Summertone was established thirty + years ago by Terry Summers who has over fifty five years’ experience in the Film, Audio and Magnetic Stripe Industry. He identified a need for a small specialist Company offering expertise in several areas, including:

  1. Magnetic head re-profile and re-lapping
  2. Magnetic heads for sale from stock
  3. UK agent for Photovox srl (Head manufacturer), Italy
  4. Publication of a Specialist book on Old Cottage Dolls

REEL TO REEL TAPE HEAD FORUM  IMPORTANT INFORMATION

It has come to my notice that some disturbing information has been posted on the Forum about head re-lapping. Some of these methods, if employed will destroy your valuable head and make your tape recorder useless.

Do not use needle files, metal polish or emery paper.  If you use a multi-meter to check the heads make sure you de-magnetise them afterwards.

The correct Items required for re-lapping are.
A good microscope.  Gap condition inspection during re-lapping is essential.
A good inductance meter using 1Khz at 1 volt.
A certified flat lapping plate
Lapping film and diamond paste with a suitable carrier for the paste.
Lapping fluid, not water.
A huge amount of experience.

Heads must be re-profiled to the exact shape they were when new. This is essential to ensure the low frequency end frequency response is unaltered.
Head magnetic materials are different in heads (Mu-metal, Amorphous Vitrovac, Ferrite etc) so the makeup must be assessed to ascertain the correct lapping material, grade and method.
Head body materials are different (brass, nickel silver, grades of aluminium, ceramic, ferrite etc.)
and require different techniques and materials to renovate them. Some aluminium bodies are particularly difficult to achieve a satisfactory finish.
It is essential that the whole area that the tape passes over is completely flat and has a fine finish.  A good polish does not guarantee that. The biggest danger is that the gap in the centre, (that is the working part of the head) is totally clean and open and is not “swaged” – partially rubbed over obscuring the gap. This can happen when using incorrect materials and methods. The other fault that can occur (and happens when metal polish is used) is the edges of the gap are rounded inwards.  This causes the head to have a wider gap than the actual one and results in high frequency loss.
I hope this helps.