Apostle
Aluminum
- Joined
- Apr 20, 2009
- Location
- Charlottesville, VA
Hi Guys,
I am stumped! I have a Sheldon No. 0 Horizontal Milling Machine on its way to my shop. While I'm pretty familiar with many machine shop operations (lathe, vert milling, welding, etc), a horizontal mill is new to me. I've had very little experience running one.
I've been readying myself for making chips shortly after its arrival. I"m having a problem in determining how to compute a reasonable table feed rate.
This Sheldon mill has x-axis feed rates of: 0.0011, 0.0023, 0.0046 and 0.0094 inches per spindle revolution. To compute the proper feed, the following formulas are provided in handbooks:
IPR (inches per revolution) = N (# cutter teeth) x F (cutter feed rate per tooth, a table look up value)
Now, RPM's are computed as: [CS (cutter speed, table lookup)x(4)]/D (diameter of cutter)
Finding the table feed value for a 4" side-tooth HSS cutter with 72 teeth, cutting a low to medium carbon steel (CS~80) yields a spindle RPM of 75 RPM. The "F," or feed in inches per tooth from the table look-up is a range from 0.002" - 0.007". Using a middle value of say 0.004", the math yields a table feed rate of 0.290 inches per spindle revolution. That represents a rate of over 30x my highest feed of 0.0094"/revolution.
I'm missing something BIG here ..these forumlas do not take into accoute the depth of cut or the HP rating of the motor. I'm stumped and I cannot find the answer. Is it possible these comps are made for a HUGE mill with a "MUCHO-HP" motor, unlike my tiny 1 hp motor (3 phase motor driven from a VFD) ??
Any and all comments are welcomed..
Regards,
Puzzled Mike in Virginia
mike at w4xn dot com
I am stumped! I have a Sheldon No. 0 Horizontal Milling Machine on its way to my shop. While I'm pretty familiar with many machine shop operations (lathe, vert milling, welding, etc), a horizontal mill is new to me. I've had very little experience running one.
I've been readying myself for making chips shortly after its arrival. I"m having a problem in determining how to compute a reasonable table feed rate.
This Sheldon mill has x-axis feed rates of: 0.0011, 0.0023, 0.0046 and 0.0094 inches per spindle revolution. To compute the proper feed, the following formulas are provided in handbooks:
IPR (inches per revolution) = N (# cutter teeth) x F (cutter feed rate per tooth, a table look up value)
Now, RPM's are computed as: [CS (cutter speed, table lookup)x(4)]/D (diameter of cutter)
Finding the table feed value for a 4" side-tooth HSS cutter with 72 teeth, cutting a low to medium carbon steel (CS~80) yields a spindle RPM of 75 RPM. The "F," or feed in inches per tooth from the table look-up is a range from 0.002" - 0.007". Using a middle value of say 0.004", the math yields a table feed rate of 0.290 inches per spindle revolution. That represents a rate of over 30x my highest feed of 0.0094"/revolution.
I'm missing something BIG here ..these forumlas do not take into accoute the depth of cut or the HP rating of the motor. I'm stumped and I cannot find the answer. Is it possible these comps are made for a HUGE mill with a "MUCHO-HP" motor, unlike my tiny 1 hp motor (3 phase motor driven from a VFD) ??
Any and all comments are welcomed..
Regards,
Puzzled Mike in Virginia
mike at w4xn dot com