1928 "Ehrlich" Lathe
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  1. #1
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    Default 1928 "Ehrlich" Lathe

    Heyho!

    I've been meaning to get a metal Lathe for a few years now; but it was always low on the priority list.
    But I do keep looking at e.g. ebay from time to time for new offers.
    This one I just couldn't resist. Price was 350Ä

    I got myself an "Ehrlich" Brand Lathe from 1928(!).
    Unfortunately there is Zero information about it online (apart from a written article), and It didn't come with any manual. If anyone has any information on it, that would be awesome!
    The previous owner had it in his garage over decades, practically unused. If anything he was using it to turn wood with it, not metal.

    This meant that it was in near perfect condition. No rust, no obvious bent/missing pieces, etc.
    Upon disassembly I also found that there was not a single tiny metal chip anywhere in the machine, not even in very hard to clean places.

    I have documented the restauration process and made a video of it, for anyone interested. Link below.

    I am pretty new to the whole metal machining world, infact this is my very first metal machining-machine. Any tips would be helpful! :)


    Here are some Photos and specs of the machine:

    Length between centers: 110cm (42")
    Max Diameter: 38cm (15")
    Max Diameter with bed section removed: 65cm (25.5")
    Spindle bore: 5cm (2")

    2.2Kw (3hp) 3-Phase Motor, 400V @1500rpm - forward and reverse
    4 speeds via flatbelt ~110rpm-800rpm
    36-Speed Screwcutting Gearbox
    Seperate Threadcutting and Surface power shafts.

    Weight roughly 700Kg (1550lbs)

    img_8623.jpgimg_8624.jpgimg_8625.jpgimg_8626.jpgimg_8633.jpg

    I know that, for a beginner, it may not be the perfect first Lathe, beeing that old. Missing some features that are just a given on newer lathes now. I hope to get some good use out of it though.

    One big question I have is about the bearings, or should I say bushings. The Spindle is running in huge tapered bronze(?) bushings. I tried my best to set a preload on them, while still having them run easily - So far its all seeming okay, but the front bearing stays completely cool while the back one gets ever so slightly warm (after about 1 hour runtime). Its not even warm enough to call it lukewarm, but its not cold anymore. Any tips on that?


    I hope I did this old Lady justice in restoring it and bringing it back to life.

    Video: YouTube

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  3. #2
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    Very nice work.
    Here is a page about Ehrlich on Tony's site in case you haven't seen it before .
    Oscar Ehrlich Lathes
    There have been a few other Ehrlich lathes shown on this forum in the past .
    Possibly another one here Looking to identify a lathe. Any help would be appreciated.
    a link to others that I posted in thin the above link as well
    Vintage Lathe ID
    Regards,
    Jim

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    "One big question I have is about the bearings, or should I say bushings. The Spindle is running in huge tapered bronze(?) bushings. I tried my best to set a preload on them, while still having them run easily"

    Only ball and roller bearings can be preloaded. Plain bearings or bushings have to have enough clearance to maintain an oil film to prevent metal to metal contact. The lathe should have some provision for keeping oil in the spindle bearings and for adding fresh oil.

    Larry

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    Ahh.....Der Rote Baron.
    (looks good)

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    That is rally nice lathe.I would imagine that it was a pretty expensive machine in its time,well built for its size..I think you made out really well.

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    Hmm yeah, I did notice that as soon as a little pressure was on them they would lock up really quickly. With preload I should have been more specific, I mean just enough so they arenít lose and wiggle side to side.
    Both taper face the same direction after all.

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    Thank you very much. Yes, the article you are referring to is just the one I found, and beeing pretty much the only thing I found.

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    I've read that company name before in regards to WW2-era Kar98k production. IIRC they supplied parts and machinery to the various subcontractors that supplied parts to the Gustloff Werk Suhl for rifle production. That company was known for having very little in-house manufacturing, but relied instead on parts made by a string of companies called the 'Saxon Group'. Might be worth doing some research in that direction.


    Fine restoration, thanks for sharing.

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    In the fourth picture it looks like an oil hole in the bearing cap. I would assume there is one in the other cap too. I would get some drip oilers for them. And it sounds to me like you have the bearings adjusted OK. Just make sure they ALWAYS have oil.

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    Nice looking machine!

    Can you post larger photos? We do like our tool porn here, but this thread will also be a resource for other people trying to identify similar machines.

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    Here are some more pictures, inside stuff and the bearings, well bushings.

    img_8594.jpgimg_8595.jpgimg_8495.jpgimg_8555.jpgimg_8580.jpg

    Here's an Imgur Link with high-res versions of the photos, including some more Photos: Ehrlich Lathe - Album on Imgur

    IF anyone wants a specific shot from something, I probably have it, so ask away!

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    Marco:

    Regarding the bearings in your lathe: We refer to this type of bearing as a "plain bearing" (meaning a bearing having no 'rolling elements') such as a bearing lined with bronze, white metal (Babbitt), or cast iron.

    To adjust the bearings in your lathe, the adjusting nuts at each end of each bearing set the clearance in the bearings. A basic procedure for checking the clearance in plain bearings in a lathe headstock is:

    1. Slacken the belt to the headstock cone pulley and disengage any gearing to the spindle (back gears, feed gears). Remove any chucks or other heavy attachments on the spindle if possible.

    2. Mount a dial indicator so its tip contacts the spindle at 12:00, close to the front headstock bearing. Put a pre-load on the indicator and set its dial to zero.

    3. Put a stick of hardwood such as a hammer handle as a lever into the spindle and push down as hard as you can. This squeezes the oil out of the bearing, and causes the spindle to "bottom" in the bearing. You may see the indicator needle move in the "-" or minus direction.

    4. While holding down on the hammer handle, re-set the indicator dial to zero.

    5. Pull up on the hammer handle with about 35-50 Kg of force. Read the dial indicator. It should have moved in the " +" direction. The amount the dial indicator reads is the clearance in the spindle bearing.

    6. I do not know the diameters of the spindle journals and bearings, so cannot tell you a clearance value that the bearings should be set to. As a rough guess, the front bearing should be adjusted to somewhere around 0.0015" (approximately 0,05 mm)

    7. A check I do when adjusting plain bearings in lathe headstocks is to try turning the spindle by hand after the adjustment is made. The spindle should turn smoothly with no jerkiness (sudden hesitation). It is not an "official" test, but I like to get the spindle turning as fast as I can using my hands, and then let the spindle come to rest. If the spindle "glides" smoothly to rest and does not stop suddenly, chances are your bearing adjustment is good.

    8. If you have the bearings adjusted to good/reasonable clearances, the next step is a "heat run" (Probelauf). Start the late under power at its slowest spindle speed (not in back-gears, but in direct belt drive). Feel the spindle bearings with the back of your hand. If they seem to be getting hot quickly, stop the lathe, and pour in lots of oil. You may have to loosen the adjusting nuts on the bearing that was getting too hot too quickly. Rule for plain bearings: if you cannot keep your hand on the bearing, it is too hot, and likely is adjusted too close a clearance.

    9. When the bearings reach a steady temperature at the lowest spindle speed (the bearings may not warm very much at the low speed/no load test), shift the belt to the next higher speed, and repeat, checking temperature rise. Keep repeating this test until you have the lathe running at its fastest spindle speed. If the bearings feel warm, but not hot enough to cause you to take your hand off them, keep the lathe running for 10-15 minutes and make sure that is the maximum heat the bearings get up to. If the heat is "comfortable", the bearing adjustments are OK.

    10. final test is a load test. Chuck a piece of steel maybe 50 mm in diameter in the lathe and take a series of turning cuts on it, working up to heavier cuts. If the spindle bearings are correctly adjusted, and your cutting tool is correctly ground and positioned, you should see a smooth surface finish. Under load, the bearings should not get any warmer.

    Lathes using the tapered bronze bearings and these are a bit easier to adjust (in my opinion). No shims to have to make up, and clearances can be precisely adjusted with the adjusting nuts. I have adjusted spindle bearing clearances in lathes with "split bearings" using shims, and also in lathes with the tapered bronze bearings.
    Either way, the method of checking clearance is the same. On larger/heavier duty lathes, I use a pry bar and a piece of aluminum or copper (to protect the spindle) to lift the spindle to check the clearance in the bearings. On smaller lathes, I use a hardwood hammer handle stuck into the spindle as a simple lever.

    Plain spindle bearings need a little clearance for the oil film between the spindle and the bearing. When the spindle is turning in the bearing, it actually rides on a wedge-shaped film of oil. On a lathe spindle, setting the clearance is a fine balance between having enough clearance to maintain this oil film and too little clearance (meaning a "tight bearing" which will run hot and probably seize). Too much clearance and the spindle is "sloppy" in the bearings, and the spindle will move relative to its centerline when taking cuts on the work (and you see it in the finish on the work). If you have had a lathe apart, it is a good idea to check the clearances in the spindle bearings before using the lathe. It is also a good idea to do a "bearing heat run" to be sure the bearings will be OK at higher spindle speeds. We used to try to get what we called a "running heat" on this type of spindle bearing, particularly on smaller size lathes where spindle speeds would be higher and where smaller diameter/more precise work was to be done.

    After you have adjusted spindle bearing clearances and done some work on your lathe, it is a good idea to re-check the bearing clearances with a dial indicator. The bearings may have "seated" or the spindle "bedded into" the bearings. Chances are you will not see much change in dial indicator readings, but it is a good idea (at least in my opinion) to re-check clearances in the bearings after some jobs have been run in your lathe. Once the bearings are seated in, if you keep the lathe properly oiled, you may be many years before you have to do any more adjustment to the bearings.

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    Hey,

    Thank you very very much for your detailed instructions!!

    From just reading it Iím guessing that my back bearing is set good, because itís getting slightly warm, but far from uncomfortable, while the front one stays completely cool.

    I had a dial indicator on it, but pulling just by hand I didnít see much movement.

    I did take a heavier cut (about 80 thou) in some 40mm cold rolled steel. No chatter that I heard but I do have problems with surface finish.


    I was planning on taking the spindle out and apart for cleaning soon anyways (didnít properly clean it inside while Restauration)
    -so i will definitely use your advice for re-seating.

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    Marco, I really like your meticulous restoration of this fine machine, It has in its day been a high class product, My only concern is that I feel you are running her rather fast (Remember she is an old lady!) I imagine by the pulleys on the countershaft primary drive she had been speeded up for woodturning .

    On the lowest speed on the back gear I would look for approximately fifteen revolutions per minute,, remember in those far off days when she was made, Machining speeds were much slower than today, Plus for screw cutting, and also achieving a nice scraping cut with a broad faced scraping tool for a finishing cut removing only about 0.002" deprth of cut and a course feed say 0.006"/revolution
    have the workpiece lubricated with soluble oil a glass finish should be the order of the day More posts on your further experiences with this lovely machine will be greatly appreciated by us all.

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    I second what Cutting Oil Mac has to say about keeping spindle speeds low. At the time that lathe was designed and built, cutting tools were often high-carbon tool steel, forged and tempered by the machinists themselves. Low cutting speeds were all the carbon steel cutting tools could be run at. High Speed Steel tools were also in use at that same time, and allowed somewhat higher cutting speeds. Whether carbon steel or high speed steel cutting tools are used, fairly low cutting speeds (and corresponding rpm or u/min) are needed.

    I am old enough to have "come up" using high speed steel cutting tools. For lathe tools, on older lathe, high speed steel tools will do a surprisingly good job. We learned to hand-grind our lathe tools by eye, and then dress the cutting edges with a small oil stone. A properly ground high speed steel tool in an old lathe can produce a surface finish that will look like it was precision ground and will not need any polishing with emery cloth. Carbide tools have their place, but on an older lathe like your Oskar Ehrlich lathe, I do not think there is any advantage to using them. You may find the high speed steel tools are all you need and get a better surface finish once you develop your skill at grinding them. High speed steel tool "blanks" are not expensive and you can grind a tool at either end of each blank, getting "two for one". You can also re-grind the high speed steel tools many times over, or re-grind them to suit a particular job. If you need to grind a "form tool" for cutting threads or cutting grooves (as for "O" rings, retaining rings, etc), you can easily do it with a high speed steel tool blank. The other advantage is you can grind the high speed steel tools on an ordinary bench grinder with an aluminum oxide grinding wheel. I have learned over the years that for most work, if the geometry of a lathe tool is correct, the angles the tool is ground to do not have to be exact. It is only when grinding threading tools or special form cutting tools that angles and geometry have to be exact. For turning and facing work, grinding cutting tools to the correct geometry without trying for exact angles will work just fine.

    For turning steel, I use a cutting oil that is also used by plumbers for thread-cutting on piping. It is a mineral oil with sulphur and lard compounded into it. I put it on with a brush and it works quite well. It is what we used in working machine shops when turning, boring, drilling, milling carbon steels. For turning or drilling aluminum, I use something thin like penetrating oil (something like WD-40, or kerosene, also known as "paraffin").

    Make sure to lubricate the bronze bearings and all other lubrication points before you start your lathe. I keep pump type oil cans handy at my older machine tools and "go over" the oiling points with the oil can before I start up the machine tools. I use an ISO 46 oil in my old machine tools, having used that type of oil for many years. What is needed is a "plain mineral based oil" with a "straight weight" (not multiple viscosity oils as are used in automobiles). I use "tractor hydraulic oil" in my machine tools. This is ISO 46 turbine oil with anti-corrosion and anti-foaming additives. No other additives needed. Tractor hydraulic oil is also known as a "DTE" oil, with DTE = "dynamo, turbine, engine". This is an ancient oil classification that is older than automobiles. It is a classification of oils still used in industrial and power generation work. For your old lathe, this is all the oil that is needed in the spindle bearings and other oiling points. You might get a "way lube" (an oil with some stickiness or "tackifiers" in it) formulated for sliding surfaces. This is used on the bedways and cross slide, topslide, lead screw (leitspindel). I personally use "bar and chain oil" as is used in chainsaws. This bar and chain oil is basically a "waylube" and is sold in local stores, as is the tractor hydraulic oil.

    To repeat what Cutting Oil Mac said, slow the lathe's drive speeds down ! Neither the lathe nor the type of cutting tools it uses for cutting steels were ever meant to be run so fast as a lathe used for wood-turning.

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