Most replacement Wetterlings and Gransfors Bruk handles fit really well into original heads. 

  •         Fitting a new handle onto an axe head should be straight forward and should not present any problem. 
  •         For safety apply electricians tape to the cutting edge
  •        Locate the head loosely onto the new handle holding onto both, hold everything vertically with the head on top and let the whole thing drop from about 6”  onto a solid (concrete?) floor, perhaps protected with a piece of old carpet or similar.  
  •       This should locate the head a short way on to the handle.  Do this several times until the head is fully home with the end of the handle proud of the head by about 8mm. 
  •        If there are any small ‘curled’ shavings  just below the head remove these with a knife
  •        At this stage you might want to carefully open up the factory made kerf with a chisel so you can better locate the wooden wedge. 
  •         Squeeze a bit of wood glue in to the kerf and tap in the wooden wedge.  Sometimes the wooden wedge can split so it would be better to put a piece of flat scrap wood over the wedge to reduce the likelihood of this happening.
  •       Typically the wooden wedge is half consumed into the handle, wait until it can go no further, it will probably make a different sound when it’s fully home.
  •      If you are in no hurry, leave overnight for the glue to set.
  •      Saw off the remnant piece of wooden wedge so it is cleanly flush with the top of the handle.  A nice Japanese pull saw is good for this job.  DO NOT cut flush with the top of the head! It’s the slight mushrooming over of the piece of handle wood that extends beyond the head that is most effective to keep the head and handle together.
  •      It is traditional to leave it just at that, however you may feel reassured to also use a steel wedge for peace of mind. Position the steel wedge at a diagonal angle and tap with an engineer’s hammer until it's fully home so it is flush with the top of the handle.  The main function of the steel wedge is to help secure the wooden wedge in place but also to apply a small amount of diagonal wedging to the wooden wedge.  Using a steel wedge however makes it a little trickier when you have to eventually replace the handle again.
  • ·         Would not do any harm to paint a bit of linseed oil on the end grain of the handle to swell it slightly and perhaps help it from drying out.