Using end mills in collets

Patrice Lemée

Patrice Lemée

Joined
Aug 13, 2002
Messages
5,703
I've read that you should use endmills in a endmill holder, not collets. Supposedly they can “unscrew” themselves while cutting. First time I've heard of this. :confused:
Is it true for all size endmills, size of the mill, depth of cut, speed etc...?
I only have a small round column mill and never had anything like that happen yet (I think) but I want to make sure it doesn't.

Any help would be greatly appreciated.
 
You can use endmills in collets or dedicated holders. If using holders, make sure the endmill has a flat on one side of the shank for the set screw. Never use endmills without the notch in holders, always use collets for those. Endmills can't "unscrew" a collet if they were set up properly.

There are other types of high precision holders like shrink fit etc but they're only for high precision, production applications and are expensive.

Never use an endmill in a drill chuck unless you're only moving along the Z axis and even then it's not the best plan.
 
I'm only experienced in using R8 collets with endmills and slotting saws, but I thought that it was the correct way. I've seen endmill holders for other spindle types, but never used them.

Maybe that is a production mentality? Like when a cutter has to perform thousands of cuts without adjustment or interruption, it will work loose from a collet?

Not that I know what I'm talking about. I hope someone who does comes along. Nathan?
 
If you get to hogging real hard in an R8 collet it can and does happen.
But like Kevin said, not if it was set up properly.

With proper torque on the drawbar, it's unlikely, but I've done it twice in the last year.

My homemade power drawbar doesn't have enough balls to torque down enough on some sizes, so I bought a few ER collet holders and solved the problem.

Even the inexpensive ones seem to run truer than the couple of dedicated endmill holders that I have.
Plus you don't have to buy endmills with the Weldon flats.
 
Collets are used to hold endmills in production all the time and are frequently considered the best way. These are commonly ER collets in CAT 40 tool holders and I have never heard of them unscrewing. You'll usually get better accuracy, finish and tool life with a collet, plus they're better balanced than setscrew holders, so they're better for your spindle at high RPM.

Now an R8 collet may be a different story, I don't know, I've never used R8 in production.

Edit to add:

You can get into some real trouble using a drill chuck with an endmill. I've seen it, and it ain't pretty.
 
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matter of fact i did it jsut last night but its cause i was hoging too much (flattening a block of guard stock and i was getting rammy)

had i tightened the draw bar more it might have been fine but reallly i should have jsut not been hogging as much and watch my speeds and feeds

my setup is a mini mill R8 tooling and a 4 flute 1/2 inch endmill :) seei im doing it all wrong
 
Thanks guys. I do use R8 collets. But no production and nothing that could be considered hogging. I do tighten the drawbar by hand and from now on I'll make sure I don't leave it too loose as it sometimes happens when I rush things.
Oh and I did try the drill chuck approach when I first got the mill. Not a good idea at all.:eek::(

Thanks again for your help.
 
Used R8's for years in production work with no problems at all. Like Nathan said that is what they are set up for. Now if you work in a production plant were they set up your tools with standard offsets that are pre-entered into your machine an R8 is not as easy to set up. So for time savings the endmill holders work better. For what the average knife maker does there should be zero problems. Unless you are like ButcherBlock and use an endmill too large for the machine, then it's just a power and rigidity problem not a collet problem
 
the things that i have made that mill do woudl kill most traind mill workers and maybe even a few that are not trained
 
Using collets with smaller endmills is not really a problem but in larger it is a little more of an issue. On a manual type machine you should never have much of an issue either way. The biggest issue with collets is most of the time, especially in production, you want to push everything to the nuts, time is money, and collects are nothing more then a type of spring and are more designed for straight loads. When you are milling you are creating side loads on the endmill and it is very possible you are actually flexing that spring just a bit causing runout witch hinders holding tolerance and tool wear. I don't recommend collets with end mills, but yes I do it myself quiet a bit, but you should not have any issues for your needs. End mill holders are just better at side loads but not as good at plunging. The hydraulic and shrinkfit are the best but as said earlier very $$$$$$$$$$$.

Travis,
 
I only use ER collets in SK40 taper holders, I don't have any experience with the direct colets and drawbars.

Even in my small Taiwan mill with a Nr. 2 Taper and drawbar I use an ER25 holder and collets.

One thing I do is clean the collets and collet nut in an ultrasonic cleaner whenever I insert a new cutter or change collets. Gets out all the little chips, oil and whatever else dont belong there!
 
I used R8 collets in an old Bridgeport J head for a year when I worked as a fabricator, no issues.

-Page
 
Kevin Wilkins said:
One thing I do is clean the collets and collet nut in an ultrasonic cleaner whenever I insert a new cutter or change collets. Gets out all the little chips, oil and whatever else dont belong there!
Click to expand...

yup

The important thing about collets is to keep everything clean and follow the manufacturers recommended torques. The saying about a collet tool holder with runout is "throw away the tool holder, the nut, the collet, and the last guy who used it". But when properly maintained and torqued, a collet tool holder holds a tool solidly enough that cutter damage will result before the tool moves, and runout is held within a few tenths.

...I flog some ER40 collet holders in 25 HP cuts every freaken day...
 
i ran the piece that i mangled lat night today with a flycutter and more easy feeds and all was jsut fine

i also made sure to Tq the draw bar better (no i still say im way over spec for the mill but i will never be held ba ck by tools if i can help it )

man i wish i had a bridge port J head but i ll keep making due with what i got for now
 
butcher_block said:
i ran the piece that i mangled lat night today with a flycutter and more easy feeds and all was jsut fine

i also made sure to Tq the draw bar better (no i still say im way over spec for the mill but i will never be held ba ck by tools if i can help it )

man i wish i had a bridge port J head but i ll keep making due with what i got for now
Click to expand...

I have a J head, but I would almost trade that for the availability of machine tools that you have in your area. You should be able to find J head fairly cheap right now!

On another note: I avoid holding endmills in collets whenever I can...For some reason, no manner of effort is going to convince me that 3 pieces of steel ( Toolholder, collet and collet nut) is going to be more solid, concentric, rigid than one piece of steel from a reputable tool manufacturer. When all else fails, kiss never fails :)
 
Patrice, when you get a chance invest in a set of quick changes. I got a set like this one and love it. Takes way less time to change tools of different shank sizes. I have had mine for 3 years with no issues. Very seldom remove the holder and have to monkey with the draw bar bolt. I also have a couple drill chucks with straight shafts that fit in one of the collets for use when I use a drill that won't fit a collet.

I don't do production, but they have worked for everything I have wanted to do.


http://cgi.ebay.com/25-PC-SET-ER40-...8602?pt=BI_Tool_Work_Holding&hash=item1e61c71
 
bhyde said:
On another note: I avoid holding endmills in collets whenever I can...For some reason, no manner of effort is going to convince me that 3 pieces of steel ( Toolholder, collet and collet nut) is going to be more solid, concentric, rigid than one piece of steel from a reputable tool manufacturer. When all else fails, kiss never fails :)
Click to expand...

Yes, I think this is largely true. A one piece holder, a setscrew and a weldon shank are about as stout as you're going to get.
 
Jim, that is a very good idea. I have a round column mill so I usually don't use the drill chuck since it is too long compared to the R8 collets. With the holder I could use both I think. :thumbup:
 
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