Milling Helical Lamp Stem On 1920's Vintage Kearney & Trecker Milling Machine
​                                                       10-2019   Newsletter
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 The lamp on the milling machine, was a school machine shop project from quite a few years ago. To cut the helical lamp stem, I adapted a universal dividing head from a horizontal Brown & Sharp milling machine to the table of a Bridgeport vertical mill, by replacing the table handwheel with a gear train to  the dividing head. The Bridgeport head was turned at an angle, and the cutting was done with an ordinary 2 inch cutter.  This new lamp project is being done on a 1920 vintage Kearney & Trecker horizontal mill having a universal table. In this case, the angle between the cutter and work is achieved by setting the table to the angle.
Above, The gearbox bolted to the table, is actually a helical milling attachment from a much newer K & T  mill with universal table. The drive shaft and gear set to complete the power train to the Cincinnati dividing head, was just made up.
​To get the three equally spaced flutes on the lamp stem, we use simple indexing, and really it is quite simple  The dividing head has a 40 / 1 ratio, so, we divide 40 by three. that results in a whole number 13 with a remainder fraction of 1/3  So, we then turn the disk 13 turns, then 1/3. We have the pined cranking rod on a circle with 39 holes, then set the brass arms with 13 holes between them . 13/39 =1/3. The brass arms are held in place by friction, but can be rotated. After you do the 13 full turns and 1/3 fraction, the arms are rotated around to the pin, and you are ready to index the next cut.
N.M.M. shop    Click the link below to view nice Youtube video about our club shop.
  https://youtu.be/DW4zb-ihf8c                                      Northern Minnesota Metalsmiths Flat Belt Machine Shop
The three feet on the lamp base are integal,not added on, but milled  from the  solid aluminum stock. There are more indexing operations on the base than I care to remember.
The video clip below was filmed at our N.M.M. shop , part of Lake Itasca Region Pioneer Farmers​ show
Gerald Fenske-  Designer - Builder  Helical Lamp​
Gerald Fenske - Editor- M.M.N.M. Newsletter
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