I am considering what end mills to get, and I would like to know what are the implicationsof using carbide vs. HSS endmills in a home setting. My understanding is that carbide endmills do not wear out as fast as HSS ones. I am not sure if they have any real disadvantages. Would like to hear some educated opinions.
i
No expert here, but a few disadvantages I can think of are:
Seems to me that carbide is in general more suited to CNC production work than manual home work.
Pete C.
My credentials: I am a hobby guy who does sell a little work.
I would get a decent set of HSS end mills to start with. As already mentioned, carbide does chip easily, so I'd wait until you have a specific job that needs lots of milling with one size cutter before investing in carbide end mills.
As you probaly know, carbide does not like interupted cuts. So, an unintentional rapid feed into the work can evoke a few swear words when your new $30 cutter goes to the scrap heap.
OTOH, I strongly suggest that you get a 1 1/2" diameter indexable end mill such as shown on page 732 of MSC's big book (along with a lot of other sizes). The one I have holds 3 TPG 322 carbide inserts and is about right for my 1 1/2 hp machine. The "TPG" stands for "Triangular", so, with a "P" (positive rake) cutter such as this, you get 3 edges per insert. Enco has both the mill and the inserts for cheaper. You can buy inserts on sale while you get used to carbide, then buy good ones later. You can get these inserts for as little as $1.50 each (in a package of 10) or you can pay as much as $10 each. I assume that you get what you pay for, but usually stick with the $3 or $4 each kinds. Maybe I should ask to a set of the $10 ones for Christmas?
I am guessing that you are asking about tooling for the M head Bridgeport you recently purchased, but I don't remember what the spindle is. So, if it's not R8, get the indexable end mill with a straight shank to fit your biggest collet.
Pete Stanaitis
-------------------------------------- Ignoramus24595 wrote:
What the others said.
Def'ly use HSS for home/proto work, unless the mat'l requires carbide, or you are doing some kind of production.
Also, HSS is more shop-sharpenable to custom sizes, bevels, etc. They also have the set-screw notch for more positive holding. I also sometimes cut double-ended em's in half, for occaisional use in a drill chuck.
Also, what hasn't been mentioned, you can wind up with cheap carbide that is not much better than HSS! Esp in brazed lathe tools. goodgawd.
He didn't get an "M" head, he got a "1J" head on a round ram base. It should be R8.
The edges on carbide endmills are very fragile - I wouldn't even think about using them until you've got a fair amount of experience and have determined that your mill is in good condition.
Good carbide endmills (I'm partial to Niagara TiAlN coated) can remove material quickly while leaving a very nice finish, and last a long time. But a tiny false move that a HSS tool wouldn't notice can knock the edge off a $40 cutter. An example that I've experienced is the practice of touching off on a part with the end of the tool to set the depth of cut to a rough zero. I've never had a problem with HSS bringing the quill down and lightly touching the part, then locking the quill. With carbide, the act of clamping the quill, even on a tight machine, seems to cause enough to movement to chip the tool. After chipping a couple carbide endmills I got in the habit of touching off on a piece of .010" plastic shim stock, then raising the knee to compensate for the thickness of the shim, and the problem disappeared.
Ned Simmons
First, you need to think about what you are going to be milling. Second, you need to think about cooling.
For cutting aluminum, use 2-flute HSS. I use a mist cooler, but you can get by with a squirt bottle. Flood cooling is awfully messy on a manual machine...
For steel, you need 4-flute cutters. A cooler is essential if you are running HSS. On the other hand, carbide should generally be run dry. Putting coolant on carbide tends to crack it.
My two most-used end mills are a 1/2" 4 flute carbide and a 3/8" 2-flute HSS. Most of us start off with a small handful and then buy as needed. Since we all then to do different things, what is a good assortment for one person may leave a lot to be desired for another.
And resolve not to cry when you bust a (relatively) new endmill. It's just part of the cost of doing business... And comfort yourself in the knowledge that, as you gain experience, the number of wrecked endmills goes down...
Jerry
If your milling head or table have any "chatter" don't use carbide. Just too easy to screw up a 30 dollar end mill. At least start out with HSS and go from there.
They chip if you are not careful moving tools or metal around them.
A misfeed, esp. when the spindle is not turning, and the cutter contacts the work, and the tool is broken.
To light a feed is tough on them. Uneven feeds are worse.
They cost more.
For the home shop. Save them for when you want to cut tougher materials.
On the plus side, you can run some scary rps, compared to HSS, but you still need to get the feed per tooth factored into it.
I refer to solid carbide, not the insert variety milling cutter.
Cheers Trevor Jones
You need a stiff machine if you are going to run carbide and get any advantage to it. Carbide is brittle and will not take to being bent when your loose machine jumps a little. Snap goes the carbid and the only thing its good for after that is to grind it down and use it for a boring bar or some other item.
HSS end mills are a lot more forgiving. They bend a little before they snap. Also they are sharpend easier on a surface grinder if you just want to touch up the ends. I would recommend looking around for a reasonably priced endmill sharpener since with that you can buy dull endmills for peanuts and resharpen them saving a lot of cash in the long run especially with the larger diameter ones.
I would look on ebay for good buys on endmills.
John
OK, I'll bite on this one...
Exactly how do you sharpen end mills on a surface grinder?
Jerry
with this fixture
========= see
stand-alone
Okaaaaayyyy.......
I have a spin indexer as well as a fixture for accurately holding something round vertical, as well as, of course, a surface grinder. What I don't know is how to use these things to sharpen an end mill.
Jerry
I know a guy that does it, with *at most* a spin fixture, I think mostly by hand. He's sort of a prick, and won't really show anyone how he does it, and no one will ask, either.
Two flute are easier than fours, larger easier than smaller. He can do the bottoms as well as the sides, I think a sharp-edge narrow green or white wheel helps. Oh, yeah, and he uses a dremel! Oh yeah, and it also helps to be able split 64sth in three, by eye. :) He can.
I know a guy that does it, with *at most* a spin fixture, I think mostly by hand. He's sort of a prick, and won't really show anyone how he does it, and no one will ask, either.
Two flute are easier than fours, larger easier than smaller. He can do the bottoms as well as the sides, I think a sharp-edge narrow green or white wheel helps. Oh, yeah, and he uses a dremel! Oh yeah, and it also helps to be able split 64sth in three, by eye. :) He can. The result is of course not like a new endmill, or a machine-sharpened em, but pretty effing good, I must say. Sometimes, on his good days, you gotta look twice. And there are limits, which can be stretched by how much time you are willing to put into the process.
I know a guy that does it, with *at most* a spin fixture, I think mostly by hand. He's sort of a prick, and won't really show anyone how he does it, and no one will ask, either.
Two flute are easier than fours, larger easier than smaller. He can do the bottoms as well as the sides, I think a sharp-edge narrow green or white wheel helps. Oh, yeah, and he uses a dremel! Oh yeah, and it also helps to be able split 64sth in three, by eye. :) He can. The result is of course not like a new endmill, or a machine-sharpened em, but pretty effing good, I must say. Sometimes, on his good days, you gotta look twice. And there are limits, which can be stretched by how much time you are willing to put into the process.
On Apr 19, 12:16 am, "Jerry Foster" wrote: e, ch. 4 (1776).
Those fixtures are for sharpening the ends only. For sharpening the lands, you need an air spindle or the spin indexer.
The fixture holds an end mill at an angle. Two angles, actually. One angle for the clearance angle for the lip, and another angle so that the lip is not ground straight across, but dips to the center of the mill. You grind one lip at a time, then index the mill around to grind the second (third, fourth, etc.) lip.
The fixture actually also has a much greater angle on the base, for grinding the relief when necessary.
John Martin
According to John Martin :
[ ... ]
Also -- there is a bit of side slope to the angles on the base, so the lips of the cutting edges are slightly deeper in the center, to the endmill cuts mostly on the outside corners.
Enjoy, DoN.
Actually, Don, I did mention that angle. I probably should have said that there are THREE different angles involved.
On my fixture, the base is flat and parallel for most of its length. The column that holds the 5C collets is tilted in two directions - one giving the clearance angle to the lips, and a lesser angle giving them that slight slope toward the center. The back part of the base bottom is ground at a steeper angle, so that when you rock the base back onto it you get the relief angle.
I do have a question, though. I've never seen any instructions for using the fixture. Are there any special procedures or tricks for setting the Y feed so that each lip is ground right to the center? I'm obviously not talking about non-center cutting mills, but about 2- flute and other center cutting mills. I typically set the edge of the wheel to the corner of the lip or the land (either by setting the land to the wheel edge with the wheel stopped, or by finding where the corner of the wheel first sparks against the corner of the lip), and then feeding the Y feed half the diameter of the mill. That's only a rough approximation, though, as I'm usually left after grinding the second lip with either a tit in the center or grinds that overlap slightly. No problem to adjust and grind again, but I just wondered if there were any ways to hit it right on the first time?
John Martin
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