Recent content by Andy Munns

Help Support HMEM:

  1. Andy Munns

    Engine learner

    Perhaps first find some drawings for an oscillating compressed air engine. Steel cylinder, standard, crank and base with 12 mm / 1/2" brass piston and connecting rod. Teaches basic lathe, drill and bench work. Many have been made by my students in high school. They don't take too much time to...
  2. Andy Munns

    COVID-19 Coronavirus Disease

    Part retired and now technology teaching 2dpw online from home as I was in higher age risk group and advised to stay away. Only a handful of students coming to school, probably children of essentials. Able to do more home workshop stuff - Taking more time and pursuing more quality. Supply of...
  3. Andy Munns

    Annealing Copper

    Softening carbon steel depends on speed of cooling through S curves (because they are "S" shaped). Copper does not have S curves so quenching is convenient but not necessary. Work hardening of say copper steam pipes required delagging every 5 odd years and a quick anneal to remove effects of...
  4. Andy Munns

    Frisco Standard Gas Engine Build

    Interesting - Did the pattern + casting + machining for a full size 5" bore Frisco some years ago. Fascinating to see how the designer managed to get the cooling water into around the recesses in the head. Also installed hardened seats into the cast iron head to allow for non-leaded fuel. Engine...
  5. Andy Munns

    Piston ring rotation

    See but no direct ref to the actual experiment report for citation.
  6. Andy Munns

    Piston ring rotation

    There was a test which used a new 4 cylinder engine - New rings, but they ran the engine and progressively opened up the ring gaps by increments until well over recommended gap limits. Results showed no real loss of compression until ring gap was huge. Conclusion was that ring gap made less...
  7. Andy Munns

    Most efficient steam engine design?

    Many people think they started with the High Pressure and added the IP and LP, but historically they started with LP atmospheric engines where the vacuum did most of the work and added higher pressure cylinders fed by higher pressure boilers. The reluctance to embrace high pressure steam was a...
  8. Andy Munns

    In surch of plans for steam launch engine

  9. Andy Munns

    In surch of plans for steam launch engine

    also see KB Harris work at
  10. Andy Munns

    Outlet for model engines

    World is changing. I once taught wood, metal and drawing classes but semi-retired still teach, but classes have changed to engineering + electronics + computing systems (not computers!). Some high schools still do wood + metal but focus shifting to mechatronics, Arduino, 3D CAD/CNC, etc. Year 9...
  11. Andy Munns

    Centring in a 4-Jaw Chuck

    School metal shops teachers will growl at students for parking keys in chucks. Students and apprentices are taught never to do this and that the chuck key must always be held, or rested in the chip tray. There have been many case examples of broken or injured hands, etc. plus broken windows...
  12. Andy Munns

    My first boiler

    Inescapable part of pressure vessel engineering is staying of flat surfaces to resist bulging - For a 3" drum perhaps 3 x 1/4" copper rods spaced equally and SS onto end plates. Your compressor air vessel avoids this issue with install of dished ends (loads are tension not bending). Stays are...
  13. Andy Munns

    Trouble turning hot rolled steel!

    On water finish - I neglected to detail that the oil stone rubs between tool and job, but the gap between tool and job is adjusted so that oil stone leans in at top, and therefore produces on the tool a tiny flat that is 'wider' than the feed rate per turn. A tiny facet on the end relief angle...
  14. Andy Munns

    Trouble turning hot rolled steel!

    Another option is a water finish - Had a problem finishing a crankshaft - Low Carbon steel with finish issues at textbook speeds on a heavy lathe. Old timer showed me how to set up a broad nosed tool and use a slip stone to hone a flat on tool face parallel with surface. Run lathe at extremely...
  15. Andy Munns

    Safety Turning

    When I did this at tech college (40 years ago at TAFE in Oz) they supplied hand made hook tools in 6 mm. rod to hook out the spirals and direct them away. We train never to use fingers for this task, but see it a lot. Again, the trainers with a lifetime in industry and training told us to stand...