Harold Hall

Workshop Processes

Horizontal steam engine "Tina", parts, Con Rod, etc.
Rotary table. using with lathe mounted milling head.
Rotary table. using with lathe mounted milling head.
Horizontal steam engine, "Tina" Con rod being made.








As many of the items to be machined on the rotary table are small, holding them firmly on its centre can be a problem if approached conventionally, such as using an overhead clamp. Positioning them will be even more difficult. Because of this I developed a workpiece locating fixture that in addition to making the task of mounting and machining a small part relatively easy it also has the advantage of needing just a simple bush added for each different hole diameter in the items being located. For details of this see my Projects pages.        


The workpieces that were made using the fixture are seen in Photograph 3. This also showing the cylinder block drilling jig and main plate of the locating fixture. Both of these used the rotary table for marking out the positions of the holes on a PCD.


Photograph 4 shows the jig in use when adding a radius to the end of a small link with two already finished seen on the rotary table. The washer seen under the component permits the workpiece to be fully machined to its lower edge without fouling the fixture.


Placing holes on a PCD in small workpieces is also a task where the jig is useful as seen in Photograph 5. You may have been surprised to see in photograph 3 that it was used for just two holes at 180° but this was much easier (and more accurate) than marking them out with a rule and scriber.


The engines connecting rod is an interesting part and will be discussed in more detail later. Even so, one end has a radius through about 270° that was produced using the jig as seen in Photograph 6.


Having made and used the jig I have found that it works very well, and is therefore worth considering making, even for readers who use their rotary table on a milling machine. If though using it as the photographs indicate and you only have one lathe you will need to plan carefully as you will not want to remove the milling head just to make another workpiece locator.



There are numerous types of engineering vices that may be considered for use with the milling head, far too many to consider here, However, in my estimation, only a toolmaker's style vice anywhere meets the requirement for use on a small machine table, such as the lathe cross slide or a vertical slide. The reason for this is that the mounting method if far more adaptable than the fixed mounting points that most vices provide.