3 flute endmills

[Sunset Machine]

Hard to find them, and until the other day I put 3 flute endmills out of my mind. Way back when, my instructor always pimped them up to us students. My 3/4" 2-flute is approaching a nubbin and I need to replace it before it's gone. Looking through a catalog it all came back to me when I saw one -- a 3 flute single end from a local supplier, for $20.

I sharpen them by hand on a bench grinder; 4 flutes are a tad fussy, 2 flutes are a piece of cake. I'm hoping a 3 flute won't be too tough to do when the time comes.

Slotting and finishing. What say you guys? Boo, hiss, or whistles and applause for the things?

[EdK]

I think they have their place. I have a few and will use them on aluminum if it's a non-slotting operation.

Ed

[wrustle]

We use 3 flute solid carbide variable flute endmills for EVERYTHING having to do with aluminum. These are run in our VMC. With the 3 flutes it allows a higher feed versus a 2 flute, yet it offers better chip evacuation than a four flute for ramping into a piece and for slotting despite the sacrifice in IPM for the four flute.

We buy all of aluminum specific end mills from Lakeshore Carbide. http://www.lakeshorecarbide.com/

Here's a video of a .500" 3 flute solid carb variable flute em in some aluminum. In this particular video, we were on the EXTREMELY conservative side of things, but the effect is clear......the 3 flute gets the job, and done quickly!

5,500 RPM's, 67 IPM, .250" DOC, .500" WOC.

http://www.youtube.com/watch?v=wgLs_8KhrX8

Here's a pic of the finished part.





Best Regards,
Russ

[Sunset Machine]

I should have said for steel. Can't do carbide on my old, slow floppies... I just bust 'em. They had 3 flutes clearly marked for aluminum with deep flutes & a high helix, but these look like regular steel cutters. Heck, the price isn't bad. Maybe I'll just find out the hard way! :)

[wrustle]

For machining mild steel we use 4 flute end mills, stainless we go up to five flutes. Again though, these are all run in our VMC and they are solid carbide.

For what you're trying to accomplish in a knee mill, I would stick with HSS for roughing and then if the tolerance and finish calls for it, go with a carbide to finish. I always climb milled in my Lagun for my finish, but kept the finish pass to approx. .005" and kept the binders on the axis' snug to prevent the table from jumping due to backlash.


My Lagun FT2 Knee Mill.

My youngest boy Christian milling a keyway in a shaft. Back then probably around 14-15, now he's 20! Geez......how time flies!!



Best Regards,
Russ

[Sunset Machine]

Time flies - no kidding! I have a GRANDSON his age. Two more in their teens, and a new GREAT-grandson. Where did they all come from?! Last time I checked, I was 40. Guess I need to check again.. ;-)

My stuff, it breaks carbide. Years ago I bought a drill press, a big honkin one they call a mill/drill. $850, brand new. Thought it would make a decent drill press with that nice X-Y table, and they said it would run endmills. Oh goody, a bonus. My knee-mill is a 100 year old horizontal, top spindle speed of 316 RPM. I've a vertical head for it but because of the mill/drill I've never had to use it. Point being none of this stuff is suitable for carbide endmills.

That mill/drill came with a 3" brazed tip carbide face mill. Curious, when I got it I put a chunk of steel on the table and promptly shattered the bits. It was doing a bobble-head thing, shaking. Re-sharpened the bits on a green wheel and have been using it on the far more rigid horizontal, where it has worked for a long time (.375" DOC typically) -- until the other day when I put a cheapo 10" rotab on the table and things went snap-crackle-pop... Thus, that little project turned into a big one for the 3/4" endmill I'm trying to replace. Carbide is now verboten, looking at replacing those face mill bits with HSS next weekend, modifying the holder for standard 1/2" square HSS. We'll see.

Home shop stuff. Time isn't money.

[PixMan]

A 3" brazed tip carbide face mill? I'd toss it and get a good carbide insert mill if I were you. Today's carbide inserts can be tough as nails (much tougher, actually) and are easy to use on home shop machines.

My dad's shop has (for now) a 1960 Bridgeport with the step pulley 1HP 3-phase drive. While I can't bury the 3" 45º 6-insert cutter I have in any material, the 2-1/2" 4-insert cutter flows chips pretty good in almost anything. I have tough, yet fairly sharp inserts that make any job easy as pie. There are many good choices out there. I can't understand why "carbide is verboten" any more than you would understand if I said "High speed steel has no use in the shop." Neither should be true, ever. The 316 rpm can be good for a 3" face mill if it has at least a little power. Any tool, whether HSS or carbide, can snap if the spindle stops in mid-cut while the feed is still going.

Perhaps time in a home shop isn't equated to dollars made like a commercial shop. Still, time spent fixing broken stuff and getting frustrated when you should just be getting a job done is not making any martyrs or heroes. We all have a learning curve and there can be some quantum leaps made with tools that work.

As for 3-flute vs. 2-flute or 4-flute end mills, I use them all. They all have their best applications. In HSS end mills a 2-flute is nice for small diameters (under 1/8") because it can be stronger. Also good in larger diameters for aluminum. I like 3-flute anytime I'm slotting, as they offer the best balance between core strength and chip evacuation. The 3-flute are also the best choice when you need a center-cutting end mill for plunging. Four flute end mills are best for steels and stainless steels, primarily for side cutting (rather than true end milling.) As material hardness goes up, so should the helix angle. Hook, clearance angles, secondary lands, grind quality and raw material quality all play a part in how well your HSS or solid carbide end mill will perform. There are many grades of HSS, and it seems only the very best makers will state the type.

I have some beautiful HSS-PM (powdered metal) 3-flute TiAln-coated end mills for aluminum from Cleveland Tool, and they just kick butt. Those are the ones from right to left, a 3/4" and two 5/8". I have a few solid carbide that I wouldn't be without, and many in between. Buy quality tools and treat them as such. You'll be rewarded with good parts and fun making them.

[Mayhem]

(02-03-2013, 02:22 PM)wrustle Wrote: ...My youngest boy Christian milling a keyway in a shaft. Back then probably around 14-15, now he's 20! Geez......how time flies!!...

So it's not just the developing world that still uses child labour

[EdK]

(02-03-2013, 06:01 PM)PixMan Wrote: As for 3-flute vs. 2-flute or 4-flute end mills, I use them all. They all have their best applications. In HSS end mills a 2-flute is nice for small diameters (under 1/8") because it can be stronger. Also good in larger diameters for aluminum. I like 3-flute anytime I'm slotting, as they offer the best balance between core strength and chip evacuation. The 3-flute are also the best choice when you need a center-cutting end mill for plunging. Four flute end mills are best for steels and stainless steels, primarily for side cutting (rather than true end milling.) As material hardness goes up, so should the helix angle. Hook, clearance angles, secondary lands, grind quality and raw material quality all play a part in how well your HSS or solid carbide end mill will perform. There are many grades of HSS, and it seems only the very best makers will state the type.

I have some beautiful HSS-PM (powdered metal) 3-flute TiAln-coated end mills for aluminum from Cleveland Tool, and they just kick butt. Those are the ones from right to left, a 3/4" and two 5/8". I have a few solid carbide that I wouldn't be without, and many in between. Buy quality tools and treat them as such. You'll be rewarded with good parts and fun making them.

Wow! That's a lot of great information. Thanks for taking the time to post it. I certainly learned a thing or two. I did not know that a 2-flute end mill is stronger than a 4-flute in smaller diameters but it does make sense.

Ed