)

Does anyone have any comments on the arrangement below?


In this I put a thread directly on the toolholder and spin it into the taper on the spindle (it has the same, non-standard 20degree taper). I'd tighten by using a spanner on the top (pink) of the spindle (which has flats) and flats machined on the toolholder.

My concern is that this means that I will be rotating the taper faces together, rather than applying an axial force, as a normal drawbar would. Would this be a problem? It's obviously fine to screw onto a register with a lathe chuck, does the fact that it's a taper make any difference?
Any other comments on the plan?