• Plastic HMP Specs
• Aluminium HMP Specs
• HMP Tip Specs
• HMP Plunger Specs
• Size Chart
• Operation
• Replacement Tips
• Replacement Plungers
• Applications

Harris Micro-Punch® (HMP) Replacement Plungers                 

Plungers rarely need replacement. The exception may be the plunger for the Harris Micro-Punch® 0.50 mm i.d. tip. Replacement may be necessary if the user does not follow sample operating instructions which identify a warning at the beginning not to depress plunger when coring a sample.  Some users depress the plunger prior to coring and then bring the plunger into contact with the substrate surface, thereby bending the more fragile 0.40 plunger.  

All plungers undergo quality control tests for fit to tip, knob-screw assembly and compression spring.

1. Wear protective gloves and place cover cap on HMP tip.
   
   
   
2. Unscrew knob-screw nut from top of barrel and pull out with plunger attached to T-joint.  Leave compression spring in barrel.
   
   
   
3. Hold T-joint shaft of knob-screw assembly firmly between fingers of one hand.  With the fingers of the other hand firmly grip the moulded plastic shaft of the plunger.  With gentle, but firm pressure slowly rotate moulded shaft of plunger until the T-shaped head is removed from T-joint in knob-screw assembly.  Hold T-joint shaft of knob-screw assembly firmly between fingers of one hand.  With the fingers of the other hand firmly grip the moulded plastic shaft of the replacement plunger. With gentle, but firm pressure slowly rotate and insert the T-shaped head of the plunger into the knob-screw assembly T-joint.
   
   
   
4. Grip knob-screw nut with fingers of one hand and grip barrel with fingers of other hand.  Insert the plunger into the compression spring still located in the Harris Micro-Punch® barrel. Apply gentle pressure by pushing knob-screw nut against compression spring and slowly inserting the plunger rod into the Harris Micro-Punch® tip. When the knob-screw nut makes contact with the threads at the top of the barrel turn the knob-screw nut onto the barrel.  When doing this you should be aware of any resistance against the plunger as it is inserted into the tip.  Assembling is not generally a problem for of 1.00mm and greater diameter tips.  However, with the 0.50mm tip care should be taken when re-inserting the plunger rod as the rod is fragile and any resistance may result in damage.
   
   
   
5. Remove cover cap from tip and depress plunger slowly to ensure properly assembled.  Replace cover cap on tip.