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35623Collets, pull out, and a long winded post about work and tool holding options WAS: Re: [MILL_DRILL] RF-30 drawbolt wrench

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  • Stan Stocker
    Mar 26, 2014
      Hi Vern,

      The antiseize is ONLY on the taper right?

      If the antiseize isn't the issue, take a really close look at the R8
      collet you're using. There may be a bit of swarf in one of the slots,
      or a rough area (spun end mills can trash a collet hole fast) causing
      your problem. Yes, I'm an end mill holder and ER collet believer, but
      it's not like I've never used an R8 collet to hold an endmill when
      necessary.

      One important thing about single acting collets: They only can close a
      few thou before they are gripping just at outer end of the bore.

      Mike the endmill. Sometimes the vendors or makers put an imperial
      sticker on a metric diameter endmill or blow the tolerance of the collet
      bore. If the endmill doesn't slide smoothly with no notable shake into
      the R8 collet bore with no tension on the drawbar either the endmill
      shank or the R8 bore is damaged or off size.

      One poster mentioned the drawbar possibly bottoming out. Still a
      possibility, you might toss a washer ot two under the drawbar hex and
      see if things snug up better. Costs nothing but a few minutes and rules
      a problem in or out.

      If none of the above apply, you've joined the end mill holder user club
      :-) Welcome aboard!

      End mill holders are one option. In fixed sizes they are fairly
      inexpensive as you only need one for each size of endmill shank you use.
      For many folks this ends up being 3/8 and 1/2.

      If you use smaller (1/4 or less) diameter end mills, you may be better
      off just skipping the end mill holders and going with an ER collet
      chuck. As the diameter goes down, the TIR due to the free space in an
      endmill holder starts to become a notable percent of the cutter
      diameter. In a 1/2 inch end mill holder it's a nit, but 3 to 5 thou of
      TIR on a 1/16 endmill starts to look like a real issue. The R8 to ER32
      set from tools4cheap has a good reputation and is $120 with collets.
      Covers tiny to 3/4 inch.

      ***FROM HERE ON GETS SORT OF WORDY! IF YOU GOT THE ANSWER YOU NEEDED
      ABOVE EVERYTHING ELSE IS OPTIONAL! :-) ***

      I'm going to talk about collets a lot in this post. When setting up my
      shop lots of collets in different styles for different machines wandered
      in, and I followed older shop methods. So now I sit on a bunch of
      seldom used collets and have done a lot of work and spent a fair bit of
      money to standardize on ER series collets wherever possible. I even
      sold my entire WW collet set and watchmakers lathe because ER16 collets
      had less runout and covered a wider range with far fewer collets.
      Basic truth of collets is that collets that squeeze down at one end only
      have very limited closing range. You need a lot of them to cover a
      range of sizes, and often will have a work piece that is too small for
      one size, and too large for the next size down. ER series collets
      overlap each other by a few thou in almost every case, so with only 10
      ER16 collets I replaced 77 WW collets. Worth thinking about these
      things as you tool up a shop.

      These things didn't really matter when I was a guy goofing off in the
      shop, fixing stuff and having the shop as a hobby. Overcoming limited
      resources was part of the fun, how much clever rather than money can be
      brought to the problem is a fun game to play and you learn a lot. I'm
      now a full time clock maker, specializing in restorations of antique
      clocks and pocket watches. I have no idea what's coming in, and play
      with at least four different measurement systems all the time.

      I became really frustrated with certain common tasks being a real PITA.
      Making a list of things that ticked me off about my shop and the
      things that made jobs take a long time or be painful to do brought out
      some common problems. I found that most of my time was being spent
      figuring out how to hold things or set up a job, not actually machining.
      Why? Because the watch and clock business ignores advances in machine
      tool technology and still lives in the old fashioned hand graver, ww
      collets, small motors, little lathes, filing rests to cut winding
      squares, hand sawing the openings in gears, putter along and eventually
      get done world. In short, the clock and watch making books mostly tell
      you to live in an 1890's sort of shop. What BS, look at the modern
      watch factories and it's all CNC and modern precise tools. You know,
      modern precision machine shops, not sheds doing one off hand work.

      In many cases changing my Taig lathe over to an ER16 headstock, adding
      ER16 collet chucks to the small (Sherline) mill, buying a mid sized mill
      (G0704) and committing to the Tormach tool holding system with Hoss'
      drawbar mods on that mill made a lot of my headaches go away. A common
      job on antique tall case clocks went from an hour plus job with lots of
      stress and ways to go wrong to a 10 minute job, almost entirely courtesy
      of using ER collets in the headstock and using $20 carbide straight
      single flute drill bits. Sure, there were other things like rearranging
      three shop workrooms, modifying my old 1939 SB lathe for metric
      threading, adding a VFD, and replacing the cross slide and compound
      screws, stuff like that. But standardizing on mainly ER collets and
      getting work and tool holding done in a consistent manner on multiple
      machines made a huge improvement in how work gets done. In many cases,
      I can now turn the work to rough dimensions, remove the chuck from a
      lathe, go to a mill, do a few things, plop the chuck back on the lathe,
      clean up, part off, and be done. Truly a joyous way to work. Or just
      hold in collets on everything and not deal with loss of center with
      rechucking.

      ER collets are double acting, so grip MUCH better than spring AKA single
      acting collets as they compress along the entire length over around a 30
      to 40 thou range. I love ER and DA series collets. An R8 to ER32
      collet chuck with 18 (I think) ER32 collets from tools4cheap.com is
      $120. You can hold anything from 1/16 to 3/4 inch cutters. Bonus point
      is you can just leave the chuck in place. ER chucks have a special nut,
      you snap the collet into the nut before mounting. Seems odd at first,
      but the nut has a retainer which also ejects the collet a bit when you
      loosen the nut. When you loosen, the nut gets loose, then gets tight
      again. Keep loosening and it gives as the collet is extracted. No more
      beating on draw bars and in turn the spindle bearings. Bonus #2, even
      cheap ER collets have less than half a thou runout in every one I've
      measured. The three smallest sizes I sprung for higher end collets as
      those are the ones used for pivot work on the smallest clocks. They all
      have less than 2 tenths TIR.

      You could go with ER40 series as well, but most small shop machines are
      really pushing their capabilities with a one inch cutter. It does give
      you the option of making very rigid flycutters and such however, so it's
      not a silly alternative.

      Slightly lower cost alternative - get the ER16 straight shank holder
      with collet set for under $100 and use that in an R8 collet to hold end
      mills 3/8 or smaller. If you need to get a small cutter down into a
      fairly small pocket or along a pulley, you need some way to extend your
      end mill or drill bit without having a big diameter holder in the way.
      Aircraft drills can be useful, but having a small diameter ER or DA
      holder to plop into the mill can get you a few inches of added depth for
      awkward jobs.

      As a bonus, making the body of an ER chuck for your lathe is pretty
      straightforward if you can do metric threads. Buy a commercial nut (20
      to 35 bucks) and you can use the same collets in the lathe. No more
      fooling with the limited closing range of 5C collets, the lack of pass
      through the spindle bore with morse collets, no expense of 5C chucks.
      Just a sweet alternative! There is one potential downside however. ER
      series are round only, so the option of hex and square stock holding in
      a collet goes away. This may be such a rare need you don't care, or you
      might need accurate hex and square work holding in the lathe often. All
      depends on what you make a lot of.

      Glad to hear things are at least moving in a better direction. Have
      courage, it will all get sorted out.

      Stan

      On 03/26/2014 12:27 AM, n7gtb wrote:
      >
      >
      > Thanks to everyone that offered up suggestions on this; and thanks to
      > everyone else for your tollerance! :)
      >
      > I finally found time to pull the cutter and collet, and gave both a
      > liberal dose of brake cleaner. Once all of that evaporated, I applied a
      > very thin film of anti-seeze, and re-installed. I tightened the
      > drawbolt/bar, and gave it another go... This time the cutter (almost)
      > stayed put...almost. It only pulled out about 10 thou, compared to 70
      > or 80 the prior pass. Cut depth (side milling), was approximately 120
      > thou...
      >
      > So correct me if I'm wrong, but at this juncture, I'm going to take a
      > wild guess and say that I have three courses of action (four if you
      > count blowing my brains out with a loaded bottle of Scotch):
      >
      > 1. Spend a bunch(?) of cash on new/different collets and holders.
      > 2. Back off the feed rate.
      > 3. Make shallower cuts.
      >
      > I'll be forging ahead with #2 above, since it seems like the thing to
      > do. I just blew my budget on a used 2hp 3ph Weg W2 for the mill-drill,
      > so #1 will have to wait. :(
      >
      >
      > Best regards,
      > -Vern
      >
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