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Zymrgy · 07-19-2003, 11:49 AM

I have never heard the terms "up milling" or "down milling", but I am sure they are talking about the difference between what I call climb mill vs conventional milling, as shown---

(edit...wow, bad pics try this
http://www.hanita.com/hanita_protected/climb.htm )
now they are showing a wheel type cutter, but the exact same thing applies to an endmill. One thing you should NEVER to is climb mill with a conventional ( non-cnc ) machine. This is becuase the screws have backlash in them ( that is, you tun the handle one direction & when you reverse directions it takes 1/2 turn or so befoer the table will start moving again ) Climb milling with a machine that has backlash will pull the workpiece into the cutter, breaking the cutter, scrapping the part & possabily damaging the machine. CNC machines have ballscrews which have very little to no backlash...much more rigid. Small endmills ( like under 1/4" ) can be used with caution climb milling on a conventional machine. One thing you can do is to snug up your table locks...snug, but not tight. This will help the cutter from pulling the part.

Now when dutting a slot like you are describing, yes, 1/2 the cut is always conventional & the other 1/2 is always climb. What happens here is that the cutting forces balance each-other out & you are safe.

07-19-2003, 11:49 AM	#23
Zymrgy Cooling Neophyte Join Date: Apr 2003 Location: USA Posts: 96	I have never heard the terms "up milling" or "down milling", but I am sure they are talking about the difference between what I call climb mill vs conventional milling, as shown--- (edit...wow, bad pics try this http://www.hanita.com/hanita_protected/climb.htm ) now they are showing a wheel type cutter, but the exact same thing applies to an endmill. One thing you should NEVER to is climb mill with a conventional ( non-cnc ) machine. This is becuase the screws have backlash in them ( that is, you tun the handle one direction & when you reverse directions it takes 1/2 turn or so befoer the table will start moving again ) Climb milling with a machine that has backlash will pull the workpiece into the cutter, breaking the cutter, scrapping the part & possabily damaging the machine. CNC machines have ballscrews which have very little to no backlash...much more rigid. Small endmills ( like under 1/4" ) can be used with caution climb milling on a conventional machine. One thing you can do is to snug up your table locks...snug, but not tight. This will help the cutter from pulling the part. Now when dutting a slot like you are describing, yes, 1/2 the cut is always conventional & the other 1/2 is always climb. What happens here is that the cutting forces balance each-other out & you are safe.