Milling .... how deep.... how wide ?

[Darren]

Reading this found here http://www.aonx97.dsl.pipex.com/WS-page/table-page/tables.htm#BA

I think I'm still trying to cut too much in one pass, even though what I'm doing looks fine to me?
My milling is getting better...honest  

It says width of cut 1/4 dia, I've been taking about 8 or 9/10ths. I notice it's even less for smaller cutters.  



End mill Speeds
NOTE: speeds are for depth of cut=1/8 diameter up to 3/16 then =1/4 diameter. Width of cut up to 1/4 diameter. Cutter is HSS four flute.

 

Cutter diameter(Inches)
   1/16    3/32    1/8    3/16    1/4    3/8    1/2    5/8    3/4
Speeds rpm                                            
Mild Steel    1800    1500    1200    800    650    450    350    250    180
Brass    2500    2000    1600    1150    850    650    450    350    250
Alloy    3500    3000    2500    1700    1400    1200    900    800    700

[Divided he ad]

I may get shouted at for this but.... I've never even considered the working out of the depth of cut! 


I used expensive cutter shattering trial and error for the first few weeks I had my mill and never strain a cutter anymore! If it sounds/looks like it's struggling it's retracted and adjusted then I (also possibly altering feed) carry on with the job.

Works for me, I figure with what I do on this little machine and the fact that I'm not under deadline pressure then 50 passes at 0.25mm per time is fine by me. Even if the gods of milling tell me that I could have gone to 0.75mm and only 16 passes untill the finishing cut(s) is (are) added.


As always "this is my way" and no one else has to do as I do or even like it..... Not trying to sound like a spoilt kid, just covering my rear!



Basically Darren...IMHO if it's working then why question it?  (it's when I've got machining issues that I get wondering! )




Ralph.

[bogstandard]

Darren,

All the charts in the world won't make a good machinist. They are for ball park guidance only. There are just too many variables to be put into chart format. Use them only as a rough guide and take it from there.

As Ralph says, sight and sound is the way to find the correct speed and feed, and that only comes from experience.

Start small, and go bigger, not the other way around. You will soon get the feel for it. If the cutter looks and sounds as though it isn't working hard, on the next cut, give it a bit more to do. I will soon show you if you go past what it really wants.

John

[Darren]

I was just musing really, perhaps I shouldn't do it out loud, in case they come.....

It's funny looking back on it now, when I first tried milling I looked at the cutter, saw it had flutes an inch long so assumed, wrongly, it could slot an inch deep 

Thankfully I'm starting to get a "feel" for it at last with some satisfying results. 

[Darren]

I fitted one of these today, had a test run and found out it's nice to know where the cutter is 



Having a job to get it parallel, nowhere seems suitable to measure to.... But it's close....