Lathe alignment (yet gain) - Page 2
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  1. #21
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    [QUOTE=jim rozen;3522594]
    Quote Originally Posted by neural revolt View Post
    Yes, I know, but this lathe can do a lot better than that ....

    Doubtful.

    Actually it will.

    But he's not listening. So you are right, doubtful...
    Last edited by Terry Keeley; 04-05-2020 at 11:47 PM.

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    I agree ,02 mm = .0008 inch. is a small amount and so small that very often setting a tail in a different place might take up or make greater that..so adjusting for each part needing near .0005 might the better solution.

    Perhaps make a chart for tail offset = change of taper for a give length..

    For OD and cylindrical grinding between centers we would touch an indicator at head and tail end and move one half of that error to very often get .00005 (fifty millionths) and better on the first try.. Often in grinding there is not try stock on the part that one can measure so be able to take another pass..Often we might hand feel the dressed wheel to the pre-measured part and use the cross dial numbers to tell the error and the adjustment...often this good for a tenth or so.

    also I think machining a long piece of stock and then measure at two ends is / can be a waste of material when to pre-measure both ends and the touch off with an indicator should tell less than .001 machine error. With machining even the wear to the tool bit or cutter can make some difference so machining a part may not a true measure of the machine related to different lengths, materials or diameters..

    The fastest wear/breakdown to any cutting tool is in the first few minuets of use.

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    I understand and agree with most of what people say, but right now I would like to try and set the machine right.

    I am not sure most people have read the first post. This lathe is in pristine condition. You'd be hard pressed to find any sign of wear anywhere. Hence my desire to give it a fighting chance to show what it can do.

    Right now I have changed tack and will try to measure twist with a long plumb bob to take out the head stock (and tail stock) unknowns. Tonight I have done the first measurement and there is a difference of about .5 to 1mm (more like 1mm) in the resting position of the plumb between head stock and the tail stock end of the bed, further out at the head stock. This is consistent with the results of the cutting test (front rail lifts at tail stock end/dips at head stock end). Not sure if it explains the entire .02mm difference I found (the head stock alignment is not checked yet) but it does suggest I am on the right path.

    I'll try to figure out a way to check head stock alignment and see what happens.

    Either way, it seems I do need something rigid under the lathe to push against when I try to remove twist.

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    Quote Originally Posted by neural revolt View Post

    [...]

    Took a skim off a bronze bar about 25mm diameter and I've got .02mm thinner at tail stock end again but this time with no tail stock support. Skim about 10cm long starting right at the chuck.

    I would say this is not consistent with the lump hanging off the back of the head stock, which would be expected to twist the bed down at the back of the left (head stock) side of the bed.

    My bed seems to be twisted the other way around, high at the back of the head stock end.

    [...]
    This interpretation seems to hold in light of the plumb experiment.

  5. #25
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    think about it as viewed from the tailstock end.

    which direction will push the cutting tool into the work and which will pull it away.

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    Let's try this.

    Any idea what the four extra threaded holes through the cabinet, under the bed are for?

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    Quote Originally Posted by Terry Keeley View Post
    Let's try this.

    Any idea what the four extra threaded holes through the cabinet, under the bed are for?
    Not sure what you're asking. There are only two holes, one at each end of the bed, central under the bed.

    The instruction manual shows another two under the head stock (either side of the central bolt) and and two under the tail stock and these are for alignment. But on my lathe (cabinet) they don't exist. Not sure if they existed on other versions of the lathe, the manual doesn't say and it doesn't say you need to drill these yourself, so I can only guess.

    Also, my lathe didn't come with the two thick plates the manual instructs to bolt the lathe to (through the cabinet, using the two central bolts) but this is a little bit more clear, because they recommend dimensions for the plates so I take it they expect you to make them (not sure why - how much can these add to manufacturing cost?). They also give recommendations for the "tightening screws" (i.e. the central bolts, so I take these don't come with the lathe either - flippin' 'eck!).

    Anyway.

    They also spec the holes for the alignment bolts and they instruct to thread those and show a picture how to poke them up from under the cabinet top through the non existing holes to push against the lathe casting either side of the central bolts. This is where I started to think they may in fact imply you need to drill those holes yourself. I was kinda hoping though someone with this lathe would come and let us know if theirs had the holes from factory.

    So yeah, I reckon I know what these extra holes are for, not sure what your point is. Perhaps you could contribute something more constructively if you read more carefully my posts rather than those of the undesirable know-it-alls with nothing better to do than insult strangers on the internet.

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    Quote Originally Posted by neural revolt View Post
    The instruction manual shows another two under the head stock (either side of the central bolt) and and two under the tail stock and these are for alignment. But on my lathe (cabinet) they don't exist.
    They are hidden from above. Look inside the cabinet, they are threaded and take screws that are used to twist the bed level or at least to make it cut straight.

    The blocks shown in the manual are only if you don't have the factory cabinet.

    Did you look at post 13? Or are you too busy telling people that are trying to help a noob that you already know what to do?

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    [QUOTE=neural revolt;3522782]... This lathe is in pristine condition.

    Like new - but not set up properly. 0.02 mm difference in turned size over 1/3 meter is about right for machine of that
    type. You left out a bunch of steps such has how this test was done, what the diameter of the stock was, what material
    it was.

    If one end was in a chuck and the other in a tailstock center, then toss the results out the window.

    If one end was in the chuck and the other end free, was the end near the chuck, the smaller diameter?

    Take the levels, the pumb bobs, the test bars, dial indicators, and the tailstock, and set them aside. You don't need them
    to dial the machine better than you have it now.

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    [QUOTE=jim rozen;3523014]
    Quote Originally Posted by neural revolt View Post
    ... This lathe is in pristine condition.

    Like new - but not set up properly. 0.02 mm difference in turned size over 1/3 meter is about right for machine of that
    type. You left out a bunch of steps such has how this test was done, what the diameter of the stock was, what material
    it was.

    If one end was in a chuck and the other in a tailstock center, then toss the results out the window.

    If one end was in the chuck and the other end free, was the end near the chuck, the smaller diameter?

    Take the levels, the pumb bobs, the test bars, dial indicators, and the tailstock, and set them aside. You don't need them
    to dial the machine better than you have it now.

    You left out how the part was measured (and with what) as well as any possible temperature variations.

    FWIW

    -Ron

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    Quote Originally Posted by Terry Keeley View Post
    They are hidden from above. Look inside the cabinet, they are threaded and take screws that are used to twist the bed level or at least to make it cut straight.

    The blocks shown in the manual are only if you don't have the factory cabinet.

    Did you look at post 13? Or are you too busy telling people that are trying to help a noob that you already know what to do?
    No, there are no holes threaded or otherwise, I looked from inside.

    Also, I see your avatar looks like my lathe, but I can see the pockets at the bottom described in the manual for the adjustable cabinet feet. Well, those pockets don't exist on mine either.

    And yes, I have read that post and commented about it.

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    [QUOTE=jim rozen;3523014]
    Quote Originally Posted by neural revolt View Post
    ... This lathe is in pristine condition.

    Like new - but not set up properly. 0.02 mm difference in turned size over 1/3 meter is about right for machine of that
    type. You left out a bunch of steps such has how this test was done, what the diameter of the stock was, what material
    it was.

    If one end was in a chuck and the other in a tailstock center, then toss the results out the window.

    If one end was in the chuck and the other end free, was the end near the chuck, the smaller diameter?

    Take the levels, the pumb bobs, the test bars, dial indicators, and the tailstock, and set them aside. You don't need them
    to dial the machine better than you have it now.
    See previous page:

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    [QUOTE=jim rozen;3523014]
    Quote Originally Posted by neural revolt View Post
    ... This lathe is in pristine condition.

    Like new - but not set up properly. 0.02 mm difference in turned size over 1/3 meter is about right for machine of that
    type. You left out a bunch of steps such has how this test was done, what the diameter of the stock was, what material
    it was.

    If one end was in a chuck and the other in a tailstock center, then toss the results out the window.

    If one end was in the chuck and the other end free, was the end near the chuck, the smaller diameter?

    [...]
    Yes, you are right, I didn't explicitly say the stock was in the chuck and supported with the tail stock. Someone however caught on and suggested a cut with no tail stock support, see post #3 and my response in post #4.

    As for the rest, first post, second sentence:

    Quote Originally Posted by neural revolt View Post
    Yes, yes same old problem.

    It's a Maximat Super 11 (I have seen the other threads, they don't answer my question) and I detected some taper in it by machining a long piece of stock at two ends, about 30cm apart. About .02mm.

    [...]
    And then further down, same post:

    Quote Originally Posted by neural revolt View Post

    [...]

    Well, it seems I do. I detected some taper in it by machining a long piece of brass stock at two ends, about 30cm apart (tail stock is properly aligned). About .02mm, thinner at tail stock end.

    [...]
    And then, there's other posts that mention these details again.

    The only thing I didn't mention is how I measured it, because I don't see how that matters. For the record however, I used a Mitutoyo micrometer, hopefully that is enough detail.

    Quote Originally Posted by jim rozen View Post

    [...]

    Take the levels, the pumb bobs, the test bars, dial indicators, and the tailstock, and set them aside. You don't need them
    to dial the machine better than you have it now.
    Interesting comment.

    What do I need then?

  16. #34
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    an endmill chucked in the tailstock?

    thats a whole nuther issue.....another variable.

    IMO you need to buy a dedicated test bar or learn how to do and apply the in situ two collar test.

    maybe i missed something.

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    no you are not missing anything, your misunderstanding perhaps comes from taking this dips hit seriously.

    I have to say, this is the single most entertaining post I've ever seen on PM! its just astounding the things he comes up with.

    I'm not QUITE rolling on the floor laughing, but this is good. can't wait to see what's next....


  18. #36
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    Quote Originally Posted by neural revolt View Post
    No, there are no holes threaded or otherwise, I looked from inside.

    Also, I see your avatar looks like my lathe, but I can see the pockets at the bottom described in the manual for the adjustable cabinet feet. Well, those pockets don't exist on mine either.

    And yes, I have read that post and commented about it.
    So you DO NOT have the screws shown as part #9 on pg. 24 here? https://groups.io/g/EmcoSuper11lathe...vice_parts.pdf

    You have to look inside the cabinet on both left and right side to see them, they cannot be seen from the top.

    Yes, I have a S11 and aligned it as in post 13 with a test bar. It cuts dead nuts straight now that the bed is straight ("leveled") and the headstock is aligned to the bed. If you don't have a test bar you do the "two collar method" in the second link in post 13 to twist the bed so it will at least cut straight close to the headstock.

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    Quote Originally Posted by iwananew10K View Post
    an endmill chucked in the tailstock?

    thats a whole nuther issue.....another variable.

    IMO you need to buy a dedicated test bar or learn how to do and apply the in situ two collar test.

    maybe i missed something.
    Well, I agree this comes with its own unknowns, but it has one big advantage. It is the best option available to me, now.

    I did mention I don't have the option of using a test bar right now and I think it is premature anyway. I think we can safely assume the lathe is not set up correctly and it may have every misalignment issue possible. What is misaligned and by how much becomes a moot point when I can't align it.

    So. For the last time. Is the idea of placing a slab of steel under the lathe and use that as a rigid base to push against worth the effort? Again, of all the options, this is the one available to me right now.

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    Quote Originally Posted by Terry Keeley View Post
    So you DO NOT have the screws shown as part #9 on pg. 24 here? https://groups.io/g/EmcoSuper11lathe...vice_parts.pdf

    You have to look inside the cabinet on both left and right side to see them, they cannot be seen from the top.

    Yes, I have a S11 and aligned it as in post 13 with a test bar. It cuts dead nuts straight now that the bed is straight ("leveled") and the headstock is aligned to the bed. If you don't have a test bar you do the "two collar method" in the second link in post 13 to twist the bed so it will at least cut straight close to the headstock.
    Well, it took two pages of going around in circles, but we see the light now.

    I assume you assume I have only ever seen the lathe attached to the cabinet. That is not true.

    I did not mention this, but when I received the lathe it came to me disassembled, so I think I wouldn't have missed four big gaping holes in the cabinet tops. But I did (pointlessly) look inside and I can certify under oath they do not exist, let's put that to rest.

    I also mentioned my cabinet is a bit different not only that it doesn't have the holes or the plates that appear to have existed at some point in the run on these lathes as pictured in the manual (there are some cross sections through the bolt holes and there you can see the plates welded o the underside with the set screws threaded and poking up through the cabinet top). It does however have two strips of 50x5mm steel welded every 10cm or so along the top inside the head stock cabinet, about 15cm apart, parallel to the bed direction and attached with the 5mm side to the top cabinet skin. The one bolt hole I have is in the middle of this 15cm space. There is no mention or picture in the manual to show these rails (the cross section pictures in the alignment chapter do not show these rails exist) so I take it my lathe might be a very late one in the run and they did away with the plates, extra holes and so on for some reason.

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    Quote Originally Posted by neural revolt View Post
    Well, it took two pages of going around in circles, but we see the light now. Yes, I did look for those holes from inside the cabinet. They do not exist, let's put that to rest.

    Then you do not have the factory stand.

    You can then use the two pieces of steel with jacking screws as shown on page 9 here, one under each mounting screw at each end of the bed:

    https://groups.io/g/EmcoSuper11lathe...%201-13%29.pdf

    Bolt the lathe down through the steel plates into the cabinet (I know it says the plates have to be fixed to the "workbench" but you've got a cabinet) and using a wrench move the screws a little at a time (corner to corner) to twist the bed slightly so it cuts straight. YouTube

    Leave the tail stock out of it, that's something else completely.

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    neural revolt: You did not mention how you know or how you went about determining that the tailstock is perfectly aligned with the headstock. Or, more accurately, how the headstock spindle bore is aligned with the tailstock spindle bore. Since the test you are trying to stake this project on depends very much on how, exactly, they are aligned and by how much I for one am very interested in how you accomplished this. Please tell us.
    You mention the best measuring instrument you have is a dial indicator that reads 2mm (or do you mean 0.02mm?) I suggest since you are trying to align things to a measurement less than the finest division on your present instrument that you get a finer instrument. You need one that reads reliably to 0.0001 inches per division (or about 0.002 mm/div)

    It is never premature to have a good test bar. Especially since you are about to undertake something that requires a lot of effort. A decent one good to 0.0001 inches is not very expensive (about 1/4-1/3 the price of a decent dial indicator.) Since you are a hobbyist you have plenty of time to order (or save up and order) the necessary instruments and standards.

    In the mean time you can get familiar with your 'new' lathe and practice making prefectly good parts even with the errors.


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