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  1. #1
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    Default Drill leading off

    Here's my dilemma.
    Drilling a .187 hole 3" deep in 316ss.
    Using a Walter carbide through coolant drill.
    Running in a HAAS Ds30y with high pressure coolant.
    I'm not breaking drills or getting chip weld but my hole keeps leading off center by .006 to .012.
    I'm spot Drilling with a 90° 1/4" carbide going. 025 deep.
    Using a g83 peck cycle withdrawing .5 out of the hole rapid back to .05 from end of last cut.
    Tried running recommend feeds and speeds of 116sf , .0045f
    I've played with peck depth from .05 to .250, feeds from .0025 to .006 and rpm from 1800 to 2500.
    I get the best results around 2300rpm peck of .200 f.003. It holds a few part about. 002 or so off center or better but will then float out then come back.
    I've indicated the drill and spot to .0003 c/l. Ive checked horizontal run out so as to make sure its sitting true to c/l length of the drill.
    I've been machining plastic for the past 15 years. Shop is now venturing into steel and this is my first job.
    Any help is appreciated.

  2. #2
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    Try drilling the first 3/4" or so with a stubby drill, then bring in the long drill.

    Regards.

    Mike

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    You should spot the hole with a tool that has a greater drill point angle than the drill itself. This allows the center of the drill to make contact first rather than the od of the flute's.

    Also +1 on the stubby drill for a pilot

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    Curious why you are pecking if you have high-pressure coolant through the drill.

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    Mainly from years ago at previous shops just how deep holes were always done. I've been reading other threads about drilling ss. I may give a steady straight pass a shot.

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    Thanks , I was pondering this but wasn't sure about chipping edge tips if the hole was slightly smaller.

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    Ok that makes sense. I'll change tge spot . Tbanks

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    You may consider feeding at 50% upon entry and then going to 100% once the tip is in.....this is useful not only in machining.

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    Listen, I am not a fan of Titan, but this video he does is pretty informative. You might find this useful.

    Incredible 40XD Deep Hole Drilling in Stainless | Kennametal SGL Drill | Vlog #107 - YouTube

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  12. #10
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    Oh yeah, don’t turn on the thru-tool coolant until the tip is in about 1/2 way.

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    The stock can work against you. Stainless alloys often bear tensions inside, with round bars you speak of core tension. Just telling

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    Quote Originally Posted by rklopp View Post
    Curious why you are pecking if you have high-pressure coolant through the drill.
    Right. Also, NEVER peck in stainless with a carbide drill if you can avoid it.

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    Ok, first question: How much pressure is "high pressure" on a Haas?

    For me, high pressure is 1000PSI, and I wouldn't peck that drill at all (I would consider using a stubby drill for the first inch or so, but we regularly do holes that are .040" or less by 3 to 6 inches long with just one gun drill).

    If high pressure for you is only 250 or 500PSI, then maybe a peck half way through, just to make sure you're evacuating chips well.

    I'm assuming your drill point is 118°, your 90° spot is not doing you any favors, either switch it to a 120° or ditch it completely and just slow your feed for the first .100" or so.

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    68machinist70, did everything work out okay for you?

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    What is the tip angle on your drill?
    Is this maybe a Titex 6685?

    I think that I prepped the start hole for those with a C'drill, followed by a SML Cobalt drill of the same D as the through hole (same tip angle as the Titex tool) and then the long drill.

    My holes were straight, but I was in a lathe and had the benefit of spindle rotation to guide it too, so ....

    I have 1000+ # pump.


    ----------------

    Think Snow Eh!
    Ox

  20. #16
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    I think I remember the Haas being 300#?
    could work holding be part of the problem?


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