Yes, John, That's the one Jeremy used in his spindle design. Must confess I didn't notice the 1mm range in compression. After all, we were told as apprentices "that to be an electrician you need to be able to read or write, not necessarily both!"
I've now got a MSc in Electronics but keep that quiet :heehee:

I was thinking along the line of the smaller shaft for ease of coupling to the DCBM, but looking at the spec for them I see they feature a 4 or 5mm shaft. So a bit of lathe work is needed whatever way.

John