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Thread: End mills- 2 flute or 4 flute?
03-09-2004, 02:25 PM #1
I'm ordering some tooling for my BP mill and need some info on end mills. As a newcomer to machining I don't know which to buy for general machining usage. Could someone explain briefly the differences in 2 flute and 4 flute designs and when you generally use each? I just need some general guidelines.
I have tried to access the US military website on machining info several times today and it seems to be down.
I want to get my order placed ASAP before SWMBO rescinds her authorization for me to buy *some* tooling.
03-09-2004, 04:08 PM #2
best bet is to have a selection of both. But a real quick rule of thumb is 4 flute for steel and 2 flute for aluminum or soft metals or any cut where you need the chips to clear out fast and easy.
disclaimer: That a real loose quick rule.
03-09-2004, 04:36 PM #3
The 2 flute have a larger gullet so more chip clearance. For smaller mills (below 1/2 inch) a 2 flute is a better roughing mill. For finish work or in hard materials, you need more cutting edges so use a 4 flute.
If you're going to be working in aluminum, you'll want to get some "high Helix" end mills. The same principle applies between 2 and 4 flute.
03-09-2004, 05:00 PM #4
2 flues are slot drills which you can use to drill into a metal and then cut, as opposed to end mills which have 3 or 4 flutes and made for side machining only.
There are always exceptions though eg. 3 fluted slotdrills etc.
03-09-2004, 05:49 PM #5
Thanks guys. I appreciate the help. I think I'd like to have some of each type. I'm looking at a 20 pc. set from Enco (imported) that are tin coated HSS. The set has 10 each- 2 flute and 4 flute, from 3/16 to 3/4 by 16ths. I understand that the imported stuff is questionable in quality but would this be OK as a starting set? It's less than $40. on sale so it won't break the bank. Oh yeah, free shipping too since I'm buying other items that will go over $50.
Thanks again, Mike
03-09-2004, 07:11 PM #6
You might want to invest in some roughing mills as well. These are often referred to as cob mills. It will mean an extra tool change,but it will save your cutting edges on your regular endmills when milling through the scale on hot rolled steel or heat affected zone on flame cut stock. I would also get some 3 flute end mills for working aluminum. Sometimes 2 flutes just want to chatter and 4 flutes do not have the chip clearance needed.
03-09-2004, 10:13 PM #7
I have had great luck buying endmills and cutters from ebay. I only buy American or good quality. The enco, made in china cutters leave a lot to be desired. I have dulled some of them very quickly and now give up on them. I have bought top quality endmill from ebay as cheap as the enco mills.
03-10-2004, 11:18 PM #8
The cheapo enco sets are okay to have around for occasional use when you need a special size, but they won't last long. I've got a cheapo set for that purpose but I use US made 1/2" or 3/4" endmills for any serious milling. I've also got some roughing endmills that I use for the first pass if I need to make a big cut, they work great.
I generally use only 2 flute endmills for both steel and aluminum since they're more versatile. If I need to take heavy cuts I'll switch to a roughing endmill and go back to the 2 flute spinning fast for a light finishing cut.
03-10-2004, 11:29 PM #9
Best to have a variety, but I agree - 2 fluters are more versatile. They plunge better than 3 or 4 fluters and when you want a smooth cut on the side just increase the speed.
03-11-2004, 07:53 AM #10
You will find that if you use a four flute "end mill" for cutting a slot, it will try and walk sideways as the cut progresses.
You need to use a two flute "slot drill" to minimise this.
The reason is that when one tooth is cutting out the material at the end of the slot, the other is in free space at the back and not influencing the direction, however with a four flute cutter you would always have at least two teeth trying to cut and more sideways deflection is imparted to the cutter. This is why the two flute ones are called slot drills, the also have one end cutting edge longer than the other which passes over the centre line and allows it to plunge cut into the work for blind ended slots. A four flute can not do this as they normally have a centre in the cutting end, and would require some sort of pilot hole.
Try it out on a bit of scrap with the same size cutters in both two and four flute versions, you will see what I mean.
03-11-2004, 11:39 AM #11
I agree on the cheap combos of 2 and 4. Ive been using a Grizzley 49.00 set for over 2 yrs now for simple tasks but when you get serious go for Carbide. Its not a thing to me but I have to plug Kodiac for performance and pricing on end mills. They are US made and priced very reasonable. MHO...Jack
03-11-2004, 12:02 PM #12
From what I've heard from friends the cheapo sets are just that, cheap. but it may make sense for you to buy the set, just to learn if the price is right. My first time using a mill I went through quite a few endmills untill I got it right. Stupid beginners mistakes like milling the wrong direction, but I am sure glad it was only $3 cutters and not nice Niagras. But once you get good you tend to want to get decent endmills. American, Polish, Israeli, and recent Japaneese so far are all good, the Chineese ones don't quite hold up.
I don't know if it is available to you, but you may be best off finding a good used source of endmills. Endmills, can sure break a meager hobbiest wallet, at a few $$'s each however at the same time, if you keep your eyes and ears open you may come across large quantities of them in nice condition either dirt cheap, or free from friends and local industries. I myself went through a period of time where I got about 300 of them both from 2 friends cleaning out their shops, and the rest from a company who takes pictures of them at work in my shop. Not bad? When these things are sold, they tend to go in large lots, I even see guys on ebay from time to time advertising 25lbs of endmills, I don't know the quality of them. Additionally we have a local used toolstore in Worcester, that tends to have endmills ranging from $1-5 each depending on if they are carbide, and size. Since my machine can take 1" endmills and most of the guys with R8 can't I once got about 5 carbide almost brand new Niagra endmills for example for $3each. Also from what I hear these types of things go pretty cheap at auction too. So keep your eyes and ears open. When a company is quoting a production run, the cost of endmills is relitively cheap and all factors into production, when you or I go to use them the $8 here, $50 there can be a killer.
Other suggestion may be to stay away from carbide till you know what you are doing, as it chips easily. By the way, whom ever suggested getting some roughers is right on the money I never used them untill recently when I got a few for free and now I just want more. They are great for all sorts of heavy hogging, and really removing material fast. Only now do I have a band saw, but prior to that I was doing cutoff operations with roughers and they just chewed right through.
03-11-2004, 02:44 PM #13
The $49 Grizzly set will definitely get you down the road. I'll take a sharp cheapie endmill over a dull quality endmill any day of the week. The import endmills are fine for anything but the most demanding jobs anyway. Do your wallet a flavor and buy what you can afford, not just what the status quo tells you.
03-11-2004, 05:05 PM #14
I have the same 20 pc. set in a MSC sales flyer for just under $40.00. I don't find this set on-line at ENCO where I would also benefit from FREE shipping on a $50.00+ order. Where did you find the set, help. TIA. Steve
[This message has been edited by Steve Stube (edited 03-11-2004).]
03-12-2004, 12:53 AM #15
Steve, I found the set listed in a flyer from ENCO. I've included a link below that you can use.
I've decided to order the set just to have all the different sizes and one of each type...also if I screw one up so what? no big deal.
Thanks all, for the great input...it is much appreciated.
Here's a link for the end mill set:
Item # CR320-0000 Page 85 of Catalog
03-12-2004, 01:41 AM #16
I'm another advocate of buying used. I didn't get quite the deal Les got by buying half a truckload of them at auction for $40.00, but I found a nice old man who was selling off his tools as his Parkinsons would no longer allow him to use them. I got an assortment of nearly all the end mills you would probably ever need for $100.00. They weren't free, but it was quite a bargain considering what I got. They're mostly all good US made stuff in everything from .050 through 2.00 (with .750 shaft). Probably over 100 pieces including all sorts of formed tools like radius cutters, ball end mills and keyway cutters. Most all of them are in sharp, ready to go condition, and the few that need sharpening can be sharpened cheaply or tossed.
At least in So. Cal there's an amazing amount of old guys who had home shops and are selling them off at fair prices to save their families from having to do it later. I've outfitted most of my shop from guys like this. Not only have I got some good deals from these smart old guys, but I've certainly learned a few things from them along the way. There's so few people who have any interest in what they did, and so many of their friends are dead, that they're happy to talk shop a bit with a younger guy (I'm 41), make you a deal on some of their most prized possesions and pass the torch. It's great to see the sparkle in their eye when theydescribe what they used to use a certain machine or fixture for. It's also a little sad when they aknowledge that they just can't do it anymore, generally for health reasons (why else would you give up your machines?). I find myself better for the experience. Sometimes when I meet a guy like I've described who wants more than what I think the stuff is worth, or I can afford. When that happens I try to realize the emotional (and perhaps financial) investment they've made in their tools and I can't bring myself to grind on price. So I enjoy the time with them, try and learn a bit and leave them with their tools and dignity.
That reminds me, I have to call the guy I got the end mills from (and a surface grinder, and a bunch of other cool stuff) this weekend to arrange to help him transfer some old reel to reel tapes of his son to CD Rom for him. Sometimes you even make a friend with these deals. From what I've found, these older fellas don't do ebay or the internet for the most part. You find them in your local paper's classified section, the Pennysaver, Recycler, etc. Most of the guys I've found have been mid 70s to mid 80s and are all in failing health. What I need to find is a 60 something master machinist who's selling his shop and wants to travel, but would like visitation rights and was in good enough health to come over and visit his stuff and mentor me.. Heck, I've got almost all the stuff needed now anyway, so I just need the old, experienced mentor who no longer has access to a shop of his own..
[This message has been edited by Excitable Boy (edited 03-11-2004).]