I decided to make a copy of the nose spindle – just the taper. This will be my gauge for the internal taper of the adapter plate. I thought this is the best way for me to “measure” the taper in the adapter plate.
   

The first thing I decided to do was to orientate the compound slide to give the correct taper.
Using a DTI to get it as close as possible. A little tedious but with patience and care it is possible to get a zero reading along the taper. Until you tighten it down that is!!.



So that done put the chuck back on. I’m using some aluminium to make the taper gauge, mainly because I didn’t have any steel of a suitable size.

A quick face.



I then turned down a “boss” 2.5005inches dia x 10mm deep, I then proceeded to cut the taper, using the compound slide.



Now it starts to get a little tedious again and messy.
I need something to gauge the taper, I chose my 4 jaw chuck, I could have used the face plate – a lot lighter, only thought of that now!
It also necessitated the removal of the locking pins from the chuck.



Now it is just a case of seeing how well the taper fits. Using engineers blue (Prussian Blue) and moving the compound slide accordingly.
It has been pointed out that if the taper has been "zeroed" no adjustment should be necessary, and using the four jaw or face plate to check the taper is not really required.
Then I got this – seems near enough.



I just cleaned up the outer diameter.



And that’s the taper gauge done.

Just have to get the engineers blue off my hands, face, glasses, and my brand new camera – tis’ messy stuff.

DaveH