Not Monarch, But Useful Info Just the Same
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  1. #1
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    Default Not Monarch, But Useful Info Just the Same

    From a long-ago post of Carla's to Paula's many-pages-long saga of her South Bend 9A restoration project (which see).

    This info has historical value independent of its 9A association, so I'm providing a place for it here.

    The concept is applicable to any small engine lathe regardless of manufacturer, and can produce a very good turning tool, capable of fine work.

    The origin is a 1942 War Production Board bulletin, which has apparently been lost to history, but is well paraphrased by Carla.

    All the following text is Carla's.

    Thank you, Carla!

    The original thread is: http://www.practicalmachinist.com/vb...d.php?t=128005



    Well, I'm very impressed with your exquisite restoration work on the little South Bend.

    If I may, I'd like to offer a suggestion about setting it up on a bench, one which may seem a ludicrous amount of work at first hearing, but really is worth the amount of work it takes to do.

    First, tho, the background.....in early 1942, our government, and the 'War Production Board' in particular, was in quite a panic, to get volume production of many different sorts of war materiel items on line.

    One of the many 'bottlenecks' was the capability for manufacture of small, but very close-tolerance, turned parts. The optical equipment manufacturers, particularly, were over-whelmed with demand for parts which had, historically, been made on Hardinge and Rivett bench lathes, with tight turn dia. tolerances, and fine threads which had to be single-pointed to gage.

    One answer to this demand was to 'enlist' the many older small lathes held by thousands of small automotive shops and in private shops, by setting them up for tight-tolerance, high-finish work.

    The War Production Board issued a pamphlet describing this procedure, of which I had a copy, years ago (yes, I know, I should have had copies made, foolish me)

    Given an unworn small lathe, like the South Bend, the 'secret' to getting it to produce high-quality work lay in providing a suitable 'foundation' for the machine.

    The WPB pamphlet had drawings of the base design with they found to be the best system, a 'monolithic' casting of poured concrete.

    This involved first making up a plate of suitable size, with drilled or drilled/tapped holes for the lathe's mounting bolts. This plate was, preferably, 1/2" or thicker steel, but could be a suitable piece of hard maple plank, well sealed against moisture with spar varnish.

    The concrete base would be cast upside-down, with the lathe base forming the bottom of the pour.

    A simple plywood form would be built, with radiused internal corners of sheet metal tacked in, a near-vertical front edge with a bit of a recess for toe-clearance in the centre, and a suitable angle to the back to allow for a wide stance on the floor.

    The form would be provided with a suitable pattern of 're-bar' to strengthen or stabilise the base.

    Care would be taken to have the board or plate for the lathe level, before the pour, and then the top of the pour, which would be the bottom of the finished base, would be finished level and smooth, creating parallelism with the top.

    After the concrete cured, which would take two weeks to a month, owing to the thickness of the concrete, the forms would be stripped, the base turned upright, moved to its intended position, and provided with a three-point mounting of three thick, dense industrial rubber 'biscuits' suitably arranged, the same idea as the three-point mounting of a granite surface plate.

    With the lathe firmly bolted down to this very heavy base (with shims as needed to take any twist out of the lathe bed), the great damping mass of the heavy base greatly strengthened the lathe itself, in terms of removing vibration and resonances.

    The next step was to re-position the motor and countershaft to isolate it from the lathe. The motor and c'shaft might be mounted on the wall or on a bench or pedestal behind the machine, or mounted on the ceiling, if the ceiling height was low enough, as in a basement.

    (back during the war, many basement and garage shops ran three shifts making small parts....often, the housework would be neglected, and meals done 'from a tin', as home-makers spent their days, and evenings was well, making parts for the war effort.......an older gentleman I knew, years ago, had a job for awhile as a driver for a manufacturing firm, in which he 'made the rounds' of quite a number of basement/garage shops, picking up parts, and leaving dwgs/material for more parts)

    Anyway....if you can see your way clearly to investing the time and work involved in setting your South Bend up per the 1942 WPB specs, you will be well and truly impressed with the way in which it will do close-tolerance, high-finish work, much more easily than if it were set up on the common sort of bench which won't inhibit resonances in the same way that heavy base will do.

    I've been shown a few of these machines which were set up with heavy bases this way, and have operated a couple of them myself, one, in particular, which impressed me, was an early '30's 13" South Bend, probably one of the last of the 13" South Bends to be built as a 'bench lathe'.

    That one had been re-fitted and scraped-in during the war sometime, and was competitive with an EE Monarch or HLVH Hardinge for quality of work.....with certain limitations, such as lead-screw lead accuracy, to be sure.

    The plain-bearing spindle of a South Bend, set up correctly, is every bit as good for roundness and workpiece finish as is the EE or a Hardinge.

    (the lead accuracy of an unworn South Bend leadscrew is plenty good enough for the generality of the short thread lengths common in optical work)

    In practise, its owner made good money on it, making up lots of small parts which would have otherwise been run on a far more costly machine....it was a truly excellent example of practical cost-effectiveness.

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  3. #2
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    My father and I set up a SB 9 with a similar arrangement in the 50's. Ours differed in that we cast a ~4' length of I-beam into the concrete with lathe attachment points welded to the upper flange of the I-beam. The difference between the bench mounted version and the concrete/steel mounted version was night and day. Sure brings back some memories!

    Rigidity and mass are good things in the lathe business.

  4. #3
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    "The origin is a 1942 War Production Board bulletin, which has apparently been lost to history, but is well paraphrased by Carla."

    A copy is undoubtedly held within the Library of Congress collections in DC or Virginia.

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    I just got around to reading this thread. A few years ago, I needed a small lathe for a trade. I found a 9" South Bend with very little wear. This was for a repair shop that had no real machinists and would be used for things like turning commutators, not real precision work. Despite my unhappy experiences with similar lathes, I figured that it would be good enough for them. Getting it ready to give them, I mounted it on a 1/2" steel plate large enough to hold the motor and jackshaft unit as well, so it was much wider than the lathe mounting. Testing it, I was amazed at the quality of work I could do on it. Once again, there is no substitute for mass and rigidity. Just bolting a lathe like that to a workbench is depriving yourself of a large fraction of the machine's capabilities. I wish my father had known that when he set up the 9" Logan I got for Christmas, birthday, and everything else in my 13th year. It would have saved me a lot of frustration.

    Bill

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    A revisit to this thread reminded me not only of the father and son SB 9" concrete and steel project 60 years ago, it jogged loose an important experience in my now long gone career.

    Task: make 14" aluminum blanks for computer disk drives with at worst a 1 micro inch surface finish (mirror finish), flat to specs that don't make sense to machinists but they could measure and hold you to it. Let's just call it very flat.

    Millions were spent before it was tossed into my lap, all efforts failed. They had put in place immense air bearing spindle Pneumo lathes, 250K each 30 years ago. Single crystal diamond tools tuned to the sharpest achievable. Those immense lathes rested upon isolated massive foundations, they swung over 20 inches and had 200 lb brass vacuum chucks to hold the carefully heat treated 6061 blanks. The company poured resources in as a machined disk blank would be less expensive than a lapped one that was the one source which could meet their requirements.

    Those lathes performed perfectly once the motor was shut off, I was a hero. We spun the spindle up, cut power to the motor and no drama.

  7. #6
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    "Those lathes performed perfectly once the motor was shut off, I was a hero. We spun the spindle up, cut power to the motor and no drama."

    My ex-father-in-law was a machinist (inspector) at IBM on Cottle Road in San Jose, CA.

    Cottle Road is (was) the proverbial "home" of disk drives (RAMAC, etcetera, all the way until the entire division was sold to Hitachi).

    The platters, then, were indeed 14" aluminum.

    The lathes were specially made for IBM by Excello and did indeed use diamond tools.

    They did a magnificent job through the 1311 (pre-System/360), 2311 (early System/360), 2314, 3330 (early System/370), 3340, 3350, 3360, 3370, 3380, etcetera.

    By the 3390 (System/390), the product had been changed to 10" platters, whereas at my former employer (Amdahl) we had gone to 8" platters.


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