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Thread: basic lathe operation, turn to shoulder

  1. #1
    Join Date
    Dec 2008
    Location
    Greensburg IN
    Posts
    35

    Default basic lathe operation, turn to shoulder

    I have a lathemaster 9x30 lathe.
    I have next to no experience in lathe operation
    I was wondering what is the proper way to turn to or make a shoulder on a shaft. Here is what I generally do. Make a pass towards the spindle with the power feed and as it gets close to the shoulder I flip up the lever to dis engage it, then I make a couple of facing passes to get the shoulder square. This makes me a bit nervous that I will wait too long and it will bind and I wont be able to disengage it and that will cause all sorts of problems.
    So I was wondering what is the proper technique. There is lots of stuff out there about more advanced lathe operation but not so much about this very basic stuff that most people probably learned in shop class.
    So after reading a couple of other posts on here about basic stuff I thought I would ask.

    Thanks
    Bernie

  2. #2
    Join Date
    Dec 2006
    Location
    iowa
    Posts
    419

    Default

    that's how I do it.
    A dial indicator mounted in the bed helps with stopping the carriage at the same spot each time. Feed until you are close to your stopping point, disengage feed and then feed by hand to the stop point. face to length once you hit diameter

  3. #3
    Join Date
    Jul 2006
    Location
    Germany
    Posts
    125

    Default

    That machine does NOT have powerfeed, it has a leadscrew which you should only use for cutting threads. (I know what the seller is writing, but believe me).
    Use the handwheels for working, that will also give you a better feel for what the machine is doing.
    Now, cutting to a shoulder: the most useful accessory I EVER made for my lathe is a carriage stop. It's basically just a block of metal that you can clemp to the ways. When the carriage runs into it, it stops. Period.

    Make certain your compound rest is aligned along the ways (handwheel sticking out right side). Wind it back away from the headstock, it is OK if 10...15 mm of the dovetails are free..
    Set the carriage stop so that the carriage can be moved left until the tool almost touches the face of your workpiece.
    Using the compound rest, advance your tool until it just scratches the surface of the end of your workpiece. Zero the compound dial.
    Wind the carriage away from the workpiece again.
    Advance the tool using the compound (use the dial on the compound) an amount that is equal to the depth of the shoulder (lenghtwise) minus 0.3...0.5 mm.

    Now using the carriage (use the handwheel) you can start working, reducing the diameter of your workpiece gradually up to the shoulder. This is completely safe, af the carriage is stopped by the stop.

    Before the last cut advance the compound the missing 0.3...0.5 mm. Do the cut, and when the carriage hits the stop this last time, reverse the tool using the cross slide. This will clean up the shoulder and you will have a very precise part.

    Best Regards,

    Benta.

  4. #4
    Join Date
    May 2009
    Posts
    157

    Default

    I use the indicator method. If you know the radius of your tool nose you can subtract that from the final shoulder (Z dim'n), then make a facing cut to length.
    Only thing to watch here, you need to break chips and not have long strings lest they snatch your indicator.

  5. #5
    Join Date
    Dec 2006
    Location
    iowa
    Posts
    419

    Default

    this should open a whole discussion on turning with the lead screw versus not using the lead screw to turn. Personally I have a SB 9" Jr. and I use the lead screw to feed. Why else would SB provide a feed gear ? I understand that I am wearing the lead screw and half nuts, but i take light cuts and I will worry about wear if and when it happens.

  6. #6
    Join Date
    Jan 2005
    Location
    Indianapolis, Fort Lauderdale, Babbit MN
    Posts
    599

    Cool Lead screw

    I have been using the lead screw to do cuts on both my Logan and Atlas for years.
    I didn't know that was a bad practice?????
    Bill
    I cut it off twice and it's still too short!

  7. #7
    Join Date
    Mar 2009
    Posts
    503

    Default

    It's quite possible that a smaller home shop oriented lathe that only has a leadscrew for carriage feed would not be the most accurate machine repeatability wise for threading anyway, so a little extra wear on the half nut is not really a huge factor.

    There are many less expensive lathes with seperate drive systems for turning and threading that also don't repeat for threading!

    Glenn

  8. #8
    Join Date
    Jun 2007
    Location
    Costa Mesa, Ca.
    Posts
    246

    Default

    Quote Originally Posted by Seastar
    I have been using the lead screw to do cuts on both my Logan and Atlas for years.
    I didn't know that was a bad practice?????
    Bill
    How does using the lead screw for feed work when you are using a stop?
    "the ocean is the ultimate solution"

  9. #9
    Join Date
    Aug 2006
    Location
    Taylorsville Ky
    Posts
    5,882

    Default

    Swing over Bed: 9 "
    Swing over Cross Slide: 5 7/8"
    Distance between centers: 30"
    Carriage Travel: 25"
    Spindle speeds: 6
    (125, 210, 450, 620, 1000, 2000 rpm)
    Longitudinal Feeds: 2 (.005,.010)
    Inch Threads: 12 (8 - 40TPI)
    Metric Threads: 12 (.4 - 3mm)
    Cross Slide Travel: 4 1/2"
    Compound Travel: 2 5/16""
    Tailstock Spindle Travel: 2 3/4"
    Tailstock Taper MT2
    Spindle Bore: 20mm (3/4")
    Spindle Taper: MT3
    Motor: 3/4 HP, 110V/60Hz
    Machine Size: 56"x19"x18 1/2"
    Machine weight: 330lbs.
    Shipping weight: 388lbs.

    Above are the specs for the Lathemaster and if you look close you will see that it has two longitudinal feeds of .005" and .010". That is not much of a selection and I suppose your could use the threads for a feed since it uses the lead screw as well.

    Now, turning to a shoulder is not always easy and if your using a standard shouldering tool the side of the cutter may rub on the work if the shoulder is deep. It's best to grind the cutter so the shank is angled away from the work. I power feed within about 1/8" of the shoulder and hand feed the rest of the way with either a dial indicator mounted on the ways or a carriage stop. The carriage stop is the best way.

    I leave about .20" on the shoulder to face off after I have the diameter about .020" oversize. Sometimes I switch to a 80 deg V tool and finish the diameter and the shoulder at the same time. Turn the diameter to size to the shoulder and then back the tool out to finish the shoulder. I usually go in .005" steps to do the finish work so I can control the finish size.
    It's only ink and paper

  10. #10
    Join Date
    May 2002
    Location
    Beaumont, TX
    Posts
    7,273

    Default

    Quote Originally Posted by steverice
    How does using the lead screw for feed work when you are using a stop?
    It doesn't work!

    I would not work this way as you will have the lead screw trying to move the carriage with considerable mechanical advantage and a solid stop trying to stop it. This reminds me of the old question, "What happens when an irresistable force encounters an immovable object?" Answer: SOMETHING has got to give. You are likely to break, bend, or distort something - whatever's the weakest link. My money is on the half nut because it's fun to replace.

    Don't do it.
    Paul A.

    Make it fit.
    You can't win and there is a penalty for trying!

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