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Drilling a really long hole

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  • Tony Ennis
    replied
    Seems to me that thick wall pipe would serve just as well.
    Or at least be a good place to start.

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  • Evan
    replied
    Seems to me that thick wall pipe would serve just as well.

    Leave a comment:


  • J Tiers
    replied
    Originally posted by Mcgyver
    Welcome Rolland

    gun drill schmun drill. If you look at post 19 in this thread, it went by without fanfar but in it I explained a technique that is almost foolproof using standard drills and reamers....the original story came with the claim of holding a thou over 3 or 4' with a 3/4" hole. Having used it, I believe it just might be that good (i haven't drilled 4') so depending on your view of 'accurate' this will probably work.
    Well, since you are in a "metric country, you wouldn't know this ( ), but that hole he wants is apparently 9 feet and 2" long.....or about 2.8 m.

    much of the problem is getting a machine to swing that length of shafting, while manipulating a drill of some sort which is the same length plus a bit.

    If you have to pull out the bit for any reason, it's gonna be a pain. Oil out the drill tip would take care of the chip issue.

    That 160" bed is going to result in only about 40" or a bit more of clear space, so some sort of clamp holder that a long drill slides through, or a slide bearing arrangement and an external frame to steady the drill rod and guide it down the center may be necessary.

    or a gun drilling setup, which is about that to begin with. You will "make" a gun drill setup to do the job, essentially.

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  • Rolland-Christians
    replied
    Thanks, it only carries air, but also is the main driveshaft and turns a large fan using a 1200HP cat engine-The air is for the air clutch. It should be concentric to maintain balance of the shaft. I bought my bridgeport and Ajax lathes from a machine shop that went out of business a couple years ago in Ocala Fl-The plant in Mn was at Eveleth, worked in the Fairlane and Thunderbird plants (Taconite processing plants, worked as a field millwright, plant millwright, and machinist-Untill they laid me off for the last time in 1981, so I moved to Florida)Worked for McGraw Edison as a machinist in Ft Lauderdale for awhile in the early eighties, and then someone bought the shop and broke it up, sold the land, and told us to go find another job-Did a lot of portable boring for them, under all the drawbridges in Fort Lauderdale, re-bored and re bushed the machinery underneath, one side at a time, and they would open the other side to let the boats through.

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  • Mcgyver
    replied
    Welcome Rolland

    gun drill schmun drill. If you look at post 19 in this thread, it went by without fanfar but in it I explained a technique that is almost foolproof using standard drills and reamers....the original story came with the claim of holding a thou over 3 or 4' with a 3/4" hole. Having used it, I believe it just might be that good (i haven't drilled 4') so depending on your view of 'accurate' this will probably work.

    http://bbs.homeshopmachinist.net/showthread.php?t=43014

    Leave a comment:


  • Rich Carlstedt
    replied
    Thats a perfect job for a gundriller
    To them its a piece of cake and a two hour job
    Rich

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  • J Tiers
    replied
    Originally posted by Rolland-Christians
    Hi-I was asked yesterday if I could rifle drill a .875" hole lengthwise through the center of a 4.5" shaft that is 110" long, and keep an accurate center. .................................................. Used to be a machinist for Ford in Mn. a long time ago)
    Sounds like a tall order without a real gun-drilling setup. It can be done, it was done by the hundreds per day in WW2.

    A machinist in MN? Would that be the Highland plant? Down by the "Ford bridge" in St Paul? Used to go by there all the time. Even had a tour of it ages ago.

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  • Black_Moons
    replied
    If it only carrys air, why are you not just buying premade hose/tube that can handle the pressure/tempature required?

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  • MrDan
    replied
    Originally posted by Rolland-Christians
    I have a small machine shop in North Florida, and take on some pretty strange projects for people.
    North Florida = ...strange people for projects. (I was born in Ocala.)

    Welcome, this is a great group here.

    Leave a comment:


  • Evan
    replied
    Seems to me that if it only carries air and not bullets or similar then the requirement for accurate centering applies only to the ends. Not so?

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  • Rolland-Christians
    started a topic Drilling a really long hole

    Drilling a really long hole

    Hi-I was asked yesterday if I could rifle drill a .875" hole lengthwise through the center of a 4.5" shaft that is 110" long, and keep an accurate center. I have been thinking about this, and am not sure. I have a lathe with a stretch bed, and can get about 160"+ between centers, and have a couple good steady rests, but am not sure about the procedure. Using a small gun tap with air or oil to start, then going up in size would be theoretically possible. The finish doesn't have to be perfect because it only carrys air, but the center would have to be pretty precise. Has anyone else tried to do this? This job may not materialize because of the expense, but now I would like to know if this is possible-Thanks, Rolland Christians (Oh, by the way, I just joined this group yesterday-I have a small machine shop in North Florida, and take on some pretty strange projects for people. Used to be a machinist for Ford in Mn. a long time ago)
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