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Repair Manual for Swiss-made BesTest and TesaTast Indicators
Complete and fully illustrated by René Urs Meyer

My father taught me how to repair indicators. My very first attempt was the Starrett Last Word model 711F. Maybe it was because he had a box full of them on the shelf. Maybe he just wanted me to have experience repairing one of the worst indicators available at that time. He may have figured that, after I mastered the Last Word, the rest would seem like a breeze. I found out that most spare parts on the Starrett had to be customized to fit and to function. I had to scrape rust off the steel bodies. I had to glue and file, demagnetize and bend and pinch… it took me four hours to finish my first repair. My father could finish one in 15 minutes.

“There may be many ways to repair an indicator, but there are no shortcuts,” he said.

Imagine my relief when he showed me the Swiss indicators: Compac, TesaTast and Interapid. There was no comparison. The workmanship struck awe. The parts, beautifully engineered, looked and fit as if I were handling a fine watch.

I was fortunate to have had my father as a teacher. He had learned the skill through a rigorous apprenticeship and at the manufacturer’s factories in Switzerland. Meticulously, he taught me everything he knew. Over the years, we experienced the comings and goings of model changes, the introduction of new technologies, and the resulting repair challenges.

Having repaired upwards of 35,000 test indicators since, and having considered my retirement years just around the corner, I thought it would be wasteful if all that I had learned along the way were lost.

Today, it gives me great pleasure to pass on these instructions for the repair of some of the finest test indicators ever manufactured.

Table of Contents

  • Specifications 6
  • Can it be fixed? 7
  • Repair Tools 10
  • Disassembly 14
  • Cleaning 23
  • Reassembly 27
  • Congratulations! 58
  • Calibration 59
  • BesTest Contact Points 61
  • TesaTast Contact Points 64
  • BesTest Dials 66
  • Horizontal test indicator spare parts list 68
  • Vertical test indicator spare parts list 71
  • Illustrated Spare Parts 75
  • Acknowledgments 94
     

 

Can it be fixed?

We shall begin by examining the BesTest or TesaTast indicator to see if it is worth repairing.

The most common reasons why these indicators come in for repair:

  • The bezel is dented and the crystal is cracked or has popped out.
  • Oil has gotten into the hair spring and the indicator no longer repeats or is sluggish.
  • The teeth on the crown gear are damaged due to shock.
  • The ball bearings are ruined due to shock at the contact point end.
  • The contact point has broken off leaving the thread in the pivot.
  • Everything is “gummed up” with coolant or grime.
  • Someone has tampered with ball bearing adjustment.

There are no parts remaining for old BesTest models which end in –1 or –2, or have no suffix at all. These were discontinued in the 1960’s. If you begin a repair on an old model and notice damaged parts, you will be best off to abandon the project right away.

Although all parts are available for current BesTest models ending in –3 and –5, it may not be cost effective to replace more than a few. Plus, it may not be worth your time and effort. It is very frustrating to have spent an hour’s worth of time to realize that this is not going to work.

 

To order your copy of this Bestest repair manual, please click here.

Resources

  • Contact Points … see page 218
  • Spare Parts and parts breakdown … see page 74

Addenda

Change is inevitable and since the publication of this repair manual, the manufacturer has introduced three modifications to take note of:

IMG1893

1. The dials are now made of plastic but, most significantly, they no longer have the model number printed on them. This will cause problems down the road when we have to replace old dials with new ones. Unless we mark the model number either on the dial or another conspicuous part of the indicators, the customer will not know which model they have and which one they might want to order when time comes to replace it.

IMG1887

2. The indicator model number is etched on the cover plate of the new test indicator, above the serial number.

IMG1891

3. A new peek-hole is present in the movement allowing us to see the meshing of the rack lever with the crown gear teeth. The jewels are no longer bright red synthetic rubies, but are now a lighter, more rosy color.

 

To order your copy of this Bestest repair manual, please click here.

What does the SwissTast indicator have in common with BesTest?

Everything is the same except for three items:

  • the bright white dial has the name SwissTast as well as the TESA logo
  • the bezel is a striking metallic red
  • the indicator comes standard with a ruby contact point

How to remove the clear plastic crystal on your BesTest or TesaTast indicator

There is no simple or easy way to do this. Suction cups have been used—like those suction darts we played with as kids— but most of the time they do not work. You can try to pry the crystal out by running a thin blade screw driver (or knife) along the edge. Be careful! The quickest way is to destroy the old crystal. Any repair looks best when you install a new crystal in the process.

Problems which beginners encounter

We have been teaching newbies how to repair these BesTest indicators and this brings to light some problems which are probably common among beginners. If you are also having trouble with your first repair attempts, pay close attention to the following points:

  • Over tightening the ball bearings
  • Not cleaning the ball bearings sufficiently
  • Lack of skill (or practice) installing a new hair spring
  • Trouble mounting the hair spring disc with proper pre-load

Corrections

I am grateful for having a number of errors brought to my attention by astute readers. Among these:

page 76: TESA 017203 should have the following B&S number: 99-7030-19 (formerly 99-988-30)

page 80: TESA 023012 should have the following B&S number: 99-7032-200

 

LONG ISLAND INDICATOR REPAIR MANUALS

BesTest and TesaTast Indicator Repair Manual … page 177
Starrett 711 Last Word Indicator Repair Manual … page 199
Interapid Indicator Repair Manual … page 208
Compac Test Indicator Repair Manual … page 194
Mitutoyo Test Indicator Repair Manual … page 102
 

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14 Sarah Drive — Hauppauge NY 11788 — USA


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This page's most recent revision: 14 JULY 2017
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Original photographs and content copyright 2017 by JWGrum

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