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Thread: Carriage lock screw - Any reason not to

  1. #1
    Join Date
    Jan 2014
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    In the desert
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    Default Carriage lock screw - Any reason not to

    I've got a 1440 Chinese lathe from Precision Mathews. Its not the cats
    meow, but its still better than any other lathe I have. Often when
    taking facing cuts or parting cuts I like to lock the carriage. The
    bolt for that is a recessed socket head screw. It works ok, but it
    seems I am always looking around for the hex key when I want to release
    it and move the tool away from the stock. Unless I am holding it in my
    hand the whole time it always takes me a couple seconds longer than I
    would like to locate where I set it down.

    I've been thinking about making a taller head replacement bolt,
    drilling it for a small vise handle. I've got a bit of 4140QT shaft on
    hand and a bit of 1/4" 1144 rod. Making it should be no big deal. Any
    reason why I shouldn't. I'd keep it as low as possible, and make the
    handle about half the difference in length between a short arm and a
    long arm hex key that size.

    Speaking of such I'd also like to lock the cross slide from time to
    time. There isn't a lock on it, but it does have a tapered gibb that's
    easily adjustable with a screw at each end. Usually I just keep the
    gibb adjusted a little bit tighter than is perfectly comfortable to spin
    the hand wheel, but on heavy roughing cuts it can still back off on
    longer pieces of stock. I wind up standing there with my hand on the
    hand wheel and my eye on the DRO the whole time. Is that just the best
    way to do it?
    *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

  2. #2
    Join Date
    Jan 2004
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    Missouri
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    31,146

    Default

    I'd just put a hex head screw on, but the "wrench head" would work.

    As for the crosslide lock, I'd not adjust the gob to do that. I think I would put in a screw to push the gib against the way instead, similar to the usual method with flat steel gibe. There will not be enough play in it to come close to breaking.
    1601

    Keep eye on ball.
    Hashim Khan

  3. #3
    Join Date
    May 2011
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    847

    Default

    What about a lever instead of a bolt head of any kind?

  4. #4
    Join Date
    May 2015
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    Somerset UK
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    2,237

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    This is a type of adjustable locking screw, they come in different sizes, some like this one, single ended and double ended are also made. They take up more room than a simple shcs. https://www.ebay.co.uk/itm/M6-Handle...IAAOSw9tlb7PSM

  5. #5
    Join Date
    Nov 2003
    Location
    Virginia
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    1,202

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    The cross slide set screw presses the gib on my Acer. The carriage lock is a socket head, I leave a wrench hanging in it so it's there.

  6. #6
    Join Date
    Mar 2008
    Location
    Barrie, Ontario, Canada
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    Bob--My lathe has the same set up.--Drove me nuts. I changed the carriage lock into a lever. It has to be a damned thin lever but it works great. I extended the bolt that was the cross slide lock and put a finger knob on it. I will root around and see if I can find a picture or a model.


    Last edited by brian Rupnow; 05-13-2019 at 04:42 PM.
    Brian Rupnow

  7. #7
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    Mar 2008
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    Barrie, Ontario, Canada
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    There is a trick to that lever. I first took the lock bolt out and drilled/tapped a #6-32 thread into the bottom of the hex socket. Then I machined a hex that would fit down into the top of that bolt and be long enough to reach from the bottom of the hex socket up to the top of the bolt. Then I welded that hex to the underside of my lever. Then drilled and countersunk from the other side of the lever and right thru the hex part for a #6 flat head capscrew. Sounds a bit complicated but works good. If you don't understand I can do up a quick 3D model for you.---Brian
    Brian Rupnow

  8. #8
    Join Date
    Jan 2017
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    163

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    I didnít have the same issue as Brian with clearance and my lock was actually a nut. I replaced the nut with a coupling nut milled short enough to clear the compound when it swings. I put a dedicated wrench on it. The extra height keeps the wrench in place but meant I didnít have to guess on the handle position and I can still remove it. Regardless of what it takes to make it work itís a good mod to have toolless. I use mine on all parting and final facing ops.

  9. #9
    Join Date
    Apr 2017
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    Kelowna BC
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    Just cut a half inch piece off an Allen wrench, and loctite it into the Allen head. Then use a wrench on it.

  10. #10
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    Or use a socket head bolt with a spacer if needed, then make a lever which can press over the head. The splines will give the lever some grip, and you'll be able to orient it right the first time and reposition it later if needed. Put that lever handle exactly where you want it. A hex head doesn't give you much choice.
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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