Cylindrical grinding

[Spark plug]

The large end of a number 7 Morse taper is about 3 1/4". If your spindle bore is more than that, it can't be a Morse taper. You can probably roughly measure the bore from the opposite end of the spindle to the chuck in advance of making the C-spanner.



If you can find something with a suitable OD and the female Morse socket already formed, that can help. E.g. https://www.zoro.co.uk/shop/spindle...et-socket-5mt-x-50mmo-s-diameter/p/ZT1124220X

The biggest problem with above is the tang ejection slot, which gives a horrible interrupted cut when turning the outside. As it is a spindle bush, maybe curtailing it just as the slot starts would be OK.

That’s a good shout, but the trouble will be finding something larger than 3-3/8”

 

[dan.taylor.1]

The large end of a number 7 Morse taper is about 3 1/4". If your spindle bore is more than that, it can't be a Morse taper. You can probably roughly measure the bore from the opposite end of the spindle to the chuck in advance of making the C-spanner.



If you can find something with a suitable OD and the female Morse socket already formed, that can help. E.g. https://www.zoro.co.uk/shop/spindle...et-socket-5mt-x-50mmo-s-diameter/p/ZT1124220X

The biggest problem with above is the tang ejection slot, which gives a horrible interrupted cut when turning the outside. As it is a spindle bush, maybe curtailing it just as the slot starts would be OK.

Pretty sure it's 2.8" or thereabouts. According to @Brad93 measurements there's a taper and it's 3.00” down to about 2.825”