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cutting flutes/miniature work - help!

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  • #16
    Finally a bit more info, doesn't sound too bad at all. Spin indexer of some sort, with that 6mm diameter it will have enough ridgidity to stick far enough out of a 5-C collet to clear cutter. Cutter will have to be small of course.

    1/4 cutter at 200sfpm is 3200 rpm, not into high speed machining ranges but will work with the right grade of carbide, and work in Bridgeport spindle if spindle in shape. This cutter I envision would be almost like a burr, with a larger shank. It will still have to protrude a ways to clear indexer, larger shank will be a must.

    Length is short enough to use collet stop.

    I remember seeing this new tool advertised in the trade magazines, it has a screw on insert. I don't remember the company selling this thing, I saw the ad in either American Machinist or Modern Machine Shop. I do believe it showed a slitting saw type cutter as well as the ball end. A posibility, depends on how big a job this is, and the cutter budget.

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    • #17
      For reference the Varmint Al website is:
      http://www.cctrap.com/~varmint/alath.htm


      ------------------
      grace & peace
      will
      grace & peace
      will

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      • #18
        for-um. n. an assembly for the discussion of public matter of current questions. BBS-"a forum reserved for feedback, criticism, kudos and good humored banter"

        That out of the way, let me offer this observation; mfg. of repeated accurate small components require precise and constant control of the cutting tool. If your crew of engineering technologists decide upon a circular flute shape then it's drill jig! drill jig! drill jig!!!! Consider using a fixture that employs a set of precision lapped drill jigs for drilling, reaming. Old, old fashioned method but so efficient. The cutters can be made in the shop out of drill rod, provided that the grade of stainless permits. But we don't know the grade or material or shape do we? (oh, I get so impatient with engineers) Anyway this tooling is not difficult to make, just takes a little time, a little know how and careful workmanship. Should be duck soup for an engineering technologist.

        Good luck, but I'd still farm it out to EDM and just take my %age for the procurement.

        I'll close with this kind thought, apoxonengineers and their offspring.
        O

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        • #19
          OK, I am a bit off on the full gist of this subject, but have a few ideas to input as I think I have the problem.

          #1, you say you will have only about 1/64th inch material left between the slots. I will give a solution to thin material milling and turning in a moment.

          #2, you have a very small slot to make lengthwise in a very small round part.

          OK, for #2, i would use a woodruff key cutter, mount the part in a spinjig or 5-C indexer, backing up the shaft with a small V-Block mounted on an angle iron, or even mill out a holder pre mounted - like a thin slot in aluminum already mounted on the angle iron - I really would have to draw out my idea, but I am a big beliver in making special tooling IN PLACE ON THE MACHINE (such as the milling of aqluminum jaws in CNC work for the job, or boring soft jaws when things are otherwise unable to be made with the standard tooling) to match a job when it fits the application. Mount scrap aluminum, mill a "V" with a slotting cutter on the mounted Aluminum (90 degree cutter if you have one. Believe it or not, a small straight cutter will work for this as well. Had to do something like this for some 16" long x 1/2" dia. parts once. Leads to less possible error from the get go.

          #1 - here is something I learnt years ago, forgot, then learnet and tried again just a couple of months back. I had to mill a casing out of aluminum - two cavities on both sides of a basically 4" length x 2" wide x .430 thick piece of aluminum. The resulting stock between the pocket on one side and the other side was .008 to .014. The pocket was wide and such. The problem was chatter and deflection of the material left. The solution took a while, but it took less time to do the following method than to monkey around forever. Learned this fom Chuck at Creare (giving credit, I know he checks this page now and then)

          We milled one side complete. Upon doing this we filled the cavity with shellac. lapped it smooth afterwards. gave a great solid backing for the milling and took deflection out of the picture. To remove the shellac afterwards, we put - of all things - Mentholatum (how do you do that "R" thing) on the shellac, and it melted it out clean as newborn cut metal.

          I have done his once again to turn a thin wall tube to .007 finish wall thickness between the bore and O.D. for a 7 inch part out of aluminum. Left .100 on the wall to begin with - finish bore.

          Your problem may not be so much indexing and such, or even the cutter all said and done, but the thin wall between slots

          Upon finishing one side pocket (or in

          [This message has been edited by spope14 (edited 01-22-2002).]
          CCBW, MAH

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          • #20
            OOPS, I meant such in the last sentence, not the bad word. I have bad arthritis in my hands, typing is a chore, thus my typos. please forgive me.......
            CCBW, MAH

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            • #21
              Click on the paper-and-pencil icon above your message, and you can go back and edit it. That way you can spare the rest of us, delicate and fragile as we are, any hint of impropriety..... ;-)

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