End Mill Shank versus Cutting Diameter

[syscore]

I guess I was under the impression that an end mill could reach as deep as the shank sticking out of the holder, but now I realize that is not the case because the diameter of the flutes is equal to the diameter of the shank and thus, the shank will touch the work. Is the only option to get end mills with longer cutting lengths, or do they make end mills with slight wider cutting diameters compared to the shank diameter.

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[SCzEngrgGroup]

Endmills with shanks larger than the flute diameter are very common, especially in smaller sizes. Endmills with shanks smaller than the flute diameter are very rare, except for very large diameters. The reason should be obvious - a reduced shank would greatly reduce stiffness. The only commoin exception is some indexable endmills.

Regards,
Ray L.

[Jim Dawson]

......... Endmills with shanks smaller than the flute diameter are very rare, except for very large diameters. The reason should be obvious - a reduced shank would greatly reduce stiffness..........

Regards,
Ray L.

Ray, I am going to have to both agree and disagree with you here. You are correct that the reduced shank would affect stiffness, but reduced shank endmills are very common even in smaller sizes. It is common to find a 7/16 endmill with a 3/8 shank, as is finding a 9/16 endmill with a 1/2 shank. The catalogs normally offer a range of shank sizes for cut diameters. Commonly a 3/8 shank is used down to very small cut diameters, but you can easily find 1/8 and 1/4 shank with larger cut diameters.

It is also common to grind the shank above the flutes to get a reduced diameter for a longer reach, I've done this many times. You only need a few thousandths clearance.

[WOTDesigns]

Ray, I am going to have to both agree and disagree with you here. You are correct that the reduced shank would affect stiffness, but reduced shank endmills are very common even in smaller sizes. It is common to find a 7/16 endmill with a 3/8 shank, as is finding a 9/16 endmill with a 1/2 shank. The catalogs normally offer a range of shank sizes for cut diameters. Commonly a 3/8 shank is used down to very small cut diameters, but you can easily find 1/8 and 1/4 shank with larger cut diameters.

It is also common to grind the shank above the flutes to get a reduced diameter for a longer reach, I've done this many times. You only need a few thousandths clearance.

I wasted well over $1,000 trying different recommended fancy brands and cutter geometries trying to find a 1/4" EM that could reach 1.25" deep. SNAP. SNAP. SNAP. SNAP. one after another they all snapped and had to be greatly reduced in speed and DOC to make it a few hours.

I gave up and bought a diamond wheel for my Dremel. Load the shank or a regular 1/4 X 3/4 em on the drill press and grind from the 3/4" Flute up 1/2 down to 0.235". Used to clean it up with diamond file, but that wasn't necessary. In action they run at 6000 rpm, 50ipm slotting at 0.05" deep... For roughly 120 hours then get tossed when the job is done. 3x a year minimum.

Now you tell me which is WEAKER? A 1.25" $56 CUTTER that snaps at 30ipm? Or a $26 DF ARF20250 ground to reach that hasn't broken without the part moving in 5 years and over 35,000 parts 1" tall cut with it? I run 4,000 parts per run then toss it and grind a new one next time.

Mind you this isn't for a perfect surface finish if I needed a perfect surface finish I would have it ground down by someone a little more skilled than myself. These are rough and then tumbled so I don't care about the witness Mark where the two step Downs on the finishing cut meet up

Virtually every reputable company that manufactures end Mills also manufactures reduce shank end Mills. They are in function far far far stronger than an end mill of the same cutting depth by way of longer flutes

[WOTDesigns]

Ray likely means that reduced shank is weaker than non reduced shank of the same length and is correct, they would be VERY marginally weaker, but that is an irrelevant fact.

Apples to Apples would be comparing a reduced shank 3/4 to a 1.25 inch flute length. The reduced Shank is many times stronger than an equivalent cutting depth that is not reduced shank.

[Steve Seebold]

I wasted well over $1,000 trying different recommended fancy brands and cutter geometries trying to find a 1/4" EM that could reach 1.25" deep. SNAP. SNAP. SNAP. SNAP. one after another they all snapped and had to be greatly reduced in speed and DOC to make it a few hours.

I gave up and bought a diamond wheel for my Dremel. Load the shank or a regular 1/4 X 3/4 em on the drill press and grind from the 3/4" Flute up 1/2 down to 0.235". Used to clean it up with diamond file, but that wasn't necessary. In action they run at 6000 rpm, 50ipm slotting at 0.05" deep... For roughly 120 hours then get tossed when the job is done. 3x a year minimum.

Now you tell me which is WEAKER? A 1.25" $56 CUTTER that snaps at 30ipm? Or a $26 DF ARF20250 ground to reach that hasn't broken without the part moving in 5 years and over 35,000 parts 1" tall cut with it? I run 4,000 parts per run then toss it and grind a new one next time.

Mind you this isn't for a perfect surface finish if I needed a perfect surface finish I would have it ground down by someone a little more skilled than myself. These are rough and then tumbled so I don't care about the witness Mark where the two step Downs on the finishing cut meet up

Virtually every reputable company that manufactures end Mills also manufactures reduce shank end Mills. They are in function far far far stronger than an end mill of the same cutting depth by way of longer flutes

Brian, I get about 90% of my end mills from Raptor End Mills .(714) 757-1994. He sells YG1 end mills for reasonable prices.

I have used the YG1 end mills for about 5 years with tremendous success.

[Steve Seebold]

I wasted well over $1,000 trying different recommended fancy brands and cutter geometries trying to find a 1/4" EM that could reach 1.25" deep. SNAP. SNAP. SNAP. SNAP. one after another they all snapped and had to be greatly reduced in speed and DOC to make it a few hours.

I gave up and bought a diamond wheel for my Dremel. Load the shank or a regular 1/4 X 3/4 em on the drill press and grind from the 3/4" Flute up 1/2 down to 0.235". Used to clean it up with diamond file, but that wasn't necessary. In action they run at 6000 rpm, 50ipm slotting at 0.05" deep... For roughly 120 hours then get tossed when the job is done. 3x a year minimum.

Now you tell me which is WEAKER? A 1.25" $56 CUTTER that snaps at 30ipm? Or a $26 DF ARF20250 ground to reach that hasn't broken without the part moving in 5 years and over 35,000 parts 1" tall cut with it? I run 4,000 parts per run then toss it and grind a new one next time.

Mind you this isn't for a perfect surface finish if I needed a perfect surface finish I would have it ground down by someone a little more skilled than myself. These are rough and then tumbled so I don't care about the witness Mark where the two step Downs on the finishing cut meet up

Virtually every reputable company that manufactures end Mills also manufactures reduce shank end Mills. They are in function far far far stronger than an end mill of the same cutting depth by way of longer flutes

Brian, I get about 90% of my end mills from Raptor End Mills .(714) 757-1994. He sells YG1 end mills for reasonable prices.

I have used the YG1 end mills for about 5 years with tremendous success.

[MFchief]

Steve, it that a local business? I googled Raptor End Mills, but came up empty.
Terry

[popspipes]

I came up with this:

Raptor Endmills Co  
WebsiteDirections
5.0
1 Google review
Tool grinding service in Santa Ana, California
Address: 2233 Ritchey St, Santa Ana, CA 92705
Phone: (714) 757-1994

I googled and cameup with this...........

[spumco]

Necked down (reduced shank) end mills are available and not ferociously expensive. If you need a long-reach 1/4" end mill that has the shank relieved about .010"-020" for deep pocketing operations, lakeshore carbide has an off-shoot business for CNC gunsmithing. They sell just such a critter for deep pocketing the fire control pocket on AR10/15 lowers.

Has a fairly short flute length and you can only take a narrow WOC, but it'll do just what you need. Pretty stiff, too because the flutes are so short.

I believe Harvey tool also sells necked-down end mills, as do other vendors.

Search terms - 'necked down endmill' or 'reduced neck' or 'neck relieved' all result in some good hits on google or bing.

-S

[MFchief]

Mike, thanks for the info on the Raptor end mills.
Terry

[Steve Seebold]

Steve, it that a local business? I googled Raptor End Mills, but came up empty.
Terry

They're in Santa Ana CA. The owner/operators name is Scott Smith.

He also has a lot of really weird stuff.

I once needed a carbide end mill, 9 inch overall length, 3 flutes, 1 1/4 inch length of cut with a .125 corner radius and he just happened to have "one" on the shelf.

[AUSTINMACHINING]

Steve, it that a local business? I googled Raptor End Mills, but came up empty.
Terry

I buy a lot of YG1 tools from suncoast tool
They seem to have stock on just about everything
Imcludimg reduced shank end mills

[syscore]

Thanks for the replies. It is good to know that reduced shank is an option. Or grinding one yourself.