2 switch Europiccola is sight glass thread M12x1 

11x1mm or 12x1mm sight glass shoulder

 

Shoulder is 11mm

Adaptor is 12mm

Gauge thread is 1/8-28TPI BSPT (tapered)

 

3120104 Pressure Gauge Adapter Nut (Professional Chrome) 1/8 BSPF to 12mm male? £5.00 + VAT

3120185 Pressure Gauge Adapter Nut (Europiccola Brass)  1/8BSPF to 11mm male?

 

1/8" Female to 1/4" BSP Male adapter available for air brush app around £2.50

 

Thread   TPI   Thread  Gauge                  Tap Drill 

                                 Length    BSP.PL (Rp) BSP.F (G)

  1/8  28    9.728 6     8.60                 8.80

  1/4  19    13.157 8    11.50               11.80

 

Drill 11mm shoulder (Europiccola) 11.8mm tap with 1/4" BSP bottom tap attach 1/8 converter or use 1/4" gauge?????

Taper thread?

 

 Steam nozzle hole 1.5mm or 1/16" M6x1 thread

Group piston cylinder diameter 44mm

 

Circlip pliers not essential but sooo much easier. Treat yourself, get one locally or Ebay. If you can't get a pair, unwind an oversize paper clip and use the ends to compress the circlip so you can get it out of the group