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  1. #21
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    Quote Originally Posted by Mcgyver View Post
    ok, I remember you now from the scraping forum. Same stance there. What do you expect to master with these spindles? Why reinvent the wheel? Just use the geometry the best makes do, its tried and true for 100+ years. Do what Schaublin does....or do you expect make a better machine ? From someone who's scraped machines to a 10th and made spindles, I say BS to your suggestion the spindle is minor bit of work in comparison. Have you scraped a machine or built a spindle before?

    Good luck on the project and please post lots of pics
    Where can I get dimensional information about the bearings used in the best makes? Are you willing to measure some and post the data?

    I want to learn the mechanical engineering of hydrodynamic, hydrostatic and aerostatic bearing design. All rolling contact bearings have periodic errors so if roundness matters they will not do. This is not something I ever studied in my 12 years of university education. But after that much time in university, one is supposed to be able to teach oneself, from books if others have studied the problem and from analysis and experiment if no one else has worked on it.

    That's why I'm searching for published literature on the topic. I don't want to reinvent the wheel, I want to learn how to design and make them. I was quite disappointed when I found that among almost 10 ft of books on machine design I did not have a single treatment of a tapered hydrodynamic bearing design.

    I'm doing this more for the education than the end result. It's analogous to an upper division graduate course semester project in electronics engineering in which the students are required to design a radio transceiver to meet certain requirements, construct the radio they designed and then demonstrate that it will interoperate with the radios designed and built by the other students.

    I scraped in my Chinese bandsaw, which was a fairly minor job, but not to a tenth. The improvement in performance was considerable. And I've done a few other odd jobs when the need arose. All long enough ago that I must assume I know nothing other than how to judge the end result and a vague recollection of how to do it.

    When Andrew Weygers went through marine engineering school in the early 1900's in Holland, one of the required tasks was to take a round steel bar and flat plate and produce a hexagonal bar which was a close sliding fit in a hexagonal hole in the plate in all 6 positions for the full length of the bar using files only. I don't know if I will ever reach that level of skill, but I'd be damn proud if I did.

    *Accurate* mensuration to a tenth is *not* trivial. Temperature becomes very critical. As the saying goes, "The burned child fears the flame."

    I'm not making a new spindle, just hydrodynamic bearings for the existing spindle. Rather less work than a spindle. I may be wrong about the relative difficulty. I know enough to know that it's an ambitious project and that all I know are the bare rudiments of the work and principles.

    Unfortunately, the machine in question is on the forbidden list, so I'm not allowed to post on it. It seems a shame I can't given I'm designing a 3 point kinematic mount to hold the bed and a version of a King Way for the project, plus an original idea for the mensuration which might be worth turning into a product.

    If someone can supply accurate hydrodynamic tapered spindle bearing details from various machines I'd be *very* grateful. I have no such information nor any idea of where I might find accurate information. So far all I have is an IIRC of 45 & 2-3 degrees from someone without any information about the length of the two tapers.

    So far I have not located a textbook on the topic though I have found papers from the 2000-2010 time frame. Unfortunately, I still don't know how to affordably get copies of ASME papers.

    I asked a question seeking a book or other relevant literature and information. I did *not* ask for advice about what I should or should not do, how difficult the project was or anything of the other things people have responded with.

    On a certain groups.io list where about two dozen people have driven off 15,000 other members all I got by way of response to a statement of the project was personal attacks and abuse. That only got worse when I posted a summary of several days investigation of rolling contact bearings (angular groove vs angular contact and roller types) along with scans of the referenced literature.

    An Aussie on YouTube who sands the carriage to relieve binding caused by twist in the bed is worthy of respect. Pointing out that he modified the wrong part of the machine was grounds for a torrent of abuse.

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    You're doing all this work to a Grizzly? That seems pretty pointless because no matter how straight/flat/etc you get it the wimpy castings are going to distort like mad any time you use it.



    Sent from my SM-G973U using Tapatalk

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    Quote Originally Posted by rhb View Post
    On a certain groups.io list where about two dozen people have driven off 15,000 other members all I got by way of response to a statement of the project was personal attacks and abuse. That only got worse when I posted a summary of several days investigation of rolling contact bearings (angular groove vs angular contact and roller types) along with scans of the referenced literature.
    .
    Everybody is out of step but my Johnny?

    You come across as yet another guy who's never built anything but nothing existing is good enough because everything has to be to tenths and probably nobody knows how make a machine as good as you need so better start by designing a bearing. You're at a place where people actually do work to tenths and know how. They know how difficult it is and how often unnecessary it is and that starting with a low end made in china lathe with that expectation is a bit of joke, heck its a bit of joke to even expect that from lathe (although you can by lapping). I don't mean to be insulting, maybe you're a great guy and will be the first one to make it happen (build the most accurate machine ever on your first try), but its a tired tale and will generate some scorn. So have at it, prove me wrong and post lots of pics; I'll happily admit when I'm wrong. I did try to support you buy recommending an excellent engineering book on plane bearings as well pointing you'd do well to replicate what the best tool makers do.

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    "An Aussie on YouTube who sands the carriage to relieve binding caused by twist in the bed is worthy of respect. Pointing out that he modified the wrong part of the machine was grounds for a torrent of abuse.
    this is the video you are talking about?YouTube
    i just happened to stumble onto that video a couple of days ago.
    as far as i could see he measured the thickness of the ways top/bottom and found they were not parallel.
    he then sanded, for lack of better equipment, the bottom to be parallel to the top
    now please tell me what part he should have worked on to regain top/bottom parallelism
    also please enlighten me how twist in the bed can cause the top/bottom to be extremely out of parallel.

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    I'm sorry, but I'm out of here. I asked for a reference to a good technical book. In response all I've gotten is pure BS. In short, you are as useless as the denizens of the [email protected] list. And *almost* as unpleasant.

    There is *no* possibility of the saddle of a Chinese minilathe binding if the rear gib is not in place. Can't happen. So for the gib to bind on the underside of the rear of the flat way, unless the thickness from the top and underside of the rear side of the way varies a lot, there must be significant wind in the bed. Whichever is the case, sanding the carriage is stupid. The fact that sanding the saddle "fixed" it proves it was wind. Anyone who thinks otherwise can't pass a high school geometry exam.

    A single prism and flat way is an exactly constrained kinematic coupling. That and the spindle bore were the primary factors in choosing a Chinese minilathe for the work I wish to do.

    The gib on the saddle makes it over constrained. One of the most important physicists of all time, James Clerk Maxwell, published on the subject of kinematic coupling in 1871.

    In essence, this list is like the McGyver TV show where he builds a harpoon gun out of a brass telescope. I only watched about 10 minutes of that. Never watched it before or since.

    Good bye,
    Reg

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    Quote Originally Posted by rhb View Post
    I'm sorry, but I'm out of here. I asked for a reference to a good technical book. In response all I've gotten is pure BS. In short, you are as useless as the denizens of the [email protected] list. And *almost* as unpleasant.

    There is *no* possibility of the saddle of a Chinese minilathe binding if the rear gib is not in place. Can't happen. So for the gib to bind on the underside of the rear of the flat way, unless the thickness from the top and underside of the rear side of the way varies a lot, there must be significant wind in the bed. Whichever is the case, sanding the carriage is stupid. The fact that sanding the saddle "fixed" it proves it was wind. Anyone who thinks otherwise can't pass a high school geometry exam.

    A single prism and flat way is an exactly constrained kinematic coupling. That and the spindle bore were the primary factors in choosing a Chinese minilathe for the work I wish to do.

    The gib on the saddle makes it over constrained. One of the most important physicists of all time, James Clerk Maxwell, published on the subject of kinematic coupling in 1871.

    In essence, this list is like the McGyver TV show where he builds a harpoon gun out of a brass telescope. I only watched about 10 minutes of that. Never watched it before or since.

    Good bye,
    Reg
    Well I agree with the last bit but that's more about trying to McGyver a Chinese mini lathe into a useful machine tool....

    Look I don't care what someone said about kinematic positioning, without a gib there's nothing to prevent lift of the saddle. If you're not applying any thrust that can have a vertical component, maybe you're right. Unfortunately most of us use lathes to cut metal not just run the saddle up & down the beds. Have you ever actually *USED* a lathe?

    I'm willing to bet that that lathe in the video (which was frankly far too painful to watch to the end) had a variable thickness bed with thickness increasing towards the headstock, which is why it was binding. Nothing necessarily to do with wind. He should have miked that flat way from HS end to TS end and written down the differences.

    As for what he did in lapping/machining the bed somehow fixing the problem, sure it did. It put that machine another large step towards getting recycled into something useful like a sewer lid.

    You have to love YouTube videos......

    As for leaving, whatever. This is a forum where you'll get peoples' opinions whether you like them or not. The more opinionated you are, the less you're likely to be able to deal with the responses.

    PDW

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    Quote Originally Posted by rhb View Post
    This is not something I ever studied in my 12 years of university education.
    But after that much time in university, one is supposed to be able to teach oneself, from books if others have studied the problem and from analysis and experiment if no one else has worked on it.
    Really? Was that 12 years of education? Or of just "hanging out"?

    And to what avail? Sad, that, but time was, proof of the ability to teach oneself and research and evaluate source material was the pre-requisite for admission to a University.

    Google finds plenty of info on plain bearings. All types. Theory & design at respected Universities:

    https://web.mit.edu/2.75/fundamental...Topic%2010.PDF

    ... to Industry pubs, to part numbers and prices.

    Sorry, but "a slew of papers" is exactly what you will have to deal with. Bigtime.
    Broad subject, dealt with as-needed. Not much market for a "Cliff Notes" version.

    Deal with that at your own speed.

    Check back in 12 years?

    Please.


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    Quote Originally Posted by PDW View Post
    Well I agree with the last bit but that's more about trying to McGyver a Chinese mini lathe into a useful machine tool....

    Look I don't care what someone said about kinematic positioning, without a gib there's nothing to prevent lift of the saddle. If you're not applying any thrust that can have a vertical component, maybe you're right. Unfortunately most of us use lathes to cut metal not just run the saddle up & down the beds. Have you ever actually *USED* a lathe?

    I'm willing to bet that that lathe in the video (which was frankly far too painful to watch to the end) had a variable thickness bed with thickness increasing towards the headstock, which is why it was binding. Nothing necessarily to do with wind. He should have miked that flat way from HS end to TS end and written down the differences.

    As for what he did in lapping/machining the bed somehow fixing the problem, sure it did. It put that machine another large step towards getting recycled into something useful like a sewer lid.

    You have to love YouTube videos......

    As for leaving, whatever. This is a forum where you'll get peoples' opinions whether you like them or not. The more opinionated you are, the less you're likely to be able to deal with the responses.

    PDW
    in the previous episode he miked the ways and the headstock end was way thicker than the tailstock end.
    he managed to get the top and bottom parallel by sanding the bottom side so the top was as straight as it was before

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    Quote Originally Posted by rhb View Post
    I'm sorry, but I'm out of here. I asked for a reference to a good technical book. In response all I've gotten is pure BS. In short, you are as useless as the denizens of the [email protected] list. And *almost* as unpleasant.

    There is *no* possibility of the saddle of a Chinese minilathe binding if the rear gib is not in place. Can't happen. So for the gib to bind on the underside of the rear of the flat way, unless the thickness from the top and underside of the rear side of the way varies a lot, there must be significant wind in the bed. Whichever is the case, sanding the carriage is stupid. The fact that sanding the saddle "fixed" it proves it was wind. Anyone who thinks otherwise can't pass a high school geometry exam.

    A single prism and flat way is an exactly constrained kinematic coupling. That and the spindle bore were the primary factors in choosing a Chinese minilathe for the work I wish to do.

    The gib on the saddle makes it over constrained. One of the most important physicists of all time, James Clerk Maxwell, published on the subject of kinematic coupling in 1871.

    In essence, this list is like the McGyver TV show where he builds a harpoon gun out of a brass telescope. I only watched about 10 minutes of that. Never watched it before or since.

    Good bye,
    Reg
    if you had been looking carefully you would have noticed the gib was in place.
    also would you have noticed that he miked the ways to find out that they were not parallel
    also you would have seen that he sanded down the underside of the ways and not the saddle

    you mentioned you were unemployable
    i totally agree
    but for completely different reasons i suspect
    did anyone ever tell you that you had very obvious narcissistic traits?

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    Quote Originally Posted by rhb View Post
    I'm sorry, but I'm out of here. I asked for a reference to a good technical book. In response all I've gotten is pure BS. In short, you are as useless as the denizens of the [email protected] list. And *almost* as unpleasant.
    So another forum you have to leave because nobody gets it. Maybe its you?

    At least in the machining forum usefulness sweepstakes, the good folks at PM know they're not totally being eclipsed by the 7x12 forum,

    Quote Originally Posted by PDW View Post
    Well I agree with the last bit but that's more about trying to McGyver a Chinese mini lathe into a useful machine tool....
    Different spelling. Not even I'd try to do that

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    Quote Originally Posted by janvanruth View Post
    in the previous episode he miked the ways and the headstock end was way thicker than the tailstock end.
    he managed to get the top and bottom parallel by sanding the bottom side so the top was as straight as it was before
    Ah, OK, I couldn't even get through that episode. I'm afraid that my attention span (and care factor) for vids on trying to make those machines into something other than oversized paperweights is very small.

    I did see the gib though which is why I assumed the ways were tapered. I stopped watching after he fscked up the V way and now the front gibbed surface was low, which of course means that the rack-pinion mesh was going to be sloppy/nonexistent and the leadscrew was going to bind. I couldn't see things getting any better if I watched more and I already knew the main learning event - those machines are POS.......

    PDW

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    Marks standard handbook for mechanical engineers ninth edition .

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    i had a tapered bearing with thrust collar area on a optical transit that i could see had a stability problem tapping on scope while looking through it.
    .
    the tapered bearing bore was out of round and the thrust collar would not allow it to go into the taper more. i ended up machining the thrust collar area .001 and lapping it the tapered bearing. i also had to thin the lapping compound with a very thin oil as it was too thick to flow into tight spaces right out of the can. when done and assembled pushing in different directions i noticed like 1% of the previous movement that i saw before lapping. when blued up i could see on taper it was in good even contact and round.
    .
    just saying often taper angle and thrust collar area the ratios were best guess. that dont mean its bearing is wearing good and even over time. like a lot of things it isnt a perfect science.


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