Extended length endmill runout question

Goff · Apr 2, 2018

I am cutting a cavity in aluminum with a necked 1/8” , 3flute, carbide endmill extending 1.6” beyond the collet nose. The actual flute length is ¼”.

I am having trouble with runout at the cutting tip, about .001” or more.

Neither shrink fit holders nor precision collets and tool holders make a difference.

The problem is the endmill itself. The manufacturers tolerance for the endmill runout is a max of .0005”. This is not so bad. The tolerance stackup for a 1.6” extension is the issue.

By trial and error, I can get the runout down to 2 or 3 tenths by rotating the endmill in a non-precision collet and testing with a tenth indicator in the mill spindle.

Does anyone make ER collets with the bore intentionally off center similar to some side lock endmill holders which are supposed to center your endmill when you tighten the setscrew?

Would it be possible to wire EDM a 3mm ER16 collet off center, and make it 1/8 “ diameter?

DMF_TomB · Apr 3, 2018

jcoehlo said:
I am cutting a cavity in aluminum with a necked 1/8” , 3flute, carbide endmill extending 1.6” beyond the collet nose. The actual flute length is ¼”.

I am having trouble with runout at the cutting tip, about .001” or more.

Neither shrink fit holders nor precision collets and tool holders make a difference.

The problem is the endmill itself. The manufacturers tolerance for the endmill runout is a max of .0005”. This is not so bad. The tolerance stackup for a 1.6” extension is the issue.

By trial and error, I can get the runout down to 2 or 3 tenths by rotating the endmill in a non-precision collet and testing with a tenth indicator in the mill spindle.

Does anyone make ER collets with the bore intentionally off center similar to some side lock endmill holders which are supposed to center your endmill when you tighten the setscrew?

Would it be possible to wire EDM a 3mm ER16 collet off center, and make it 1/8 “ diameter?

.
in my experience
.
1) any tool the flutes themselves when end mill sharpened can have runout so even if you put a dowel pin in instead of end mill you will get different runout from the actual end mill
.
2) if you use a optical tool presetter looking at actual cutting edges you will see actual runout in the tool presetter but in my experience each CNC spindle has its own different runout error. for example setting a boring bar on a optical tool setter it will measure slightly different than what it will do in many different CNC spindles
.
3) each CNC spindle has its own runout error with a test bar and dirt, oil, rust etc effects the runout and each tool in tool holder with runout can combine and cancel out spindle runout. many a tool extension adapter in a tool holder collet i have just moved or rotated 90 or 180 or 270 degrees to get runout to cancel out
.
4) even if you got tool tip runout down to .0001" i would not be surprised if you did 10 tool changes and measured runout each time tool goes in spindle runout would vary easily .0003" differently on every tool change

Kaszub · Apr 3, 2018

Buy a better quality tool and even then at that dia-length ratio it will be very hard.

fmari --MariTool- · Apr 3, 2018

Hanging the tool out effectively 13:1 ratio is always a challenge. Just the blank itself can runout a few tenths over that distance. Especially an 1/8 shank.

DMF_TomB · Apr 3, 2018

wouldnt surprise me to get different runout on every tool change. many spindle tapers pick up dirt, oil, rust etc

litlerob1 · Apr 3, 2018

There are Collet Chucks with adjustment, like this one. I have never used one, so I cannot testify to them. I believe there are some Wazzzooo!! types that can be adjusted more accurately, seems like someone was spamming them some time ago. 13:1 aint no joke, especially if you nee to do any Milling

runout-adjustment-system-improves-collet-holder-accuracy-0.jpg

kenton · Apr 3, 2018

How long is the shank? If the shank does not extend most of the way through an ER collet then you are sure to have runout issues and likely tool retention issues.

brian.pallas · Apr 3, 2018

Used Command "zero adjust" (I think that is the name) on reamers. They have set screws in the sides to dial in your runout.

They worked great for reamers.

Matt@RFR · Apr 3, 2018

We are in this LxD range for the majority of our parts. It's not fun, and it's never easy. We've tried a bunch of different whiz-bang tool holders and none solve this issue. So I've settled on Techniks ER standard collets for everything and have excellent luck with them. And yes, just accept the fact that it's going to take 13 assemble/disassemble cycles to get some tools to run right. It's part of the game. Cleaning more than you've ever cleaned a collet / tool holder / tool shank before is not clean enough. Then very lightly oil the toolholder and collet nut tapers, and the collet nut threads.

Goff · Apr 3, 2018

Thanks for all the comments. I am using Harvey endmills, and Techniks tool holders. I am doing exactly what Matt@RFR is doing. Brian.Pallas & Litlerob1, I will look into those tool holders. I was not aware of them.

Kaszub · Apr 3, 2018

Matt@RFR said:
We are in this LxD range for the majority of our parts. It's not fun, and it's never easy. We've tried a bunch of different whiz-bang tool holders and none solve this issue. So I've settled on Techniks ER standard collets for everything and have excellent luck with them. And yes, just accept the fact that it's going to take 13 assemble/disassemble cycles to get some tools to run right. It's part of the game. Cleaning more than you've ever cleaned a collet / tool holder / tool shank before is not clean enough. Then very lightly oil the toolholder and collet nut tapers, and the collet nut threads.

I wouldnt call this luck, what you doing you just fishing for best combo in your not so good tooling. Look up Mizoguchi DETa holders.

Matt@RFR · Apr 3, 2018

Kaszub said:
I wouldnt call this luck, what you doing you just fishing for best combo in your not so good tooling. Look up Mizoguchi DETa holders.

When you're looking for .0001 to .0002" TIR max on a consistent basis on long extension tools, you'll find (at least we found) that the tool holder can be anything you'd like to spend your money on, you're still going to be assembling and disassembling to find the lowest runout. There are too many variables for anything to just work 100% of the time, the first time. If you have .0000,5" of runout in your spindle, how much is that at 4" gage length?

Also, provide a link to Mizoguchi holders please. A quick search came up empty except one holder on ebay.

Kaszub · Apr 3, 2018

Matt@RFR said:
When you're looking for .0001 to .0002" TIR max on a consistent basis on long extension tools, you'll find (at least we found) that the tool holder can be anything you'd like to spend your money on, you're still going to be assembling and disassembling to find the lowest runout. There are too many variables for anything to just work 100% of the time, the first time. If you have .0000,5" of runout in your spindle, how much is that at 4" gage length?

Also, provide a link to Mizoguchi holders please. A quick search came up empty except one holder on ebay.

Thats exactly my point , you got a 100% holder and 100% collet and when you get a shity tool you know what to do......send the shit back to vendor just like your customer would send a bad part right back to you.

If by redoing your holder and a collet 13 times to get it right you calling this consistent? You must be joking.

litlerob1 · Apr 3, 2018

Kaszub said:
Thats exactly my point , you got a 100% holder and 100% collet and when you get a shity tool you know what to do......send the shit back to vendor just like your customer would send a bad part right back to you.

If by redoing your holder and a collet 13 times to get it right you calling this consistent? You must be joking.

View attachment 224858

No linky. I sure would like to read the specs. on these things.

R

HuFlungDung · Apr 3, 2018

jcoehlo said:
I am cutting a cavity in aluminum with a necked 1/8” , 3flute, carbide endmill extending 1.6” beyond the collet nose. The actual flute length is ¼”.

I am having trouble with runout at the cutting tip, about .001” or more.

Neither shrink fit holders nor precision collets and tool holders make a difference.

The problem is the endmill itself. The manufacturers tolerance for the endmill runout is a max of .0005”. This is not so bad. The tolerance stackup for a 1.6” extension is the issue.

By trial and error, I can get the runout down to 2 or 3 tenths by rotating the endmill in a non-precision collet and testing with a tenth indicator in the mill spindle.

Does anyone make ER collets with the bore intentionally off center similar to some side lock endmill holders which are supposed to center your endmill when you tighten the setscrew?

Would it be possible to wire EDM a 3mm ER16 collet off center, and make it 1/8 “ diameter?

When you consider the 'wet noodle' factor of a tool running with that extension ratio, I'd have to wonder if the runout even matters? How stable is the tool tip position once it's started taking chips?

Milland · Apr 3, 2018

Matt@RFR said:
Also, provide a link to Mizoguchi holders please. A quick search came up empty except one holder on ebay.

Here ya' go, Matt: http://www.mst-corp.co.jp/en/

riabma77 · Apr 3, 2018

Tooling Div. Tools - CNC Machine Tools

riabma77 · Apr 3, 2018

jcoehlo said:
I am cutting a cavity in aluminum with a necked 1/8” , 3flute, carbide endmill extending 1.6” beyond the collet nose. The actual flute length is ¼”.

I am having trouble with runout at the cutting tip, about .001” or more.

Neither shrink fit holders nor precision collets and tool holders make a difference.

The problem is the endmill itself. The manufacturers tolerance for the endmill runout is a max of .0005”. This is not so bad. The tolerance stackup for a 1.6” extension is the issue.

By trial and error, I can get the runout down to 2 or 3 tenths by rotating the endmill in a non-precision collet and testing with a tenth indicator in the mill spindle.

Does anyone make ER collets with the bore intentionally off center similar to some side lock endmill holders which are supposed to center your endmill when you tighten the setscrew?

Would it be possible to wire EDM a 3mm ER16 collet off center, and make it 1/8 “ diameter?

Maybe is a stupid question, but what is the run-out in the spindle taper?

Matt@RFR · Apr 3, 2018

Thank you Milland.

Kaszub said:
Thats exactly my point , you got a 100% holder and 100% collet and when you get a shity tool you know what to do......send the shit back to vendor just like your customer would send a bad part right back to you.

But nothing is "100%". On page 2 of the .pdf that Milland posted a link to, it says the DET collet is accurate to 3 micron (.0001") when clamping on a nominal size shank at 4xD. Ok, but what's it like at 15xD? And the literature says that is only the collet. The tool holder will introduce more uncertainty, so will the machine spindle, and the tool itself. Now at 15xD your whiz bang collet setup is potentially at, what, .0005" of runout? More? I'm not poopooing your setup, I'm sure it works very well. But I highly doubt it would help what we do. Even if it did, what's it cost?

If by redoing your holder and a collet 13 times to get it right you calling this consistent? You must be joking.

I'm betting you know that was sarcastic, but whatever. With our ER collets we are generally no more than .0004", probably averaging .0003" or so on longer tools. If we need it better than that, we'll usually screw with it 2-4 times before getting under .0002". Not bad for a $14 collet in a $100 holder, ehh? The fun part is when the tool gets long enough / small enough to be pushed around by the force of a .0001" DTI so it always reads zero runout no matter what.

HuFlungDung said:
When you consider the 'wet noodle' factor of a tool running with that extension ratio, I'd have to wonder if the runout even matters? How stable is the tool tip position once it's started taking chips?

In my experience, the worse the LxD is, the more important runout gets. I don't know the physics for sure, 'taint that smart, but it seems to me that with zero runout, the tool will deflect, but the deflection will be consistent. Add runout to that deflection and things get out of control quickly since the tool has less rigidity to fight it. I tend to think about an unsupported bar out the back of a lathe headstock. Everything is cool until that fucker gets a little runout to it...

Fal Grunt · Apr 4, 2018

Maybe I am too old fashioned, or too practical, but I wouldn't give your run out a second thought.

I would be more concerned about feeds and speeds, the resulting finish, the resulting error and how to correct those. I have more run out just on the collet taper. So it is a game I play regularly. I did a job recently with a .062" endmill that was 10x, I went through several holders and collets and finally got a setup with .0006" at the tool tip. I was thrilled. I had far more effect with my speeds and feeds than the run out did. I took a couple great videos of the tool whipping and flexing for those that say carbide doesn't flex :eek:

Extended length endmill runout question

Aluminum

Diamond

Hot Rolled

Titanium

Diamond

Diamond

Stainless

Hot Rolled

Titanium

Aluminum

Hot Rolled

Titanium

Hot Rolled

Diamond

Diamond

Diamond

Hot Rolled

Hot Rolled

Titanium

Titanium

Similar threads