Air feed on 16" drill press -- usefulness?
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    Default Air feed on 16" drill press -- usefulness?

    A friend has offered me a spare pneumatic feed for my 16" drill press. This is the type that mounts to the top of the drill and has a pneumatic cylinder that pushes directly down onto the spindle. I believe it does not affect the ability to use the manual lever.

    Having never used powerfeed on a drill in any shop I've worked in, I'm wondering how useful it is in a non-production setting. Why don't I see them in many job shops?

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    Because a pneumatic rams a crap way to feed a drill. All the real power fed drills do it through gear reduction just like a lathe feed, all a pneumatic cylinder does is apply a given pressure based on air supply regulator settings, which works shit at the moment of break through!

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    The units I have seen are "air-drualic" Schrader made them with a oil filled cylinder
    hanging on the side with flow controls to regulate the speed.

    I never looked at these too much, how is the return stroke set ?

    I have a couple of snow drill/tapping machines, with a very similar air/draulic
    feed, and there are solenoid micro switches on the depth stop rod to reverse
    the feed.

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    Quote Originally Posted by adama View Post
    Because a pneumatic rams a crap way to feed a drill. All the real power fed drills do it through gear reduction just like a lathe feed, all a pneumatic cylinder does is apply a given pressure based on air supply regulator settings, which works shit at the moment of break through!
    Can you be more specific about the problem at breakthrough? Is the issue that the pressure is constant so it the drill gets stuck when breaking through, vs. geared feeds where the feed speed is constant (and can muster extra pressure to punch through)?

    And yes, it's an air-over-hydraulic feed system.

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    Years ago I contacted marsdaam rapid_drill re the feasibility of using one of their dp feeds on an 18" Buffalo and was advised it would be too hard on the seals, long term. The Schrader bellows pinion shaft feeds are the way to go imho.

    Sent from my QTAQZ3 using Tapatalk

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    Some of these units have a peck cycle which eliminates breakout.

    Sent from my QTAQZ3 using Tapatalk

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    If you're planning to use your drill in a mass production environment they're OK, not so much in a " one off " type jobbing shop environment.

    Regards Tyrone.

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    I've automated DP's for production work with airclamps, pullers, etc such as the 20,000 oak plug job this past winter. Auto feed is useful for stuff like that & an air over hydraulic system would be easy to tie in with the rest of the air controls. For big bits as well as some specific ops, the gearbox type can be handy for controlled feed.

    For regular DP use, the time wasted dialing in the feedrate or waiting for it depending how the retract cycle works can be a nuisance.

    If he is throwing it out, put it on a shelf or rat-hole somewhere until a job comes along that compels you to get it out, dust it off, and put it to use.

    smt

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    Found this link in a search for Schrader Bellows piston cups for an air power feed couple months ago and thought I'd put in my 2c worth. Breakout is a non-existent issue (unlike how manual feed can be) with their hydrocheck system. Nor is advancement or retraction speed. I reconditioned one on an old drill press about 25 years ago and still use it today regularly.

    The hydraulic check is infinitely adjustable to both regulate feed speed and where it kicks in, and the against whatever pressure you have the air cylinder pressure valve set for. The feed I use is an older unit that has manual, rather than micro-switched valving, and trip dogs to advance and retract the drill spindle and set where the hydro-check is engaged.

    Amazingly, despite the fact that Shrader Bellows was acquired by Parker Hannifin, the piston cups I needed are still available, but it took a long time to get them, so I tore apart a couple backup units I had and one set wasn't too dried out, but did leak air by it into the exhaust port, though not too badly. It actually works out well, because I rout the air cylinder exhaust port to a tube on the drill quill to blow the swarf off of the drill, and the continuous air flow helps cool the drill. The sudden burst of exhaust blows it off into the shop vac.

    Here's a short video my daughter took of her mom on her first cam drilling session. Her speed picked up enormously after drilling a few hundred. You will notice there is no waiting time nor is there a hint of chatter or squeeking on break through. The material is Delrin 150. Like any material, Delrin wants to climb the drill on breakthrough, so it has to be held down firmly. Also, the cutting edge where the flute meets it may need to be honed on a bit more obtuse angle so you don't get a burr on the breakout side. It seems counter intuitive, but it works.

    That aluminum spacer riding on the reduced shank of the drill is there so I can pound a Morse #2 to straight shank adapter into the spindle nose tight enough to prevent the reduced shank drill from slipping in the adapter. I bore out a bar of aluminum on the lathe with the same drill used in the machine , and part off an inch beyond the drill depth. Then I put in a ½” drill and drill the bar (still in the lathe) and part off for the spacer. The spacer then goes onto the drill shank before putting it and the adapter into the spindle nose, and the long bar goes over the drill and shoves the spacer up to the adapter without touching the end of the drill.

    It can then be pounded up however much is required to really tighten up the cheap adapter without damage to the drill. It also works out handily for getting a good angle for the air nozzle blowing down the drill flutes.

    Incidentally, for those of you who micky mouse things the way I do, that blue painter’s tape is not affected by oil the way other tape is.

    As others have said, unless you need a production machine, this type would require too much setup time for general shop use.

    http://www.miterclamp.com/videos/Mar...lling_11mb.mp4

    Cheers,
    Jim
    Last edited by clampman; 08-25-2019 at 12:19 PM. Reason: clarify a bit


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