Collet vs. End Mill Holder

nnam said:
So your er holders are r8 adapters, meaning r8 to ERx?

What is your mill native holder type?
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My native spindle is R8. My ER40 chuck is an ETM chuck with an R8 shank. I use the TTS system with a modified R8 collet to hold my ER32 and ER20 chucks.
 
Tozguy said:
mikey, do you have any measurements comparing the accuracy of the end mill holders you used and your ER collets? Did the end mill holders disappoint you in any other way than accuracy? I ask because in my limited experience with entry level Weldon holders and ER collets, the holders are more convenient, less expensive and perfectly adequate for what I do. No end mill ever came loose in the holder. But I might be missing something.

More money would probably get me more accuracy with either type. Of course the ER system is more versatile and has other uses so it would make sense to invest in high quality ER parts.
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Morning, Mike. Yeah, for all of us, tool holder choice is a balance between what is adequate for our purpose and the cost we're willing to pay. I'll give you my rationale for what it's worth.

When I first started playing machinist, I began with a Sherline mill and used end mill holders. The mill was accurate; spindle run out was and still is about a tenth (I have ABEC 3 bearings in there) but the end mill holders ran out a LOT more and I had end mills dropping and digging into the work on occasion. I don't have them anymore so I don't have numbers for you but I remember thinking it was so bad that I jumped to a Beall ER32 chuck as soon as it came on the market. That is when I learned about how big a difference an ER system can make.

My Beall chuck runs out about 0.0001" inside the taper, no joke. This is pretty good for something that screws onto a spindle, and it helps that the spindle itself is accurate. I began using the collets that came with the chuck; these are imports I'm sure, but they are good imports and I noticed I could cut deeper with a better finish than with end mill holders. Here, I'm talking about a 3/8" depth of cut with a 3/8" roughing end mill in aluminum using a mill that weighs maybe 45#. No way could I do that with end mill holders. I noticed that finish end mills also seemed to finish better and lasted longer and that really got my attention. I stumbled onto a white paper from Techniks that pointed out that for every 0.0001" of run out, end mill life declines by 10%. They also pointed out that ER chucks reduce vibration better than any other system I could hope to afford. These two things - tool life and vibration reduction - really made me realize why an ER chuck worked so well on my little mill. It also made it clear that good collets are required so I bought a set of Techniks ER32 collets and ran tests. In my Beall chuck the import collets have about 0.0004" TIR max, if I recall correctly; the Techniks are half that at about 0.0002 or less in that chuck. I also found that the Beall nut is really good but a Rego-Fix nut is better; it actually cut down TIR with the better collets. That sold me on the ER system - more accurate, no slippage, less vibration, improved cutting performance and better tool life. This is all on a little Sherline mill but I didn't forget.

Then my neighbor gave me an RF-31, for free! It came with some import R8 collets and a few import end mill holders. He only used the mill to drill bowling balls and never maintained the mill so the first thing I did was evaluate the spindle. It had something like 0.004-0.006" TIR! Yeah, really bad. I set out to rebuild the spindle and got it down to just under 0.0001" TIR, which I think is pretty good for an import mill. I don't recall the numbers but the run out with the end mill holders, even in an accurate spindle, was pretty bad. The second or third time I used one of those end mill holders the end mill dropped and snapped a Niagara Cutter end mill and that was it; I passed them on to a friend and never looked back. I figured that I had a decent spindle on this mill and I was going to invest in good tooling for it.

I bought a set of Crawford R8 collets. Crawford makes the collets for Royal so they're pretty good, in the range of 0.0002" TIR in my machine. Then I bought an ETM ER40 chuck that came with collets and nut and these run out 0.0001-0.0002" so they are pretty good but the chuck is huge and limited access on some of my projects so I wanted a smaller chuck. Since I already had Techniks ER32 collets, getting a decent ER32 chuck made sense. As I looked over the field, the TTS system came to my attention and to make this novel a bit shorter, I decided to go with that system. I bought their ER32 chuck and later bought the ER20 chuck, too. The TTS chucks are fairly good. Not as accurate as a high end chuck but I can hold 0.0002-0.0003" TIR with a Techniks collet. You have to use their nuts on their chucks, which is a bummer because I think I could get better run out with a better nut but so far this system has worked okay for me.

So, now I run all my non-critical stuff like fly cutters in import R8 collets and more accurate big cutters in my Crawford R8 collets. For all end mills I use an ER chuck. If I am doing heavy work, I try to use the ER40 ETM chuck. For average cuts I use the ER32 and when I do finer detailed work that requires me to get close or if I'm using smaller end mills like 1/4" or smaller cutters, I use the ER20.

That's my story and I'm sticking to it. I put a lot of thought into choosing this system because I won't lie to you, it was expensive, but I'm happy with my choices.
 
rwm said:
I have a lot of double ended mills. I guess I will be using R8 collets on those. Maybe get a holder for my 1/2" and 3/4" single end end mills. Good discussion guys!
Robert
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I use a lot of double ended end mills, too, and they work just fine in all of my ER chucks. If you do go with R8 collets, get good ones. Hardinge makes the best but Crawford and Lyndex are also very good. I don't have experience with any of the other higher end collets, just the import ones that I wouldn't use for precision tools.
 
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mikey said:
Morning, Mike. Yeah, for all of us, tool holder choice is a balance between what is adequate for our purpose and the cost we're willing to pay. I'll give you my rationale for what it's worth.

When I first started playing machinist, I began with a Sherline mill and used end mill holders. The mill was accurate; spindle run out was and still is about a tenth (I have ABEC 3 bearings in there) but the end mill holders ran out a LOT more and I had end mills dropping and digging into the work on occasion. I don't have them anymore so I don't have numbers for you but I remember thinking it was so bad that I jumped to a Beall ER32 chuck as soon as it came on the market. That is when I learned about how big a difference an ER system can make.

My Beall chuck runs out about 0.0001" inside the taper, no joke. This is pretty good for something that screws onto a spindle, and it helps that the spindle itself is accurate. I began using the collets that came with the chuck; these are imports I'm sure, but they are good imports and I noticed I could cut deeper with a better finish than with end mill holders. Here, I'm talking about a 3/8" depth of cut with a 3/8" roughing end mill in aluminum using a mill that weighs maybe 45#. No way could I do that with end mill holders. I noticed that finish end mills also seemed to finish better and lasted longer and that really got my attention. I stumbled onto a white paper from Techniks that pointed out that for every 0.0001" of run out, end mill life declines by 10%. They also pointed out that ER chucks reduce vibration better than any other system I could hope to afford. These two things - tool life and vibration reduction - really made me realize why an ER chuck worked so well on my little mill. It also made it clear that good collets are required so I bought a set of Techniks ER32 collets and ran tests. In my Beall chuck the import collets have about 0.0004" TIR max, if I recall correctly; the Techniks are half that at about 0.0002 or less in that chuck. I also found that the Beall nut is really good but a Rego-Fix nut is better; it actually cut down TIR with the better collets. That sold me on the ER system - more accurate, no slippage, less vibration, improved cutting performance and better tool life. This is all on a little Sherline mill but I didn't forget.

Then my neighbor gave me an RF-31, for free! It came with some import R8 collets and a few import end mill holders. He only used the mill to drill bowling balls and never maintained the mill so the first thing I did was evaluate the spindle. It had something like 0.004-0.006" TIR! Yeah, really bad. I set out to rebuild the spindle and got it down to just under 0.0001" TIR, which I think is pretty good for an import mill. I don't recall the numbers but the run out with the end mill holders, even in an accurate spindle, was pretty bad. The second or third time I used one of those end mill holders the end mill dropped and snapped a Niagara Cutter end mill and that was it; I passed them on to a friend and never looked back. I figured that I had a decent spindle on this mill and I was going to invest in good tooling for it.

I bought a set of Crawford R8 collets. Crawford makes the collets for Royal so they're pretty good, in the range of 0.0002" TIR in my machine. Then I bought an ETM ER40 chuck that came with collets and nut and these run out 0.0001-0.0002" so they are pretty good but the chuck is huge and limited access on some of my projects so I wanted a smaller chuck. Since I already had Techniks ER32 collets, getting a decent ER32 chuck made sense. As I looked over the field, the TTS system came to my attention and to make this novel a bit shorter, I decided to go with that system. I bought their ER32 chuck and later bought the ER20 chuck, too. The TTS chucks are fairly good. Not as accurate as a high end chuck but I can hold 0.0002-0.0003" TIR with a Techniks collet. You have to use their nuts on their chucks, which is a bummer because I think I could get better run out with a better nut but so far this system has worked okay for me.

So, now I run all my non-critical stuff like fly cutters in import R8 collets and more accurate big cutters in my Crawford R8 collets. For all end mills I use an ER chuck. If I am doing heavy work, I try to use the ER40 ETM chuck. For average cuts I use the ER32 and when I do finer detailed work that requires me to get close or if I'm using smaller end mills like 1/4" or smaller cutters, I use the ER20.

That's my story and I'm sticking to it. I put a lot of thought into choosing this system because I won't lie to you, it was expensive, but I'm happy with my choices.
Click to expand...
Okay, Mike. You're talking a bit of a foreign language to me and perhaps some others of us neophytes. This discussion is very interesting to me, but I'm completely lost in the language. I don't believe I've ever been in the same room with an 'ER Chuck' or 'ER Collet'. I have a Vectrax mill and use both R8 collets and end mill holders. Would an ER system be compatible with my machine? What would be a good starting package to experiment? I have had end mill slippage in the past (that's why I got the end mill holders), but I'm curious if ER tooling might be an improvement.

If you have time to answer, is it possible to perhaps post some pictures of your tooling along with your descriptions?

As always, thanks for sharing your knowledge.

Regards,
Terry
 
First let me clarify something. End mill holders are commonly used and there is nothing wrong with using them. My experience has been with import end mill holders that I got for free and I think they were horrible. Better quality end mill holders are not in the same category so I don't want to come off like I'm putting them down; I am not. I have had an end mill come loose and drop down maybe 3 times but each time it broke the end mill or ruined the work or both. I also do not like that in the cheap holders I had, the end mill shank has enough room to be pushed to one side by the set screw and that affects tool life and accuracy. I understand better tool holders minimize this but there has to be some displacement in order to fit the shank of the end mill in there and that is enough to make me not want to use them. On the other hand, this is just my preference and I know that a lot of other guys use them successfully.

An ER chuck is just a holder for ER collets. The chuck fits into the spindle of the mill with, in my case, an R8 shank and is held in the spindle with a drawbar similar to an R8 collet. Once the chuck is locked into the spindle, all tool changes happen at the chuck; you do not loosen the drawbar until you have to take the chuck out. The ER chuck has an internal taper that matches the external taper of an ER collet and a nut holds the collet and pushes it into the chuck's taper as the nut is tightened. As this happens, the collet is concentrically squeezed into the taper. As it does so, it surrounds and squeezes down on the tool/end mill that is inserted into the center of the collet. When the nut is torqued properly, the tool is held securely and accurately. Look up pics of ER chucks and collets and you'll see what I mean. The collets have cuts in them that allow them to collapse and this allows them to grab onto stuff. ER collets can collapse down by about 0.040" so they have a pretty good range but it is always more accuratge to use collets close to the nominal size of your tooling.

I think you can see from this chain why having good components is important. You have a lot of interfaces stacking up here - the spindle, the fit of the chuck in the spindle's taper, the taper in the chuck, the collet that fits the taper, the nut and then the tool. Big chain and every single component has its own run out. This is why most of us who use these kinds of tools tell you to buy the best you can afford because if any of these components is junk then the run out at the tool is affected.

The size of the ER system you choose depends on your needs. No one size fits all and that is a disadvantage to the ER system. For every chuck size you have, you must have collets and nuts to fit it and that can get expensive very quickly if you buy good stuff. ER40 collets and nuts will only fit an ER40 chuck. ER32 collets and nuts will only fit an ER32 chuck, and so on. This all adds up very quickly. Thing is, the bigger chucks are more rigid and reduce vibration more so if you do a lot of heavy cutting then the larger size works better for this. You can still hold small end mills in an ER40 chuck so its actually quite useful. If you only do moderate cuts using common tools 1/2" shanks and below, an ER32 would work fine for most projects. I have found that as good and as flexible as the ER32 size is, the chuck sometimes is too big to allow me to get in close to the work so I had to buy and ER20 system for that. An ER16 would have been even better and cheaper but so far, the ER20 works okay for me.

Since your mill has an R8 spindle, yes, an ER system will work for you. The size you choose is up to you but if I had to pick one system that seems to work for most things, it would be an ER32 system. If I were to buy a package today, I would buy a Glacern ER32 chuck with an integral R8 shank, Technicks ER32 collets and a Rego-Fix Hi/Q Friction ER32 bearing nut. I would start there and build my system as my needs dictate. This package is NOT the best but it is very good and the cost is "reasonable". I would buy Imperial sized collets because we mostly use Imperial sized tooling. You can buy Metric collets but it is more accurate to stay with collets that are close to the nominal size of the tools you use.

There are many options when choosing your tools and it would be a good idea to open a thread and ask for opinions before spending money. I know there are guys who favor end mill holders, while others prefer an ER system or R8 collets. It comes down to what you prefer. I've run the gamut and have settled with the ER system but I'm just one hack bumbling along. Ask the guys and they'll set you straight.
 
rwm said:
I have a lot of double ended mills. I guess I will be using R8 collets on those. Maybe get a holder for my 1/2" and 3/4" single end end mills. Good discussion guys!
Robert
Click to expand...

Yep, I use double ended end mills in my ER chucks also. Most ER chucks have an internal adjustable stop that can also be removed. Not sure up to what size end mill & depends on the brand/size of the chuck. The largest I have for double ended end mills are 1/2"
 
mikey said:
If you do go with R8 collets, get good ones. Hardinge makes the best but Crawford and Lyndex are also very good.
Click to expand...

Unfortunately Crawford/PBA/600 Group stopped making R8 collets years ago. Some can still be found new on ebay but not in the most common nominal sizes. Lyndex are hit & miss for a while now since they moved production to India. Hardinge were too expensive for me. I just went through this search again recently. This time I bought TMX R8 collets made in Italy. Hopefully they are decent. They should be here Friday.
 
Mikey, thanks for the details, I can't help but think that you got more than your share of bad end mill holders.
Considering that there is more machining involved in making ER chucks and collets than in making Weldon end mill holders, I see no theoretical reason why end mill holders can not be made with the same precision. The hole in an end mill holder can be indexed to the side instead of on the axis. Any clearance allowed for insertion of the end mill would have little consequence if the index was on the side opposite the set screw. The Weldon end mills shanks that I have seen are ground to very close tolerances. It stands to reason however that any variation in the shank diameter would have twice the impact on alignment in a Weldon holder than in a collet. I just wish that we could put some numbers on the dimensions we are talking about.
I totally respect that we each arrive at our choices from different experiences. It is fascinating to learn about yours and other persons journey to satisfaction.
 
mikey said:
First let me clarify something. End mill holders are commonly used and there is nothing wrong with using them. My experience has been with import end mill holders that I got for free and I think they were horrible. Better quality end mill holders are not in the same category so I don't want to come off like I'm putting them down; I am not. I have had an end mill come loose and drop down maybe 3 times but each time it broke the end mill or ruined the work or both. I also do not like that in the cheap holders I had, the end mill shank has enough room to be pushed to one side by the set screw and that affects tool life and accuracy. I understand better tool holders minimize this but there has to be some displacement in order to fit the shank of the end mill in there and that is enough to make me not want to use them. On the other hand, this is just my preference and I know that a lot of other guys use them successfully.

An ER chuck is just a holder for ER collets. The chuck fits into the spindle of the mill with, in my case, an R8 shank and is held in the spindle with a drawbar similar to an R8 collet. Once the chuck is locked into the spindle, all tool changes happen at the chuck; you do not loosen the drawbar until you have to take the chuck out. The ER chuck has an internal taper that matches the external taper of an ER collet and a nut holds the collet and pushes it into the chuck's taper as the nut is tightened. As this happens, the collet is concentrically squeezed into the taper. As it does so, it surrounds and squeezes down on the tool/end mill that is inserted into the center of the collet. When the nut is torqued properly, the tool is held securely and accurately. Look up pics of ER chucks and collets and you'll see what I mean. The collets have cuts in them that allow them to collapse and this allows them to grab onto stuff. ER collets can collapse down by about 0.040" so they have a pretty good range but it is always more accuratge to use collets close to the nominal size of your tooling.

I think you can see from this chain why having good components is important. You have a lot of interfaces stacking up here - the spindle, the fit of the chuck in the spindle's taper, the taper in the chuck, the collet that fits the taper, the nut and then the tool. Big chain and every single component has its own run out. This is why most of us who use these kinds of tools tell you to buy the best you can afford because if any of these components is junk then the run out at the tool is affected.

The size of the ER system you choose depends on your needs. No one size fits all and that is a disadvantage to the ER system. For every chuck size you have, you must have collets and nuts to fit it and that can get expensive very quickly if you buy good stuff. ER40 collets and nuts will only fit an ER40 chuck. ER32 collets and nuts will only fit an ER32 chuck, and so on. This all adds up very quickly. Thing is, the bigger chucks are more rigid and reduce vibration more so if you do a lot of heavy cutting then the larger size works better for this. You can still hold small end mills in an ER40 chuck so its actually quite useful. If you only do moderate cuts using common tools 1/2" shanks and below, an ER32 would work fine for most projects. I have found that as good and as flexible as the ER32 size is, the chuck sometimes is too big to allow me to get in close to the work so I had to buy and ER20 system for that. An ER16 would have been even better and cheaper but so far, the ER20 works okay for me.

Since your mill has an R8 spindle, yes, an ER system will work for you. The size you choose is up to you but if I had to pick one system that seems to work for most things, it would be an ER32 system. If I were to buy a package today, I would buy a Glacern ER32 chuck with an integral R8 shank, Technicks ER32 collets and a Rego-Fix Hi/Q Friction ER32 bearing nut. I would start there and build my system as my needs dictate. This package is NOT the best but it is very good and the cost is "reasonable". I would buy Imperial sized collets because we mostly use Imperial sized tooling. You can buy Metric collets but it is more accurate to stay with collets that are close to the nominal size of the tools you use.

There are many options when choosing your tools and it would be a good idea to open a thread and ask for opinions before spending money. I know there are guys who favor end mill holders, while others prefer an ER system or R8 collets. It comes down to what you prefer. I've run the gamut and have settled with the ER system but I'm just one hack bumbling along. Ask the guys and they'll set you straight.
Click to expand...
Thanks, Mike.

Exactly the kind of thoughtful answer I anticipated from you. The theory you've outlined underlying ER collets is logical and makes sense, and I can see how it may well be a superior system. Two sets of questions:
1. Any feel for the range of collets that are available and practical for the ER32 system? What do you consider the extremes in both directions where a larger or smaller system would be superior?
2. Are you aware of any vendors that might sell the collets in kits?

I have had good luck with my end mill holders but I was able to find some very nice ones. All except one are Collis, and the other is a Shars. They strike me as being much more rigid than R8's for larger end mills (5/8" and up), but I also have one for 1/2" - that's the size I've had a couple of instances of end mills slipping in an R8 collet.

I also like your idea of having a thread to canvas our experts on the subject. Seems to me we already have one going right here. Would love to hear the opinions of any others willing to chime in.

Regards,
Terry
 
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