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Thread: Fly Cutting

  1. #21
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    Quote Originally Posted by 9100 View Post
    An old timer called fly cutters "Spline wreckers".

    Bill
    They love fly cutters where I work...no thanks I'll stick with a face mill.

  2. #22
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    Quote Originally Posted by plastikdreams View Post
    They love fly cutters where I work...no thanks I'll stick with a face mill.
    I don't understand. Fly cutting is very easy, but a face mill is way too big for the job. You need a really itty bitty cutter to cut flies.

    Wait ... that is what we're talking about, right?


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    I don't know what the designer of the R8 spindle had in mind about the screw but is obviously not a driving key.I think it is only to stop the collet from spinning while tightening the draw bar till it seats.Properly tightened it won't slip.Both of our mills have 3hp and I have never noticed any slip.That's probably the R8 limit and I don't think any body actually uses the full 3hp specially in low range.

    Why any one would use low range with a fly cutter is a mystery.That's one way to deliberately make it slip and stress the drive.

    I generally flycut with 2-3" brazed carbide lathe bits at 1,200-1,400 rpm.The tooth load is low and the drive spindle and pulley inertia work in your favor to not have to apply large amounts of torque as would happen in low range.With the independent feed drives most of these type mills have there is no way to calculate accurately the actual load except by measuring the chip.

    So speed it up and get mirror finishes.

    BTW I do have an assortment multi-tooth insert cutters but for one offs,clean ups I usually just grab a flycutter.

  4. #24
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    Quote Originally Posted by ratbldr427 View Post
    I don't know what the designer of the R8 spindle had in mind about the screw but is obviously not a driving key.I think it is only to stop the collet from spinning while tightening the draw bar till it seats.Properly tightened it won't slip.Both of our mills have 3hp and I have never noticed any slip.That's probably the R8 limit and I don't think any body actually uses the full 3hp specially in low range.

    Why any one would use low range with a fly cutter is a mystery.That's one way to deliberately make it slip and stress the drive.

    I generally flycut with 2-3" brazed carbide lathe bits at 1,200-1,400 rpm.The tooth load is low and the drive spindle and pulley inertia work in your favor to not have to apply large amounts of torque as would happen in low range.With the independent feed drives most of these type mills have there is no way to calculate accurately the actual load except by measuring the chip.

    So speed it up and get mirror finishes.

    BTW I do have an assortment multi-tooth insert cutters but for one offs,clean ups I usually just grab a flycutter.
    I don't think the designer of the R8 collet had a mind. A 3/4" four flute carbide end mill will pull down on a heavy cut, no matter how tight it is. Unless the shank is a perfect match to the collet and the taper in the spindle, the shank will only be gripped by an edge and it will rock on that edge slightly. A few microinches add up to a lot of rocking when it is spinning. I got rid of my R8 machine and never want another. You will break the cutter before my TG100 collets slip.

    Bill

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    I've never had problems with BP collets slipping, or things pulling out, when using that F45ST facemill, boring heads, or the occasional large bit (the screw is long-gone). Use good quality (not Chinese mystery-metal, and dimensioned ones) non-worn-out collets (preferable new Hardinge, only a few are needed). Clean the spindle and collet, and if a demanding load, I'll wipe off the shank, collet and bore with acetone. Of course, if the spindle bore is not good, all bets are off, the last, or first, thing to remember is it's a Bridgeport, not a Cincinnati and use accordingly.

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    Quote Originally Posted by 9100 View Post
    I don't think the designer of the R8 collet had a mind. A 3/4" four flute carbide end mill will pull down on a heavy cut, no matter how tight it is. Unless the shank is a perfect match to the collet and the taper in the spindle, the shank will only be gripped by an edge and it will rock on that edge slightly. A few microinches add up to a lot of rocking when it is spinning. I got rid of my R8 machine and never want another. You will break the cutter before my TG100 collets slip.

    Bill
    Your ability with a standard or oversized sized R8 B-port or clone is noted.
    You are most certainly a whizz EE as you have proven here over and over but maybe not a machinist.
    Bob

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    Quote Originally Posted by CarbideBob View Post
    Your ability with a standard or oversized sized R8 B-port or clone is noted.
    You are most certainly a whizz EE as you have proven here over and over but maybe not a machinist.
    Bob
    I'm not sure what you mean. Lots of machinists, including some I know to be very good, have the same opinion of R8 collets that I have. I bought an English made Pal mill in 1969 when you would have to wait over a year for a BP. Later I bought a Promax, AKA Supermax, mill with a 30 taper spindle and got rid of the Pal which was a good machine but I used end mill holders because of its poor holding power with collets. I also have a
    Boston Digital CNC mill with a 40 taper spindle and TG 100 collets, which I really like.

    I have been independent since 1968 and have done my own electronic, mechanical and hydraulic design and fabrication.

    Bill

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    It was very interesting to know about Fly cutters. Thanks for sharing the post.

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    Good to mention the tram of your head is critical. If your off a half thow in 3 inches your part will be off angle that much , and being off will/may make a convex or concave scalp surface in your part. Yes you can shim your vise to rid the off angle, but you cant do much for the concave or convex tool path.
    Yes same with a mill cutter.

    End mills are more forgiving for off-tram because multiple passes of a small diameter make for a less wide error.

    Good to have a hefty shank and be some what balanced because high spindle speed can make a light mill want to show out of balance wobble doing high speed..
    2" of tool bit sticking out only one way can make an out of balance condition.

  10. #30
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    True, but offsetting the head a tiny amount, I mean really tiny, can make the cutter hit on 1/2 the rotation, eliminating crisscross machine marks and making a nicer looking finish.

    Bill


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