1964 FP2 horizontal spindle adjustment - Page 3
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  1. #41
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    Hi to all,

    though, as a true hobbyist, I tend to overcomplicate things more often than not, I think that I might have actually done some real progress here without getting into much fuss and, mostly, without doing any damage.

    I did manage to find some workshop quality time and started by putting the spindle on the lathe and getting a measurement on the bearing-seat's taper in order to get an idea how much metal I should remove, as Ross had initially suggested:



    I opted to indicate off the top of the spindle so, using the cross-slide, it was easy to find the high spot and secure that I was, indeed, on center (which is my main fear when trying to indicate a taper 'horizontally' in order to replicate it with the top slide). I got 0.046 mm taper, radially, per 1 mm of axial move. So, we are talking about 92 um/mm in diameter.

    I had let's say 0.006 mm play, so, in order to get it to zero, I need to move the bearing 0.065 mm towards the fat part of the taper, so that's how much I had to remove off the spacer.

    So, I thought it wouldn't mind if I worked on the original spacer and get it over with. I tried to measure the spacer and note the values, it worked only with a micrometer. On the surface plate I din't have that much luck since the spacer was quite bent, I had around 0.04 mm of rocking!
    You night be able to see the transfer-blue gaps here:



    So, I spent quite some time lapping the spacer applying hand pressure on the high spots. After some effort, I got it really flat (very thing layer of blue, I hope it's visible):



    Next, I worked on actually thinning the spacer down. I chucked a round mag chuck on soft jaws and faced it true. Then, I used a parallel, double sided tape and some emery cloth, following Peter's advice on thinning the spacer down. That took some time, stopping, cleaning, confirming flatness on the surface plate and measuring thickness with a micrometer.



    continued in next post....

  2. #42
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    ...continued from previous post.

    After quite some time, I reached the 0.06 mm that I had to remove, so it was test time.

    Spacer looks like this now:



    I cleaned everything, wasted a century to insert the spindle in the quill, bottom bearing can be really tricky if it decides to, and assembled everything. Spindle rotated freely, so I didn't overshoot to cause binding, that's a first win.

    Measuring play yet another time:



    And I got an easy 0.001-0.0015 mm!!! Which, I will call just perfect! I will allow for a bit of extra squezzing if I find the guts to do the heavy mallet tightening that Mr. Singer suggested, and, in any case, I would hate to risk going too far, so I'll stay on the safe side.

    As next steps, I am taking everything apart again, maybe do just a final pass on the spacer again, to get a finer finish just for fun. Then, clean everything and, finally, assemble.

    I am very happy for how this turned out. Some notes:
    - it's great that I only needed one iteration, I don't have that much time, especially not at once, to run multiple iterations of thinning the spacer, assembling spindle, measuring play, disassembling, repeating...
    - it's great that my 'risk' worked out and I didn't overshoot, that would be an issue.
    - it's really great that calculations worked out relatively accurately, that's not something that I see very often working at such precisions.
    - it's always 'fun' to realize that the simplest of parts, a small spacer, is sooooo difficult to make with close flatness/parallelism tolerances.

    I will update after the final assembly/measurements.

    Thanks for all the assistance so far!
    BR,
    Thanos

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  4. #43
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    Hi Thanos,

    Nice job! Amazing what's possible by hand if you have a reliable way to measure the results.

    Quote Originally Posted by thanvg View Post
    And I got an easy 0.001-0.0015 mm!!! Which, I will call just perfect! I will allow for a bit of extra squeezing if I find the guts to do the heavy mallet tightening that Mr. Singer suggested, and, in any case, I would hate to risk going too far, so I'll stay on the safe side.
    I think these roller bearings are similar to tapered roller bearings which often are operated with some preload. So I think if you went slightly too far (meaning 1 micron of negative clearance = preload) it would be no problem. I think that's why Franz said "plus or minus". But I am no expert on this.

    Cheers,
    Bruce

    PS: possibly the taper you saw is actually 1:10 in diameter to length. This seems to be a very standard European taper, for example it's what is used on the journal bearings of my Studer grinder.

  5. #44
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    Quote Originally Posted by ballen View Post
    ...
    I think that's why Franz said "plus or minus". But I am no expert on this.

    ...
    PS: possibly the taper you saw is actually 1:10 in diameter to length. This seems to be a very standard European taper, for example it's what is used on the journal bearings of my Studer grinder.
    And I was wondering what the 'plus or minus' meant...I had interpreted it as 'roughly'...
    Anyhow, no bearing expert myself either, so I really don't know. If it is as you suggest then it relaxes the fitting procedure quite a bit, which is a good thing! Only problem is that when you enter the preload-region then you have nothing to measure anymore, no play...so you really can't tell what's going on and how far you have went, until you bind the spindle of course
    Jokes aside, it would be a very interesting question to Mr. Singer, if you remember to ask next time you chat with him.

    Regarding the taper, I guess you are right, I had no idea 1:10 was a common choice, I bet I am the one that lost the 4 um/mm in radius. Measuring to such precision is new territory for me.

    BR,
    Thanos

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  7. #45
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    I am not sure these bearings are ment for a pre-load
    I think it wat on a Schaublin I read play to be about 0,002mm positive play
    Could be Weiler too
    Also If I push a little hard I can change play 0.005mm easily


    Peter

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  9. #46
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    Believe Peter here is correct. In my experience, roller bearings running in straight races are never preloaded....
    Ball bearings and tapered roller bearings are a different matter..
    Cheers Ross

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  11. #47
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    Hi to all,

    after quite some delay, time to wrap this up. It took so long since, after the installation of the spindle on the machine, I wanted to find the opportunity and run a cut horizontally.

    The thing is that, what initiated this investigation was this awful finish I got facing a still part horizontally, which could not be explained:



    Of course, given that crazy axial play I had, that's easily expected.

    Anyhow, facing yesterday a piece of hard steel (off a large clamp) I can say that the issue is, as expected, gone:



    Finish is not shinny, but that's an insert thing, I am about to cut some sensitive parts and didn't want to hurt the inserts on my 'good' face mill.

    So, after all this hard work and investigation, I can admit that the whole problem was, not strangely, a user inflicted issue: I had put together my spindle without using the proper wrench, so I could not even get close to the tightening force required to properly seat the taper-bored bearing. I couldn't, ever, imagine the force that is really needed, as per F. Singer's instructions, but, to be honest, I din't even dare to fully follow them! I got it tight, but did not hit it 'very hard with a 1 kgr mallet'! Tight enough though . In any case, as is already known, yet another proof that, in the end, you loose much more time by not using the proper tool than spending the effort to make/buy what is actually needed for the job at hand.

    Of course, even without that bug, the spindle needed some care, regarding the front bearing radial play. I would have never known about that had I not got into this (and, of course, if Bruce hadn't asked Mr. Singer). So, even stemming from my own mistake, I finally got my machine a little better!

    I'd like to thank all who helped me out on this, especially Ross that provided the tapered-bore insight and, of course, Bruce that derived precious information from Mr. Singer.

    (we might want to save all this in a 'specifications' sticky thread, for future reference).

    Many thanks again.
    Thanos

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