idea for faster er collet tool changes


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    Default idea for faster er collet tool changes

    for me changing tools isnt really a big deal, the main hold up is setting z. seems to be a couple options like an auto z touch plate, but i think even better would just be getting a consistent tool height when loading the tool so the height offset can just be stored. collar on the tool seems like one option but i imagine if you want precision, the height would probably vary slightly based on how hard you tighten the nut since the collet compresses. What about something that replaces the er collet and holds the tool with a set screw. Same shape as an er collet to be a direct replacement for one, but just a solid piece with various bores for different tool sizes. each tool you want setup gets one that it stays in. tool stays locked in with the set screw and lives in its own er replacement. since its a solid piece, it wouldnt work with some er nuts. some of them need the collet to compress a bit to get past the pulling lip, but the one i have from maritool has the pulling lip set off center so the collet can drop in slightly to the side without compressing. once lined up center, the pulling lip does its job when loosening the nut. so anyway, does such a thing exist? any reason why it wouldnt work? Just trying to think of a way to get faster with my multi tool parts and an auto tool changer is definitely out of my budget since this is a home built machine.

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    scaring mice @ north pole deadlykitten's Avatar
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    Default Re: idea for faster er collet tool changes

    hy quinn

    it wouldnt work with some er nuts. some of them need the collet to compress a bit to get past the pulling lip : er_nuts and er_collets are crafted within kind-of-similar tolerances, regardless of brand; truth is that collet_deviations are <<< nut_deviations, thus there is a big chance to get a messed up nut, but a low chance to get a messed up collet

    but the one i have from maritool has the pulling lip set off center so the collet can drop in slightly to the side without compressing : when it comes to the inner excentric, excentricity and dimension is a thing; but it can also be a shape <> a circle ( like 2 horns, or 2 claws )


    if a collet is inside a good nut, and you turn it upside down, so the nut to face the sky, than the collet should fall ( or just hang in there ) ; that's all

    maritool boss knows important things, that are in the hot spot, so, if i may, he knows the ' good s**** ' and, most important, he delivers




    about your idea : if i got it right, you wish to replace the elastic_collet with a weldon_chuck with er_collet od shape ... just do it

    if tool life will be similar, if tir will be normal, then there is no reason not to use a quick rigid er_coolet ( especially to achieve position repetability for the cutting edge ) even more, i would advice reducing the number of parts, thus going from " tool + rigid_collet + nut + holder " to "
    tool + a_single_intermediate_part + holder " : this requires more work, but there will be less downtime

    there is another way to do it : use a hydraulic collet inside the er collet
    ( you will work less, but you will pay more ... ) or inside a specialized chuck ( this requires modifing the axle to suit the hydraulic collet )

    i hope you will find this reply useful / kindly


    Last edited by deadlykitten; 06-15-2018 at 04:47 AM.
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    scaring mice @ north pole deadlykitten's Avatar
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    Default Re: idea for faster er collet tool changes

    one more thing :
    ... targeting fast tool change with minimal offset difference is a good thing to do
    ... next, you should consider tool change with minimal forces and minimal tir deviation, without compromising the slip-torque ( for example, in case of big er collet with small tool inside, the force required to clamp/unclamp the nut is bigger than the cutting forces, and this may lead to light holder position shifting, with big impact on the cutting forces that are manifested on the tool; a holder position may be subject to change also because of other factors, but this is another story called " small archery with gentle giants " )



    ps : posibility to switch between through and peripheral cooling

    Last edited by deadlykitten; 06-15-2018 at 02:40 PM.
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    Default Re: idea for faster er collet tool changes

    there may be a thing with your approach : you will have to be sure that all tools have a weldon flat with similar geometry; this may require cutting some tools, or grinding the flat ( if there is none )

    also, there is a problem when a screw clamps directly a carbide shank, comparing to clamping a hss shank : is about that elastic-plastic deformation, and the fact that, after the screw makes contact, a carbide shank is tighten with less rotation than a hss shank : this may deliver a false sense of safety; this is why is recomanded to use 2 screws, or at least try one with a bronze head ?; whatever the approach, the part that makes contact with the tool shank should be flatten, thus you may use an intermediate small cilinder with paralel frontals : the screw may damage one face of this cilinder, while the other will make a nice smooth contact with the carbide shank; even if you flat-out the screw head, this does not mean that it will grip as expected, and unwanted tool ration may occur as you tighten the screw, leaving the tool in an undesired position ( a bit of rotation, that may lead to losing grip during cutting )


    hmm ... i don't know how you feel about this, but for me, there are too many variables





    look, there is a product that handles all these : pls checked attached image and next link : this collet delivers exactly what you need : fast tool changing with good positioning repetability ( for wheldon shanks )

    pls be aware : when cutting forces are higher, or when tool wear increases, then this collet may rotate inside the collet chuck / kindly

    https://www.wnt.com/uk/cutting-tools...range-419.html



    for non-weldon shanks ( simple cilinders ) , you may use a normal collet and an adjustment screw inside the collet chuck, with a through hole for the coolant; this involves a mother-thread inside the collet chuck

    Attached Thumbnails Attached Thumbnails idea for faster er collet tool changes-01-jpg  
    Last edited by deadlykitten; 06-15-2018 at 01:21 PM.
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    Default Re: idea for faster er collet tool changes

    thanks for the suggestions! yes, i think this type of setup would definitely require weldon type tools to work properly. the collet you listed looks like it could work, but unfortunately only in er40 and er32 sizes, mine is er20. I currently dont have a lathe, just 3 axis cnc, but the lathe will be my next toy once i can afford it. once i have that, i may try to turn some of these out, although i doubt i would be able to hit the tolerances i would want for these, but ill try. Another possibility i have considered is just buying multiple er20 collets, one for each of my commonly used tools (90% of my work with 5 of them) and bonding them to the tool by applying the appropriate loctite to the tool shank, loading it into the collet, adjusting runout best i can, tighten and allow it to set up. hopefully when pulling the collet back out, it stays compressed and bonded to the tool. Couple issues with this idea though. The upper half of the collet would still not be rigid and probably wouldnt get perfectly consistent tool length each time tightening the nut. Another issue is this would probably be a one time setup for both the tool and collet. Heat could be used to separate the tool and collet when needed, but the residual loctite left behind would be difficult to remove and cause inaccuracy when loading another tool in it, unless there is a type of loctite that can be completely removed with some type of solvent so it can be reused. Replacing the collet every time a tool is replaced would get very expensive. Still, even if the loctite bond was good enough and i had a way to remove it so it can be reused when replacing the tool, it still may not be rigid enough to give the repeatable tool depth i would want. I would really like to hit within .01mm depth when loading a tool. I do have some old cheaper collets that i no longer use (they have been replaced with maritool collets) and also some old worn out tools, so ill try the loctite idea to see if it would even hold and measure they repeatability of it. Most likely that idea isnt going to work, but free for me to try. Once i have a lathe, ill experiment with the solid collet/weldon set screw idea. Also i might as well try a 1/4 inch set screw secured collar right on the tool to see what kind of repeatability that gives when loading into a collet, probably not great, but worth trying just to see.

    A couple other thoughts, i might try contacting maritool and see if they can sell me some collets that havent been slotted yet. I think they sell actual 1/4 inch rather than 6-7mm so maybe the bore would be right for the tool, just needs to be drilled and tapped for set screw.

    another thing, for this system to be optimal, i think shrink fit would be the ticket. solves the issues of set screw possibly not grabbing well enough, and also would give excellent TIR.



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    Default Re: idea for faster er collet tool changes

    wow, here it is. https://www.cutwel.co.uk/tool-holdin...llet-er20-bilz

    no idea what a shrink fit machine costs though, maybe i can build one.

    After looking around some more, it seems er20 shrink fit collets are pretty common. Spendy though, about 90 bucks each. I think worth it though. if i had a few 1/4 inch and a few 1/8 inch, i could have all my common tools set up for repeatable height tool changes and the added perk of awesome TIR on all of them (they claim 3 micron). now to see if i can build an affordable shrink machine

    looks like its not too hard to heat a collet and get a tool into it, problem is getting it back out. Thats the part that requires extremely fast heating and perfect timing to get the tool out. collet needs to expand and tool pushed out before too much heat transfers into the tool and expands that too. Although with carbide tools, which is all i use, its less of an issue since carbide has relatively lower CTE compared to collet. Not sure if its enough to just heat the whole assembly slowly and push the tool out though. Maybe the heating can be done slowly and then a fast cooling of the tool to get it out, if it doesnt shatter. Sure would be sweet if i could find an affordable way to use these shrink fit collets. the actual machine for it is way out of my budget

    found a post by a guy that says he does it with a torch no problem as long as its a carbide tool. The difference in CTE is apparently enough to get it out. I may have to try this

    Last edited by QuinnSjoblom; 06-16-2018 at 01:03 PM.


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    Default Re: idea for faster er collet tool changes

    hi if you wish to achieve repetability :
    ... when clamping the collet, right at the cnc, i still believe that you should use a screw inside the collet chuck : you put the collet, you put the nut, you push the tool so to make contact with that screw, and you tighten the nut obviously, tightening the nut may shift a bif the tool, thus the tool may go forward ... but you have to try to see how it works

    ... before clamping the collet, thus to come at the cnc with the collet and the tool as a fix position, then :
    ...... using loctite may work for a while, but does not sound cool; also you have to be sure that there is no loctite on the outside of the coolet, etc
    ...... you may consider a collet that is not through-hole :
    ......... for example a collet for taps : if you put inside such a collet a normal tool, it will clamp it right, always at same position ( you have to be carefull, because a tap collet may have problems when clamping a normal cilindrical shank, for example if there is a back chamfer on the tool shank that is not handled well by the square zone of the collet )
    ......... speak with maritool to deliver you a normal collet, that is not through-hole, thus to have a shoulder at the end ( pls check attached image : that part should fit into the back of your collet ); maybe there is a way to craft them yourself : try welding a shoulder on the back of the collet / maybe it works




    there are products for easy tool change with good repetability, but they cost unfortunately, i can't make you an accurate recomandation, since i don't know your machine, but just go google " quick change tooling " : maybe there is something affordable

    have a nice day




    ps : if you start thinking about a shrink_fit collet, the time that you will loose each time to hot-up & cool-down the coollet, it may cost you precious time, and in the end you may reach the conclusion that it would be better to simply buy a " quick change something "; ... try welding the shoulder; maybe you will ruin 2-3 collets, but the 4th will be ok check how much clearance is between the collet-bottom and the collet-chuck, and use a shoulder with a right dimension, that will fit in there

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    Default Re: idea for faster er collet tool changes

    If your not doing production work, a simple auto zero plate is all you need. You can configure it to be fully automatic.
    Change the tool, press the button, the machine measures the tool and continue's on it way. Probably 15-20 seconds slower than using shrink fit collets. But you save the time of measuring all the tools in the shrink fit collets. And save the $500-$1000 in collets, And the few thousand $$ that the heater costs.

    Gerry

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    Default Re: idea for faster er collet tool changes

    There are also these: https://www.genswiss.com/er_taper_in...ooling_cte.htm
    I am not sure of the cost though.

    bob



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    Default

    Quote Originally Posted by rowbare View Post
    There are also these: https://www.genswiss.com/er_taper_in...ooling_cte.htm
    I am not sure of the cost though.

    bob
    Very interesting. I'll look into those. Potential for more runout since the tool has to stick out further compared to a regular er collet or shrink er collet, but definitely an option.



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    Quote Originally Posted by ger21 View Post
    If your not doing production work, a simple auto zero plate is all you need. You can configure it to be fully automatic.
    Change the tool, press the button, the machine measures the tool and continue's on it way. Probably 15-20 seconds slower than using shrink fit collets. But you save the time of measuring all the tools in the shrink fit collets. And save the $500-$1000 in collets, And the few thousand $$ that the heater costs.
    I'll look into the auto zero setup. It will take me some learning though. Mine would have to be setup a bit more complicated than most videos I see. Most guys I see are just putting the touch plate on their table and have a constant height offset for the touch plate thickness. I would want my touch plate mounted somewhere permanently on the machine and be able to press one button, have it locate to the specific xy position, then probe. Other thing is, I don't have a constant z offset between my part zero and touch plate zero. It depends on what parallels are in my vice, or if I want to zero on top of the part. So I would need to be able to initially zero on my part, then have it probe the plate to set the offset between plate and part zero, then have it probe after each tool change. Is it possible to set it up this way? Also I have a pretty large swing in my tool lengths. From 10mm stick out to like 80mm stick out with some of my reduced shank mills. I imagine to get the accuracy I want, I would need snail speed feed for probing which I imagine takes a while if I need to set it up for 80mm of range.



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    Default Re: idea for faster er collet tool changes

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