left hand boring bar

Why? Explain the job and you might get a better idea how to do it.

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The only thing i could think of is left hand inside threading, but he's not looking for a thread tool. But it got me thinking, I don't know how to cut a left hand thread on my manual lathe anyway. How is this done?

Boring a hole with a bridgeport in back gear? Except you can reverse the rotation on the motor. Double chuck CNC lathe, and he needs tooling for the finish operations in the 2nd chuck?

Simply put, spindle running forwards, thread away from the headstock; or thread towards the headstock with the spindle in reverse. Note that you'll have to change the relief on the cutting tool to compensate. --Glenn Lyford

Glenn Lyford fired this volley in news:2d4c9153-9414- snipped-for-privacy@a32g2000yqm.googlegroups.com:

yeah... quite some large amount, too, if you're running in reverse... almost like running the tool upside-down. (no... wait... it IS upside- down!)

LLoyd

You'll need one if you put it in the side hole of a boring head :-)

Mark Rand RTFM

EXACTLY!!! That is what I'm doing.......very large hole.

Note: E-mailed *and* posted.

In article , mikec wrote: :On Dec 17, 10:28=A0am, Mark Rand wrote: :> On Thu, 17 Dec 2009 05:46:13 -0600, "Karl Townsend" :>

:> wrote: :>

:> >>> looking for a left hand boring bar; C6 or m42 tip , small radius :> >>> cutting edge is acceptable. Anybody got a lead on where I can buy one :> >>> of these? :> >... :> >> Why? =A0Explain the job and you might get a better idea how to do it. :>

:> >The only thing i could think of is left hand inside threading, but he's = :not :> >looking for a thread tool. But it got me thinking, I don't know how to c= :ut a :> >left hand thread on my manual lathe anyway. How is this done? :>

:> You'll need one if you put it in the side hole of a boring head :-) :>

:> Mark Rand :> RTFM : :EXACTLY!!! That is what I'm doing.......very large hole.

Your mill can't run its spindle in reverse?????????????

Many of the boring heads use a threaded fitment to the arbor so you can't run them in reverse unless you take special precautions to stop them coming undone.

EXACTLY!!! That is what I'm doing.......very large hole.

We never had any of them fancy "Store-Bought" tools when I was young. We made boring bars by drilling a hole in a steel bar. I have some that the hole is drilled at a 45 deg angle and some perpendicular. A HHS tool bit fits in the hole and is held with a set screw.

In article , David Billington wrote: :Robert Nichols wrote: :>

:> Your mill can't run its spindle in reverse????????????? :>

:> :Many of the boring heads use a threaded fitment to the arbor so you :can't run them in reverse unless you take special precautions to stop :them coming undone.

Ahh yes, that would be a problem. My boring head has an integral shank, so I didn't consider that factor.

So I bought a solid carbide bit....$56 (OUCH!) Should get here monday via ups.

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It's called "Loctite", works well and releases when heated. I simply screwed the head on tight. The boring bar will break before it can apply as much torque as a big wrench

You know, the extra stiffness of solid carbide isn't necessary when you cut with the end of the bar. A little deflection won't change the diameter of the hole.

You can regrind the end of a right hand boring bit. The lost shank clearance generally doesn't matter for the side hole of a boring head.

jsw

It's called "Loctite", works well and releases when heated. I simply screwed the head on tight. The boring bar will break before it can apply as much torque as a big wrench

Maybe I'll try this next time.......don't think I want to take a chance of breaking my $56 bit!

You know, the extra stiffness of solid carbide isn't necessary when you cut with the end of the bar. A little deflection won't change the diameter of the hole.

Not very concerned with that tight of tolerances so not worried about any deflection but I could not locate a carbide tipped bar....any suggestions as to where I could get one?

You can regrind the end of a right hand boring bit. The lost shank clearance generally doesn't matter for the side hole of a boring head.

How would you do this on a carbide tipped bar? I might think about trying that next.

Thanks Mike