Hi Michael,
The correspondent whose remarks I quoted was clearly partially in error regarding the collets. Seems only to have muddied the waters slightly.
The unit was sold to a very high quality professional watchmaker. Wisely, he contacted me after paying for but before shipping to clarify the collet size and kindly sent me a 6mm collet which was way too large.
This has at least avoided the anxiety of sending a cast iron item through the post not once but twice!
I have since refunded him and continue to try and find out exactly what this machine takes in order to describe it more accurately when I list it for sale next time. He too has some 4.5mm collets with a female thread for the drawbar which according to my measurements will also be too large
It is difficult for me to measure this small opening accurately but have done my best.
Any help on this would be really welcome!
Regards,
Martin.