Material and tool selection

[MeJasonT]

Thanks guys, its got the topic off to a good start.
The direction which I was hoping this post would go in was more of a mind dump of peoples knowledge, I appreciate the interest and feedback so far.

When I first started to machine with CNC I went down the youtube and machinists forum route but somehow the question keeps getting asked by novices and hobbyist's over and over again. Its really hard to say to those who are knowledgeable what you are trying to get your head around even though they must have been at the same starting point at some time. the calculations are all well and good but rarely coincide with those provided by the tool manufactures which tend to suggest much higher feeds and speeds. When you first enter the the art of machining you become overwhelmed by the amount of information and the contradictions of different sources. I agree there are a vast array of variable which need to be taken into account mainly about the machine and its idiosyncrasies. If for a moment to set that aside and state that the machine is sturdy, no loose mechanisms and sufficient torque - lets face it even big machine shops will find the limit of their machines eventually. When faced with the daunting task of running a machine for the first time, running the spindle at 10,000 RPM and cringing as the tool speeds its way towards the work piece scares the crap out of any normal red blooded person especially if it end in a ping or clunk. No quite as bad as a high pitched scream - crashed helicopters are far worse, that noise of an engine trying to spin a rotor through a seized gearbox, that noise never leaves you. Most newbies just want to avoid the initial pain especially if you have built, retro fitted or purchased a machine and using it for the first time.

CNC also has the gotcha of having its own brain to keep going whatever happens, thank the almighty for the big red button.

If we collate all the experimentation and material trials we do then hopefully we can find a common thread which can be used as a template.

Nelson,s reply giving me/us an insight to material he has worked with is insightful, I wasn't expecting not getting reamed for using mild steel. Bright steel bar seems to be the better choice but if there are some out there who can tell us what they usually order and machine with and a direction to tool, feeds and speeds used would hopefully provide us/newbies with a good starting reference.
(John) hemmjo & PJ fantastic info many thanks guys. jmparker, i've got the book, thanks for the suggestion.

Any commercial machinist who has a point of view of well its simple just use the formula etc. then you should reassure yourself that you may be responsible for injury or death of newbies, lets faced it theses things are killers they have teeth and everything. Its too late reducing the feed if you are wearing a 3/8th 3 flute HSS tool in your head, look on the bright side it didn't get you in the eyes thanks to those safety glasses. your advice should reassure not intimidate or scare.

The topic of cutting/coolant fluid is an interesting subject, Ive got a white paper somewhere explaining the pros, cons and new formulas involved in the wizardry of such stuff. I will try and remember to attach the PDF to the post.