Lathe alignment (yet gain)
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  1. #1
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    Default Lathe alignment (yet gain)

    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.

    Now here's my dilemma.

    The instruction book walks you through an alignment procedure that relies on two thick steel block/plate (one for tail one for head stock) you are supposed to make (lathe didn't come with these to me) and install under the cabinet top plate with two bolts coming from above to clamp the lathe at one point underneath the head stock and one point at the tail stock. Now, at the head stock you are supposed to drill and tap the plate for two bolts to come up from underneath, through the cabinet top and pushing up against the headstock casting feet on either side of the clamp down bolt. These two bolts are used to adjust for twist in the bed, I guess.

    Now, that is fine, I get it, but my cabinet doesn't have the two holes these two screws are supposed to poke through the cabinet top and the whole lathe is in such a pristine condition I can't bring myself to start putting holes in it.

    Another detail, just in case. My cabinet (the original factory Emco) has two thick (50x5mm) flat reinforcing bars running (welded every 10cm or so thin side on) under the top plate on the head stock side to give it some rigidity I suppose (it's all obviously factory) but like I said, no holes for these two adjusting screws. I mention this because I am not sure all cabinets are the same (after all mine doesn't have the two holes or provision for adjustable feet as pictured in the manual).

    So I made these two blocks from 25mm thick steel, but only used the clamping bolts through as yet.

    I put the cabinet on some sturdy frames with adjustable feet just to keep it off the ground and leveled everything as best I can (no machinist super duper level here). I used a precision digital level (or three) and I get consistent readings along the bed, all at 0 (with whatever precision these things have - my guess is pretty good but not prefect).

    I just wanted to see if I had any twist to worry about before I started drilling or coming up with a solution.

    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.

    Adjusting the feet on the frames I made (there's eight of them) works brilliantly to move the whole lathe in the desired position, but it does nothing to twist. So I loosened all the bolts in the stand/cabinet, chip tray, etc. just to see if that makes any difference, but it doesn't. Measured with all these loose/tightened up everything comes up the same so I would say the twist is not imparted by the stand pulling the lathe this way or that.

    The cabinet is made of pretty thick steel (3mm), but I would say the way the lathe is bolted down (two bolts, one at either longitudinal end) doesn't lend itself to correcting twist so I'd say I need to use the twist correcting method suggested in the manual.

    Now as I said, I would like to avoid drilling the cabinet, so I was thinking of getting a thick steel plate (say 25mm or so) to run underneath the full length of the lathe from head stock to tail stock and sandwich that in between the lathe and cabinet and put the two adjusting bolts at the head stock end through that. Not sure how I would get at the heads to make adjustments, maybe mill some pockets in the sides of this plate so I can put a spanner on or some such, but that's detail.

    And yes, I am aware that some random piece of (most likely cold rolled) steel will come with its own twist, but I hope the adjustability I gain with the two bolts will be enough to take that out plus I also expect rigidity to increase a little bit (not that I noticed any problems with the kind of hobby work I do).

    And I forgot to say, the ways have absolutely no sign of wear. As in they look like the lathe has never been used.

    What do people think about this idea?

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    No, just ..NO.

    put the bottle down, have a nanna's, and a bit of a think when you sober up mate!

    you gotta figure out whats actually going on before you dream up some wanky fix. go back and do some basic research on doing a proper evaluation of a lathe.

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    tailstocks wear.
    on a used machine you cant expect to use the method described in the book like would be ok an a new machine.

    the question is...how does it turn without the tailstock in play?

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    Good question. I didn't check, but I will. That said, I don't expect there will be much given I can't turn 30cm away from the chuck without tail stock support. I have a 2 micrometer dial test indicator and will run a test though.

    Considering how well everything is presented on the lathe I assumed there was no wear in the tail stock.

    OK. Test done.

    And here we are.

    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.

    Anyhoo, looks like the tail stock however is improving things considerably given I only get .02 over 30cm with tail stock support.

    Funny. I almost want to drill the cabinet now.

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    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.
    Are you mad ? That's eight tenths in twelve inches. Who gives a crap ?

    And if it's turning a taper no the tailstock is not "properly aligned." That's why it's turning a taper (or one of the reasons anyhow.)

    Maybe go into the bathroom and give it another pull or two ... jesus.

    They could change the site name to Wackoff Machinist if this continues.

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    How do you know the tail stock is aligned?

    Your description shows it may NOT be

    If you do 2 coller test close to Chuck and get true alignment then repeat with TS at end of bed then bed may be twisted but the carriage would follow bed and the test may remain good.

    If turning unsupported stock then bed twist can be evaluated but other failures in machine can miss lead.

    A known test bar properly secured in headstock running true can be measured and bed twisted to make a indicator track the length.



    Sent from my SAMSUNG-SM-G930A using Tapatalk

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    I would really appreciate people with no helpful input refrain from posting, thank you very much.

    I have aligned the tail stock myself so I know it's aligned.

    But none of that is the point. Let's just assume it's all as I say it is. The question was whether it was worth having a steel plate bolted to the cabinet and using that as a base to align the lathe (take twist out if any).

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    what makes you think the headstock is aligned with the bed?

    lets assume it was when it left the factory, (which is highly probable, but not by any means a certainty), even IF it was never miss-handled in coming half way around the world 40 years ago, well god knows what has happened since then.

    you seem to be treating this lightweight like its some kind of sacred object. "it couldn't POSSIBLY be mis-aligned"...

    oh, and my advice was very helpful!

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    Hey, dude, check this out:

    capture.jpg

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    Quote Originally Posted by neural revolt View Post
    I would really appreciate people with no helpful input refrain from posting, thank you very much.

    I have aligned the tail stock myself so I know it's aligned.
    Well that settles that.

    But none of that is the point. Let's just assume it's all as I say it is. The question was whether it was worth having a steel plate bolted to the cabinet and using that as a base to align the lathe (take twist out if any).
    Yes, it's imperative, that's how this is done. I'd use a steel plate bolted under the cabinet about 6" longer and wider than the base. 2" thick might be enough, 3" would be better. If that isn't readily available, a concrete slab that size would work.

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    Quote Originally Posted by neural revolt View Post
    Hey, dude, check this out:

    capture.jpg

    oh, I'm SO hurt, he put me on ignore..

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    Quote Originally Posted by cyanidekid View Post
    oh, I'm SO hurt, he put me on ignore.. I think I'll go commit seppuku. I'm a big poopy head.
    Now he has to see what you wrote.

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    If you want to do it right: Lathe alignment - Emco Super11.

    If you just want it to cut straight over a set distance: YouTube

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    Before you go any further, do a two collar test to check your headstock alignment. Only after that you can start on tailstock alignment.

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    "I detected some taper in it by machining a long piece of stock at two ends, about 30cm apart. About .02mm."

    Yes you are probably under a stay-home order now. But don't you have better things to do?

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    Quote Originally Posted by neural revolt View Post
    ......I detected some taper in it by machining a long piece of stock at two ends, about 30cm apart. About .02mm.

    ........................(not that I noticed any problems with the kind of hobby work I do).
    For a hobby machine, .0008" taper is awful good.....

    I mean, there are 24/7 production machines with more taper than that......

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    Quote Originally Posted by Mud View Post
    Well that settles that.



    Yes, it's imperative, that's how this is done. I'd use a steel plate bolted under the cabinet about 6" longer and wider than the base. 2" thick might be enough, 3" would be better. If that isn't readily available, a concrete slab that size would work.
    Thank you. Yes, I know.

    The question comes from not having any means of actually leveling the lathe even if I did measure with a test bar, etc. right now.

    As for the head stock alignment I don't have a test bar nor means to access one. Will think about how to get around that when I can actually do something about it.

    So I am trying to solve the first problem first. Once I can actually twist the lathe the way I want, I will take it from there.

    Aligning the tail stock. I don't know what the two collar method is, but I used a piece of stock in the head stock turned to a known accurate diameter and an end mill chucked in the tail stock and sweeping an indicator from one to the other at two points on the diameter. I have a 1 micron test indicator that says I am good.

    Yep, a steel plate like that would be good, I agree, but placed UNDER the cabinet I doubt it would help any. The cabinet sits on eight adjustable feet on concrete (not bolted to it - I can't drill in the concrete) and was adjusted to be horizontal sideways and front to back that way. But like I said, there are no means to take twist out because adjusting the feet does not make the lathe follow or respond in any way. What happens is that the tail stock being very light simply follows the head stock if you want to impart some twist that way. You can completely lift three of the tail stock feet off the ground and the tail stock doesn't care. Conversely, if you adjust the twist at the head stock end, the whole thing will tilt this way or that until you end up lifting the tail stock end feet off the ground and the twist is still there.

    I think this points quite clearly that I need to have some means of actually imparting twist on the bed and the plate on top the cabinet I thought of is my best option as far as I can see. That would have some comparable rigidity to the lathe so it could fight it a bit. I understand that the plate itself will twist some as well but as long as it can control the lathe twist I think I have made a step in the right direction.

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    Quote Originally Posted by ChipSplitter View Post
    For a hobby machine, .0008" taper is awful good.....

    I mean, there are 24/7 production machines with more taper than that......
    Yes, I know, but this lathe can do a lot better than that and I would like it to. I bought it to do very small and fiddly work on it and I need that precision and accuracy. After all I managed to achieve better results on a chinese mini lathe and that just isn't right.

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    [QUOTE=neural revolt;3522419]Yes, I know, but this lathe can do a lot better than that ....

    Doubtful.

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    ^^^ I'm w/ jim rozen (post above).... You are sitting pretty good. I would be happy with the amount of taper you are getting.

    If you really have to make true shafts, perhaps you need to get some sort of cylindrical grinder. Or you can offset your tailstock to compensate?

    The difference in Diameter Measurement between headstock end and tailstock end was .02mm - .02/25.4 mm = .0008 inch. Chasing machine alignment numbers in the 4 decimal place range on a used machine is a whole nother level of difficulty.

    My $.02 FWIW ($US).... OP uses $AUS

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