Speed and feed calculations

[Guldberg]

All new to turning (or almost, had a 8hour course a couple of years ago) im looking for some sort of excel sheets or even better a small program similar to one i have for milling, that can calculate feed and speeds for different types of material. I know it somewhat depends on the "feeling", but when you are new to the buisness its nice with some guidelines:-)

[M-man]

well, check out the homepage of any INSERT manufactor, the all have programs to calculate feeds and speeds for their cutting grades.

[Reggie]

Try searching "Cutting speed Wikipedia"

[Guldberg]

I found the program MEconsultant. Works great and it also indicates the workload to give you some sort of idea of how far you can go in terms of motor power

[Trapper14]

M-man, those speeds and feeds are made for industrial machines that go balls to the well, unfortunately they can't be used on the mini lathe...

[Mcgyver]

Originally Posted by Trapper14 M-man, those speeds and feeds are made for industrial machines that go balls to the well, unfortunately they can't be used on the mini lathe...

theoretical speed calcs are not done for a machine, they are done for the cutter and workpiece material, its the optimal surface rate between a work material and cutter material, tool wear skyrockets past this, like 15:1....figuring out what the machine can handle is being a machinist . its usually for this optimal condition to be unobtainable because of machine rigidity, wear, etc. you want to strike the balance of speed and feed that is hitting your machine's maximum removal rate (vol/time) while maximizing cutter life, ie no point in have spindle going a million miles per hour with the feed so slow its making dust. quickly that theory becomes intuitive.

imo forget about using carbides on such a light machine, you'll do better work with hss because it uses less cutting force, is easy to sharpen. you will never approach their removal rates.

your speed formula is rpm = 4*CS/dia (in inch's) this works for drills, lathe, mill whatever, its simple. CS (CS= cutting speed, in feet per minute) will vary for different materials, for HSS say 80 for steel, 60 for tool steel & stainless, 120 for brass and 300 for AL. you can push higher, these are guidelines, but remember tool wear rises rapidly with small increases in rpm

pick up some basic machining books, high texts are perfect, this will help you make sense of it all. hope that helps.