Bought a nice looking EE It bores .o03 taper in 3 inches ...how ? why?
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    Default Bought a nice looking EE It bores .o03 taper in 3 inches ...how ? why?

    Several years ago I bought really nice looking EE off eBay, turned out it was in a shop close where I live, so I get it home and

    the drive not working, rigged up an external motor, worked fine. Testing it out it bored .003 taper { on the diameter } in three inches.

    SO... there being no leg bolts for leveling I sold it. The spindle seemed smooth and tight. The guy that bought it wanted to test the bearings

    so before he loaded it we took a 2X4 and pried up on the spindle nose....I think it was about 1000 pounds upward push, and the DI registered

    perhaps one thou or a little less. He was satisfied that the bearings were OK so he bought it. Did I do the right thing ? what could I

    have done ?

    Thanks
    Dave Lawrence

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    Did you bore it or turn it? You said bored, then mentioned taper on diameter (not ID). Test piece in chuck if bored? Between centers if turned?

    If bored (as you say) - sharp positive rake on the boring bar and spring cuts? Chips look the same all the way in (no work hardening, build-up on tip, etc.)? How far was the workpiece sticking out of the chuck? Condition of chuck jaws (bell mouthed?) How did you measure the ID?

    If turned, was the workpiece between centers? Diameter of workpiece (could it deflect)? Tailstock center exactly in line with speindle center??

    Everything tight in terms of gibs, backlash, saddle, tailstock (if turned between centers)?

    Could be lots of things but .003" in 3" - .012" in a foot - seems excessive for a problem solely with machine geometry for anything other than an obviously clapped-out machine.

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    Quote Originally Posted by lalatheman View Post
    Several years ago I bought really nice looking EE off eBay, turned out it was in a shop close where I live, so I get it home and

    the drive not working, rigged up an external motor, worked fine. Testing it out it bored .003 taper { on the diameter } in three inches.

    SO... there being no leg bolts for leveling I sold it. The spindle seemed smooth and tight. The guy that bought it wanted to test the bearings

    so before he loaded it we took a 2X4 and pried up on the spindle nose....I think it was about 1000 pounds upward push, and the DI registered

    perhaps one thou or a little less. He was satisfied that the bearings were OK so he bought it. Did I do the right thing ? what could I

    have done ?

    Thanks
    Dave Lawrence
    Given the price of the spindle bearings it seemed to need, I'd say you were well rid of it.

    Standard TIR was 50 MILLIONTHS, special order 35 MILLIONTHS, and that spindle don't move 20 times the spec for a lousy half-ton of force.

    That said, use of an ID rather than OD to check for taper is chasing yer tail.

    Far harder to be sure a(ny) pass is actually cutting cleanly.

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    The best way to test the machine out is to do repetitive cuts on the OD of a piece of material, while adjusting the ball bearing gibs.
    Often the front ball bearings are too tight, and many times backing them all the way off will show improvement on machines with wear.
    A good example would be, the ball bearings are set to barley touch the under side of the ways, but get tight close to the chuck, as when "boring"...
    On extremely worn machines such as my 1951 manufacturing model ee, the tool post needs to be moved back toward the rear on the top slide, because when the carriage climbs up on the less worn area, the tool rises causing inaccuracy. That can be determined with the test cuts on an OD, but will have more effect on an ID.
    After using a machine for a period of time, the "mechanic" will find the "Sweet spots" of an old machine, and keep going.
    The ee is very sensitive to adjustments, a good machine can produce poor results.

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    Crapped out/ holding device/as PeteM said cutting tool/a ton of reasons.

    But did the buyer ask "Is there anything wrong with this machine"...?
    Did youask that question when you bought it?
    Buying a machine that is a very good question.

    This put a glitch in all the PM guys loving an EE.

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    In my experience shot bearings mean chatter, worn bed/saddle gives taper. The check would be with a parallel test bar mounted in the spindle.

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    You say .003 taper, is it linear or erratic in nature?


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