Jump to content

demoncase

Forum Regular
  • Content Count

    839
  • Joined

  • Last visited

  • Days Won

    4

Posts posted by demoncase


  1. Going back to nozzle failures earlier in the thread: That looks like a brittle failure, rather than an overstressed failure, judging* by the shell-shaped tide marks in the failure face on the pictures shown.

     

    This is an injection moulded part- Understand that an injection mould will have 3-50 part spaces in each tool, so a single 'shot' produces as many as possible.

     

     

    It's most likely that there are 10 or so nozzles in each shot. If the tool is poorly designed and/or process controls aren't being adhered to, you often get the part-mould furthest from the shot being poorly cast- The plastic is cooling and not flowing as well, so you get 'cold weld' lines which will result in creating a stress raiser in use- The crack is already there, and it's a question of when not if it fails....I've seen this in metal-injection moulded parts and polymer parts equally over the years.

     

     

    This happens over time and as the mould wears- each shot of molten plastic reduces the polish on the inside of the tool, increasing friction and slowing the time the plastic take to travel around the mould. Without regular refinishing of the tool, you can even get 'short shots' where some parts aren't fully 'filled' with plastic.

     

     

    What's at fault here- again extrapolating based on experience- is probably QC not picking up that the process has drifted over time and a small proportion of each batch are non-conforming....In this case, without something like a dye-penetrant inspection of every part, it's hard to spot cold weld on dark plastic parts- short of reported failures. You only use dye-pen on safety critical components due to the cost/time implication, and that ain't airsoft. You can test-to-destruction a sample, then accept or reject the batch- but if there is a variation across a batch (as I describe) it's luck of the draw if you get a non-forming one.....and here we are....

     

    The airvoid in that first noted failure is telling- that's clear a symptom of poor material flow inside the mould as I describe above.

     

     

    Just to note- these are problems that EVERY manufacturer of injection mouldings has to keep on top of- airsoft or not....I went into Homebase to buy a new kitchen bin a few weeks ago and found the 'reduced to clear' ones all had a clear 'cold weld' line running down the length of the body.

    I didn't buy one.

     

    Would all the above stop me buying an MP7 if I was in the market? Nope....It's a production hiccup, for my money.

     

     

    *Not wanting to get into an internet 'willy length' competion, but I've a Bsc in Materials Science, 5 years in a technical materials laboratory specialising in polymers and ceramics, 10 years experience as a NADCAP heat-treatment/chemical processing auditor and 15 years overall in the aerospace industry.

    • Like 13

  2. In lieu of an off-the-shelf Carl Gustav M45, here's my little effort....Based on an ICS M3:

    IMAG1218.jpg

    IMAG1219.jpg

    All your silent sentry removal needs.... :)

    IMAG1221.jpg

    VERY front heavy now- it's an all steel unit I've had machined and custom blued...not 100% sure I'll keep it.

    IMAG1222.jpg

    Just to show everyone it's a slip on/slip off unit- single grub screw means I can convert back to the usual M3 style in seconds.

    • Like 1

  3. This started life as a Tercel full metal/wood pump action- which is nice but not right for the diddy-bopping down them rice paddies in the Delta.

     

    So I:

    ~Stripped off the vile orange varnish on the wood

    ~Left it rough in places to simulate combat usage

    ~Stained it with dark oak

    ~Rubbed in about 7 coats of Danish Oil

    ~Ripped off the 'slugster' sights and added a 1970s 'Speedbead' at the front

    ~Added a 1960s dated utility strap.

     

    And got something rather more 'battle worn' for use with 'Nam period gear.

    DSC02391.jpg

    DSC02393.jpg


  4. My current 1911s.

     

    WE MEUSOC with custom extended slide catch

    WE 1911a1 with real Colt wood grips

    WE 'Defender' clone- custom 'bobbed' hammer and grip safety, ambidextrous safety and fingergroove grips. Stainless steel custom paint

     

    DSC01670.jpg

    DSC01671.jpg

    DSC01672.jpg

×

Important Information

By using this site, you agree to our Terms of Use and the use of session cookies.