Speeds and feeds info for a newbie

[Involute]

How do you determine the proper cutter, RPM, and feed rate for a particular milling operation? There seems to be a lot of anecdotal information floating around ("I've had good results with 1700 RPM and high-speed steel when cutting blahblahblah"), but is this all just passed on from master to apprentice? Seems like there should be some tables, one for each material and thickness, that say for this type of cutter use this RPM and this feed rate. Or something like that. Do they exist? Is this info available in some other form?

Thanks.

[joecnc1234]

The first thing you should do is get a machinist handbook. They cost somewhere around 60 bucks. Their are sections on feeds and speeds based on the type of machining you're doing and tool material. also tool manufacturers catalogs give some recommendations for their tools. Just remember the tool companies always exaggerate feeds and speeds so cut them in half and work up from there. In general I use 1/2 diameter depth of cut and axial depth, carbide tools 75-100% of spindle speed on aluminum depending on rigidity of the set-up 400-2500rpm for stainless 2500 for small diameter tools like 1/8" 400 for 3/4". The best thing to do is decide the tool life you want and adjust feeds and speeds to match. As we like to say "crank it up till it breaks than back it down 10%". There are so many variables no one can ever give a "bible" on feeds and speeds and cutter selection. It's basically trial and error. I hope this is of some help to you.

[Mcgyver]

like Joe said, the theoretical values are easily arrived at. I agree, if you are cutting metal you'd do well to have a machinery's handbook. any high school machine shop text (a great beginners guide) will show you the theory and how to arrive at the numbers (get a couple, they're cheap and a great newbie reference) a search here will show basic formulas (ie rpm = 4x CS / dia) etc. where the skill/experience comes in is in putting it all together in the context of the particular machine and set up to achieve the main objectives (which can also vary, might be removal rate, surface finish etc)

[mrainey]

Here are some informative sites to supplement what the others have said:

twist drills:
http://www.precisiontwistdrill.com/t...length_amg.asp


end mills:
http://www.niagaracutter.com/techinfo/index.html