[danielsun]

I have successfully fitted a crayford 10:1 crayford focuser to my saxon 10" dob without the need of drilling any extra holes in the tube or having to use an extention tube.
In the photos below you will see that the base mounts on both focusers can be removed, so i have been able to turn up an adapter bush to go from the original r&p focuser base plate fit to the new crayford and give it the height needed for normal focus travel.
The only minor mod you must do is drill and tap two M4 threads in the under side of the focuser base plate as shown in the pics and the new adapter sleeve will need 3 M4 holes drilled and tapped to hold the new crayford to it.
Lucky for me i was able to get access to a lathe and the material cost about $60.
It may cost a bit to get an engineering shop to turn one up but i think its the best way to go to do it properly.