On Tuesday, February 14, 2012 06:27:36 AM Jon Elson did opine: > gene heskett wrote: > > This effect was discussed at length when we made the first 'test' > > cases for our tv cameras out of alu we had cad plated back in 1960 > > and discovered that no amount of cad plating could protect them from > > 8 hours over the side of an LST 50 miles west of San Diego. > > I am NOT disputing that aluminum oxidizes and corrodes, only that the > thin film of oxide > is NOT a huge impediment to milling, and that you need to do all > aluminum milling > submerged in an oxygen barrier. > > > However, this does lead to the question: > > > > Is there a calculator, online or downloadable that will tell one the > > ball park correct feedrate for a given bit and depth of cut at x > > rpms? I would have far less problems with my un-SWAG methods of > > doing this if I had a good, known to be safe, starting point. > > I have these slide-rule type gadgets from McDonnell-Douglas that I got > at a local > scrap yard. But, there are some calculators. I have used Mr. Machinst, > but I think > my trial copy timed out. http://www.mrmachinist.net/ > I just checked, it seems to still have the feed rate, etc. calculator. > Needs wine & $70.
> The basics I use, even without the slide rule, is that plunge should > never exceed 1/2 > the end mill diameter, and then in softer stuff the feed per tooth > should be around .010" per inch of tool diameter. So, for a 1/8" end > mill, it should be .00125" per tooth. At 2500 RPM with a 4-flute > cutter, then you get 12.5 IPM. For your 1/16" cutter, you should be > around 6 IPM for the .030" plunge, but I'm conservative, so I'd keep > the plunge to .020" and maybe feed around 5 IPM. Keep the slot clear > of chips, so use the minimum of cutting oil if you are not flooding it, > and either keep brushing the chips away or blast it with air. The > above may sound confusing. What you want to do is keep the chips from > recutting. So, either use minimum oil and brushing or air, or a FLOW > of some coolant that carries the chips away. Since I have yet to stumble over a suitable pan to catch & recycle the coolant, air seems like the best bet then, delivered via the mister I built, and which I can position about an inch from the tool, following the tool. My run times for that are relatively short as the reservoir only holds about 2 ci. It also fogs up my glasses as the safflower oil just seems to hang in the air for hours. It does work well, giving me the best finish ever. If I open the door & stick a box fan blowing out, the air is tolerable. 40 years ago you could buy a needle valve to regulate the oil flow, but no one makes such a beast today. What you can get is one that when stopped down as tight as you can turn it, still leaks about 10x what you need. :( Something else I'll have to make I guess. Thanks Jon. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> <Mercury> You don't have to be crazy to be a member of the project, but you will be.. <=:] ------------------------------------------------------------------------------ Keep Your Developer Skills Current with LearnDevNow! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-d2d _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
