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crossfeed nut: brass or bronze?

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  • #16
    Noob response, so let the flaming begin...?

    From what I have read/heard/seen I was under the impression that
    660 was quite uniform in stripe (regular but also in orientation to the axis...) and sort of a medium dark color http://www.ebay.com/itm/Aluminum-Bro...item1e69443a0a, whereas the aluminum bronze (954 ?) the striping is uniform but "pulled" so more of a wave and is also a bit more silver in color http://www.ebay.com/itm/Aluminum-Bro...item1e69443a0a

    I am thinking this is mostly hearsay/old machinist's tale...for whatever its worth, pics I've seen of Ampco 18 does look like those photos, not as dark as 660 say...but again, the whole thing is skewed to my eye since looks are very different between "as cast" and machined

    Good work Tony! A similar project is very near the top of the list for the lathe once it gets warm...oh, and adding a thrust bearing/washer of some sort as well since it had none...
    Last edited by RussZHC; 01-08-2012, 03:52 PM.

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    • #17
      Looks good.

      Regarding the need for reducing the backlash, my thoughts simply lean toward the feel. I always like it when I reverse the crank and the slide moves right away rather than having all that play to swing through first. It's true enough that you can still do accurate work if backlash exists, but I'll get rid of it if I can just because it's more of a pleasure to use when things are tighter.

      Sounds like Tony feels the same. It does feel better now doesn't it?

      I have a little old Hardinge lathe and the cross feed has .018" backlash that I'd like to get rid of. Since the compound gets used much less of course, it has very little wear, and I'm not sure how they did it but it has about a half-thou backlash !! And it's still free and smooth too. FWIW, on the Hardinge, both the cross slide and compound nuts are bronze.

      edit to add: I've heard that Hardinge has a special little drill/ream/tap fixture process which attaches in place of the screw. And when they made their lathes, they would assemble it all with the nut un-machined, then use the fixture thing to machine the threads in the nut so it's all sweet.
      Last edited by tyrone shewlaces; 01-08-2012, 04:09 PM.

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      • #18
        Feels nice indeed.

        What I should've done is switched over to a 10tpi screw.. so my dial made
        sense to me. I suppose its the English way, but i much prefer dialing in 10
        thou and what i'm working on gets 10 thou smaller. not 20.

        McMaster lists LH 3/4-10 taps for $200+! 20thou it is!

        or maybe I just make a new handwheel with half as many graduations.

        at any rate, 1 step at a time! That'll be next years project (right
        after I get used to the direct reading dial of course)

        thanks all for following along.

        Tony

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        • #19
          Excessive backlash in the cross-slide is a good way to make parting off more stressful!
          Paul Compton
          www.morini-mania.co.uk
          http://www.youtube.com/user/EVguru

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          • #20
            Originally posted by EVguru
            Excessive backlash in the cross-slide is a good way to make parting off more stressful!
            Thanks for the warning.

            Not to be rude, but you are doing something wrong. There should be no difference due to the amount of backlash. I grew up using early flatbelt machines which still produce great work despite their excess (one is ~.100) backlash.
            Last edited by justanengineer; 01-08-2012, 07:47 PM.
            "I am, and ever will be, a white-socks, pocket-protector, nerdy engineer -- born under the second law of thermodynamics, steeped in the steam tables, in love with free-body diagrams, transformed by Laplace, and propelled by compressible flow."

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            • #21
              Originally posted by EVguru
              Excessive backlash in the cross-slide is a good way to make parting off more stressful!
              Any time your parting eats the backlash is gonna be a day for new underwear!

              Use less posative rake, drag the cross slide lock/gibs if you have to, but don't let your parting tool eat the backlash!
              Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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              • #22
                Originally posted by Black_Moons
                Any time your parting eats the backlash is gonna be a day for new underwear!

                Use less posative rake, drag the cross slide lock/gibs if you have to, but don't let your parting tool eat the backlash!
                I have no idea what that means.

                Backlash means diddly-squat. Cutting forces will keep the backlash at zero if your tools are setup correctly. Unless, of course, your cutting from both sides at the same time.

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