Arm restrainer

  • Grip 10mm nut vertically in vice and drill through side with 4.5mm bit before threading with 5mm tap
  • Grip 10mm nut flat in vice and drill through with 10mm bit
  • Grip large coin in vice and drill through with 10mm bit after drilling 2.5mm pilot hole first.
  • Now drill 4mm hole after drilling 2.5mm pilot hole first.
  • Check nut is smooth fit on barrel and file slightly if necessary before applying epoxy resin to outside fedge of face of nut only
  • This image shows how not to do it! A small bead or a couple of drops are all that is necessary. Ensure no epoxy is placed on barr as we are gluing the coin to the nut - nothing else!
  • Drop coin onto barrel and press down gently onto nut. Allow to sit for 2 minutes to bond slightly before removing from barrel carefully so as not to disturb positions.
  • A view showing underneah of 2 glued components.
  • When coin and nut bond is dry apply small drop of epoxy to 4mm hole and insert arm retaining pin. When dry screw 5mm grub screw into nut.
  • The finished arm restrainer slipped temporarily onto barrel.

 

 

Barrel - simple form

First cut 65mm length of 10mm diameter aluminium or brass tube and smooth and polish ends.

Further details in gallery below:-

 

  • Stack 5 or 6 M4 nuts onto screw taking care not to lock screws against each other as screw must e removable after gluing.
  • Apply lashings of epoxy resin to nut exteriors making sure not to apply any to screw.
  • Slide glued up nuts into barrel making sure no glue transfers to screw.
  • When dry remove screw and drill with 4.00mm drill bit.
  • File and smooth nut assembly interior to allow piston to slide completely freely and smoothly. This is essential for smooth operation and is an easy but critical step.
  • Blow out any swarf or dust from last process and apply glue to exterior of single M4 nut.
  • Glue nut into tube interior ensuring no glue transfers to thread.
  • Drill coin with 4mm bit and glue to M4 x 25mm stainless steel cap screw. The coin represents me adding my 50 cents worth!
  • Completed barrel and drive screw,.

 

 

Barrel - classic lathe model

Instructions

for turning barrel from 65mm of 10mm stainless rod.

  1. Part off 65mm of rod.
  2. Chuck up and centre drill before drilling 4.5mm hole to depth of 40mm / 45mm.
  3. Reverse rod in chuck and centre drill before drilling 4.0mm hole through.
  4. File and smooth to ensure piston travels extremely smoothly and freely.
  5. Reverse rod again and tap M5 to depth of 25mm.

Drive Screw

  1. Chuck knurled coin, centre drill and tap M5.
  2. Spin coin onto M5 x 25mm A2 cap screw and secure with drop of epoxy.
  • Make drive screw by centre drilling and tapping knurled coin and inserting M5 x25mm A2 stainless cap set screw.
  • Completed barrel and drive screw.