Here is a spreadsheet that I created to use in conjunction with Terry McCreary’s Propel20 worksheet or similar Kn chart. The Aerotech Medusa Nozzle creates a problem when you try to compute Kn because the Kn chart gives results based on a single nozzle diameter. The Medusa nozzle has more than one nozzle and you can’t simply add them together. This spreadsheet converts each diameter to area, then adds the areas of all the nozzles and computes a corresponding single diameter for that value. This “diameter” is used in the Propel20 spreadsheet to compute Kn for your medusa nozzle. I’ve also included a chart with fraction to decimal conversions for sizing drill bits.

Excel spreadsheet

Submitted by: Jerry L. Scafidel