[Update: added X carriage for new version 2.2 belt tension "gantry-X_carriage-Extruder_Holder.12mmRods.v2.2.stl" and gantry-X_carriage-10mmbelt-tensioner.stl]
[Update: added Nema 23 mount for XY]
Some of UK providers are still blocking the main website (they are slow to react) you may access mirror at http://s728416714.onlinehome.us.
[Update: check "v2" versions for gantry corner parts, changes are for motor side previous do not hold pipes; idler side was missing nut slots]
[Update: Found that some idlers for 10mm belt may be 14mm tall, please check new versions tagged "v1.1"]
This is 19.9 or 20mm pipe version upgrade (UK version).
By default, Piper 2 (https://www.thingiverse.com/thing:3036472) is designed to use 8mm guiding rods. Guiding rods will become unstable under belt tension if bed size will be stretched larger than 300mm. This upgrade allows the use of 12 mm rods and 10 mm GT2 belt. It should allow expansion of Piper 2 to a bed size beyond 300mm for example 500x500mm. Some dimensions have changed so bed size will be 123 mm less than Y rod and 113 mm less than X rod.