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I'd like to build a carriage stop.

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  • J Tiers
    replied
    Looks good...

    As for the mic, I made the one in the pics.... I very carefully threaded 1/4-20 TPI and got a very close fit on the spindle to stem thread clearances. Would have done larger, but I wanted it to be interchangeable with an indicator stem.

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  • MotorradMike
    replied
    Closing off carriage stop thread.

    Hi guys:

    I finally made the carriage stop I asked you all about back in December of last year.
    I like to close off threads just so you know I really am listening.

    I mostly stole 'J Tiers' design and made it wider as he suggested.
    The big Aluminum part turned out quite well. I'm very happy with how square it seems to be as well as how nicely the finish came out. I bought a boring head to make the pocket for the dial indicator and couldn't get boring bars for it so the cutter was ground from 1/4" HSS and mounted in a holder I also milled. I was a bit apprehensive about how it would cut but the finish tells the story.
    For now, I can put a 3/8" bar in to make it a hard stop. Maybe I should modify one of those $10 micrometers to make it adjustable!

    The machinery is Chicom but the cutters were all made in the USA.

    Cutter holder.


    Carriage Stop.
    Last edited by MotorradMike; 10-17-2010, 06:18 PM.

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  • Roy Andrews
    replied
    i built this to indicate travel but use it mostly as a quick stop. easy to adjust and no tools.


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  • Boucher
    replied
    Material Choices

    Stuart: My first choice would be 7075-T6 Aluminum because I have it and I like working with it. 416 Stainless or 12L14 would be next. Plane Jane hot rolled 1018 will work fine it is just harder to finish.

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  • fciron
    replied
    Originally posted by Carld
    fciron, I see your in the "BIG L", I'm not far from you. Glad to see another local machinist here.
    Carld, I noticed you were down the road. I are not a machinist yet. I've got a little blacksmith shop mostly doing ornamental work.

    Also, after all of my fussing I did the trig wrong. The slide moves on the hypotenuse, so the 30-60-90 triangle will not work. Maybe I will just go to your method instead.

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  • Stuart Br
    replied
    I'm looking at making a stop, material choice??

    I am new to this game and am looking to make a carriage stop for my Chipmaster. I am wondering about the best material to use that is going to give some durability but still be relatively easy to machine.

    Thanks

    Stuart

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  • Carld
    replied
    fciron, I see your in the "BIG L", I'm not far from you. Glad to see another local machinist here.

    The best use for angling the compound is when grinding. As to the compound, I keep it parallel to the ways and use it when taking clean up cuts on face cuts or to a shoulder.

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  • fciron
    replied
    Oops, always refresh the browser before asking what happened to your post.

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  • fciron
    replied
    Yup, the angle trick only good for fine control in one axis at a time. It will have the opposite effect on the other axis. (At 84 degrees there will be ten thousandths movement axially for each thousandth radially. Thanks for the reminder, it suck to find that out the hard way.

    Motorradmike was talking about facing, where can be a useful trick.
    Last edited by fciron; 01-05-2010, 01:08 PM.

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  • J Tiers
    replied
    The ONE BIGGEST trouble with angles for fine feed is that, at least in my case, the need for good precision often coincides with turning to a shoulder.

    Naturally, when one angles the topslide for precise RADIAL travel, the whole notion of turning to a shoulder with a stop goes right out the window, because there is a larger axial travel of the cutter. You are continually changing the required position of the stop, making it useless.

    In my opinion, everything you can actually USE for radial precision is attainable with a larger handle and dial on the crosslide. Larger dial to see the movement better, and larger handle to give better control.

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  • fciron
    replied
    I was not recommending feeds of several tenths. At a setting of 84 degrees (or six degrees for facing) an entire turn of the compound screw would give a one thousandth cut, my compound has plenty of travel to make the average finish cut of .002-.005 inches with a high degree of control.

    If that is too much precision then compound angles of 30 or 60 degrees could be used to give a ratio of 2:1.

    I poached that tip from a South Bend publication because that I thought the mathematical use of the compound for fine feed control was useful. Using the compound gives a lot more control than the carriage feed wheel.

    Any ratio can be calculated with basic trig. (Plenty of tutorials available on YouTube, much simpler than you think.) The travel of the cross slide is along the hypotoneuse of a triangle with sides of the ration you want to use. There Use of 14 or 76 degree angles will give a 4:1 ratio.

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  • Carld
    replied
    Many lathes have a friction clutch on the carriage and crossfeed that is either flat plate or cone. The clutch on mine is a flat plate and is positioned to work on the carriage and crossfeed. Some have a ratchet type clutch like the feed on a BridgePort quill feed.

    The repeated use of the clutch on the carriage/crossfeed causes wear on the plates. At some point they will need replacing. You have to decide if the continued use of slipping the clutch is worth the effort to repair the clutch.

    The fact is you could get by with doing it for years or the entire time you own the lathe but at some point it will fail from over use of the clutch.

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  • Ian B
    replied
    Where I find a bedstop most useful of all is when boring blind holes. My lathe has an adjustable overload dropout on long & cross feed, which I always thought was designed for running up against an adjustable bedstop. The bedstop is from the lathe's manufacturer, Harrison, and is pretty stout.

    I normally run with the feed disengage clutch backed all the way off, which still gives plenty of push to feed the tool. When the carriage contacts the stop, there's no obvious signs of anything getting overstressed, the feed just drops out. It makes boring to a set depth a breeze.

    However, I must admit, I very often drop the feed out a fraction before contact with the bedstop, and finish the last mm of travel by hand.

    Ian

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  • Carld
    replied
    While setting the compound to the 84 deg angle does produce an in feed of .0001" for every .001" of compound feed there are few lathes that can actually remove metal in those increments. I have tried and it does not always work. You have better luck with a file and emery cloth.

    With my current lathe I can take .001" per pass off of the work most the time. It depends on the type and quality of the metal many times.

    I will say that if your using a tool post grinder then setting the compound at 84 deg could be helpful.

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  • fciron
    replied
    In addition to a dial indicator, you might appreciate this tip on making fine cuts from South Bend's How to Run a Lathe "When the the compound is set at an angle of 84 degrees (84 - 16' to be exact) each graduation on the compound collar represents an angular movement of .001 in. and a cross-feed movement of .0001 in. or a reduction in diameter of .0002 in."

    I would assume that a corollary of this would be that setting the compound at six degrees would remove one thousandth off the face of your work with each complete turn of the compound screw.

    In regards to the earlier debate, South Bend offered a micrometer carriage stop for all of their lathes, so the original post was perfectly sensible, and a CNC lathe is no guarantee against crashes. You can program it to do all kinds of stupid things.

    I can't believe I have to use my first post in this forum to tell people to take a deep breath.

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