Collets for End Mills

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Harry.

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I was wondering if there is a reason for using ER collets with end mills? Does it reduces runout because it has more contact points?
 

goldstar31

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I was wondering if there is a reason for using ER collets with end mills? Does it reduces runout because it has more contact points?
Nope! If you use an ER collet tp hold and end mill, you will most likely reach a state where the endmill will pull out and probably ruin your work. What you probably need is something like a proper collet chuck such as a Clarkson one which will also provide further security having a threaded end to lock things down tight.
Opinions may differ about what sort of collet and taper and a lot of other considerations but that is the way that I'd go and I do go with a very basic mill drill- out of China.



Incidentally, Aldi Stores is selling digital callipers for £7.99. Not bad except that they tend to use up batteries very quickly. Again,they can be cut and drilled and used for measuring tools on lathes and mills.

Methinks that you could do with a few classic books rather than either plain guessing or accessing U Tubes where the provenance of the writer is often less than the exuberance of their verbosity.
 

tornitore45

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I know of three ways to hold an end mill.
The Weldon end mill holder with the side screw. The screw guarantees drive without slippage and positive detent to keep from pulling out.
Good for heavy hogging

The R8 or MT ,or whatever your spindle has, COLLET. Like all collets they works by friction. Properly maintained and torqued, one must do something wrong to have the tool pull out. I like them for heavy work because they do not stick out much off the spindle.

ER type are super practical when one has to change tool size, drill and ream or spot drill, drill, chanfer and tap or any case of many tool for light cutting.
I prefer them for every operation except roughing out or when I know I wont have to change size for some time.

There are consideration of run out and balance but in home shop, supplied with the cheapest stuff is a moot point.
 

goldstar31

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We are both guessing. It is really time that the poster informs all and sundry what he possesses.Secondly, how big is his wallet/pocket book .
Over to Harry, I suppose


Norman
 

BobsModels

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About 8 years ago I spruced up my Clausing 8530 with a Servo 140, a 3 axis Shooting Star DRO, a new 3ph motor with a VFD, and a ER25 Collet system. The first ER set I purchased was from a commercial supplier claiming excellent runout, the set was from China. It was a real looser. Sold it on ebay and got my money almost back. As usual I knew I should have paid up front. I then purchased a ETM set for about 3x the cost. They are dead nuts on and indicate as good as the spindle for all practical purposes. I have never had a cutter pull out of course it is a small mill and I do not take monster cuts. I think if you get a good set you will be pleased. One issue is even though the set was sold as an inch set the collets were all metric. I did find a supplier of inch sizes that has good quality. I got some common sizes from them, only sent one back as bad and it was replaced. The reason for the common sizes 3/16, 1/4, 5/16, 3/8, 1/2 was it made using some of my tooling easier to load in.

Bob
 

tornitore45

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If one has a 20,000 RPM spindle and uses 0.032 end mills then a run out of even 0.001" is going to shake and break the tool.
On a larger end mill a little run out means that one flute may be loaded with 0.005" and the opposite flute is loaded 0.004". Some people would scream in horror, some would just slow down a bit and get the job done.
 

goldstar31

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If one has a 20,000 RPM spindle and uses 0.032 end mills then a run out of even 0.001" is going to shake and break the tool.
On a larger end mill a little run out means that one flute may be loaded with 0.005" and the opposite flute is loaded 0.004". Some people would scream in horror, some would just slow down a bit and get the job done.
If 'If's and an's were pots and pans, there would be no room for tinkers'
I've been in this game- and it is a game for nigh on 80+ years and have never found need of 20, 000 RPM.
It's a hobby- end of story?
 

tornitore45

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Goldstar31 wrote
80+ years and have never found need of 20, 000 RPM.
The OP was concerned about run out.
My last post was a way of saying the same thing. In a home shop, a collet run out is not much concern on an end mill.
On a lathe is another story, but that is why the 4 jaws chuck lives almost permanently on the lathe spindle.
 

BaronJ

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Hi Guys,

Interesting thread ! I always thought that ER collets were designed for tool holding !

One thing that I can say is that the Chinese quality control can be very poor.
I have some pictures of some very cheap collets that I bought, if I can find them, which show the lack of care taken with their manufacture. Actually once the collets are properly fettled they are actually fine. After properly cleaning they have around 1/10th thou run out. It was investigating a poor run out on a couple that led me to discover this.

When I find the pictures I will post them.
26-06-2019-Collets-01.JPG
26-06-2019-Collets-02.JPG
26-06-2019-Collets-03.JPG
26-06-2019-Collets-04.JPG
 
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Bazzer

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If 'If's and an's were pots and pans, there would be no room for tinkers'
I've been in this game- and it is a game for nigh on 80+ years and have never found need of 20, 000 RPM.
It's a hobby- end of story?
Goldie

20,000 rpm might be fast but could just as easy to be dead slow depends on what part of the hobby you are involved with, I admit I don't get the 50,000 rpm Jager spindle out that often but it is there when needed.
 

BaronJ

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Hi Bazzer,

I must confess I'm curious as to what you would do with 20K spindles and why that kind of speed is needed !
 

Bazzer

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Hi Bazzer,

I must confess I'm curious as to what you would do with 20K spindles and why that kind of speed is needed !
Hello Baron

I do a lot of model parts from G10 and carbon fibre sheet, the 1.5mm PCB cutters really like plus 20,000 rpm, so I have 3000 on the mill for metal etc. with the option to hold the 50,000 rpm Jager, then 24,000 on the gantry router with the option to mount the Jager in that as well.

Going to do crankcase parts this year and 3D machining into the tight corners with tiny little bits will need high RPM, if you don't have the RPM you have to slow the feeds down. Biggest programme I have run was 1.4 million lines of code on a pattern, from memory that one was running at 16,000.

Regards

Barrie
 

BaronJ

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Hi Barrie,

Thankyou for your reply !
Machining Glass and Carbon fibre materials never occurred to me :(
 

Dalee

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Hi,

There are a number of different tool holding systems for mill spindles these days. Which one is best? I have personal experience in using all of them but the Clarkson. Because it's very difficult to find in the US.

No system is perfect, there are downsides to everything.
R8s need accurately made tool shanks. And can slip if you don't pay attention when tightening them.
ERs have a relatively large grip range. Which can allow tools to fall free if you ain't careful. Swapping collets can be a pain in the backside. It's easy to ruin a nut if you don't get that collet groove in the nut correctly. And collets are known to break after using them a while.
Morse Tapers are hard to release. And come in limited sizes.
Weldon holders don't do endmill shanks under 1/4" well or solid carbide cutters at all. And despite the hype, they allow slipping of tools as easily as R8s do if you don't really torque that single setscrew down hard. And have you ever tried to drill out a stripped out hardened socket setscrew holding a HSS endmill?
And Clarkson tooling is an ecosystem and not easy to find in many parts of the world. And it's very expensive to buy compared to the rest.

The advantages of different systems might be.
R8s are cheap and common to get. And are good enough for 99.999% of all milling operations we get into as home gamers.
ERs offer expanded gripping ranges. So one set of collets can grip drills and either metric or imperial shank endmills. And despite being designed to be used only as tool holding collets, many here have pressed them into to work holding also. Perhaps not ideal, but when egg money for new toys is tight, it works.
I see little reason to go for Morse Taper holders in a mill. But they can grip a tool shank well enough in light table top machines. They seem a bit iffy in heavier machines though.
Weldon holders excel at large shank tooling. You need to hold a 1" or bigger shank endmill? Weldons are it.
Clarskson has great tool holding and pretty good accuracy for runout. And certainly give the owner bragging rights.
You want the best? Get shrink fit tool holders. Not cheap and not easy to use at home. It's really meant for larger commercial shop use. But near perfect runout and superior tool holding under the most demanding conditions. It currently don't get better.

For most of us home guys, R8 and ER collets may well be the best fit. Cheap and easy find and buy, they are perhaps all we need. If you are fitting out a new mill at home, R8 is perhaps the default spindle these days. But ER collet adapters are readily available. And not overly expensive when purchased as cheap, cheerful Chinese tooling. While there is a QC risk, I think at the price point is worth it. And a set of ERs can be used to hold tooling and work and shared between a mill and lathe to do double duty. I have both R8 and ER in my home shop and use either depending on my mood or needs. Though I do not use ER collets for work holding, I use 5C for that.
 

comstock-friend

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I have a manual Bridgeport J head, R8 spindle, and Index 55 with native B&S #9 and R8 recently ground into it (by Wells-Index); it now holds both, and a Tormach PCNC 1100. Thus I use R8/Weldon, R8 collets and the Tormach TTS system with several ER systems. These work in all three mills, although a TTS master collet (3/4" R8) is usually in all the spindles with the TTS holders shared. Depending on the tool, they could be in any of the holding systems, although odd drill sizes are limited to conventional drill chucks or the ER holders. I have a few Chinese ER collets but the full sets are Maritool made in USA. Similar to what I ran at the local Junior College running a Haas VF-3. The modern CNC machine shop use a lot of the ER collet holders. Careful set up has eliminated most (but not all) pull outs. Spindle RPM is about 2000 for the manual machines and 5500 max for the CNC Tormach.

John
 

Mechanicboy

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In my milling machine, im using SC25.4 collets to hold the milling tools. It hold the tool very precise and firmly. :)
 

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