Steve from Socal
Well-known member
I picked up a new to me lathe on Friday and I am still trying to figure out exactly what it is but, I can say it is either a Monarch 13EE or a Model 70. It is actually the oldest lathe I own now being made in Jan 1955, it predates me!
This lathe is a bigger iteration of the Monarch 10EE and originally had a 20HP DC motor with variable speed range of 12-2000 RPM. It also has a very unique feature for 1955 called constant surface speed, this is where the spindle speeds up as the diameter is reduced to maintain a constant surface feed on the cutting tool. This machine has a 10HP AC motor with an inverter that works but, won't make top speed as set. The inverter is set to 88Hz max right now and it would need to go to 146Hz, that is pretty high and I am looking at different pulley options as well. These lathes were all DC when new and in addition to the spindle motor there is a hydraulic pump and rapid traverse motor, they have all been replaced with AC motors.
The reason DC motors were used in machine tools in the past was because they offered a 100:1 speed range and a wide torque range. It has only been common to use AC motors and variable frequency drives since the mid 1980's. By that time machine tools were primarily CNC and used servo motors and drives. Manual lathes reached the acme in the late 1950's early 1960's. These lathes the Monarch 13EE-1000EE and, Models 70-71 were state of the art in their day. It is alleged that these were actually a form of government welfare; Monarch was told to create the ultimate lathe sparing no expense and having no preconceived specs. The largest buyer of these lathes was the US government with most going to the DOE and, DOD. When new these cost more than a fine house in a good location.
I have a Monarch 10EE and Series 62 2013, these are quite a contrast, the 10EE is good for small work and the Series 62 can do small work but is an overkill with 20 HP. The new lathe fits nearly perfectly between them with about half the center distance of my Series 62 half the horsepower and just about double that of the 10EE. The trilogy of Monarchs is complete!
Now to get this thing running right and perhaps rework the CSS function.
Steve
This lathe is a bigger iteration of the Monarch 10EE and originally had a 20HP DC motor with variable speed range of 12-2000 RPM. It also has a very unique feature for 1955 called constant surface speed, this is where the spindle speeds up as the diameter is reduced to maintain a constant surface feed on the cutting tool. This machine has a 10HP AC motor with an inverter that works but, won't make top speed as set. The inverter is set to 88Hz max right now and it would need to go to 146Hz, that is pretty high and I am looking at different pulley options as well. These lathes were all DC when new and in addition to the spindle motor there is a hydraulic pump and rapid traverse motor, they have all been replaced with AC motors.
The reason DC motors were used in machine tools in the past was because they offered a 100:1 speed range and a wide torque range. It has only been common to use AC motors and variable frequency drives since the mid 1980's. By that time machine tools were primarily CNC and used servo motors and drives. Manual lathes reached the acme in the late 1950's early 1960's. These lathes the Monarch 13EE-1000EE and, Models 70-71 were state of the art in their day. It is alleged that these were actually a form of government welfare; Monarch was told to create the ultimate lathe sparing no expense and having no preconceived specs. The largest buyer of these lathes was the US government with most going to the DOE and, DOD. When new these cost more than a fine house in a good location.
I have a Monarch 10EE and Series 62 2013, these are quite a contrast, the 10EE is good for small work and the Series 62 can do small work but is an overkill with 20 HP. The new lathe fits nearly perfectly between them with about half the center distance of my Series 62 half the horsepower and just about double that of the 10EE. The trilogy of Monarchs is complete!
Now to get this thing running right and perhaps rework the CSS function.
Steve
