Two Questions

[JimN]

I have two questions that I am sure someone here can answer!

1. I have both the 3 jaw and 4 jaw chuck for my Sherline lathe, in turning down round stock is there any advantage to using one or the other?

2. In milling slots in brass and aluminum with a 1/16 inch end mill, what is the different with 2 fluke and 4 fluke? I have tried both and can't seem to see much difference, but since I broke one today and need to order couple more, not sure which I should order.

Thanks
JimN

 

[hammers-n-nails]

the 3 jaw chuck is faster, but may or may not be perfectly concentric to the motion of the lathe, the 4 jaw can be lined up exactally with a dial indicator or offset if your making an eccentric or something. i like the 4 flute endmills alot better myself they have a more even cutting action(less vibration) and you can run higher feed rates at the same rpm but you have to go fast or you will wear out the cutter faster, so they say, but i can see a 4-flute that small getting pluged up with shavings in aluminum especially if your not using cutting fluid. thats all i got.

zach

 

[rake60]

If the part being made can be done in one set up the 3 jaw is a quick and easy way to go.
Even if it does require 2 set ups the 3 jaw can be used for the 1st stage.

For the end mills, you will get the best finish and accuracy from a 2 flute.
You just can't feed it as fast as a 4 flute. There are complicated load per tooth
formulas out there that explain all of that but for a home hobby machine it is
easy. When using any end mill you want to see clean shiny chips. If they are
blue in steel or browning in aluminum or brass, you are pushing it too hard.
Be patient, listen to and watch the chip. The material will tell you what it will
take to cut it.

Rick

 

[doc1955]

In end mills it depends on what material you are cutting. If it is aluminum you use a 2 or 2 flute for best performance. A 4 flute end mill the clearances are for steel and harder materials. In aluminum the margin clearance angles will cause it to not preform as good. Not to say you cant use a 4 flute in aluminum but you will generate more heat in part and like I said performance is degraded.

If on the lathe you are going to do some heavy cutting a 4 jaw will grip your stock better than a 3 jaw.

 

[JimN]

Thanks, think I will order some 2 fluke then since they are for brass or aluminum. I tend to use the four jaw more, it seems to hold better and I have less problems dialing the material in with it. Was curious why alot of times see a 3 jaw in pictures.

My sherline has both 4 jaw that is the same as the 3 jaw, and a 4 jaw independent for offsets.

I just need to learn how to use each to the benifit of each type.

JimN

 

[zeeprogrammer]

For the end mills, you will get the best finish and accuracy from a 2 flute.

Well that's interesting. I was recently talking to someone about how it seemed I had more luck with a 2 flute. While I understand it may not always be the case...as a newbie (or less than a newbie)...my initial reaction would have been (er...was) that 4 is better than 2.

This is great info. Thanks for the question JimN and for the all the answers everyone.

 

[JimN]

ok Zee, now its your turn, by the way as a newbie which I am, know anyplace that gives discount on end mills by the gross?????

They sure don't make those 1/16 end mills very good,,they break all the time!

JimN

 

[bentprop]

My understanding is that a 2 flute is designed for slots,whereas a 4 flute is designed for end milling or surfacing.With a 2flute,you can plunge cut,which a 4 flute can not do.
Just to confuse you further,in the larger sizes you can come across 6,or even 8 flute cutters.
Then there's the 3 flute unimill,which supposedly gives you the best of both worlds.Personally ,I found they are no better than a 2 flute,thus not worth the extra cost.
For larger surfaces,I prefer the flycutter.Slower,but gives a much better finish.
My$0.02.

 

[doc1955]

My understanding is that a 2 flute is designed for slots,whereas a 4 flute is designed for end milling or surfacing.With a 2flute,you can plunge cut,which a 4 flute can not do.
Just to confuse you further,in the larger sizes you can come across 6,or even 8 flute cutters.
Then there's the 3 flute unimill,which supposedly gives you the best of both worlds.Personally ,I found they are no better than a 2 flute,thus not worth the extra cost.
For larger surfaces,I prefer the flycutter.Slower,but gives a much better finish.
My$0.02.

Not true there are 4 flute end mills used for plunging it depends if it is an center cutting end mill or not.
3 flute end mills are still made for aluminum the cutter geometry is set for softer material. For cutting steel you will get a better finish with a 4 flute plus it is easier on your machine than trying to do the same with a flute. For surface milling aluminum or steel invest in a shell mill they are worth the investment. Depending on your machine you can take a shell mill and take a substantial depth of cut and get a nice finish. A flycutter is my last choice in cutters slow clunky and not the greatest thing for your machine.

 

[Russel]

Thanks, think I will order some 2 fluke then since they are for brass or aluminum. I tend to use the four jaw more, it seems to hold better and I have less problems dialing the material in with it. Was curious why alot of times see a 3 jaw in pictures.

My sherline has both 4 jaw that is the same as the 3 jaw, and a 4 jaw independent for offsets.

I just need to learn how to use each to the benifit of each type.

JimN

If you want to get your part centered with the most accuracy, use the 4 independent jaw chuck. If it isn't that critical the 3 jaw self centering chuck is faster because you don't have to center the part with a dial indicator. If you have the 3/8" tool post you can use it to hod your DI:

After getting tired of swapping the tool post from cutting bit to DI holder I finally made a little DI holder (that uses a little $10 DI) that you can mount on the other side of the cross slide so that the cutting bit tool post can remain on the handwheel side.

If you are going to complete all your machining with the 3 jaw SC chuck, and cut the outside diameter of the part, your part will become centered when you cut it. If you need to flip it end for end to do more machining, then the 4 jaw chuck may be a better choice because you can center the exsisting outside diameter with a DI. I hope this makes sense!

Russ

[edit] I forgot to add that I find the 4 jaw 2.5" self centering chuck great for the mill. for holding those big drill bits.

 

[rake60]

On the basics of end mills, most 2 flute end mills are center cutting.
Some 4 flute end mills are center cutting.

OK you can not drill a straight hole with a non-center cutting end mill
That means it is impossible to plunge cut with a non-center cutting end mill
in any capacity. Or NOT. I have cut many keyways with non-center cutting end mills
by working them back and forth on the Z axis and plunging .030" at a time to get
to depth. When the shops tool crib doesn't have what you need you can't set
the job aside until they get more in. You make what you have work for the situation.
The only difference is that in a home hobby shop you can slow down to allow
that to be done safely.

Rick

 

[Artie]

...as a newbie (or less than a newbie)...

You're kidding me right...?

Zee, your skills, as demonstrated on this site are awesome..... Im a long-term home-taught mill user and I have learnt ABSOLUTELY heaps from your posts and the subsequent replys you have received. I must also say this applies to several regulars to name a few..... Tel, Deanofid, rake60, Cedge, Brain Rup, GailinNM, Jimn, Doc1955 et al... (sorry if I didnt name you other legends but there is only so much space to use... YOU KNOW WHO YOU ARE!)

Zee, please dont sell yourself short mate.... you ARE in good company.....

:bow: :bow: :bow:

 

[zeeprogrammer]

JimN...no idea where to get end mills by the gross. Let me know too when you find out. ;D.

Right now I'm trying to follow the Rule "When you break one, buy two". This helps to protect against the Rule "If you only have one, it will break."

Thanks Artie. I appreciate it. I just want to make it clear how new I am to this hobby and that I too am learning a lot from the replies.

Working that ratio of "I know how to do that!" to "huh?"

 

[mu38&Bg#]

The number of flutes also depends on how fast you might be turning the tool and if you have a maximum feed rate in the case of homeshop CNC. I run some small bits in my little CNC at high RPM and have found 2 flute to work much better. You don't want to feed too slow because the cutter ends up working in a work hardened area depending on material (aluminum).

I've read that 3 flute cutters are best when the slot is the width of the cutter. And two is better than four. So far my only experience has been 2 and 4, and 2 seems to work better for me.

The quality of the cutter can make a huge difference. Lately, I try to buy brand name endmills. I've been using some Kyocera Dataflute endmills under 1/8" and they cut aluminum and even 4140, 4340 like butter. I have some OSG, Matrix, Fullerton, Kennametal, and others in larger sizes I haven't used much. They do cost more, but to me are well worth it.

Do get yourself a 10X loupe to inspect your used tools. A chipped edge on a 1/16" endmill is going to be impossible to see with the naked eye and it will still cut, just poorly.

 

[BobWarfield]

Oh man, complex topic!

Some thoughts:

- The more flutes, the more its like running your spindle faster. For the same spindle speed, a 4 flute can be fed twice as fast as a 2 flute, and a 3 flute can be fed 50% faster. Think of it as a "spindle speed multiplier". Many mills in home shops are rpm challenged, particularly on materials like aluminum that want a lot of rpm, hence you can gain some advantage with more flutes.

- If you stick more flutes down the hole, it means less room for the chips though. Some materials, like aluminum, have some "sticky" chips that like to cause trouble. Hence we prefer fewer flutes in aluminum when we are worried about clearing out the chips. 2 or 3 flutes work best.

- Get the chips out! Recutting is hard on tools and ruins the surface finish. You probably don't want the mess of flood coolant, but at least try a strong air blast. It's easy to arrange a nozzle on your spindle to keep the chips out of your way. Your tools will thank you as will your work.

- If you must slot full width, and this is never the most accurate way to slot (you should full width down the middle leaving room for a finish pass that only cuts one side of the slot or other), a 2 flute is more accurate because of the way the flutes pull against the sides of the hole. I have not noticed much difference on this phenomenon personally, BTW.

- You can use 4 flutes, 5 flutes, or however many flutes on aluminum just fine provided there is adequate chip clearance. I always get a better finish peripheral milling around the outside of a part with a 4 flute. It's that faster spindle speed phenomenon again. And, because it isn't down in a hole, but cutting around the outside, there is plenty of room for the chips to get out of the way, so the cutter is not bothered. This is a trick I learned from Widgitmaster over on CNCZone.


Speeds and feeds matter more than you'd think for finish and tool life. There are lots of rules of thumb, but is surprising how far many of them will put you from the manufacturer's recommended speeds and feeds. One of the biggest advantages of CNC is you can reproduce exactly the feedrates called for on a job over and over again. You can dial it in to perfection.

I wrote a feed and speed calculator after I got tired of figuring it all out by hand every cut to get it right. It's called G-Wizard and you're all welcome to try it.

Cheers,

BW

 

[doc1955]

Oh man, complex topic!

Some thoughts:

- The more flutes, the more its like running your spindle faster. For the same spindle speed, a 4 flute can be fed twice as fast as a 2 flute, and a 3 flute can be fed 50% faster. Think of it as a "spindle speed multiplier". Many mills in home shops are rpm challenged, particularly on materials like aluminum that want a lot of rpm, hence you can gain some advantage with more flutes.

This is not true cutter geometry from a 2 and 3 flute to a 4 flute changes considerably and the 4 flute does not have the correct margin clearance for softer material. It may sound logical but it isn't you will actually be able to feed faster with a 2 flute in aluminum due to the clearance.

- If you stick more flutes down the hole, it means less room for the chips though. Some materials, like aluminum, have some "sticky" chips that like to cause trouble. Hence we prefer fewer flutes in aluminum when we are worried about clearing out the chips. 2 or 3 flutes work best.

- Get the chips out! Recutting is hard on tools and ruins the surface finish. You probably don't want the mess of flood coolant, but at least try a strong air blast. It's easy to arrange a nozzle on your spindle to keep the chips out of your way. Your tools will thank you as will your work.

This is true the reason the chips are hard on tools they are harder than the material being cut.

- If you must slot full width, and this is never the most accurate way to slot (you should full width down the middle leaving room for a finish pass that only cuts one side of the slot or other), a 2 flute is more accurate because of the way the flutes pull against the sides of the hole. I have not noticed much difference on this phenomenon personally, BTW.

Cutter flex is always there you may notnotice it if you cut your feed down.

- You can use 4 flutes, 5 flutes, or however many flutes on aluminum just fine provided there is adequate chip clearance. I always get a better finish peripheral milling around the outside of a part with a 4 flute. It's that faster spindle speed phenomenon again. And, because it isn't down in a hole, but cutting around the outside, there is plenty of room for the chips to get out of the way, so the cutter is not bothered. This is a trick I learned from Widgitmaster over on CNCZone.


Again I humbly disagree you can get a better finish with faster feed in aluminum with a 3 or a 2 flute em.It all has to do with the cutter geometry. Believe me I've been doing this for 35 years and there are a lot of misconceptions when it comes to feed and tool selection.

Speeds and feeds matter more than you'd think for finish and tool life. There are lots of rules of thumb, but is surprising how far many of them will put you from the manufacturer's recommended speeds and feeds. One of the biggest advantages of CNC is you can reproduce exactly the feedrates called for on a job over and over again. You can dial it in to perfection.

I wrote a feed and speed calculator after I got tired of figuring it all out by hand every cut to get it right. It's called G-Wizard and you're all welcome to try it.

Cheers,

BW

 

[BobWarfield]

Doc, I appreciate what you have to say, but there are others with lots of experience that disagree with some of that too.

More specifically:

Your point about feed rates is covered by my point on the last about whether you can clear the chips or not. Go back and look at the feed and speed equations--more flutes = more feedrate all other things being equal. If you've got a slower spindle, try to get more flutes working for you. Lots of these home machines are slower spindles.

In some cases, the chips are harder (work hardened), but in every case wedging some additional work between your cutter and your workpiece isn't helpful.

Agree, there is always some cutter flex. Nothing is perfectly rigid.

RE better finish and faster feeds in aluminum, sorry Doc, been there done that myself. If you don't believe me, go ask the guy I learned it from, Widgitmaster over on CNC Zone. He's a 35 year veteran too. Here is just one project where he used that technique that came out looking awesome:

http://www.cnczone.com/forums/showthread.php?postid=690271

If you want to optimize the geometry futher to cut aluminum with a 4 flute, companies like SGS make 4 flute cutters especially for aluminum:
http://www.sgstool.com/products/endmills.asp

Or, you can read this bunch of experienced machinists who have no prob with 4 flute so long as there is chip clearance:

http://www.practicalmachinist.com/vb/showthread.php/2flute-4-flute-118948.html

We all have our set ways we like to do things. That's fine. I just like to try the other ways too, and when I see some evidence they work, as I have here, I adopt them.

Cheers,

BW

 

[doc1955]

Yes we do all have our opinions and what I posted was from my experience only.
We do high speed milling here and I've been at it for over 35 years now. The shop I work at we mill everything from cast aluminum to titanium and everything in between. Don't take my comments the wrong way it is just that I disagree with your statements (sorry we all don't have the same opinion).
The shop I work at is an areo structures plant we also did a lot of military stuff.
The thing with the feed rate is you will never be able to put full chip load to a standard 4 flute end mill in aluminum and get away with it but you can with a 3 or 2 flute thus you actually can feed faster and get a much better finish.

 

[hammers-n-nails]

i have some 3/4" 6flute endmills and i have noticed that they dont leave the best finish, might not even be relevant.

someone was talking about flycutters earlier, i have this face mill http://www.grizzly.com/products/Fly-Cutter/G2861 i couldnt get it to work good at first but it turns out i just wasnt pushing it hard enough, in the end it works great for surfacing, i can take .100" at a time at about 4-5in/minute with a exelant finish, sorry a little off-topic.

 

[BobWarfield]

The thing with the feed rate is you will never be able to put full chip load to a standard 4 flute end mill in aluminum and get away with it but you can with a 3 or 2 flute thus you actually can feed faster and get a much better finish.

We are in absolute agreement for a pocket, slot, or any condition where the chips are the least bit constrained. That 4 flute will pack up and you'll be hating life.

For peripheral milling when everything is exposed and the chips can get out of the way, more flutes work great. This is not aluminum, but this is the sort of op I'm talking about:

[ame]http://www.youtube.com/watch?v=EFUnV_MCV7o[/ame]

The trouble is slow slow spindles on these home shop machines. Nothing like your high speed spindles for HSM. I need to make a video of such a cut and do a surface finish comparison with a 2 flute.

RE your face mill, hammers, that looks more like a steam engine book. What taper does it use and what feeds and speeds (LOL)?
I just got a new 45 degree lead face mill from Glacern. $99 during their "Black Friday" sale. Man is it a nice cutter. I wrote a little mini-review over on www.cnccookbook.com. Just search for "Glacern" if it has scrolled down the list of articles.

Best,

BW