0.001 dial indicator for barrel set up

Discussion in 'Gunsmithing' started by Lefty Hunter, Dec 11, 2011.

  1. Lefty Hunter

    Lefty Hunter Active Member

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    Would a 0.001 dial indicator be accurate enough for setting up a barrel in the lathe for threading and chambering? Thanks
     
  2. Loner

    Loner Well-Known Member

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    I have seen quite a few smiths that talk in the ten thousandths not thousands when it
    comes to barrels. As do most of the barrel manufacturers.
     

  3. J E Custom

    J E Custom Well-Known Member

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    I would recomend a .0005 to .00010 Indicator for precision work.

    A .001 indicator would probably work if you could hold all readings below the .001 mark to .000.

    J E CUSTOM
     
  4. shortgrass

    shortgrass Well-Known Member

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    Barrel making and chambering are two different things. You can make do with a .001 grad indicator, just make sure when ya' call it good, that the needle doesn't move barely at all. Most manual lathes used for chambering are going to have .001 to .0005" of spindle play. If you tighten the bearings more than that don't turn very fast for very long as you must take into account the heat expansion that will result ( I use my lathe for much more than just chambering. Many tools are made there, too). It's all in the set-up. Warm your lathe up before putting a barrel in to dial it in. As long as the indicator is quality made, Starrett, Federal, ect., ect., take your time dialing in so there is no movement of the pointer, you'll be OK. I read lots about working to 4 and 5 places to the right of the decimal point. I've worked in the machining business since '74, few manual machines are capable (accept tool and cutter grinders) even fewer operators are. Manual lathes that are capable are usually far out of reach, dollar wize, for most.
     
  5. Trickymissfit

    Trickymissfit Well-Known Member

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    if you gotta get by with a .001" dial indicator, make sure you use a wand type. The big gear and rack ones are border line junk when it comes to being precise. Years ago they did make a jewled gear rack indicator that was certified for 3% lag. The normal gear and rack type have about 10% lag in them. Most folks could get by with a good B&S "Last Word" indicator for 85% of their work, and never look down on a GEM. I prefer Interrapids for their zero lag, and of them (I think I own six) I like the .0005" best. Brown & Sharpe sells a similar one, and it's a very good one as well. Avoid the Chinese built ones as they are not even up to junk statis
    gary
     
  6. Trickymissfit

    Trickymissfit Well-Known Member

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    a good rule of the thumb is that a precision tool room manual lathe is good for about .0005". I've seen a couple small Hardinghs that would do .0003" day in and day out, but's that's not a common thing. The spindle line alone won't let you get much better than .0005" on a perfectly aligned machine. Even a brand new Bridgeport mill is only built to a .001" spec. But on the otherhand a well maintained Monarch Double E with scales is capable of sub five tenths work with light cuts. Reason I mentioned the Monarch is that it's well known as the single most accurate tool room lathe ever built, and 90% of the time it's never goona be much less than .00075" on a good day.
    gary
     
  7. ken snyder

    ken snyder Well-Known Member

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    .0005 test indicator for run out. They're just easier to see whats going on is all. More important is a good base to put it on. Tenths is mainly spoken as a tolerance around a number ending in a thousandths - just a language for a tolerance around the last significant decimal place. If the last decimal place is a tenth then the tolerances will be spoken as hundredths (.00001) - Barrels are a Mystery judging by all the different sized pilots available for each caliber.
     
  8. J E Custom

    J E Custom Well-Known Member

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    When I first started building rifles I used .001 indicators and did fine. The trick (Like shortgrass
    said) was to keep the indicator on .000.

    I finally bought a better lathe and though I needed better instrumentation so I bought a
    last word with .0005 capability and several dials with the same.

    I found that my lathe would not consistently work within .00001 tolerances and that I
    could stay in the .0001 to .0003 range.

    The .00001 indicators are very sensitive and will make it easier to read any thing under .0001
    but they dont have much travel so for most work I use the .0005 indicators and the last word
    .00001 on the chambers.

    The main advantage of the .0005 indicators is ease of seeing the slight run out of the work and
    the Lathe.

    Most of the factory rifles have a .003 or .004 + or - tolerance and lots of production gunsmiths are
    fine with that also.

    I have been told by several barrel makers that barrel run out within .007 is fine (Acceptable to
    them). but I wont except any more than .001 to .002 TIR end to end because I feel that the
    heart of any rifle is the barrel and there are barrel makers that can and do build barrels that are
    perfict ( under.00001 TIR).

    Buy good barrels and stay within 1 or 2 ten thousandths and you will be fine and sometimes the
    build will go perfict (All readings were below .0001) if you keep trying to do better than the last
    rifle on every build.

    This is where the craftsmanship is important.

    J E CUSTOM
     
  9. Trickymissfit

    Trickymissfit Well-Known Member

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    slightly off subject, but regarding dial indicators if it matters a lot. I said earlier that I use a lot of Interrapids, and most folks think of them as the Roll Royce of dial indicators (I've seen one that's better). The onething I hate about a dial indicator is when you adjust the dial face (turn it) is that most will move all over the place. That .0005" Interapid stays put everytime. Now I have one of their .0001" ones, and hate it! It's just too sensitive to movement. But when I had to be right on the money it was dragged out of the box. The Federals are pretty good, but their dials are too stiff for adjusting in my book.

    A good rule of the thumb is that if you want to work within .001", it's best to use a .0005" indicator that has fairly good travel (.025" is plenty enough). I even had a couple .000050" Federals I used for splitting tenths when building gauges, and I often commentted that they were pretty much a joke to use! Still it made other folks happy. Also keep in mind that 80% of the dial indicators sold do not like to be set at the 12 oclock position, and then be turned upside down (6 oclock). The only ones you can do that with are the Interrapids and the B&S Best Test
    gary