Lathes and Attachments

Levin watchmaker's lathe

`

The basic workhorse in my shop. Most watch parts I make are fabricated on this lathe using one or more of its attachments. This lathe features precision (class 7) preloaded ball bearings in the headstock. Show here is the configuration for turning with the slide rest.

Micro drilling attachment

 

When drilling small holes in the lathe, better concentricity and less drill breakage can be obtained by turning the drill and the work in opposite directions.. The big brass handle supplies cutting force like a drill press, but the actual feed is controlled by a micrometer knob on the right. This makes it possible to clear out the chips rapidly and resume the cut without "bumping" the bottom of the hole or suddenly breaking through at the end. The dial indicator reads the hole depth directly.The concept of not bumping the hole bottom is important: In steel, any force applied to the drill while not cutting will burnish and harden the surface. This effect is quite pronounced in very tiny holes and was a major problem for the watchmakers in the old days. Modern carbide drills solve this problem, but they are very brittle and won't stand up to any sudden loads. Carbide drills are not (to my knowledge) available is sizes less than 0.004". Using very small drills in deep holes requires careful attention to centering. The photo on the right shows the micrometer slides for horizontal and vertical adjustment of the spindle. A pair of ground WW collet centers are place in the headstock and drilling spindle. These centers have small round pins rather than points.  Under magnification, the micrometers are adjusted to bring these pins into alignment. This is the ultimate tool for repivoting work or any other precision drilling of small holes. I found this nifty item tossed in a barrel of old fixtures. The feed handle was broken off but it was otherwise undamaged. Levin still sells them for the price of a nice used car.

Boley Turns
 

  

This is a pair of steel turns from around the turn of the century. It is illustrated and discussed in Saunier's Watchmakers Handbook.  He shows it set up to be a lathe. Boley made a large number of attachments for this "prismatic" lathe bed. I have the set of runners for this tool, but no lathe spindle attachment. Occasionally I use it to finish a staff between dead centers.  A part held between dead centers can be adjusted to have practically no radial runout. This insures that the part is concentric. By contrast, a lathe spindle with plain cone bearings must have some radial clearance to carry the oil film. When loaded during the cut, the spindle compresses the oil and can make the part slightly elliptical.

The view on the right shows the turns up close fitted with a brass driving pulley. The pulley rotates around the fixed center. The pin that sticks out of the pulley engages a spoke on the watch wheel or a small carrier attached to the work.

Plain steel turns

In the good old days, this was the principle tool used by the watchmaker for fitting and making round parts. The tool is clamped in the bench vise. The work is held between dead centers and driven with a horsehair bow.

Lorch-Schmidt lathe outfit

 

This 6mm European lathe is shown in its box with accessories. It is designed to be operated with the headstock on the right. (Although it can be switched around, it won't fit in the box that way.)  The accessories consist of several drive wheels with pins for turning parts between dead centers, collets, graduated boring cutters and a Jacot drum for clock pivots.Some people make the following distinctions between turning devices:
• Lathe : Has a spindle that rotates in some kind of bearing.
• Turns: Dead centers. A split pulley (ferrule) is attached directly to the part.
• Throw: Dead centers. A pulley runs on one of the centers. A pin extends from the pulley to drive a spoke or carrier (lathe dog) attached to the part. The term throw for this type of drive setup is used mostly by clockmakers e.g. a clockmaker's throw.

Bottum wax lathe

A "wax" lathe is used for turning parts held with a meltable adhesive. This goop, conventionally called wax or lathe cement is actually more like violin rosin. Don't be fooled by the primitive look of this tool. It can support accurate turning that rivals that of most lathes with cone bearings.  This technique has been used to make watches for two hundred years. I frequently use lathe cement for holding irregular parts or finishing a balance staff.  A glob of cement is inside the hollow spindle which has a recess cut with an accurate female center. The cement is softened with an alcohol lamp and the part is inserted. Now for the magic step: the spindle is revolved while holding a match stick gently against the part. The part will center itself as the cement hardens and (if done properly) the result is extremely concentric. Far better than most collets. I am unable to see any runout (not even vibration) with a Hamilton 0.00005" reading dial gauge.There are lots of recipes for lathe cement. Some folks even use superglue. I mix melted flake shellac with a dab of diamond setter's pitch. The pitch makes the shellac less brittle. I plan to put up a page with recipes for lathe cement. If you have a good one, please send it and you'll get one of the credits! Our work might make Yahoo's bizarre web page of the day...

Swiss lathe with mandrill

  

A Swiss wax-lathe with attachments from the late 19th century. Show configured as a mandrill on the left and on the right, as a wax lathe. At about this time, the American WW collet lathes were about to displace these attractive, but inconvenient "brass engines".

Swiss lathe bearing

  

The front bearing of the lathe opens to allow rapid replacement of the whole spindle assembly. In the right hand view, the type-metal insert can be seen that supports the wax lathe spindle. When used with the larger mandrill spindle, the insert is removed.

Webster-Whitcomb lathe

The lathe on the bench top shown above is a Webster-Whitcomb. This pattern, usually nickel plated, dominated watch lathe design for the next 75 years, displacing both the mandrill and the turns as the most important tool for making and fitting parts.Actually, since the 1940's, the only tools required by the average watch repairer were tweezers, screwdrivers, a cleaning machine and a staking set. The ready availability of interchangeable parts made turning and milling skills unnecessary. Although present on the bench in most jewelry stores, the watch lathe was largely an ornament. Today, with the old factory stocks finally depleted, fine antique watches and clocks must once again be maintained by creating new parts from raw materials.

Boley F1 lathe

This machine is one of the few modernized versions of the watchmakers lathe. Between 1900 and 1970, watchmaker's lathes all looked pretty much like the Webster-Whitcomb shown in the previous section. The F1 is (was?) one of the last designs from the now moribund Boley company, dating from the late 1960's to early 1970s. (Can someone help me date this thing?) One of its unusual features is that the operator may sit at the tailstock end looking into the headstock. A hand rest on the right (behind in this view) supports the right wrist holding the graver on the t-rest, also placed on the right side.  The headstock end has a prop that tilts the whole bed toward the operator. In addition, the entire bed rotates along the axis to present a comfortable view. The lathe is ideal for pivoting work in this orientation.The left side (or front as shown here) has a lever that operates an indirect friction drive to a concentric "throw" wheel. The work is held between micro dead centers. A carrier attached to the work is driven by a pin that extends from the throw wheel. This is essentially a modern version of the antique turns discussed above. The dead centers insure absolute concentricity. The friction drive allows the operator to limit the force applied to the work.  If the graver catches in the work, the throw wheel will simply stop. Sometimes. This was my first watch lathe given to me by my wife many years ago. She was quite supportive back before my hobby got completely out of control. To get even, she is now devoted to horsing. It worked.

Pivot drilling lathe

When a pivot is broken off, this tool can be used to redrill the arbor so a new one can be pressed into place. Pivots can be as small as 0.004", so this takes some care. To make matters worse, the arbors are commonly hardened. The work is held between centers and driven with a bow as in the turns. The center on the right side is hollow. On the far right side of the case are two small runners that hold the drill.  The drill is inserted through the hollow center and pressed against the work while the bow drives it back and forth. The drill is sharpened so it cuts in both directions.

Jacot tool

 

The Jacot tool is special purpose dead center lathe. It is used to burnish and adjust the size of cone pivots, most frequently on the balance staff. The balance wheel and staff assembly are placed on the tool with one pivot in the female center and the other resting in a groove. The balance is rotated back and forth with a horsehair bow while a burnishing file presses the pivot into the groove. The result is a concentric pivot with a burnished finish.  Each of the extra runners has  a series of graduated grooves cut on one end. A small gage is included for measuring the pivots.