Quick milling question

Cutting a slot in MS with 1/2" end mill. What is maximum depth of cut I can take in each pass.

Best to cut and feel how the machine reacts, too many variables to be accurate. Variables as some will ask for, machine power input, spindle speed, federate, cutter material, number of flutes and the actual machine. A heavy industrial machine is usually the basis for all cutter calculations, a Chinese machine is a trial and error job for what the user is comfortable with.

Rule of thumb 10 to 20% of the diameter of the cutter. But as HowardT says the limit on a small mill is likely to be the power of the motor and the rigidity of the machine (weight, wear and adjustment), also how sharp the tool is, carbide vs HSS, whether you're cooling, the properties of the steel, and how firmly clamped the job is etc. I like my mill to sound as if it's working hard about 10% short of sounding in distress. Roughing out I normally go in at about 15% diameter and adjust the feed-rate to suit my 'no distress rule'. My hobby mill is capable of taking hard fast deep cuts when I'm in a hurry, but I'm sure it appreciates the lighter touch. No smoke or broken gears!  Owners of industrial machines could be more aggressive.

Dave

Edited By SillyOldDuffer on 22/06/2018 12:13:23

Also, I have a light, Chinese hobby type milling machine. If it was a plain 1/2" wide slot, I would definitely drill a series of holes slightly smaller than 1/2" (chain linked) then finish with the half inch slot cutter or even an end mill. It reduces the wear on the relatively expensive cutters and the poor little machine.

Phil H

As Dave says on a 1/2" cutter about 20% depth is the most I would ask of my X3 and more than likely 15% would be what I would use more often than not. This is 2.5mm deep with a 12mm cutter so about 20%

Yes I’ve done this Phil, drilling a series of holes is quick and easy and drill bits are cheap.