I had an accident with my original UBIS hot-end, and since it was out of stock at PrintrBot, and because it probably would cost a small fortune to ship to Denmark...
At first I got some one to print MicaelAtOz's adapter, thinking that would do the trick... but no, the adapter doesn't fit the PrintrBot Simple Metal. I had to cut a big chunk out of the cone, to get the hot-end to stay where I wanted it to be.
So, I decided to make an adapter myself, and see where that would get me.
First lesson I learned, was to make sure the JHead-heatblock was oriented so it didn't collide with the chassis, because there's so little space available when Y axis is fully retracted, and Z is low (just look at the fan shroud, there's reason it is shaped that way!)... My first print worked all right for a few layers, but there was a crack due to the collision, and then it snapped clean off (see second image)
You will need to have 2 M3x30 mm screws plus 2 M3 nut's in order to secure the JHead firmly.
My most successful print was with ColorFabb XT:
first layer 0.381mm at 250deg
layer height: 0.1905mm at 250deg
2 perimeters + 100% infill rectilinear
No support needed.
It took a while, but the result was very good.