Last update Nov. 23rd. 2015

Lathe Tools

November 22nd. 2014

  

One of the most important tools for use with lathe is Tungsten Carbide graver.

To be able to cut hardest steel graver needs to be sharp. To sharpen it one needs to apply diamond wheel to shape and sharpen the graver.

One of the tools is the Levin Carbide Graver Grinding Tool.

    
Image to the right shows Levin tool mounted onto the lathe ready to grind the Tungsten Carbide graver bits.

Levin tool allows easy and precise mounting of the graver bit. 

Any number of graver bits can be ground to exactly the same angles without need of resetting the tool holder.

     
Several Tungsten Carbide graver bits 1.6 mm (1/16") square, ground for turning balance staffs out of blued pivot steel.
 
Besides Levin Tungsten Carbide gravers, there are sets of Barkus Horological Laboratory gravers. 

Reckoned by many watchmakers to be the finest carbide gravers there are for use in horology.

A boxed set of five graver bits with handle, for general turning, for parting, for staff turning and for pivot turning.

 
Barkus Horological Laboratory handle and Carbide graver bits 2.5 mm (~0.1") square, 64 mm (2.5") long, shown out of the box.

All of the bits are double ended, so that if one side gets dull, one just turns the bit around and can continue with turning.

   
Yet another set of carbide gravers with handle and iron lap for for sharpening graver bits.

These graver bits 1.6 mm (1/16") square, are produced by Waller. 

  
Of course, one needs means to hold the carbide graver securely. For that purpose there are devices similar to pin vices.

Picture to the right shows three Levin graver holders  designed to hold 1/16" (~1.6 mm) square TC or HSS graver bits.

 
For classic gravers, made of carbon steel, I have made holders myself using 8 mm aluminium tubing and a short piece of brass rod, drilled through to size of 3.5 mm, just big enough to accept graver. 

The graver is fixed into its position by a hex set screw, long enough to hold graver but staying fully inside the hole, so not to interfere while turning.

These particular gravers were ground for slotting, e.g. winding stems etc.

 
A set of lathe cutters ground specially for turning in the watchmaker's lathe, mainly for turning brass. 

These cutters are 5 mm square (3/16"), 50 mm long (2"), fitting either the standard tool post or the Tripan QC.

 
Talking about lathe cutters, one should never forget to mention boring cutters. 

Boring cutters are used with cross slide, mounted in tool holder for boring openings as small as 0.50 mm in diameter.

Boring is usually done when it is necessary to re-centre a hole enlarged by wear, like the hole in the mainspring bridge, or the mainspring barrel, or its cover. 

Boring cutters use in watch work is practically endless. 

 
Here, one of the boring cutters mounted in QC tool holder ready to use. 

The two types of boring cutter form and sizes are shown in table, presented within second image.

The first two digits signify size of the boring tool in 1/10 mm steps.

   
A Levin Lathe Utility Set. 

It is intended for grinding and preparing HSS graver bits 1.6 mm (1/16") square, for turning in lathe.

Also, it can be used for various slotting of parts or screw-head slotting.

    
Image to the right shows set-up for the screw-head slotting. Collet ready to accept finished screw which needs slotting.
  
And here we have a screw head already slotted in a matter of few seconds, exactly centred.
 
Another possible use is precise screwdriver bit grinding symmetrically, to fit any screw-head without possibility of slipping.

Each screwdriver bit is fitted into the collet of corresponding size, ground quickly and accurately. 

Possibilities of the tool set are as large as is imagination of the watchmaker.

 
It is very important to have screwdriver blades shaped  correctly, otherwise slot in the screw head can easily be marred, requiring that it be refinished, or having screw replaced.  

Correctly and incorrectly shaped screwdriver blades.

 

  
Next to the turning gravers and lathe cutting tools drill bits are just as important.

There are several types used in watchmaking. The spade drill bits, the straight flute and the spiral drill bits.

They vary in size, diameter of normally used drill bit is in range from 8/100 mm up to 3.0 mm.

  
Here are the pivot drills, sized from 10/100mm to 50/100mm, step is 1/100 and 2/100 mm, some are spade type and some are spiral.

Type of drill bit used in full depends on the material that needs to be drilled, and on the job that needs to be done.

 
The big set of Eureka twin straight flute, Sphinx brand drill bits, diameter ranges from 0.5mm to 3.0mm, increasing in steps of 1/10 mm.

The straight flute drill bits are by far superior to spade and to spiral flute drill bits. They will drill deeper holes centred straight and will not wander off, nor will they break easily. 

Drill bit shank varies with the drill bit size and are: 1.5mm, 2.0mm, 2.5mm and 3.0mm.

 
A smaller set of Eureka twin straight flute, Sphinx brand drill bits, diameter ranges from 0.5mm to 1.4mm, increasing in steps of 1/10 mm.

The shank of drill bits in this set is 1.5mm and is the same for all sizes.

 
This is a set of spade drill bits, Sphinx brand sized from 10/100mm-30/100mm, increasing in steps of 2/100 mm, shank of all bits is 1.0mm in diameter.
    
Another lathe tool designed by Levin is the Pivot Straightening and Burnishing Tool
    
It can be used without lathe as well, driven by a bow fastened to the bench side with a special holder provided with the set.

When used in lathe it is mounted onto a special holder that mounts in place of T-rest, in the usual manner.

Lathe is used to drive it with a small pulley provided with a set, mounted in a collet.

 

    
Image from the Levin catalogue shows application of the tool in a lathe.
 
Set of Levin Balloon chucks, one sized for use with pocket watch balances and smaller one for the wrist watches.
 
Balance wheel is securely mounted inside the chuck and then mounted in the lathe. 

No further centring is needed as the balloon is mounted onto the 8 mm collet. 

Used only for minor repairs of pivots without dismantling hairspring from the balance wheel.

I would not advise its use on high grade watches.

The lathe faceplate, a tool quite indispensable when having to do any up-righting in the lathe, replacing a jewel, or bushing a plate or bridge.

Usually faceplate is supplied with a pump centre, used to ease centring of the plate or bridge, pump centre shown in the second image. 

 
A PW plate mounted onto the faceplate with the pump centre retracted, ready for turning.
  
Another important lathe tool is vertical slide with the milling/drilling attachment. 

This one is a heavy duty, Wolf Jahn, vertical slide with milling/drilling collet bearing attachment.

It is usually mounted onto the cross slide, and is driven by use of overhead drive. 

 
Images show Vertical slide as seen from various sides with the milling/drilling attachment mounted vertically.
 
Vertical slide as seen from various sides with milling/drilling attachment mounted horizontally.

Of course drilling/milling attachment can be mounted at any angle in relation to the vertical slide 90.

It can be lowered or raised travelling the full length of 70 mm.  

  
Watchmakers often make screws, either to replace a damaged one, or to make a new screw as part of some tool he makes himself.

The fastest method is to use dies to cut thread. However, thread must be started at the right angle to the screw axis, or thread will not be cut properly.

To be able to start, and cut, thread properly I have designed and made a double sided die holder, accepting dies of 8 and 12 mm, for threading most of the screw sizes used in watches, from 0.30 - 2.0 mm in diameter.

 
One side is bored to accept 8 mm dies, and the other to take in 12 mm dies, and the body is bored through to a 4.0 mm diameter.

The principle of die holder usage is simple, a rod 4.0 mm in diameter is mounted in the tailstock, and die holder is slid onto it, free to move along.

The body has three holes drilled about the middle, 120 apart, to accept tommy bar so that extra force can be applied, if needed, when cutting thread. 

 
 
 
 
 
 
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