# R8 collet or end mill holder?



## tcweb (Apr 6, 2020)

A lot of older machinists HATE putting end mills in R8 collets, as they can slip and the Z can change during a cut.  But I still know people who do it.
What is the general concensus: end mill holders or collets?  Any restrictions, such as "HSS only"?  (carbide may be a problem for end mill holders, et)


-Tom


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## mikey (Apr 6, 2020)

I vote for an ER chuck with a good nut and good collets. Better control of run out and has better vibration damping. The better ER setups can get run out down into the very low tenths, which improves accuracy, finishes and extends tool life.


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## Alexander McGilton (Apr 6, 2020)

Finding a consensus  of opinion would be hard to find on this topic. The rule of thumb I was told is collets for finishing operations and end mill holders for roughing. That way you optimism the benefits of each and mitigate the draw backs of each. In roughing your feed per tooth should be substantial greater than runout, and with every tooth having a comparable chip, runout is less of an issue. In finishing your cutting forces should already be small enough that you never worry about slippage. In a production setting in where they blur the lines between roughing and finishing, to save an operating and or time, its worth while to spend on the high tech options to get the best of either option. thats where Hydraulic holders and endmill chucks come in. Well out of budget for the hobbyist.    

At my work the two mills are equip for such a manner of roughing to finishing, though using ER collets as they don't make NT 40 draw bar collets collets. 
At home I use the R8 draw bar collets as it preserve Z height. Endmill holders, or a R8 to ER adapter will consume an inch or two. Also a lesser reason is that there is an organic motion to changing draw bar collets that is missing in using ER collets. I know that this is meaningless as far as productivity or quality of work produced, though it means a lot in a shop that is meant for enjoyment over productivity. Side not ER collets are a pain to use if there is no spindle lock or it can't resist enough torque and you need to double wrench them. The Bridgeport at my technical school had this situation.


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## ErichKeane (Apr 6, 2020)

ER Chuck usually means giving up some of your Z travel, right?  For some mills, that is a big sacrifice.  FWIW, I use R8 for all of my endmills and have never had the mill slip during a cut.  Additionally, my runout is darn-near-zero.


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## ttabbal (Apr 6, 2020)

I have ER40 and R8 on the Bridgeport. I have been using R8 more lately, but I go back and forth. Unless the end mill has a flat, I don't see how a holder is better than a collet. If it does, the set screw probably does hold it better in tough situations. That said, I have never had one slip. I've used 3/4 and 3/8 roughers and finish tools without issue. Carbide and HSS. I know it can happen, and if it happens to me I'll probably change my tune, but so far I'm happy with collets. I also don't push my machines really hard. Nothing like what a production shop would do. 

My ER40 chuck does take about 2" of Z. It isn't a problem for me, but I can see how it would be a deal breaker on smaller machines. It's amazing what you can do with a couple inches of Z.


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## Alexander McGilton (Apr 6, 2020)

Anyone use substantially reduced shank or Hi helix end mills? Those are a prone to tool slippage if improperly used.


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## Mitch Alsup (Apr 6, 2020)

ttabbal said:


> I have ER40 and R8 on the Bridgeport. I have been using R8 more lately, but I go back and forth. <snip>
> 
> My ER40 chuck does take about 2" of Z.



I have been using ER-40 holder in my G0730 for the past couple of years. It holds the end mills (and other things) nice and tight.

However, I have recently been looking for an R8 collet set to gain that 2" back, especially since I put my vise (semi-permanently on my 10" rotary table.)


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## Bob Korves (Apr 6, 2020)

I use end mill holders for anything at danger of pulling out, mostly heavier work with larger cutters, and R8 collets for ordinary work.  No ER stuff, so far...


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## Janderso (Apr 6, 2020)

My full size knee mill has a NT30 taper spindle. The mill came with the basic sizes of end mill holders.
I bought a quality ER40 chuck and collets. I have only had an end mill slip one time. I forgot to tighten it and there was an oily residue on the collett.
ER40 has been a good fit for me.


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## Tozguy (Apr 6, 2020)

For my milling on a lathe the extra reach of an end mill holder is welcome.


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## tjb (Apr 6, 2020)

mikey said:


> I vote for an ER chuck with a good nut and good collets. Better control of run out and has better vibration damping. The better ER setups can get run out down into the very low tenths, which improves accuracy, finishes and extends tool life.


I agree with Mike!  He knows what he's talking about.


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## jbobb1 (Apr 6, 2020)

Used collets for many years on some large stuff.  Of course the endmill sizes we used were mostly 3/4" and below. Don't recall one ever slipping.


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## mikey (Apr 6, 2020)

Alexander McGilton said:


> Anyone use substantially reduced shank or Hi helix end mills? Those are a prone to tool slippage if improperly used.



I use High Helix roughers and end mills all the time with aluminum but I just use little guys in the 3/8" range. Never had one pull out of an ER collet but I imagine that a big one might.


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## BGHansen (Apr 6, 2020)

I have all three, but generally go with R8 collets.  My Jet JVM-830 draw bar hex end is at eye level, so easy to get to.  I only use R8 collets on that mill.  My Bridgeport draw bar hex is at 6 1/2 - 7 feet up.  I pretty much leave an ER32 collet chuck on that mill.  Pretty handy to pop the mill into back gear, apply the spindle brake and change the collet/tooling at chest level. 

I have R8 end mill holders in the common sizes from 1/8" - 3/4" but have never used them.

Bruce


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## epanzella (Apr 6, 2020)

I was told by a guy I trust to use  collets  up to 3/4 and to use an end mill holder for 3/4 and above. That's what I do and never had a problem.


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## theperfessor (Apr 6, 2020)

I have a 10 x 54 Enco knee mill and use R8 collets for end mills almost exclusively except when milling copper or other gummy materials. I use setscrew type holders for T slot cutters and keyseat cutters.

Edit to add: I never use end mills over 3/4", I have insert type end mills with their own R8 shanks for anything 1" or over.


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## mmcmdl (Apr 7, 2020)

I use collets with the smaller end mills 3/4s and below , then step up to the EM holders for the bigger mills . Ive never had an end mill slip from either and I've pushed the envelope over the years . I do recall an apprentice scrapped a large Worthington Pump shaft on a Devlieg using an end mill holder though . He did not pull the end mill down to the bottom of the flat and it pulled out while machining a keyway .


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## Mike_Mac (Apr 7, 2020)

Having just bought and had delivered a secondhand Bridgeport which came with a selection of R8 collets and R8 Clarkson Autolock chucks. I have yet to try out either as yet, as I have been cleaning up the machine and checking it over before I get around to using it. I have found the above information interesting reading. Seeing the quote "ER chuck with a good nut and good collets". Can anybody recommend a make and type of ER collets at a  reasonable price to buy for a hobbyist?


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## projectnut (Apr 7, 2020)

Bob Korves said:


> I use end mill holders for anything at danger of pulling out, mostly heavier work with larger cutters, and R8 collets for ordinary work.  No ER stuff, so far...



Same here.  As mentioned you're going to loose some Z height with an end mill holder.  You'll also have to use Weldon style end mills (flats ground on the side) to retain the end mill in the holder.  






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When working within the parameters of the machine, using sharp end mills, and tightening the drawbar to the proper torque (40-45 ft. lbs.) you shouldn't have problems with the end mills pulling down, or spinning in the collet.

If the end mill, shell mill, etc. is too large for the machine, the drawbar isn't properly torqued, or the feed or depth of cut are too aggressive it really doesn't matter if you  secure the tool in in a collet or tool holder.  Either will spin in the spindle.


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## theperfessor (Apr 7, 2020)

We use a lot of carbide 1/2" end mills in our CNC mill and manual knee mill.  Four flute roughers and four flute finishing/conventional end mills. They get used in ER32 collets in the CNC and R8 in the knee mill. They have no flats for a setscrew! Nor do any of the other four flute carbide end mills in any diameter I keep in stock. Hard to use an endmill holder when there is no flat on the endmill...

I can only assume that the carbide end mills I use have no flat because (a) the slight extra expense of grinding a flat on a piece of carbide, and (b) the imbalance a flat might cause when running in a high speed spindle. (Shrink fit holders, no screws or nuts to cause imbalance.)


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## ttabbal (Apr 7, 2020)

Mike_Mac said:


> Having just bought and had delivered a secondhand Bridgeport which came with a selection of R8 collets and R8 Clarkson Autolock chucks. I have yet to try out either as yet, as I have been cleaning up the machine and checking it over before I get around to using it. I have found the above information interesting reading. Seeing the quote "ER chuck with a good nut and good collets". Can anybody recommend a make and type of ER collets at a  reasonable price to buy for a hobbyist?




For ER40 collets, Techniks has been great for me and others. More expensive than some, but less than others. 

My R8-ER40 chuck is from Shars. It does add a couple tenths of runout over the spindle, but compared to the R8 collets I have holding the same ground bar and an end mill shows the same TIR. I only have one to examine, so I can't say if I got lucky or if it's normal from them. 

The chuck does take up Z space, and does add stick out. It's possible that rigidity is negatively effected. I haven't seen any issues with it, but it's fair to say.


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## tcweb (Apr 7, 2020)

BGHansen said:


> I have R8 end mill holders in the common sizes from 1/8" - 3/4" but have never used them.
> 
> Bruce



Bruce, want to sell them?


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## mikey (Apr 7, 2020)

Mike_Mac said:


> Seeing the quote "ER chuck with a good nut and good collets". Can anybody recommend a make and type of ER collets at a  reasonable price to buy for a hobbyist?



Mike, I suggest you take a look at the Glacern line of ER chucks. They are reasonably priced and are accurate. To be sure, there are others but they cost more for not a lot of gain. I prefer and use an ETM ER40 chuck, nut and collets but I also use a Tormach ER32 and ER20 chucks, too. The size of ER chuck depends on the size of the end mills you use and the need for access. I use the ER20 when I need to get close to the part and the larger chucks would just get in the way.

The ER nut you use makes a difference in accuracy. The best solid nuts are made by ETM, Rego-Fix, Techniks and Lyndex. There are also nuts with bearings in them to help cinch down tighter and if you go that route, get a Rego-Fix. 

ER collets range from cheap to really expensive. The best bang for the buck is Techniks, no question. Made in Taiwan, these things have a guaranteed run out of 0.0002" or less. In actual use, it is usually less. Lyndex is okay, Rego-Fix is about the best you can buy and ETM is also top of the line. 

Keep in mind that each ER chuck size requires a chuck, nut and collet set. If I had to choose only one size, it would be an ER32. It is small enough to access most things and big and solid enough to grab most end mills solidly. I try to keep my end mill size to 1/2" and below. I can do that because I'm a hobby guy and don't have to make money at this.

So, if I was a hobby guy on a budget but wanted a solid ER set up, I would buy a Glacern chuck, a Rego-Fix nut and Techniks collets. These items will maximize accuracy at a reasonable cost.


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## BGHansen (Apr 7, 2020)

tcweb said:


> Bruce, want to sell them?


Thanks for the offer, but I'll hang on to them. I bought most of them used from eBay seller "stm_surplus 2". They can be had for about $10 each if you're patient.

Bruce


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## Mike_Mac (Apr 8, 2020)

Thanks guys for your feedback on my question regarding ER collets to fit in the Bridgeport. I'll check out your suggestions. Mike


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## Lo-Fi (Apr 8, 2020)

My ER32 set are my most commonly used tools on my bridgeport. I don't even bother with the Jacobs chuck when drilling anymore! If I need maximum rigidity in a milling op, I'll switch to my R8 collets or tools with their own shank.


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## burdickjp (Apr 8, 2020)

I run TTS ER16 and ER32 collet chucks.


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