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Collet Chuck - How does it work?

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  • ConductorX
    replied
    Thanks for the replies. I didn't tighten it enough. Since I am new to this I guess I have some learning to do. My router (organic material called wood) uses a collet system and does not require much more than very snug tightness.

    Thanks again for all of the advice and replies.

    "G"

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  • BCRider
    replied
    I got to go tool shopping for the new mill at work some years back. With the budget I was given I was able to buy a Clarkson chuck and a set of 2 and 4 flute end mills to go with it.

    .... that system is a slice of perfection with a cherry on top .....

    So easy to set and and use and so thoughtfully designed to encourage automatic setting for trueness and consistency. Makes Weldon look like a lazy slapdash guy that took the first half assed option that came to mind and ran with it......

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  • David Powell
    replied
    In 42 years at work, 50 plus years as a hobbyist.

    I have ruined exactly two jobs through end mills creeping downwards while held in collets. I agree heartily with the correspondents who emphasise cleanliness and that correct sized collets are important. The biggest mistake some beginners used to make , before collet chucks and milling machines were common in home workshops, was to hold end mills in 3 jaw lathe chucks and expect them to stay put while milling work in a vertical slide. I am a slow learner, wrecked several jobs that way when I was a beginner. Almost all tools have a potential to fail to produce perfect results if not used with the utmost care. But let's encourage beginners to learn how that level of care can produce very reliable consistent results instead of worrying over much about the rare possibilities of failure. Regards David Powell.

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  • _Paul_
    replied
    I have Clarkson Autolock no flat but use threaded cutters though (which I have quite a few of), I have never had one slip.

    I do like ER32 too it has a nice wide clamping range and given the eclectic collection of odd size cutters I have I do use this too, if you're concerned about ER clamping pressure use a Ball Bearing type nut which has a higher clamping force.

    Paul

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  • BCRider
    replied
    One thing I do is ensure I sink the end mills into the collet as deeply as I can shy of any transition to TiN plating, the top of the fluting or any hint of a radius. This ensures the flat for the set screw on the Weldon shanks is well up inside and I'm getting the most support I can from the mouth of the collet.

    This seemed to me to be fairly obvious when I switched to using collets with the new milling machine. But it may be worth mentioning just in case.

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  • danlb
    replied
    Originally posted by J Tiers View Post
    What they SHOULD HAVE SAID, BUT DID NOT is that collets are not all the same. A typical US collet, morse taper, 3AT, 3C, 5C, or even R-8, is a piece of crap mechanically. It works, but is best for soft materials of perfect size. An ER collet is much better for tool holding because it has a longer and parallel grip
    Thanks for bringing that up. It motivated me to do a little more learning about the subject. I found the R-8 specification calls for 1 inch of grip. My 2MT Morse taper collets provide a grip area that appears to be 5 to 10 times the bore diameter. The ER styles seem to vary a lot.

    I'd noted long ago that ER collets had multiple styles. Some appeared solid from end to end, some have a pocket on the end furthest from the nut. As a result, one style has a shorter gripping area than the other due to the counter bore. I found charts (1) that specified the gripping area for various ER collets. It confirmed the observation that the smaller ER collets (er 11, 16, etc) have less gripping area than the R-8. In addition, the larger ER collets (er20 and above) have that pocket for gripping shafts smaller than 8mm (1/3 inch) and thus have less than 1 inch of grip. Once they are above 8mm they are the full length of the collet.

    The reality is that a closely matched shaft in a quality collet will do fine when the gripping length is significantly longer than the diameter of the shaft that is being gripped. I have never seen a 1/2 inch shaft wobble in an undamaged 1/2 inch collet of any design.

    Dan
    1. http://www.takayama-shoji.co.jp/rego...nformation.pdf

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  • BCRider
    replied
    I like the idea of the nail polish and I can see how if the end mill pulls that it would form a visible line. But the spot of color would be up underneath in a spot we don't casually see during operations. I still like the idea of nail polish or a sharpie spot but it DOES mean needing to bend over and look up at the spot. And likely with a flashlight since it would be shaded from most work lights. So it's not the sort of thing you'd be looking at during most cuts. It is more a thing to check at the ends of passes until you figure out if the torque used can be trusted on that size of end mill.

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  • Rich Carlstedt
    replied
    There are collets made especially for holding endmills.
    Here is a sample, it is a Universal Engineering collet ( now Devlieg) . Note the button on the side.
    when you insert the endmill, and tighten the collet, the button locks into the flat space, preventing the endmill from coming out.
    http://www.tools-n-gizmos.com/store/...xm=on&ppinc=1a
    Click on more and larger pictures

    Jerry Tiers is absolutely right , somewhere along the path, you will "pull" an endmill ( been there, done that)
    And it will always be on that "Rush" and important job !
    A good way to protect yourself is to get some Red Nail Polish ( NOT paint, and not any other color )
    and place a dab right at the junction of the endmill and the collet.
    "IF" the endmill pulls , instead of seeing a pink blurr at the junction point , you will easily see a sharp bright clear line.
    Nail polish is quick drying, so it works well in moments, and the lacquer is hard, allowing it to crack and not smear. It also has an easy applicator for the function - perfect--! and its cheap.....

    Rich
    Last edited by Rich Carlstedt; 03-26-2017, 01:12 PM.

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  • danlb
    replied
    Originally posted by dalee100 View Post
    Hi,


    In 30 years of machining and 20 years of running the floors, I have found tool slippage for either collets or endmill holders to only be a problem when you are pushing a tool right up to and perhaps a bit past it's capability for depth of cut and feed rates. Something that so seldom happens in a home shop as to be non-existent.
    It's important to note that beginners are the ones most likely to push a tool beyond it's capabilities, and thus are likely to run into endmills that slip in a collet. They are the ones most likely to try "innovative" work holding techniques and climb milling.

    So advice to the beginners:

    Whether you use an R8 collet or an ER style collet, make sure the collet is exactly the same size as the tool shaft. R8 collets do not work well when you force a 1/2 inch shaft into a 15/32" or 12 mm collet. They work badly when the collet is too big too. Note: All my endmills have shafts that are in increments of 1/8 inch. There is something wrong if I find I need a collet measured in 32th.

    Make sure there is no swarf inside the collet nor on the shaft of the tool.

    Make sure the tool is dry. Oil will diminish the holding power of the collet.

    Watch the cut as you go. A slipping endmill will slowly dig deeper and deeper as it pulls out of the holder. I once milled a 3 inch x 1/2 wide inch pocket into aluminum. It started at 1/4 inch deep, but was closer to 1/2 inch by the end of the first pass.

    I use end mill holders for larger mills, and R8 or ER collets for the smaller ones.

    Dan

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  • BCRider
    replied
    A good practice until you get a feel for how tight the collets need to be is to put a witness mark like across from the collet face to the end mill. Then inspect it after the first cut to see if the line indicates any creeping.

    I found on my new R8 mill that a snug but no where near white knuckle tightening was enough to hold even mills that were larger than the shank for cuts as heavy as I'd want to make on a belt drive head.

    But on the 5C collet blocks I found the opposite. Namely to hold work against moving I needed to really torque down on the nut for larger size collets and anything other than a light cut.

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  • J Tiers
    replied
    Yes, they DO work fine..... USUALLY.

    Like I said, they will screw up only when it is important that they do not. I may use the collet 100 times and have no issue. When # 101 comes along, then there is a problem.

    WHO CARES WHO OR WHAT GETS THE BLAME?

    You ARE gonna screw up, it's a fact of life. So make it less likely. When you have the setscrew version, it just is not an issue. It's harder to screw up.

    And, there is another factor. The end mill does three things. It applies torque, it applies a side load, AND it applies an impact load as the cutter teeth hit the material several time per rev. That is very much the case as the cut starts, less so, but still present, during the cut. Just the sort of thing to loosen up and move the cutter.

    Then there is the issue that the flat often ends up right where you want to grip with the collet. Don;t do that with a US collet like 3AT etc, it will cause trouble with holding force, and raise the risk of movement. The grip length of a typical collet of that sort is not long, and the grip is often not parallel. It can't grip well when part of the shank is missing, even if it is lined up to cover and extend past the flat.

    In fact, the same guys "who never make a mistake", and say collets are great, will razz your azz if they see a picture you post of an end mill in a drill chuck. THAT they will say will OBVIOUSLY slide around and cause trouble. Yet they say a collet, which often contacts on a similar area in reality, they say is perfect, no problem, etc. Truth is the two can be very similar unless the collet is new and totally unworn, being used in a new, perfect, and un-worn collet closer.

    What they SHOULD HAVE SAID, BUT DID NOT is that collets are not all the same. A typical US collet, morse taper, 3AT, 3C, 5C, or even R-8, is a piece of crap mechanically. It works, but is best for soft materials of perfect size. An ER collet is much better for tool holding because it has a longer and parallel grip

    Not all end mill holders are made the same. I have some for MT2 that stick out a whopping 3/8 of an inch beyond the spindle. Not a big issue for taking up space.
    Last edited by J Tiers; 03-26-2017, 12:31 PM.

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  • Magicniner
    replied
    I have Collets and EM holders, I hand grind a flat on tooling I want to use in holders and use tooling with flats in collets, I even use small straight shank collet chucks in EM holders, it's all good ;-)

    - Nick

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  • Toolguy
    replied
    All end mills work fine in a collet. You need the ones with the flat for the setscrew holder. Many carbide tools don't have the flat. Each kind has it's place. You don't say what kind of collet chuck you have. Be advised, ER collets must be put into the nut before inserting the endmill, drill or other tool. This is because they have an eccentric ring in the nut that goes in the groove of the collet in order to pull the collet out of the taper when changing tools. If you don't put the collet in the nut first, noting works right.

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  • MattiJ
    replied
    Originally posted by dalee100 View Post
    Hi,

    If your tooling slips, YOU screwed up - not the collet. In 30 years of machining and 20 years of running the floors, I have found tool slippage for either collets or endmill holders to only be a problem when you are pushing a tool right up to and perhaps a bit past it's capability for depth of cut and feed rates. Something that so seldom happens in a home shop as to be non-existent.

    Dalee
    Agreed.
    Common problem with collets is not tightening them properly. Recommended ER32 tightening torque is 100...135Nm for tool shanks over 3mm.
    With the typical tiny collet nut wrench that is pretty much "white knuckles and key shape imbedded to your aching fingers"-torque. I'd guess that most people would instinctively tighten ER32 to something like 20Nm, only 15% of the maximum allowed tightening torque.

    http://us.rego-fix.com/er-system/pdf...rque-chart.pdf
    Last edited by MattiJ; 03-26-2017, 11:58 AM.

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  • Magicniner
    replied
    Originally posted by J Tiers View Post
    Collets WILL let the cutter creep outward and ruin the work.
    If you don't keep them clean and don't tighten them adequately, check the recommended torque for your collet system, you'll realise why so many people guess low, have a SNAFU and blame the collet system ;-)

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