Chambering with long spindle lathe
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  1. #1
    jhmcgowin Guest

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    Hi to All,
    I’d like to compare notes on the issue of head stock length and how we work with …or around it related to cambering. For sometime now I’ve done it with the aid of an adjustable center that’s mounted on the back of the spindle and can be adjusted for length, to hold the barrel on center inside the spindle. My mentor built this a few years ago and it works great but takes a long time to set up correctly. I have seen and heard of many others that use this type of method to get around the long spindle issue. Some even use delrin bushings. Most of the internal center remedies require that true centers be cut after the barrel is cut to length to make weight. This is similar to doing between centers but you know have the 4 or 6 jaw to work with, a big plus for me, may not be for others. What if you use a cathead for the back of the spindle and mark the barrel for the cutoff points but only cut the chamber end off, leaving the muzzle end long so it would go through the spindle. (May work with spindles a little to long, but may have to use a cats head at both ends of spindle for longer ones.) All chamber end work is done with the through spindle setup. After chamber end is done, cut barrel off on the muzzle end mark and crown. At this point what will be the simplest way to crown? Between centers or with the internal center and or use a 4 or 6 jaw to drive the barrel and a cats head to run the steady rest on or maybe the long tube cathead driven by the chuck and also to run the steady rest on. Did I leave one out? The Question, if your lathe spindle is a little to long, is it worth it? The set up is very easy and the results are very good using the through spindle method. Then use an alternant set up to deal with the crown. What are your thoughts on this?
    Thanks, Jim M.


    [This message has been edited by jhmcgowin (edited 11-15-2003).]

  2. #2
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    Jim, I don't know your headstock dimension,but, I have to have a cathead on both sides of my headstock. I have a 6913 Clausing and 21 3/4 is best I can do. I have talked to Ed Shilen about the center in the headstock and he sees merit in it if done properly. Thebarrelman

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    Jim, I agree with Butch about having the barrel mounted with adjustment on both ends, it's the best way to go. But when a big lathe is used, an internal bushing of sorts to center the barrel in the spindle will work, but doesn't give you the adjustment for alignment.

    Some time ago I posted a question about a mounted bearing to be used in place of a steady rest. I received a picture of such a set-up and I think it would work fine. In a nutshell, it's a precision bearing mounted in a fixture which is mounted to the ways and set to lathe center. In the bearing is a collar that has four screws for adjustment. In effect, it's a steady-rest-bearing, that is rigid. Nothing running on bushings like a steady. If made properly, I see no reason you couldn't set up a barrel, thread and chamber it on one end, then turn it around and crown the other. A four-jaw could be used on the heastock, then the bearing/collar used to indicate the other.

    I plan on making such a fixture this winter to work on barrels that are larger diameter than my spindle bore. All I have to figure out is a way to set up a barrel flush system when the end of the barrel is in the chuck.

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    I am interested in your steady rest bearing system. Could you send me a jpg. photo of the device?

    Ron in Boise
    [email protected]

  5. #5
    jhmcgowin Guest

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    RWS,
    I would sure like to see the photo of that setup...sounds like it would work very well for my unlimited barrels for the rail gun. I only have a 1 3/8 spindle bore and there a pain to set up in the long pipe cathead I use.
    Jim M.

    [This message has been edited by jhmcgowin (edited 11-15-2003).]

  6. #6
    jhmcgowin Guest

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    Butch,
    The best I can do with my 13" SB is a 23-1/2" long barrel with a 4-screw collar at both ends. I like my BR LV barrels at 21.5 to 22”, so without leaving my barrels a few inches long at the muzzle end I can’t use the through spindle setup. Not a big thing, but a lot more setup time to crown with a different method. A new lathe would be nice but the SB is smooth as silk and very user friendly.
    Jim M.

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    Sorry Jim, I was hoping. Regards Butch

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    If you want to see a picture of one, go over to AccurateReloading and do a search in the gunsmithing forum. I think it was John Ricks that posted a pic of one he built. James

  9. #9
    John Ricks Guest

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    Here ya go:




    And another:



    Two more things you need:
    (Rotary coolant union and 4-screw cathead)




    Other end of the barrel showing coolant flow:



    Note the dial indicators on the steady. The singlemost failure among hobby gunsmiths is a lack of understanding of the proper use of dial indicators.

    The steady works like a 4-jaw chuck, very easy to dial in the barrel bore, does not marr bluing, and you can straddle a front sight ramp.

    Another note: I mainly use "barrel through spindle" method. Order your blanks the full 28 inch length, does not cost any more. This lets you go through the spindle and use the cathead. Plus you have the cut off stub to make bullet seat guages. Often I use the steady if the barrel is too short to go through the spindle. Or if I want to leave the barrel in the receiver, chuck up the receiver in the 4 jaw, and run the muzzle in the steady for installing a brake.
    Also workes great for cutting off the muzzle end and crowning.

    Dialing in a 4 screw cathead is very easy, just like a 4 jaw chuck.

    Where do you get this thing? You gotta make it, as the lathe manufacturers have not figured out how. If you make one, build in alignment movement, as you have to use the old millwright method of reverse dial indicator coupling alingment to get the steady spindle in alignment with the lathe axis. (don't forget indicator sag!!)

    Here you go for dialing the bore:
    Note the "bore pin" and the copper shim to protect the barrel. That rod extending from the lathe has a lot of uses.





    One more comment: Forget about making up a bushing to fit around the muzzle, and to fit the inside of the lathe spindle. Ain't no way you can properly align the barrel bore to the lathe axis this way. The bore in a lathe spindle is just a rough bore, not necessarily true or aligned to the axis of spindle rotation. Only true portion (if it has not been abused) is the ground tapered section for receiving the headstock center.

    [This message has been edited by John Ricks (edited 11-13-2003).]

    [This message has been edited by John Ricks (edited 11-13-2003).]

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    Nice pics John. Your bearing/steady is a little different than the other one I've seen, yours looks heavier. The pic I have is on another PC, so I'll have to forward it tomorrow.

    Have you ever turned and threaded using the steady? Is it rigid enough?

  11. #11
    John Ricks Guest

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    Yep, it is fairly heavy, I turn barrel threads, chamber, and use the cut off tool with this steady. It has a one piece spindle, and there is a SKF angular contac ball bearing on each end. Note the SKF locknut and tab washer for adjusting bearing preload.

    This thing started out as a cast iron pillow block housing that had babbitt inside, pretty old stuff. It was as new, never used. I bored out the babbitt and enough CI to make room for the SKF ball bearings with a locating shoulder on each side. Base is made from 4 inch ship channel, which is heaver than regular channel. The two way pads are machined to fit the ways and I allowed enough room for shimming to get the alighment correct, then doweled everything.

    All mating surfaces are machined.

    It is about 500 times better than the standard finger steady, and about 100 times better than a finger steady with tiny rollers on each finger. The beauty is the ability to correctly dial in the barrel bore. Plus it will not mark a blued barrel, I use rolled copper shims to protect the finish.

    [This message has been edited by John Ricks (edited 11-13-2003).]

  12. #12
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    Hi John,

    I like your set-up.

    "Note the dial indicators on the steady. The singlemost failure among hobby gunsmiths is a lack of understanding of the proper use of dial indicators."

    Okay, I'll bite. Care to elaborate?

    Regards,
    Webb



  13. #13
    jhmcgowin Guest

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    John,
    Thanks for posting photos, great job on that bearing style steady! Gives me a lot to consider on how to build one with available parts. Through the head by leaving the muzzle end long is a very rigid and easy setup. I can find no reason not to do it. With your style steady it would be a snap to setup for crowns or do both ends if needed. If you were going to build another but didn’t have the bearing housing you had used / built on the last one, is there one commonly available that you would consider from a power transmission supplier?
    Jim M.



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