# Er32 Vs Dedicated Endmil Holders



## petertha (Jan 4, 2017)

I've got some nice dedicated R8 endmill holders in typical N-Am hole sizes, 0.375, 0.500. I rarely use the 0.250" or larger ones so kind of regretting buying a set way back when without knowing better. These have the lateral set screw to retain EM's against the anti-rotation notch ground in the shank. (Is that called Weldon shank?). I need to get some smallish metric EM's & typically their shanks are nominally same diameter as cutter vs. so-called 'standardized' NAm shank.

This got me thinking. My N-Am holders were not exactly cheap. I could probably justify buying say an ER32 holder for my R8 mill & collets and be set up for pretty much any EM, imperial or metric in this range. Is there a fundamental disadvantage to using ER collet for this purpose? For example there must have been a reason for integrating the set screw in this style. So is ER collet more prone to slipping in the collet? Coincidentally I bought a 0.5" carbide EM on ebay that had no ground flat so ended up grinding one in order to use. They said CNC so presumably some of those machines use spring collets? For reference I would say probably 0.5" would be the biggest size I'd consider running in ER.

What are good ER brands runout/quality wise?
I'm guessing tool change would be about the same effort - unscrew the ER cap vs. loosen the set screw?


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## Bob Korves (Jan 4, 2017)

The ER collet chucks and the Weldon style end mill holders both use up machine head room vs. a collet in the spindle.  The Weldon holders are very strong at holding the end mills, the ER collets less so, but you really have to gronk down on them to hold things tight, or they can slip.  Check the specs. for ER collet torque.  End mills can slip and suck into the work if held in a R8 collet, but many or most of us do that anyway.  I try to only use end mills in R8 collets on reasonably light work, and always tighten them down quite snug.  I have a full set of Weldon end mill holders up to 1-1/4", not likely to use that size any time soon on my Millrite mill.

I am by no means an ER collet expert, and have actually never used one, but I think from my reading that buying a set by metric sizes makes the most sense, because that is what they were designed for, to fill all the sizes within their range using the minimum number of collets and without much overlap.  The Imperial sized ER collets are more haphazardly sized and I think many of them are just relabeled metric collets.  ER gurus, do I have that correct?


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## Bob Korves (Jan 4, 2017)

I have seen quite a few machinists make their own ER collet chucks to fit their various machines directly, buying just the nut and the collets.  You definitely would need to be able to produce precision work to do that successfully, but it does help to save money and to eliminate stacked tolerances.


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## petertha (Jan 4, 2017)

Hmm.. you've raised some good points there. To numerically quantify ER gronk, I found this link. I now think by looking at collet size range that ER25 probably better suites me.  But even for that they recommend 77 ft-lbs. That's a fair tug.
http://www.techniksusa.com/metal/torque_chart.htm

Another link about importance of collet cleanliness & holding power.
http://blog.cnccookbook.com/2016/10/11/getting-the-best-performance-from-er-collet-chucks/


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## mksj (Jan 4, 2017)

In theory Bob is correct that a metric set of ER collets are suppose to have enough clamping range to fit both metric and imperial. In practice, it seems to depend on the quality of the set and I have had some issues where they where suppose to cover a smaller range and didn't clamp down well. You are correct that the imperial sets almost never come as a complete set, vs. metric which usually comes in 1 mm increments. I went with a 1/32" inch set and had to back fill a few holes that they left out, this gives you a 0.0031 clamping differential between collets as opposed to .0394 for a 1 mm set. Since my indicators use both 10 mm and 12 mm shafts, I have metric collets for these specific diameters. These work much better than clamping down a 1/2" collet to 12mm. 

On holding power, I have never had an end mill suck out of an ER holder, it clamps along the whole shaft of the end mill. I have had some apparent twist of the collet in the holder using a 3/4" end mill in an ER-32 collet system. This was in the early days when I was not aware of cleaning off the oil on the collets/holder, and I also use a bearing nut now which allows you to torque the collet in with less force. Beware, that the ER bearing nut does not work well when you compress a collet to its theoretical limit, I had the bearing go when a clamped my 1/2" ER collet down to 12mm.  The ER collets seem to be more precise then my R-8 collets, but we are talking a few 1/10,000".  You loose  a little stack height using an ER system, I have never found it a problem, and can always use an R-8 collet if I have something very tall on the table. When it comes down to it, if you are only using the collets for end mills, you would be fine with an abbreviated set, most end mill shanks come in fixed dimensions, usually by 1/8". Since I also use the ER system on the lathe, I have invested in a 1/32" set of ER-40 because of the size range. I primarily use an ER-32 size on the mill, except for 7/8" and 1" shank end mills, and other large diameter shank tooling.


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## sanddan (Jan 5, 2017)

I've been using an ER32 set on my mill since I got it. I had a 1/2" EM slip out into the work recently. Even cranking down on the torque wouldn't get it not to slip. I ended up using a reg R8 collet for that job. Usually it hasn't been an issue.


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## mikey (Jan 5, 2017)

I use an ER-32 chuck on the mill and an ER-40 chuck on the lathe. I've found the ER system to be an excellent tool holding system and have never had one slip. If you use collets of good quality, they are more accurate and secure than the R8 collets because they grab along the entire length of the collet instead of just the front 1/2" or so like an R8 does. If you need the best accuracy, a good nut made from hardened/tempered steel is recommended; I have an ETM and a Rego-Fix hardened nut for both chucks and they are vastly better than the cheap Chinese nuts out there, including the bearing-type nuts that I also have. 

I also found that the quality of the collet makes a big difference. When I tested my ER-40 chuck on the lathe I got about 0.0007" of run out with cheap Chinese collets. My ETM collets got the run out down to 0.0002" so if accuracy and gripping power are of prime importance then having good quality collets and the right nut is important. You do need to torque the nuts down properly on an ER chuck. This is to prevent slipping but also because the accuracy ratings are measured at the proper torque.

I have an Imperial set of both ER-32 and ER-40 collets in 1/32" increments and, like all collets, they hold best at their stated size. While they will squeeze down to accommodate odd sizes they are not as accurate when doing so. This is fine for work holding in the lathe but for milling cutters you are better off getting the right size collet for that tool shank. I have metric ER collets for metric sized tooling and it does make a difference in grabbing power when the collet fits the tool. 

If I were to buy an ER chuck again for use in a hobby-class mill, I would buy a Glacern ER-25/R8 chuck and a set of collets in 1/8" increments from Techniks, Lyndex, ETM or Crawford. This would hold most Imperial tooling that smaller mills can handle. I would buy metric collets as needed from the same makers to hold whatever metric tooling I have.


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## sanddan (Jan 5, 2017)

I have the Glacern ER32-R8 chuck and their 1/32" collet set. I have several Glacern products and I think they are very well made.


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## T Bredehoft (Jan 5, 2017)

I have a set of 1/16 R8 collets for my mill, and a couple of Weldon R8 holders, 3/16 and 3/8. I'd use, if I had more of same plus 1/4, its handy to have end mills set up in the Weldon holders of various sizes. If changing from a drill chuck to an end mill, the Weldons require less head movement. 
Both have their use.


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## petertha (Jan 5, 2017)

I bought a Glacern keyless drill chuck for my lathe a while back when it came on sale. I agree, very nice quality & I was happy. I'm 99% sure they source from a 'good' Taiwan supplier because it looks conspicuously identical to another label I've seen sans label. Unfortunately with $U$C FX, their crazy shipping costs & obligatory dinger fees (outside their control), its coming out quite a bit more expensive landed. I can get a Lyndex/Japan locally for a competitive price. If its anything like the Lyndex mill arbor I have, very nice quality. Run-out was inside of what I could measure.

Speaking of, any feedback on Lyndex ER collets? They are coming out less than Techniks but I need to reference specs. I'm not quite as game to try Chinese bargain brand, sometimes you get lucky, sometimes not. Guess it depends on what the end use is but I read a story about a guy who figured he marred up his good toolholder with inferior out of spec collets that weren't fitting properly by the time he figured out what was going on.


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## mikey (Jan 5, 2017)

Both Lyndex and Techniks are good. The former is made in Japan and has 0.0001" runout. The latter is made in Taiwan with 0.0002" runout specs. I have ER-32 collets from both and both are very accurate. I also have an ER-40 set of ETM (Iscar) collets that are really good. 

I run a diamond file over the outside of every slot on an ER collet when I get them to get rid of the burrs present on any new collet. I agree that the potential for damage to the internal taper of the chuck is possible so I use a file. 

eBay is your friend if you're patient.


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## brino (Jan 5, 2017)

@Uglydog posted a great Tormach document about preventing collet slip here:
http://www.hobby-machinist.com/threads/is-there-a-definitive-article-on-collets.36227/#post-308271

-brino


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## Tony Wells (Jan 5, 2017)

I didn't see it mentioned, but one thing to note is that the end mill holders will generally give you a little runout on the end mill. Of necessity there is clearance in their ID, and when you tighten the set screw it will push the end mill to the opposite side. It's possible they finish grind those ID's a little off center to comp for it, but I doubt it. I can't recall ever actually putting an indicator on one, but I have noticed some visible "wobble" on some end mills. I suspect it is because of this clearance. So then, obviously the more clearance you have, the more runout you will see. If you use an edge finder and just trust the DRO and dial off a cut, you may get a surprise if you didn't know whether the end mill was running true or not.


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## RJSakowski (Jan 6, 2017)

When considering an ER type tool holder for a mill, there is a distinct advantage in using a Tormach TTS style system.  The Tormach ER tool chucks mount in a 3/4" R8 collet and as the collet is tightened, the ER chuck draws tight to the spindle face, giving a very repeatable tool length.  Like the quick change tool post system for lathes, it allows rapid interchange of tools without a need for re-referencing for tool offset with each tool change.  Should a tool break, a new tool can be mounted and referenced off-line.

I use the TTS system on my Tormach 770 and also adapted it to my old mill/drill.  I use the ER20 collets and am limited to 1/2" tool shanks.  For any larger tooling, I use an R8 collet or R8 end mill holder but due to limited torque on the Tormach, I rarely use end mills larger than 1/2".  

Tormach and several other vendors also supply TTS style collet chucks for ER32 collets.  

There are several disadvantages.  Adding an ER collet chuck to an R8 collet adds an extra layer for runout.  I have had tooling slip in either the collet chuck or the collet chuck slip in the R8 collet.  Generally, these are not issues though.

My collection of collets include multiples of 1/8", 3/16", 1/4", 5/16", 3/8" and 1/2" plus a full set from 1mm through 13mm to accommodate drills and other tooling.   Additionally, I have a TTS boring head, several TTS set screw type end mill holders, and 3 TTS 1/4" three jaw chucks and 3 TTS 1/2" the jaw chucks.


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## Ed ke6bnl (Jan 6, 2017)

RJSakowski said:


> When considering an ER type tool holder for a mill, there is a distinct advantage in using a Tormach TTS style system.  The Tormach ER tool chucks mount in a 3/4" R8 collet and as the collet is tightened, the ER chuck draws tight to the spindle face, giving a very repeatable tool length.  Like the quick change tool post system for lathes, it allows rapid interchange of tools without a need for re-referencing for tool offset with each tool change.  Should a tool break, a new tool can be mounted and referenced off-line.
> 
> I use the TTS system on my Tormach 770 and also adapted it to my old mill/drill.  I use the ER20 collets and am limited to 1/2" tool shanks.  For any larger tooling, I use an R8 collet or R8 end mill holder but due to limited torque on the Tormach, I rarely use end mills larger than 1/2".
> 
> ...


I was not familiar with the TTS to ER 32 system, and already purchased an R8 to ER32 and the price is reasonable 

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