Boring Bar Holder I.D.
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    Default Boring Bar Holder I.D.

    Hello again with the questions. I have had this boring bar holder for a few years and I am now going to put it to use after a failed effort due to a small one not being rigid enough for the job. No name on this holder. It will take a 1 3/8 inch bar. Only marking is the cast number 212. No name as per usual. Very strong holder of American manufacture I would think. Any help and guesses will be a great. Thanks, Ted
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    Quote Originally Posted by Ted1928HD View Post
    Hello again with the questions. I have had this boring bar holder for a few years and I am now going to put it to use after a failed effort due to a small one not being rigid enough for the job. No name on this holder. It will take a 1 3/8 inch bar. Only marking is the cast number 212. No name as per usual. Very strong holder of American manufacture I would think. Any help and guesses will be a great. Thanks, Ted
    Only "guess" I can offer is you don't have any significant boring to do. The lathe and compound UNDER it, it may as well be a McCormack-Deering hay rake.

    Research and consider this - I surely ain't the "inventor" of it. Not by 150 years or more.:

    - pull the compound rest.

    - find or fab a solid monolith Cast Iron or steel "tower".

    - mount it directly to the top of the cross slide. Center it.

    - Drill the cross for a taper pin you can insert and remove by hand.

    - Now drill the tower block from the headstock. Bore it HS to TS center, "line bore" style.

    - A bore of 2" that can take recycled turret lathe bushings is good.

    - split it for clamping bolts if you forgot to make it two-piece to begin with.

    Look around. Folks even sell these, ready-made. Or at least they do/did in England? See "Gibralter".

    Now:

    Taper-pin IN, you are dead-nuts on-center for drilling with the carriage. No "measuring" required.

    Taper-pin OUT you are set up to use boring bars up to two inches with the minimal deflection the cross slide (carriage and bed..) can deliver, CLAMPED if/as/when need be between cutting passes.

    Compound is still "elsewhere".

    A compound rest only ever WAS an add-on accessory many a serious lathe never saw the arse of in 100 years of hard work.

    Not even for single-point threading, given the alternative to a Gibralter-type bar holder is a 4-Way mounted directly to the topslide.

    Compounds are for cutting tapers too short and steep for TS setover or a taper attachment.
    Not a lot more than that. Rest of the time their primary job is to add slop, flex, and vibration.

    2CW

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    Quote Originally Posted by Ted1928HD View Post
    No name on this holder. It will take a 1 3/8 inch bar. Only marking is the cast number 212. No name as per usual. Very strong holder of American manufacture I would think. Any help and guesses will be a great. Thanks, Ted
    It is an Armstrong Bros. Tool Co. of Chicago.
    Their No.212.
    The 212 is rated for boring bars from 1/4" to 1 5/16".
    A 1 5/16" x 21" bar with a 3/8" tool bit would have come with it.
    It was rated for lathes with a swing of 14 to 18 inch.

    Rob

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    Hi, makes sense that it would be by Armstrong. Seems a nice rigid piece. Just the mounting needs work. Was just to get an idea of age. Thanks, Ted

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    Hi, just placed that on my lathe to take the picture. I do understand what you mean . Yes, much bigger and more rigid bars are much better. Good idea as you stated. I have done a fair bit or boring on the lathe . It is a South Bend Nordic 15. Usually use a Dorian post with a 1 inch bar with a 432 cnmg bit. Last week bored out some cast iron with a 4 inch hole taking a cut of 1/4 inch for a total removal of 1/2 inch . No problem. But where I ran into a problem was threading a 6 thread per inch. No where as rigid as needed to be and just made a mess. High speed bit in a flexible set up was a disaster. Was not with the Dorian. Your ideas would for sure eliminate the common problems encountered by someone who has had to learn this on the fly. Thanks, Ted

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    Sure looks to me like there is lettering on the clamp's upper surface, in a ring around the toolpost.

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    Default Boring Bar Holder

    Armstrong Adjustable Boring Bar Holder....
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