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Surface grinder troubles - won't grind the chuck flat

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  • Richard King
    replied
    I wanted to be polite as the one guy said it was Christmas... You grinder looks more like a mill then a grinder. The short saddle that rides on the knee needs to be scraped really close as if it is loose and rocks the multiple of the error will be 2 or 3 to one up on the chuck, I would imagine. The ways look worn and I don't see any scraping at all. If you can get a copy of the Sleshinger Book "Testing Machine Tools" it shows the disadvantage of a short saddle over a long saddle. Send me you Email address and I'll scan that page.
    We can also work together on your rebuild and you can post pictures here OK? To bad you can't organize a rebuilding / scraping seminar over there because we could scrape your machine as a class project. I will be selling the DVD over the internet to download in a couple of months. My email address is [email protected] Happy New Year...Cheers :-)
    Last edited by Richard King; 12-26-2012, 08:25 PM.

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  • loply
    replied
    Hi guys,

    Thanks for all the help so far.

    Richard - Please find some more pics of the machine below. I'm resigned now to the fact that it's just worn. This still surprises me a bit as the ways are distinctly unlike my other machines which show patterns or bright patches where the wear occurs most, whereas this grinder looks uniform in every spot, with no obvious worn spots. Maybe it's just worn so much that it's worn all over!

    In any case I was wondering what the best approach will be for rebuilding this thing. My scraping is approaching the speed where this will be practical now, though I'm still struggling to get good points per inch. I'm still meaning to order a copy of Richard's DVD to see if I can sort that issue out.

    I've read Connelly's book and his chapter on the horizontal mill closely resembles this machine. I think the sequence of steps to ensure that I don't make one thing worse by scraping another is the bit I'll struggle with the most, but with the machine laid on it's back and the right tools I think I'll manage.

    I really had intended for the first machine that got this treatment to be my RF45 clone, alas, that was when I was blisfully unaware my surface grinder was knocking out dog's back legs'!

    Anyway, before I can commence I need to acquire a few things so it may be a while but I'll post a thread with the outcome when I do.

    Cheers,
    Rich







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  • Jaakko Fagerlund
    replied
    Originally posted by JoeLee View Post
    It doesn't look like a very good design for a surface grinder.

    JL...............
    Yup, looks more like a T&C grinder or a drill press.

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  • JoeLee
    replied
    It doesn't look like a very good design for a surface grinder.

    JL...............

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  • metalmagpie
    replied
    Even on a machine with no coolant setup you can jury-rig one by using a pond pump, a plastic bucket and some plastic tubing. I did that to rig flood coolant on my KO Lee 6x12 grinder when I had to grind in a mag chuck. Start with the chuck upside down and take a cleanup grind across the bottom, then right side up and do the top. You *have* to use flood coolant.

    metalmagpie

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  • Richard King
    replied
    Set the gibs with a max of .0005" lost motion so there is an oil film. To tight will gall up the ways. The picture is for a tapered gib, but the technique is the same. Push release, zero indicator, pull release and that's the error.When pushing and pulling you will bend or stretch the metal a little, that's why you release it. If the ways and gibs are worn you may not be able to get it that tight it might bind up when it gets close to the ends of the travel. Ooops...not easy to put a pic on here ..or for me anyway. Email me and I will send you the picture via E-Mail and maybe you can add it to the post. [email protected]

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  • loply
    replied
    Hi folks,

    Thanks for the replies, I've got a few more things to try before I conclude that it needs rebuilt/rescraped, I want to bolt the machine down as even tough it's quite heavy (>600lbs) I've noticed I can rock the precision level a bit by pushing on the head, and I also want to have another look at the gibs, as they're an unusual design and the procedure for adjustment isn't clear.

    Richard - That isn't my machine. They are all quite old, I think mine is from the 60s, but it appears to have had a bit of a rebuild at some point as some parts are distinctly 'fresh' looking. No flaking/frosting visible anywhere though.

    One of the problems is that, unlike the machine pictured, the column on mine is cast onto the base, meaning getting the thing horizontal for scraping the column ways would be interesting!

    The gib strips are built as in the picture below, and on most of them, tightening screw 'B' (of which there are 2 or 3 on each gib) tightens the slide, as well as tightening screw 'A'. If you tighten B first, then A, then it's difficult to tighten A as the gib is locked... If you tighten A first, then B, then the gib locks up as B tightens. You'd think that the procedure would be to loosely tighten 'B' then tighten 'A' as required before nipping up 'B', but inevitably nipping up 'B' then locks everything! It's all a bit fiddly.



    Cheers,
    Rich
    Last edited by loply; 12-24-2012, 06:20 AM.

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  • Richard King
    replied
    Can you remove the table and take some more pictures. If this is your machine it looks pretty rough to me. If the scraping is gone or you can't see any, then the machine is worn and no matter how tight you adjust the gib's it won't get better. I've scraped hundreds of grinders and i'm not guessing at the problem or what it could be. This design does not lead me to believe you could get much better then .0003" even after it is scraped. If there is a local machine rebuilder in your area have him come over and give you a quote to rebuild it and read his mind. Get a professions opinion who can look at it first hand. I don't charge for giving quotes.
    Last edited by Richard King; 12-23-2012, 10:53 PM.

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  • oldtiffie
    replied
    Being charitable (Festive Season and all) - it seems that will be quite a project.

    If it were me and I wanted to keep it, I'd put it in corner on a "to do" and "think about" list and sort out what really needs doing and what time, space and tools (and money) are required to do it. Unless I had another, I would not have a surface grinder or the floor and bench space it needed for the period of the project.

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  • tdmidget
    replied
    Originally posted by loply View Post
    Hi folks,

    Just been out and spent some time inspecting the machine. Here are some of my findings-

    1) With the table removed, the bottom surface of the rear slideway on the saddle is 2 thou lower than the front one, measured by placing the same parallel on each and indicating it from the head. This error isn't removable by lifting the front of the knee or by tightening the knee's gibs.
    Lifting the front of the knee would make it worse, not better. Try tightening the gibs on the knee at the top ONLY to the point of binding or at least some resistance. Lower the knee enough to take some pressure off. Indicate again and see if there is any change.

    2) With the saddle locked tight and the knee gibs well adjusted, a precision level on the table reveals that the ends of the table rise and fall as the table is moved left and right. It seemed that adjusting the table gibs tighter didn't really stop this from occurring.
    This common and caused by not using the full travel of the table.
    3) With the table mounted, indicating it from the head, the front of the table is 3.5 thou higher than the rear
    Not conclusive but seems consistent with the indication of the ways on the saddle. Might mean that the table surface and ways are not parallel.


    I'm a little bit exasperated at present, as all of these problems don't seem to go away by mere tightening of gibs, which is what you'd hope for. I would like to know how to indicate the ways of the knee to see if the knee is not sitting parallel to the spindle axis, but I'm not sure how.
    Remove the saddle and check them to the column ways with a precision square.

    At the moment I'm trying to decide if all of these problems can be rectified with ease, or, if the machine is just worn out of shape! It doesn't look so, all the ways almost look newly ground, smooth and evenly finished with no sign of wear, albeit no scrape marks either.
    If the ways are as good as they appear then the wear is in the knee and table slideways. You will need a precision straight edge and surface plate to check them. They can be scraped in to match the ways, assuming the ways are good.



    Cheers,
    Rich
    It's got simplicity going for it. As a home project it is repairable. You would put more time into it than it is worth but then you have skills that could be applied to scraping elsewhere.

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  • Jaakko Fagerlund
    replied
    Originally posted by loply View Post
    At the moment I'm trying to decide if all of these problems can be rectified with ease, or, if the machine is just worn out of shape! It doesn't look so, all the ways almost look newly ground, smooth and evenly finished with no sign of wear, albeit no scrape marks either.
    I have seen some worn out machines that don't look like the ways are worn, until you see that there should be frosting on the whole surface! For example, the horizontal milling machine at work has this on its Y-axis, the top and bottom show nice frosted surface, but the usually used middle area is worn so much that all the frosting has gone away, but the surface still looks good.

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  • loply
    replied
    Hi folks,

    Just been out and spent some time inspecting the machine. Here are some of my findings-

    1) With the table removed, the bottom surface of the rear slideway on the saddle is 2 thou lower than the front one, measured by placing the same parallel on each and indicating it from the head. This error isn't removable by lifting the front of the knee or by tightening the knee's gibs.

    2) With the saddle locked tight and the knee gibs well adjusted, a precision level on the table reveals that the ends of the table rise and fall as the table is moved left and right. It seemed that adjusting the table gibs tighter didn't really stop this from occurring.

    3) With the table mounted, indicating it from the head, the front of the table is 3.5 thou higher than the rear


    I'm a little bit exasperated at present, as all of these problems don't seem to go away by mere tightening of gibs, which is what you'd hope for. I would like to know how to indicate the ways of the knee to see if the knee is not sitting parallel to the spindle axis, but I'm not sure how.

    At the moment I'm trying to decide if all of these problems can be rectified with ease, or, if the machine is just worn out of shape! It doesn't look so, all the ways almost look newly ground, smooth and evenly finished with no sign of wear, albeit no scrape marks either.



    Cheers,
    Rich

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  • Mcgyver
    replied
    Originally posted by bborr01 View Post
    TD,

    You have not spent much time grinding have you?

    Brian
    what exactly from the paragraph you quoted did you find fault with? TD's comments on indications are the same as what I posted about - ie zero reading does not mean flat....why do you think this is wrong?

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  • MichaelP
    replied
    Actually, I think Tdmidget's advice and explanations here are quite sound. The form could've been better, but the substance is OK.

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  • Jaakko Fagerlund
    replied
    Originally posted by tdmidget View Post
    Looking in the mirror? Still waiting on your vast grinding experience.
    Sorry but no, I'm only 30. My experience has nothing to do with this and as said, it doesn't prove anything, as anyone can claim whatever they want about anything. It is just if your text seems credible and if your claims/ideas/experience has some explanations behind them as to the why's 'n but's.

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