March 18, 2005, 08:50Wayne C. Anderson
Another Unique Tool
This set is on display at the CRMI? Would any IHC185 member know the name and usage of these tools?
March 18, 2005, 11:41Greg Crockett
Those are all attachments for a screw finishing tool, or screw head lathe.
The long holders are called runners. These were used to hold screws and other small parts in need of turning. The two flat items to the left with holes in the center are laps.
In use the frame of the lathe is held in a vise. Then, a runner is positioned in the frame (it looks like you have the frame partially pictured below).
At this point, the screw head may be worked on with hand files or hand held burnishers as the runner is worked back and forth with the other hand. If a dome headed screw is desired, then only the hand tools may be used.
One or two shafts are attached to the side of the frame parallel with the axis of the runner. These posts have two uses, one is to act as tool rest for files or hand held burnishers. If it is necessary to have a dead-flat screw head, or to lap a small part, then a circular lap ( to the left in your image) is placed upon the post so that it may spin against the screw head.
With the runner in the frame, as above, A lap (charged with diamond powder or some other polishing compound) is placed on the post on the side of the frame so that the flat side of the lap may turn against the item to polished, such as a screw head fastened to the runner. The lap is made to spin with a bow, back and forth, as the runner is turned back and forth against it. In this manner, a dead flat screw head may be made.
This type of tool was especially necessary when all the shop had was a turns as a lathe. Given that the turns is a dead center lathe, it is not possible to work on the end of something, like a screw head, and so the screw head tool was used for such work.
In addition to the runners pictured, there were some which used lathe wax to hold work, such as crowns, etc.
The screw head lathe is an interesting and ubiquitous tool. At one time is was common, but not well understood today.
March 18, 2005, 12:05Wayne C. Anderson
Great description - wonder how many IHC185 members have ever seen or used this tool?
March 18, 2005, 19:59Frank Juchniewicz
I think it would really be great, if somehow all these tools could be shown in actual use, close-up, thru films.