Rocketry Engine Casing

• The importance of good machining drawings!

• Single point threading on a manual lathe

• Considerations for machining graphite

• Thread galling between materials of similar hardness

For the Olin Rocketry Club which I was a part of my first year at Olin, I was tasked with machining an engine casing. This casing would be filled with a solid fuel to test performance before making an even larger engine for a future rocket.  I wasn't involved with the design of the casing, just tasked with making it.  This turned out to be not the best idea, as the drawing I was given didn't have any tolerances!  After talking to the guy who designed it and remaking a drawing, I used the project as a great opportunity to get in the shop and machine the graphite nozzle along with learning how to single point thread.  Sadly, the design of the assembly was such that it couldn't actually be used since the extruded tubing was too far out of round to accept the Phenolic liner that was supposed to keep the aluminum from melting.  Even though I never got to see it fire, I did gain lots of experience with the manual lathes.