Lathe Boring Bar Holder Plan?

Okay, I give up! 20 or 30 years ago I built a boring bar holder for my
Atlas Lathe from plans that I thought had been around for decades. I
want to pass them on to a friend, but I cant' find them!!!! believe me,
This is a cylindrical toolpost that replaces the lantern style tool
holder that came with the lathe. The central clamp "Bolt" that squeezes
the two halves of the "clamp" around the boring bar is drilled through
its side to allow the boring bar to fit right through it. This
particular model has three holes in the clamps to accept 1/4", 3/8" and
1/2" boring bars.
I did find a similar plan on the web someplace, but it only has one hole
in its side---- for a 1/2" bar, I think.
Yah, I know, why not just scale the needed dimensions and add them to
the existing plans. No, that plan is somewhat more complicated and
besides, I now obsessed with the need for that VERY plan,
If someone has it, or reference to it, I'd appreciate that info. I just
spent about an hour at the drop box and I can't find it there, either.
----The NEAT thing about this style of boring bar holder is that it is
probably the stiffest possible way to hold a boring bar that there is.
If my arm is twisted hard enough, I suppose I could draw it up and/or
add a couple of pix of it to the drop box.
Pete Stanaitis
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I've seen a few plans like that, and by happy accident, one was in the book "The Shop Wisdom of D E Johnson", titled "A Classic Boring Bar Holder" that I happened to have out. Given the copyright dates, the original article is in an issue of - ahem - last century's HSM or PM.
The basics: (a) A combined centerpost/T-nut that's drilled through larger than the largest boring bar, in this case 15/16" for a 3/4" bar. The bottom is turned to fit the T-slot, the center is a hair under 1.36" and the top is threaded 5/8"-11. (b) Two cylinders, 2.25" od and a hair over 1.36" id, height equal to the distance from the top of the compound to the lathe axis. There is a spring pin keeping the two cylinders in alignment radially. (c) A top cap, 2.25" od and 3/8" thick, with 1/8" turned down to the same diameter as the centerpost so it fits inside the upper cylinder, drilled to clear the 5/8" stud. (d) Assemble the pieces, align the hole in the centerpost with the lathe axis, put the appropriate drill in the chuck, then drill and ream one of the three pairs of holes, being careful not to drill through the spring pin. Loosen the nut, turn the cylinders but NOT the centerpost by 120 degrees, and do the second hole. And third. (e) Separate the cylinders and face 0.020 off the mating surfaces, so you'll get a better grip on the boring bar when it's clamped. (f) If all your boring bars use the same size bit and the holes in the bars are centered, face the top of the upper cylinder to remove half the thickness of the bit. Normally, the cylinders hold the bar so its center is on the lathe axis, but when you turn the cylinders over, the bar is lower and the top of the bit is on the lathe axis.
Reply to
Tove Momerathsson
See, that's how a newsgroup is supposed to work! Thank you, Tom. I had googled for hours, but the word "classic" is what I was missing!!! It's in HSM M/J, 1983 which is about 2 years before my collection started. But, for some unknown reason, I have 2 original printed copies of the specific article in PiM, (it is undated)!!!! How neat is that????
Pete Stanaitis ---------------------
Tove Momerathss> I've seen a few plans like that, and by happy accident, one was in the
Reply to
PM used to send a reprint of that article in subscription offers, I got 3 or 4 because of my HSM subscription. I finally got them to stop sending them by getting a subscription to PiM...
Reply to
David R.Birch
[ ... ]
I've seen the design in a book of projects for the apprentice, reprinted by whoever it is who reprints out-of-copyright metalworking books. (Old-Timer's disease is keeping me from remembering the name.)
Enjoy, DoN.
Reply to
DoN. Nichols
That is the name which I was trying to remember.
I'm now wandering through the list of books trying to find the one in question. I *think* that it is:
South Bend Lathe Works's Machine Shop Projects
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but I'm not sure. It is a pity that they don't show the cover, which would be more likely to trigger my memory.
They say:
"Projects include: lathe mandrel, lathe centers, spur center, 1" bolt and nut, screw drive, machinist's clamp, clamp lathe dog, boring bar for lathe, milling arbor for lathe, surface gauge, small bench vise, adjustable tap wrench, 6" improved water motor, arbor press, hand power emery grinder, and more."
so the question is whether the "boring bar for lathe" project includes the holder in question.
Of course, they drop books from their list as they add others, so who knows whether the one which I remember is still there. (Now if I just knew where my copy submerged. :-)
Enjoy, DoN.
Reply to
DoN. Nichols
============== The boring bar on page 40 is the between centers type for line boring with the part bolted to the cross slide.
If you are looking for what most people think of as a boring bar and holder see Milne's "Machine Shop Methods" p 212-213 for the holder and p 211-212 for the bar. Book available from Lindseys ISBN 1-55918-223-7 their sku No. 22237 ... $18.95
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Unka' George [George McDuffee] ------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?
Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).
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F. George McDuffee

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