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  1. #1
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    Default Threaded milling cutters

    I was reading Harold Halls book on milling and he recommends the threaded shaft type end mills over the plain shank type. He says they are more accurate and have a firmer hold in the machine .

    The machine I used at at TAFE used the threaded end mills with a special collet . You screwed the cutter up into the chuck to the end of it' s travel, then you backed it down a tad before tightening the chuck around the collet.

    Is it possible to use the threaded cutters in a R8 spindle ?

    Any comments appreciated

    Mike

  2. #2
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    Default

    Depends on what's on the end of the R8 arbor Mike. If it's say, a ER collet chuck, yes.

    I don't know if I would agree with Harold's view on accuracy though. I have ER chucks and Autolock chucks. Some of the ER chucks and their collets may not be as accurate as the Autolock but the accuracy of the cutters used in them would come down to manufacturers and their tolerances. The majority of the cutters I use in both types of chucks are the screw shank variety made by Clarkson, Dormer, Presto, Sutton and P&N amongst others. All of them as accurate as I would ever want.

    BT

  3. #3
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    Default

    Hi Bob,
    I think Mike might be asking if you can get a Clarkson chuck on an R8 taper.
    Stuart

  4. #4
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    Default Thanks

    Found this on EPAY

    POSILOCK MILLING CHUCK R8 FOR ENDMILLS ETC BRIDGEPORT | eBay

    Not sure if that system uses threaded end mills or plain ?

    I didn't think the ER chuck could handle threaded cutters ?

  5. #5
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    Default

    Hi Mike,
    From the listing "SUITABLE FOR STANDARD THREADED ENDMILLS & SLOT DRILLS".
    These chucks wont hold plain shank cutters

    Threaded cutters will go in a ER chuck but the thread wont be doing anything(unless you can get some threaded collets like BT has)

    I use threaded cutters as a clarkson chuck came with the mill(its a little different to the posilock but does the same thing). I've just bought a set of ER32 collets, am yet to make an M12 draw bar for the mill so havent used them.

    Stuart

  6. #6
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    Default

    Mike,

    It's a far eastern version of the Clarkson Autolock. I've been using screwed shank cutters in ER collets for about 6 years. ER collets don't grip the entire length of the collet so the threaded cutter end is not gripped. I will have a look for a sectional drawing to illustrate this.

    BT

    p.s. sluggish typing enabled Stu to beat me to the draw. "These chucks wont hold plain shank cutters" . If you are concerned about cutter slippage stick with a screw shank chuck like the Auto/ Posi Lock. Otherwise go for an ER. I have not yet had a cutter slip in my ERs.

  7. #7
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    Default

    Google "Osborn Titanic R8" - you should be able to find a used set pretty cheap.

  8. #8
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    Default right

    OK, sounds like the ER system is the most versatile being able to handle either shank version , plain or threaded. But, it would be nice to also have a screw type chuck as a backup for possibly milling the harder material like 4140 ... Mike



    osborn titanic collet chuck with 4 COLLETS | eBay

    PS also on EPAY ..looks rather well used though !

  9. #9
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    Mike,

    If you feel you need a screw type chuck, a search on Ebay UK is usually the most fruitful. Search for "Clarkson", "Osborn", "Dormer", "Autolock", "Titanic".....

    Clarkson made small, medium and large chucks. The collets are readily available for the small and large in both imperial and metric sizes. The medium collets tend to be thin on the ground. My search for 3/4" and 19mm medium collets started 4 years ago. Still looking.

    BT

  10. #10
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    Default Ok

    OK on that Bob I guess we will just have to keep perusing ebay to see what pops up Mike

  11. #11
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    Default collets

    Just reading a book that says the OSBORN/CLARKSON collets have a 20tpi thread form irrespective of diameter. That sounds rather unorthodox. Does anyone know if the newer cutters still use that standard ? Or are they more orthodox eg UNF and Metric form.

    Mike

  12. #12
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    Hi Mike,
    All mine are they same pitch. Well ok I didn't check them all but all the ones I checked were the same pitch(thats four cifferent sizes). Most of my threaded cutters are imp though, I'll see if I can dig out a metric one.
    Stuart

  13. #13
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    Default Ok

    Quote Originally Posted by Stustoys View Post
    Hi Mike,
    All mine are they same pitch. Well ok I didn't check them all but all the ones I checked were the same pitch(thats four cifferent sizes). Most of my threaded cutters are imp though, I'll see if I can dig out a metric one.
    Stuart
    Ok thanks Stuart . This book I am reading is rather old, so it may be outdated by now. Still, it may be a trap for us who use the threaded cutters. You have 4 with the same pitch ..Hmmm it might be true then. Mike ............................ PS 20tpi = 1/4 BSW and 3/8 BSF , the other diameters are all odd ball

  14. #14
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    Default

    I have seven collets, all appear to be the same pitch. This is the best I can find as cutters go. 3/4, 1/2, 10mm, 3/8, 1/4
    Stuart

  15. #15
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    Default Right

    Quote Originally Posted by Stustoys View Post
    I have seven collets, all appear to be the same pitch. This is the best I can find as cutters go. 3/4, 1/2, 10mm, 3/8, 1/4
    Stuart
    Right. Seems like they are all 20tpi . Interesting. Do you sharpen them yourself ? Or send them out ? Mike

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