Cincinnati Tray Top compound and crossfeed brass nuts
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  1. #1
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    Default Cincinnati Tray Top compound and crossfeed brass nuts

    Hi everyone.

    I would like to replace the feed nuts on my 1951 Tray Top. I can certainly live with the backlash but new nuts would be nirvana. A little guidance would greatly appreciated. I am open to having one made, but not by me.


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    A little guidance
    Bronze, not brass - a choice could be C932 Bearing Bronze

    A first step in accomplishing such a goal would be to have the existing items out, cleaned, measured completely and sketches suitable for shop use executed

    Such activity has been long termed Reverse Engineering

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    Bronze - right, thank you.

    No problem pulling them and drawing or even just providing them for duplication. That's what I will do if there is nothing "available" or compatible. Just have to finish up a few small projects and be willing to be 'down' for a few weeks. I guess what I am asking is if anyone knows how to source these or if i need to have them made. Looks like the latter...


    Thanks man, appreciate the comment!

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    This outfit is known to make some lathe parts - Brian might be worth talking to

    Products – Miller Machine and Fabrication

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    Quote Originally Posted by johnoder View Post
    This outfit is known to make some lathe parts - Brian might be worth talking to

    Products – Miller Machine and Fabrication
    Thank you. I will give him a call.

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    I am over the border. Might be able to knock one out

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    I left a message with Miller Mach.
    @ Mebfab, thank you for that offer. May take you up on it.

    I was thinking i might be overthinking this. Seems like once I identify the ACME thread, a piece of over-sized 932 bar and the right ACME tap is all I need, I have mill and probably have the right taps for the mounting bolt. Center-line to top of flat of the nut seems to be the only critical measurement. Is it that simple?





    Thanks again guys!

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    Tried to reply a couple of times, guess I am still too new...

    Anyway, Thanks for the recommendations. I contacted and left a voice message with the Miller, waiting to hear back. Also, Mefab I may take you up on that offer. Thank you Sir!

    It occurs to me this may be an easy task. Seem like I need to just identify the ACME thread, get the proper TAP and buy some oversize 932 stock. I have a mill to machine the flat and can certainly thread the mount hole. Only critical dimension being center-line to top of flat. Is that simple?

    Thanks again!!




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    Just to follow-up.

    I spoke to Miller - super awesome guy and very helpful. He saved my butt actually. Turns out I have 9/16 * 8 TPI Acme screw - very uncommon. I then found an outfit that makes unique taps. I am waiting for a quote. If the cost is not too crazy, I will get the tap and make the nut. Here's what I am hoping to replace.





    Thanks everyone.

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    Why not change the thread to 5/8-8 Acme-3G or 3C? Be a lot easier to single point the thread or get a tap for. You have room for doing so.

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    A good thought and appealing. Yes there is room but the lead screw has a number of tapers/features that is above my capability to reproduce and probably expensive. A suggestion for going the other way and turning down the current screw to 1/2 inch is also an option to get to a common standard, though less appealing to me.

    Appreciate the thought!

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    Nice lathe! I have a 15" tray top. Mine has a nut which allows the backlash to be adjusted out. You could modify yours easily, it's just a slot milled from the top down half way through the acme threads with a set screw which allows the nut to be deformed a bit to take out the backlash. It probably won't last nearly as long as a new nut, but in my case it might outlast me.....

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    Not to piss further on your efforts but you do realize that most lathe cross feed screws are left hand hence making it even harder to get.

    That said, i replaced the cross feed nut on my harrison earlier this year after finding a source for them, wow what a diffrence to not have 30 thou of slop.

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    Thanks for the kind words.

    I am having the tap custom made in HHS. wasn't that expensive, maybe a c-note more than a good quality typical off-the-shelf acme tap. We'll see how that goes... Heck, I may have the only one in the country Hoping it will alleviate a decent amount of the backlash. Pretty sure there will be some left but I can live with worse. I may try the slotting suggestion too - thanks! I really love this machine. It's super straight and runs like a dream. It's also perfect for my workspace. I can see spending whatever on a screw in the future. Even at a grand plus, it would be far more expensive to replace the lathe with something better.

    Thanks guys!

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    I can't fully tell from the photos, are you sure that thread is acme? it looks like a square thread to me rather than an acme thread. I could be reading the photos completely wrong though.

    Pete- another tray top owner

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    Hey Pete! Pretty sure it's ACME. Which Tray Top have you? Got a pic?

    Thanks

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    Been a while. Too many small projects and too much work. Wanted to follow-up on the results for anyone interested. I can echo Adama's sentiment above. Wow! What a difference! I was expecting a little, to no improvement at all but the result is truly shocking. Far surpassing expectations, the improvement is huge. Maybe I just had an enormous amount of play so even a partial fix yielded a big benefit, I don't now but I am super pleased. I made the nut oversize where I could get away with it. The picture is before I added a smaller shoulder in along the edges of the mating surface to fit the relief in the metal chip cover under the compound. In hindsight, I would have made the nut 4 or 5 inches long (so what if it protrudes out the back). That would ensure the nut is always on good threads of thread screw. Needless to say, the custom made to order 9/16 LH ACME tap was excellent.




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    Looks great Mike. Got me thinking about doing mine. Would you be interested in making one for me. Even just the bronze block with the taped hole. I could finish it off. Want would you want ?

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    I don't mind taking a crack at doing another, the ACME thread anyway, you can cut the external dimensions and common thread on mating surface to suit. Just send the raw piece of material and feel free to mark the center. In hindsight to my initial hindsight, I don't think I can do one much longer than what I did due to the length of the tap/shank.

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    Oh, also no promises. If a break the tap, I ain't buying another - lol.

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