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Abner
10-08-2011, 10:44 AM
I'm a very part time mill user. So I don't have justifiable reasons to spend big bucks for loads of tooling. However, I recognize that higher quality is more likely than not better value.

I use 3/16 and 1/4" end mills for cutting key ways. The Shars TNN ones I have are either junk or I push too hard. I cut mild steel and HR shaft.

So my question;

Are small end mills like small drill bits - buy a hand full and when they break toss them?

Is it worth the money for carbide or should I buy better HSS/

Thanks,
Abner

Carld
10-08-2011, 10:53 AM
I usually buy the import brands from Enco and have good luck with them. Perhaps your not using the right feed and rpm with them. I brush on cutting oil as they are cutting. I don't run them real fast and I feed according to feel and the look of the chip. To high rpm and to low feed will dull the end mill.

PixMan
10-08-2011, 11:08 AM
The Shars end mills you'd been buying are really cheap junk. In this case it's not you, but the tool.

If you move to carbide, the first order of business is to understand that you have to run them at MUCH higher speeds than HSS. You can now get excellent quality Made In USA carbide (and HSS) end mills for very attractive prices from JTS Machinery & Supply of Mentor OH, Cutting Edge Supply of Colorado Springs CO, KBC Tools, Enco, and many others. Just avoid the "import" branded ones and you'll be fine.

http://www.jtsmach.com/jtswebshop/asp/endmills_index.asp
http://www.cetsonline.com/flyers/2011/monster_s4_2011.html
http://kbctools.com/usa/main.cfm

I have found that almost any Made In USA high-quality HSS can yield better value than cheap carbide.

dalee100
10-08-2011, 12:06 PM
Hi,

I tend to look at small end mills like 1/16, 1/8, 3/16, and even 1/4" sometimes pretty much as disposable. Because they tend to lose chip clearance very quickly when you resharpen them. And then they just break anyway. But I send out for resharpening, so the economics are maybe a bit different than if I did it in-house.

I think at these small sizes, there isn't much money to be saved by buying imported end mills. The USA made are only slightly higher in price, but do last longer.

I will say that I have been testing a few of Korean, (South Korea - not Best Korea), made 1/4" end mills. Only real problem with them is that they are M2 and not M42 cobalt type. So they wear a bit quicker. Still, at less than half the price of Atraxx, I get better than 75% of the run time.

dalee

SGW
10-08-2011, 12:16 PM
I try to buy Niagara end mills from www.travers.com when they have a sale in their monthly flyer. Things being what they are, generally the sizes I need aren't on sale when I need them, but since I don't buy many anyway the non-sale cost premium isn't onerous.

As Carld said, pay attention to speed/feed. Within reason, the thickness of the chip doesn't significantly affect wear. What does affect wear is the number of times a tooth has to cut. If you take a 0.003" cut, you'll get twice as much wear as you would with a 0.006" cut (roughly speaking). And of course there is a limit to how big a cut an end mill will take.

I tend to run my end mills fairly slowly. I'm not concerned about maximum production speed. I'd rather not destroy an end mill. There is, however, a "correct" speed/feed that I think you can learn to recognize with practice. The end mil doesn't "thunk" when it cuts, the chips are coming off as good chips, and they aren't getting so hot they turn blue.

beanbag
10-08-2011, 05:29 PM
Since you are slotting, chip clearance will be the main determinant of end mill life. Have air blow out the chips, or use coolant so that there is at least better lubrication. A better quality end mill helps. A corner radius helps. Having enough feed so that there aren't too many chips helps. Don't exceed 1% diameter for chip load per tooth, or that will also kill the cutter quickly.

If you do things just right, the chips will fly right out and there will be minimal chip recutting and minimal crunching noises.

MotorradMike
10-08-2011, 05:46 PM
I'm surprised nobody has said you should be using a keyway cutter instead of an endmill. I could be wrong but I'm still surprised.

At any rate, buy one endmill from Niagara Cutter just so you get to try something good.
I did that and now won't buy Chinese cutters unless I need to mill a brick.

Carld
10-08-2011, 07:32 PM
Keyway cutters work fine on a horizontal mill or a vertical mill with a horizontal attachment.

Andrew_D
10-08-2011, 07:49 PM
Keyway cutters work fine on a horizontal mill or a vertical mill with a horizontal attachment.

So is there something wrong with using a keyway cutter in a vertical mill without a horizontal attachment?

You're just milling on the side of the shaft instead of the top aren't you...??? :rolleyes:

Maybe I've been doing it wrong all these years?!?!? :eek:

Andrew

DATo
10-08-2011, 08:16 PM
The whole point is in how you hold the workpiece when cutting with a keyway cutter. Those who mention horizontal milling are making the point that you cannot hold the workpiece in a vise and cut the side of the diameter using a vertical mill. If you hold the workpiece in such a way that the side of the shaft is exposed then a keyway cutter would work just fine.

If you do a lot of this I would suggest making a fixture out of a block of aluminum with a hole running down the length of it equal to the diameter of your workpiece. Put some set screws in it to hold the workpiece securely in the hole. Mill a flat horizontally which intersects the hole down its entire length. The bottom part of the fixture would be held in the mill vise in such a way as to make your workpiece sit above the jaws and in a horizontal position. Now you can use the keyway cutter to put in your slot.

SGW
10-08-2011, 09:39 PM
Re: DATo's fixture idea.

If, instead of setscrews, you incorporate a couple of split cotters into the fixture, there will be no chance of scaring the work and they clamp tenaciously with little pressure. Guy Lautard's MBR #1 gives details on making split cotters. It is a significant amount of work to make split cotters though, so you would have to be doing a lot of this particular machining operation to make the effort worthwhile (which, as DATo said, applies to making the fixture at all).

Carld
10-08-2011, 11:27 PM
Or you can clamp the bar in a slot on the table. Or you can use V blocks against a dowel pin and clamp the bar down. Or you can use two vises to hold the bar. However, all this depends on where and how long the keyway is.

I have done it a lot of ways and you can to with some thought.

It depends on how you need the ends of the keyway, with a radius on the bottom or a radius on the side of the ends.