This might be an unanswerable or simply a religious question, in which case I apologize...
Should I get a set of cheap end mills, or should I gradually acquire more expensive ones? (Or both?)
The context is that I'm a relative newbie to machining, building up my tool collection. I don't do large quantities of anything; I generally (but not always?) work in soft materials like aluminum, brass, and plastic; and my "mill" is actually a mill/drill. So this is light duty work; but at the same time, I want the pieces I make to come out nicely, and I know that with a dull or imprecise tool there's just no way to cut a straight line or get a smooth finish.
One option I've considered is starting with a set of cheapo end mills in order to get a lot of sizes, and then gradually replacing the ones that I find myself using most often with better quality. But am I shooting myself in the foot to consider cheap end mills at all?
And, a subsidiary question: does TiN make any difference? E.g., I'm looking in the Grizzly catalog at all the cheapo plain HSS and TiN-coated HSS sets, trying to decide.
Thanks for all the help you guys have been giving me. (Hey, I signed up for a continuing-ed machining class at the local technical college this fall!)
Get a cheapo coated set in 1/16" increments. I use these occasionally when I need a special size, and if you don't push them too hard they'll give you some usage, and it saves a lot of time to have the special size on hand when you need it. Make sure you have the right size collets to use the full set. Unless you are planning really heavy cuts, you can use collets for all your milling rather than special endmill holders.
As you described, add on some "real" endmills in sizes you use most of the time. In my case, 3/8" 1/2" and 3/4". For these ones I buy USA made (Putnam, etc.) when they go on sale at MSC or Enco. I use these for all the heavy cutting. I also added a 4 piece set of roughing endmills that I use when I need to cut a lot of metal fast.
I like insert tools on my lathe, and some people use insert based endmills even in a home shop. I haven't messed with these yet so I can't tell you anything about them, maybe somebody else will have something to say about those.
Good question... and one that really has no "right" answer. Since you are working with soft brass, alumimum and plastics, the Chinese ones will work just fine for the first set of cuts.
The real difference between cheap Chinese and more expensive American tooling tends to be the quality of the steel used, followed by the tolerances (a chinese 1/4" end mill might be .245 to .255). You can easily get around this "non standard" sizing by intentionally using a smaller end mill to cut and make two or more passes --- use a 3/6" end mill and make two passes to cut a 1/4" groove. A pain in the butt as it takes more time, but this is a good procedure to make ANY high tolerance cut.
Sharpness ( i.e. resulting in a nice cut) is a function of the steel or carbide that is used. Be aware that many carbide bits from China are made from recycled carbide bits -- C2, C4, C6 ... and who knows what the final mix is. A mixed carbide end mill will make a noticeably worse cut than a good Micro 100, Kenmetal or other good USA end mill. Sharpness and durability are not what most Chinese bits are known for.
BUT, they do and will work, and they work surprisingly well for the price. I have over 100 assorted, cheap chinese end mills that I bought on Ebay for
10.00. Many of the used ones are still usable after pretty good use over several years , and if they get too dull to cut steel, well, I have a bunch of new ones rarin' to go. And the dull ones will still cut AL.
You can buy Chinese bits very inexpensively on closeouts everywhere--- I tend to avoid Harbor Freight as their bits tend to be REALLY junk bits. (Your mileage may vary... some guys have no problem with HF stuff...)
As for the Titanium coating, it helps initially -- maybe--, but not for long. The coating is supposed to act as a lubricate, thereby making the cut easier and smoother. Maybe it is also supposed to provide a "harder" cutting edge, such that you can mill or drill harder materials, but I have never found any difference between regular HSS and Ti coated steel. If y ou need to lubricate, than use a real lubricate likeTapMagic or kerosene for Al...
(To be blunt, I have often suspected that the Ti coating is often used to just "cover up" cheap steel, and make the bits or end mills look pretty. Novices too often fall for what looks good orwhat is hyped to the nth degree must be good... and this goes back to my first comment.. Chinese steel is often suspect...)
You also can not resharpen drill bits or end mills with the coating as the grinding immediately wears the coating off -- as does normal wear and tear. I have never paid the money for TI, if I was going to pay extra, I always would go for carbide or Cobalt tooling.
As you said, I would (and did) start with a cheaper set, mill like crazy, and then buy "real" ones as your needs indicate. Check Ebay, Reliable tool, MSC, Enco, J &L, et all for closeouts on HSS , carbide or cobalt tooling. It won't take long (or a lot of money) to get a decent set of tooling.
FWIW, I am a big advocate of carbide for cutting any type of steel and I tend to use HSS/cobalt for everything else... ALL my lathe tooling now is carbide and the mill uses anything that works !
I got some cheap end mills in blue plastic tubes, with the size rubber stamped on a paper label, and made in China. These were the worst excuse for a cutting tool I have ever seen, and I'm going to be much more careful in the future. They looked like they were sharpened (gashed and relieved, technically) by a blind 80-year old, and that is even an insult to the blind and aged, they were that bad!
I have been moving more to solid carbide cutters, as they take certain kinds of abuse and keep on cutting. (Sharp impacts cause them to shatter, however.)
But, I think the best value out there is Cobalt-enhanced HSS, with such trade designations as M-42, M-57 and such. These are many times harder (or at leat longer lasting) than regular HSS, and cost maybe one Dollar extra! Also, you can be pretty sure they are not totally crummy junk.
I got a bunch of good stuff through eBay from a guy who used to sell as reliable end mill, but I think he is now using "reliable tools" (or maybe just tool, no "s".) I never had anything I was less than 100% satisfied with from him.
I haven't found the TiN coatings to be a great help. It may make a lot more difference if you are cutting very hard materials, or running the machine very hard in terms of feedrates, with the tool nearly red hot at times. Not likely for a small manual machine.
I have, by far, the best results on my small mill/drill with 1/2" solid carbide tooling. Usually import and/or when on sale. I have purchased a couple of sets of the import TIN coated mills and have removed a lot of material with them, but for finish & durability, I still prefer the solid carbide. I have on occasion purchased "top brand" american-made mills and really can't say they out-perform any other HSS I've run. I'm sure in even a moderately rigid machine they would perform better. In my case not so much.
I've tried the TNG insert tooling, on a lark. It was stupid. I just can't get rigid enough to even come close.
Agreed here -- though TiN coatings (not really Ti) do offer improvements on good quality tool steels when cutting the kind of materials where the coatings are worthwhile.
Actually, in drills and mills the place where the coating offers benefits is the inside of the flute, where it lubricates the sliding of the chips, and helps to avoid a built-up edge (and also reduces the transfer of heat to the tool itself. Under normal sharpening, this area is *not* removed, and also does not wear as fast as the ends of the flutes where the sharpening does its work.
If I were going to pay extra, I would really like TiN (or one of the other specialized coatings) over *good* carbide or Cobalt steels. Obviously, TiN over junk steel still gives you junk tools.
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That is what matters, after all.
Now, I start answering the original article, which has not yet made it to my news server, so I have to work from the quoted copy here.
Note that some plastics are rather abrasive, so carbides will give you longer life in those. But here you really *don't* want a coating, because that rounds the edges, losing you significant amounts of sharpness, which most plastics really demand.
Try medium cheap. I've got a set of TiN coated double-end ones, both two-flute and four-flute in a convenient range of sizes up to 1/2" (bought on sale from MSC), which work well in spite of being from China. They are nice to have on hand -- but for sizes which I use most frequently, I want to have high quality ones.
It can increase the life of a tool -- *if* it is on good steel. But beware that inexpensive tools with TiN coatings are mostly coated to
*look* more expensive.
And in plastics, where sharp is important, your really *don't* want TiN coatings (or any of the others) as they round off the edges a bit.
For light duty work on soft materials, the Chinese end mills work fine (at least the ones that I have). One thing that I did find very useful is a decent quality roughing mill. I have a 3/8 M2 end mill that eats aluminum like butter. I use that for major material removal and then use end mills from my Chinese set to do the finishing and details. For a hobbyist, it's a good low-cost solution.
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