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  1. #61
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    It is possible to buy whitworth allthread down here in melbourne happy to send you some. Also worth considering is just milling off the nut boss from the bottom of the cross slide and mechanically fixing a new nut on. Can you post a photo of the bottom of the cross slide and the trench the screw runs in on the saddle?

  2. #62
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    Sure. Good suggestions. I'll duck down the shed and take a couple of photos.

    As I think you said earlier, it would also be a good opportunity to put a calibrated dial on the handwheel for the cross-feed at the same time. The total length of the screw is only 4 3/4" so a 125mm piece of threaded bar would suffice. I haven't done much searching as yet, mainly because I'm not convinced that it isn't all down to the nut. However, this area has become and engineering supplies wasteland. If the big B doesn't have it good luck. Well, not quite that bad but you get the idea.

    Edit: Photos as requested.
    The saddle assembly is in 3 main pieces. A Front Plate is held under the Slide by the 2 machine screws and the Full Nut is held to Front Plate by the single bolt. As you can see, there is very little thickness to the metal above the threaded nut hole.
    Carriage Side.jpgCarraige Top.jpgCarriage Front.jpgCarriage Channel.jpgCarriage behind.jpg

    Here are a couple of pics of the under side of the Cross Slide. It consists of the main body casting with a Front Plate attached with 2 Allan key cap head screws. The feed screw is passed through the plate and held in place by the collar and the Hand Wheel on either side of the plate. Obviously the Top Slide comes off.

    Cross slide underneath.jpgCross slide behind.jpg
    Last edited by glivo; 9th Jul 2018 at 01:54 PM. Reason: Additional information + pics

  3. #63
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    Hmm the only decent solution i can think of is either to make a mutant leadscrew to take up slack in the nut or just mill that nut completely out and put in a new nut. PM me if you decide you could do with a hand and feel like mailing it down to Melbourne.

  4. #64
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    My thoughts exactly CW. My main question is: Do you think these old Advance lathes ever had tolerance better than this? It's possibly up to 60 years old (or more) and it really is just a toy. Pretty little thing though. It might be something to play with in a Men's Shed, with no offence intended to anybody involved in Men's Sheds around the country.

    I can easily make a timber crate and pack up the bits to send down to you if you think you can fix it. Or I can just go around to one of the few remaining machine shops in existence here and hope that the guy wont butcher it. Past experience with other people helping me with little machining jobs isn't great.

    Is it financially worth it? I don't have a lot invested so far, so possibly.
    Collectors value as an Aussie product? Maybe worth something to someone.
    Useful to me? Limited value for non-critical applications and not big enough for a decent boat mooring.

    Even though the slop / free play in the cross feed in adjustable down to 0.25mm or less, if I put a threaded bolt or bar into the nut, at a distance of 50 mm, out I can rotate the end of that bolt or bar to cover a 10 mm diameter. It is a pretty loose fit.

  5. #65
    Join Date
    Sep 2012
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    North Yorkshire UK
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    Thumbs up Top slide Leadscrew

    Hi Glivo, Caskwarrior, Guys,

    I think caskwarrior is right, this is a good candidate for milling out the old hole and fitting a square PB nut.

    As far as threads go, I would certainly look for some metric fine M10 by 1.0mm pitch which looks like it would have enough meat to turn the end for the dial and handle, if you need to, make a new plate or bush the hole in it to suit. It would also give you that bit of extra length if needed to mount the dial, suitably calibrated of course.
    Best Regards:
    BaronJ.

  6. #66
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    Sep 2012
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    Default New nut.

    Hi Glivo, Caskwarrior, Guys,

    This is what I would suggest,

    Mill out the area inside the red lines. Make a phosphor bronze nut to fit into the milled out slot. Drill and thread to suit whatever you decide to use. Locktite the PB block into the slot, clamping it in place overnight. Then where I have marked the crosses drill and thread, say M6, to make "Scotch Keys". This will prevent the block from ever moving. I would use hex socket grub screws so that you can get them tight and below the surface.

    Carraige Top-1.jpg Carriage Front-1.jpg

    After that do whatever you need to fit new dials and handle. One of the reasons that I suggested M10 x 1.0 mm is that it will give you 1 mm travel per handle turn, and can be calibrated easily, particularly with the dial gauge set up that you have made.

    A potential alternative would be to make an Acetal nut as I described in the other thread, instead of PB.
    Best Regards:
    BaronJ.

  7. #67
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    That looks like a plan. Today, I will measure up and draw.

  8. #68
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    Advance Saddle.jpgAdvance Screw.jpg
    Dimension of flange on screw should be 31/64" 12mm. Not 31/32". Oops.

  9. #69
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    Default Leadscrew !

    Hi Glivo,

    Not a problem Turn a groove in the shaft and put on a circlip, E clip or just drill through the shaft and use a split pin or roll pin in to support a thrust bearing or ring. If you wanted to go whole hog you could even put a ball race on there.

    Your sketches look OK. Pity you are not in the UK, I have a short (10") length of threaded bar that is about 14mm X 2.0 that you could have.
    Best Regards:
    BaronJ.

  10. #70
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    Not sure I'm with you here BaronJ. We are talking about milling out the threaded hole and replacing it with an insert, then making a new screw that fits the thread (possibly M10 X 1.0). A 14mm X 2.0 screw is going to be too large? Keeping the same centre height of the screw would see the nut hole break through at the top of the saddle dovetail and the screw would protrude, preventing the slide from even going on. The channel for the screw is only 13.5mm deep. Even using a M12 would be pushing to very thin wall thickness.

    My drawings are very crude. Done with a plastic rule, a pencil and a felt tip. I have lost all of my drafting gear and the versions of CAD software I own are antiquated and no longer work on modern PC. Let's not get started on the extortionist pricing of lease to use Software, or Apps as they are now known. It appears that owning software is a thing of the past, or if it isn't already, it soon will be. If anybody knows of a half decent affordable CAD program for home use I'd appreciate knowing what it is.

  11. #71
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    Have you considered removing about 1" or a touch more of the dovetail section with your worn crosslide thread and replacing it with a new piece, similar to what has been suggested with the bronze insert.

  12. #72
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    That's the plan now. It looks to be the best way to obtain a working mechanism. I don't have facility to do it so Caskwarrior has kindly offered to maybe do it for me, hence the drawings so he can see where it goes from here.

  13. #73
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    Hi Glivo,

    Sorry for any confusion ! My last post was referring to the leadscrew itself rather than the nut, and dealing with the collar.
    My mention of 14mm threaded bar was simply because I had it and it might have been usable.

    I didn't have a lot of time this morning to go into much detail, hospital appointment to keep.
    Best Regards:
    BaronJ.

  14. #74
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    Quote Originally Posted by glivo View Post
    Not sure I'm with you here BaronJ. We are talking about milling out the threaded hole and replacing it with an insert, then making a new screw that fits the thread (possibly M10 X 1.0). A 14mm X 2.0 screw is going to be too large? Keeping the same centre height of the screw would see the nut hole break through at the top of the saddle dovetail and the screw would protrude, preventing the slide from even going on. The channel for the screw is only 13.5mm deep. Even using a M12 would be pushing to very thin wall thickness.
    Yes you are right ! 14mm would be too big to be usable.

    My drawings are very crude. Done with a plastic rule, a pencil and a felt tip. I have lost all of my drafting gear and the versions of CAD software I own are antiquated and no longer work on modern PC. Let's not get started on the extortionist pricing of lease to use Software, or Apps as they are now known. It appears that owning software is a thing of the past, or if it isn't already, it soon will be. If anybody knows of a half decent affordable CAD program for home use I'd appreciate knowing what it is.
    I don't run Windows at all ! I'm a Linux user and my preferred CAD program is "QCad" it is a free open source program that reads and writes DFX among other formats. There is a commercial version if you want to use it for machine Gcode. In use it is very similar to "Autocad" and some others that cost a fortune just to licence.

    But just like any program it takes a little time to become familiar with it.
    Best Regards:
    BaronJ.

  15. #75
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    Drawings seen, Ill get to it in the next couple of weeks. I only have imperial machinery so it will probably stay 3/8 - 16tpi 55deg if thats okay.

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