HSS Era Lathe Performance
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  1. #1
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    Recent thread on super lathes enthused me to go looking for these. Both from early to mid thirties, about tail end of makers trying to sell HSS based performance. First is from Pratt & Whitney in the marvelous Model B catalog. Second from Reed Prentiss. Notably two makes that never made it to the "super" category. The 3/4" DOC and .112 IPR feed on the RP is impressive, as is the "handful" hogging chip from Pratt & Whitney. Largest lathe from either maker at this perid was 20". Also amazing is the unsupported cut on the RP. Both these makes were plain bearing machines. Leads one to appreciate what the more capable makes could do, even though so far I have no photos. Thanks to P&W and RP for bothering to photograph what these could do. On edit: Note for their acid test RP selected tough old 3140 nickle steel.





    John

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    There are members of this forum who can say when the crucible steels were developed and when the high speed steel versons were first available.

    There is always a time lag between when such tools come on the market and when those tools become popular enough to be in general use.

    As a reference point I use my copy of "Machinery Magazine" from 1919.

    Cone pulley driven machines were very much still in vogue. Manufacturers like Monarch had both geared head and cone pulley lathes pictured side by side on their assembly floor.

    Both high speed steel and Stellite tool bits were advertized. There was even a "Uraneum" tool steel advertized although the manufacutere didn't verify that the element was used in their alloy.

    We might then date the HSS era from about 1920 or so.

    One characteristic of the second tier lathe manufacturers was the addition of the geared head to their already patterned iron. Change boxes, aprons, tailstocks and beds didn't change.

    Carroll-Jamieson was a prime example. Right up until the late 1960's the CJ lathe bed and apron and tailstock was recognizable from their 1920's lathes. The thread change box only underwent cosmetic changes.

    As I constantly harp, you can do an amazing amount of rough cutting with HSS if the cutting tool has significant rake and is fed heavily at slow cutting speeds.

    This is the HSS era lathe performance criteria. A heavy, strong pulling lathe that doesn't necessairily run at fast rotative speed.

    Since the speed is low, the torque at the spindle can be very high while the power requirement can be held under 10 HP and in most cases to 5 HP.

    I digression here: In Monarch's publication "Feeds and Speeds For Better Turning Results" (1957) they strongly allude that you can move much more metal with heavy feeds than you can with high spindle speeds. The advise carried over from the HSS era into the Carbide era unchanged.

    So, if you want a line of demarkation between HSS lathe era performance and the Super-Lathes of the carbide era just look at the increase in overall machine strength, the increase in available top end spinlde speeds and the increase in total power applied.

    Most of the general purpose workshop lathes that you will find in a typical machine shop are HSS era lathes when judged by the above criteria. This is regardless of whether the machine is American made or not and it is regardless of the age of the lathe.

    You might want to look at it this way. The economic necessity of the Super-Lathes came and went. The economic reality of the need for a reasonably priced general purpose lathe was always present and has never gone away.

  3. #3
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    Great pictures, John. I don't suppose the operator felt too relaxed when taking the 3" wide cut in the last photo.

    It’s hard to say when HSS tools caught on in a big way, but Taylor and White did their development over 25 years starting in about 1880, conducting over 50,000 experiments, mostly at Midvale and Bethlehem Steel.

    As far as the lathes are concerned, I came across an example in ‘The Engineer’ of 1903 adapted by Armstrong Whitworth of Manchester for experiments on their own HSS tools, and some details may be of interest. To be honest, I don’t suppose they will, but I’ll carry on anyway. The lathe was modified from a standard machine used for machining armour-piercing shells. The four step cone pulley was replaced by a two step one to accommodate a 7 inch wide lineshaft belt. As far as I can make out from the photo, it looks like a steel link belt, like a toothless silent chain. The other change was that the final drive was taken by helical gears.

    The gear drive was similar to that on this later (1911) lathe built by Armstrong Whitworth for experimental purposes:-

    http://www.practicalmachinist.com/cg.../11/1720.html?

    This had its own 60 HP motor and a means of measuring tool load by hydraulic pressure.


    The following link is a PDF file, and 90% of the way down is a graph of year against relative cutting time for the various classes of cutting tool materials, showing the acceleration that occurred:-

    Machining time

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    This is somewhat related to the threads but I believe that the lathe manufacturers were responding to demands placed upon them by industry.

    For example, I am currently reading a book about WW1 German raids on England. People in WW1 were starting to grasp and place bigger demands on industry which the industry needed to develop. Engines, airplanes and navigation had not evolved yet to make the attack of Britian from the air truly feasible until 30 years after it was first concieved by the Germans in WW1.

    Couple that with the Cold War and Space Race and the change over in machine tools designs start to make sense.

    Just my 2 cents.

    Rick

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    Rick,
    To make a very tenuous link: in JimK’s super-lathe post I mentioned WW2 munitions being machined on special lathes made by Garrett’s of Leiston, and that I’d recently visited the museum in Garrett’s old works. This has on display some remains of Zeppelin L48 that crashed a few miles away. Zeppelins caused a fair bit of damage, and were not as vulnerable to attack as I would have expected, because they flew too high for attack by aircraft. In the case of L48, I think there were engine problems, the crew were suffering from cold, and the compass was frozen. They decided to come down to 13,000 feet, and were then attacked by a fighter firing incendiary shells.

    I’ve just recalled another war-related link to cutting tool materials. In the 1930s, Metropolitan-Vickers Ltd wanted to end dependence on Europe for supplies of sintered tungsten carbide, and developed their own range, starting with titanium carbide. These materials were sold as tool tips under the name ‘Cutanit’. Vast quantities of these carbides were produced by M-V in WW2 and received by the German forces in the form of armour-piercing shell tips.

    Regarding JimK's 'Uraneum' tool material, I have just the machines for those tools, in a dealer's catalogue from the early 1960s: some beefy shapers with the brand name 'Atomic'.

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    Asquith:

    A fat hippie chick who I knew in the '70's said that her boy friend drove the Atomic Salami Truck.

    I could never find that name amongst our American truck makers.

    Would that be a British vehicle??

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    Atomic Salami truck? You wouldn't want to stand too close to the *radiator* on one of those

    Not British, Jim. In fact I'm pretty sure the 'Atomic' shapers weren't British. They looked stylish, so probably Italian.

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    Atomic Salami Truck.... now if that ain't just suggestive as hell.

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    [img]tongue.gif[/img]

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    Asquith,

    I just read about the L48 crash yesterday. It again it points to the fact that people were putting demands on industry for better more reliable stuff and it took industry awhile to respond. Alot of the Zepplins never reached the UK becuase of mechanical failure in the engines.

    Look at the inital Me-262's if I remember correctly they were replacing engines after fewer then 4 flights. What is the replacement cycle on jet engines now?

    Rick

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    :rolleyes:

    Five out of nine totally unrelated. We can do better.

    John

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    OK, John:

    The two topics concerning lathes here were centered on engine lathes used for medium and small lot production.

    By the 1920's the Sundstrand, the Fay and the Seneca Falls Lo Swing lathes were the best known production lathes. They were made for mass production.

    These lathes were cahracterized by the use of many cutting tools and the separation of the longitudinal feed functions from the cross feed functions.

    A production lathe may turn a shaft length of 20 to 24 or more inches in length but the carriage would move only about 1/4 or 1/3 the distance. The turning tool cross slide would operate on a box cycle.

    The carriage starts at the right hand limit. A flat cam advances the turning tools to depth in the first part of the right to left move. The cut is completed, the tools are retracted and the carriage returns under power to it's far right start position.

    If there are cross slide operations the rear cross slide advances rapidly, slows to the feed rate, takes the forming, chamfering and necking cuts, dwells and then rapiddly retracts.

    The addition of the two above cycles constitutes one machine cycle. The work is always complete in one machine cycle.

    Obviously a shaft or other kind of part would need more than one machine cycle to finish, so production lathes were usually used in pairs.

    Automatic production lathes are univesally HSS era machines. Their main object was to use as many different cuting edges simultaneously so as to divide the cutting forces and the tool wear amongst the greatest number of working edges.

    Even a straight turned outside diameter may be cut by two or three turning tools. These would be mounted on the same tool holding fixture as the tools thet turned other stepped diameters on the same shaft. Not only would the cutting work be divided, but the machine cycle time would be reduced.

    Needless to say that the tooling cost, the set up time and the time for change over are horrendous. These lathes are mass production machines and usually not found in general industry.

    The automatic production lathes benefitted greatly from the brazed carbide shank type tools, that benefit accruing mostly from increased edge life and not from increased operating speed or feed. HSS or Carbide these machines were noted for their fast cycle times.

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    Thank you sir. See also my thread on the L&S Manufacturing Lathe. In the same mid-twenties catalog are the first Duomatics, something I had first hand experience with in the early seventies at Reed Roller Bit here in town. The catalog bothers to have many photos of set ups - all with muliple HSS tools - roughing in rear slide and finishing in front slide.

    John

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    John:

    The L&S Duomatics were different from the above mentioned lathes. As it was any Duomatic could be significantly different from any other. The machine was used as the chassis for many highly specialized set ups.

    The ordinay vairety had a carriage and a single narrow cross slide. The cross slide had a manual adjustment of finished OD. The carriage was screw fed rather than cam fed, this gave the machine a little more versatility and ease of set up. Most if not all cross slide operations were taken by one of the optional rear cross slides offered.

    There was also a rear carriage that was functionally the same as the front one. Machine cycles were set by trip stops, there were no cycle cams.

    The Duoamtic survived into the early 1950's.

    The later Duomatic had brute power (30HP) and a top speed of 1996 RPM. Definately a brazed carbide era machine.

    Mention was made of shell making. The USA, even by WW I had the automatic production lathes. Shell work was easily adapted to these already special purpose machines. OD's were turned by a cross carriage using a modified cycle cam for the contour.

    Boring set ups featured specialized rests with work holding and rotating bearings out board of the head stock.

    Again, a flat cam guided the tool for the internal profile.

    The basic machines were already invented, shell making was just another 'special' that got tooled up for USA style mass production.

    Now we have five out of fourteen off topic. No more Atomic Salami Truck.

    Now, who else has lathe stories?

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    Wonder what kind of lathe turned the axle shafts for the Atomic Salami Truck?

    There. Now they are all on topic. You are welcome.

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    I am confused. Experiments with HSS were going on in the late 1800's. My American Tool Works 20" is masive and shows a 1903 patent date. Is it a HSS machine or is it a stelite machine? I was previously unaware of Stelaite's use for cuting tools. I only had heard of it being used for valves in engines?

    Mike

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    I am confused
    Don't be:

    Your ATW likely used lots of carbon tool steels, later in life lots of high speed steel, and the occasional chunk of Stellite.

    John

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    As Jim points out, the vast majority of lathes ever built are best compatible with HSS tooling as far as hp and spindle speeds are concerned.

    Your ATW is actually bordering on being a carbon steel lathe at that age. The big Dreses radial drill at work has a plate giving speeds and feeds for certain sized holes, at the bottom is a note to double these figures for HSS. It's probably about as old as your lathe. What is top speed? That's a good indicator. It'll need about 70ft/min at 16-28" diam to use HSS to best effect. Carbon steel would be half that. Your lathe is massive to handle a solid cast iron 16" diameter part full length between centers. It is probably capable of supporting several thousand pounds in work alone. You could literally park an Atomic Salami Truck on the bed and it wouldn't break (heheh, how's that for relevance?!).

    Maybe the gear head lathe was the line that marks the entrance of power, speed and rigidity required to really run HSS to max gain. With a backgeared cone head lathe, you still had an awful lot of loss through the belts. Flat belt to the countershaft and then a flat belt to the cone pulley. If each was 80% efficient, you have still lost 40% by the time it gets to the work. Reduce speed in an attempt to get more torque and the belt efficiency goes down even further. You could end up with 50% or so of what is actually being creaed by the motor or lineshaft. With a single belt and gear transmisison, you could cut that to 20% or so and it wouldn't change with speed changes as the belt speed remains constant. You wouldn't want a multi-speed belt-drive Atomic Salami Truck, it wouldn't pull a hill very well at all due to belt slippage (pretty good, eh?). Same with lathes.

    As for Stellite, it may have not been long-lived enough to have convinced builders to make lathes able to take advantage of it. If a real heavy HSS lathe could push it hard enough, why upgrade? Carbide wasn't but a few years behind and light years ahead. Why have a baloney sandwich when instead you could have... heheh... SALAMI! delivered in.... what else?

    BTW, here's where you can order an Atomic Salami Truck... http://www.atomicequipment.com/ I'm sure they could build one up for you. They'd need to know if it was cotto or hard and what size loaves to expect.

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    There are certainly issues getting power through
    a belt, but as an old farmer who used to have belt driven equipment around, we learned that long belts worked better than short belts, and of course the high ceilings provided space for longer belts.

    The only thing I'm not sure about is whether the vertical configuration was a negative in improving the efficiency. When they were set
    horizontally, the weight of the belt served
    as the tensioning mechanism.

    And I'm not talking about 5 feet vs. 10 feet either. the guys running threshing machines would get a belt that would allow the tractor to be parked a 100 feet away. then give the belt a twist (half a twist if you needed a directio change or a full twist if you didn't so it wouldn't flap around and you were ready to go.

    When we were in the hog business we had a feed mill with a drive pulley that was about 5"---small because the hammer mill needed high RPM and the tractor belt pully only turned 1000 rpm.

    We had best results with an endless leather belt that we had made in a belt shop in portland.

    We were moving 50 hp through the 4" belt, but probably at more speed than is typical of machine tools as our power source was a 2 cylinder John Deere diesel turning at 1000 rpm.

  20. #20
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    When you want to move a lot of power through a flat belt you have to have big diameter pulleys and run them at high (relatively) speeds.

    Lathes had back gears because of the limitations on head stock pulley diameter. Of course the slow speeds in back gear had other advantages, especially when cutting screw threads.

    The HSS gear lathes were characterized by the elevation of mid range speeds. The additional speeds offered by the geared head transmission were all in the ranges above normal back gear speeds and clustered under the highest one or two spindle speeds.

    Lathe and milling machine manufacturers chose gear ratios that allowed the spindle speeds to be arranged as close as possible to a geometric progression. Remember, as work piece or milling cutter diameters get smaller, their rotative speed has to increase in a hurry to maintain the same surface speed.

    Atomic Salami Trucks are still with us, at least that is what I gather from hearing guys who say that they drive one.

    The hardened axles must be worked on Super Tools due to their legendary length and diameter.


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