Newbie need help drilling a stupid hole...


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    Default need help drilling a stupid hole...

    I am obviously making a stupid mistake somewhere...
    simple hole/drill op in 6061...
    0.404" #Y standard off the shelf twist drill.... in tormach's medium TTS J chuck 30244 - Drill Chuck - 3/8" - JT2
    ~1.5" deep...
    feed = 8.7
    spindle RPM = 1702
    G83: Peck drilling cycle (Full Retract) .101" peck

    Problem:
    towards the end of the hole, most of the way through, the drill gets 'caught' and starts spinning in the chuck... or stalling? not sure the proper term, but spindle is spinning fine, and drill isn't... as such, hole is not as happy as it could/should be... and drill gits auto extracted from chuck on the retract.... also, fwiw, the drill shank gets very hot when this happens...

    I have tried cranking down on the chuck as much has possible, but I suspect the key will strip if I try much harder...
    besides, it 'feels' like a feeds and speed issue to me... I tried dropping feed to 68% but that didn't help... just wondering if upping the RPM would help any?

    I guess using a proper "CNC approved" drill would probably be better than your standard hardware grade twist drill... but I already have the twist drill,,, and I recently found myself gainfully unemployed, without the gain part... so not really looking to spend cash if I don't need to...

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    NOTE:As one wise professional something once stated, I am ignorant & childish, with a mindset comparable to 9/11 troofers and wackjob conspiracy theorists.


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    Default Re: need help drilling a stupid hole...

    The Tormach chucks are no better than "ok". You have to REALLY crank the snot out of them to make them secure on larger drills, and that is hard to do without the key slipping. I nearly always use ER chucks for drills - they never slip. Doing a 0.404 hole in one pass is also going to be tough. You'd be much better off drilling a 1/4" pilot hole first. Also, a hole that large, and that deep, will pretty much require lubrication, not just coolant. Very likely you're welding chips to the drill.

    Regards,
    Ray L.



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    Default Re: need help drilling a stupid hole...

    Are you tightening all 3 positions on the chuck? Believe it or not it does matter.



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    Default Re: need help drilling a stupid hole...

    Your feed and speed should work fine. In 6061 I can drill up to .500 without a pilot hole in high gear, have to watch the load meter and reduce the feed a little. If you tighten the Tormach drill chuck properly the spindle will stall before it slips. G83 is the right strategy, make sure your coolant nozzle is adjusted so it fills the hole with coolant when the drill retracts on each peck.
    Anything larger than .500 I will drill a pilot hole and switch to low gear.



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    Default Re: need help drilling a stupid hole...

    I always had better luck drilling with some oil, coolant will keep it cool but not so good in the lube department.

    Using coolant, once the drill gets a bit of aluminum color on it the drilling gets much worse, it seems to be a form of chip welding, and the chips do not slide as easily up the flutes as they should.

    mike sr


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    Default Re: need help drilling a stupid hole...

    I would drill that hole at 2500 RPM 15 IPM put the drill in an ER20 collet holder and use flood coolant.

    Spray or brush on coolant just won't work.

    You can buy GOOD PARTS or you can buy CHEAP PARTS, but you can't buy GOOD CHEAP PARTS.


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    Default Re: need help drilling a stupid hole...

    You can also buy drill bits with three flats on them. I get this type from McMaster Carr. They are excellent drills bits too, so win win.
    I hate using a drill chuck in cnc machines. It's a necessary evil sometimes and may save your butt, but extra oomph needs to be applied to them over and above what you would normally do on a manual drill press.
    Your feeds and speeds are still pretty relevant with drills.

    Lee


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    Default Re: need help drilling a stupid hole...

    1st, thanks for all the suggestions....

    the thing is, I have had far less issues drilling 1/2" holes than I am having with this stupid 0.404 hole and that is confusing me and sort of pissing me off at the same time...
    actually, the only issue I have ever had with the 1/2" is that it is fairly easy to stall the spindle if you push it to hard/fast...

    differences that I can see is that my 1/2 drill is a proper "cnc" style jobber drill, nothing special, fairly cheap black oxide which I cant imaging is of any benefit for aluminum... and my #Y is just your average "Titanium coated" (sure it is... looks like cheap gold paint/electroplating to me) came from a cheap set from a hardware store type drill..'
    and the 1/2" is in Tormach's large chuck...
    I do use flood coolant, haven't tried oil yet... but it isn't chip welding... at least not to the drill, it looks fine...
    I think I will just a pre-drilling op to drill it out to 1/4" as suggested, and I will try tightening all three positions, even if that does seem odd...

    NOTE:As one wise professional something once stated, I am ignorant & childish, with a mindset comparable to 9/11 troofers and wackjob conspiracy theorists.


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    Default Re: need help drilling a stupid hole...

    Cheap tool are... cheap.
    I have a set of Silver and Demming drills from HF that do just fine cutting wood. Use them for misc stuff around the house. I tried to use one for aluminum on my mill, ended up going to the tool supply and getting a quality drill (cost as much for 1 as the whole HF set).



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    Default Re: need help drilling a stupid hole...

    I'm assuming this is on an 1100? I wouldn't attempt a hole like this in one shot on my 770...I'd center drill and pilot hole first. I had a run of parts that required a slightly smaller hole (.386") and I found the larger Tormach drill chuck worked better for me.

    But like it was said before, these chucks work but are nothing to write home about.



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    Default Re: need help drilling a stupid hole...

    Quote Originally Posted by IMT View Post
    Cheap tool are... cheap.
    I have a set of Silver and Demming drills from HF that do just fine cutting wood. Use them for misc stuff around the house. I tried to use one for aluminum on my mill, ended up going to the tool supply and getting a quality drill (cost as much for 1 as the whole HF set).
    I have a set of Silver and Demming and they appear to be quality drills?? I also have a set of HF look alikes and they dont perform as well in steel. they are OK in wood ,plastic etc..

    mike sr


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    Gold Member Steve Seebold's Avatar
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    Default

    Quote Originally Posted by IMT View Post
    Cheap tool are... cheap.
    I have a set of Silver and Demming drills from HF that do just fine cutting wood. Use them for misc stuff around the house. I tried to use one for aluminum on my mill, ended up going to the tool supply and getting a quality drill (cost as much for 1 as the whole HF set).
    Don't EVER buy cutting tools at Home Depot or Lowe's. Spend the time and a little money and buy your tools at a local industrial supplier. You won't regret it.

    Last edited by Steve Seebold; 06-14-2017 at 01:09 PM.


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