Looking for some advice on machining/drilling for a prop...

Comments

• danjaq_0ff The SwampsPosts: 7,283MI6 Agent

  February 2014

  Im not one of the prop makers, but FE GG is made out of the same sort of thing and they managed to machine it.
  
  I would say they the american tap sizes are imperial and the UK metric -{
• don p Posts: 607MI6 Agent

  February 2014

  put it in a vice, and tap it your self slowly using a lubricant.
• Thunderpussy Behind you !Posts: 63,792MI6 Agent

  February 2014

  Ah, the motto of AJB. )

  "I've been informed that there ARE a couple of QAnon supporters who are fairly regular posters in AJB."
• danjaq_0ff The SwampsPosts: 7,283MI6 Agent

  February 2014

  Thunderpussy wrote:

  Ah, the motto of AJB. )

  
  ) ) )
• Charmed & Dangerous Posts: 7,358MI6 Agent

  February 2014 edited February 2014

  don p wrote:

  put it in a vice, and tap it your self slowly using a lubricant.

  
  Sadly I'm the least technical person on the planet and my idea of "put it in a vice, and tap it yourself slowly using a lubricant" means holding it very firmly and tapping it with a pencil while necking a can of lager. )
  
  Seriously I don't have a vice or any of the proper tools and would be too worried of making a c0ck-up of the job. but thank you for replying all the same -{

  "How was your lamb?" "Skewered. One sympathises."
• Charmed & Dangerous Posts: 7,358MI6 Agent

  February 2014

  danjaq_0ff wrote:

  Im not one of the prop makers, but FE GG is made out of the same sort of thing and they managed to machine it.
  
  I would say they the american tap sizes are imperial and the UK metric -{

  
  Thank you - that gives me some confidence so I will try and locate a trade machinist locally. -{

  "How was your lamb?" "Skewered. One sympathises."
• minigeff EnglandPosts: 7,884MI6 Agent

  February 2014

  Oh blimey, tapping for the novice? Scary stuff.
  
  Ok, so it's not as hair raising as some might think but like any job, you do need the right tools and if you've not done anything like it before it's always handy to have someone show you how.
  
  Zinc alloy (that's that zamack crap ain't it) can be notoriously soft and therefore problematic to machine.
  
  Some might assume a softer alloy would he easier to machine, but the softness can actuall cause issues as the metal tends to tear instead of cutting sharply. A good example would be cz121 brass as opposed the cz108 grade. Copper is also a bitch to machine, I've never had great experiences with it.
  
  Anyways, grades of metal aside, the job of threading a barrel isn't too tricky, but you need a well setup lathe to do it to ensure the thread is cut concentric to the bore, otherwise ya silencer or flash hider will be all wonky, and in extreme cases this could cause the bullet to contact the inside of the silencer. Cripes.
  
  Put simply the bore needs to be prepared so it's the correct size, then the tap is used to cut the thread into the metal.
  
  When cutting any thread using taps and dies is recommend taking your time, use so lubricant like cheapo engine oil or 3-in-1, and it's generally a third of a rotation in at a time, making sure to screw back each time to remove the swarf produced. Also on deep threads I tend to do to a depth of about 5-10mm at a time, removing the tap completely from the hole to clear it of swarf, and the hole to before restarting the process.
  
  As for a '40 tap' I dunno what that is. 40 tpi (teeth per inch) perhaps, but what diameter? And what type of thread? UNC, BSW? Sounds like the advisors are trying to be helpful but not giving you the full details for some reason.
  
  Hope this helps charmed, and I hope it helps others who are thinking of tapping their holes too

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• Charmed & Dangerous Posts: 7,358MI6 Agent

  February 2014

  Hi MG,
  
  Thank you for your excellent and informative post - that's very helpful. {[]

  "How was your lamb?" "Skewered. One sympathises."