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Thread: Chambering a Panda

  1. #16
    Join Date
    Feb 2003
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    Poetry, Tex.
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    5,877
    Quote Originally Posted by liljoe View Post
    I think the melonite has something to do with the tighter fit. Both of my coated actions have loosened up after a few barrels. That feeling of getting tighter as you screw the barrel on makes the pucker factor go up considerably.
    Joe Hynes
    No, Melonite is not a coating and does not increase dimensions.

  2. #17
    Join Date
    Feb 2005
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    266
    Quote Originally Posted by liljoe View Post
    I think the melonite has something to do with the tighter fit. Both of my coated actions have loosened up after a few barrels. That feeling of getting tighter as you screw the barrel on makes the pucker factor go up considerably.
    Joe Hynes
    More than likely you are cutting your threads in too few coarse steps. When there is no allowance for failure, most cut lathe threads with the least passes possible. Doing that you are leaving a thread which has sharp edge steps on the back of the thread. That side of the thread is the most important, and all that pretty, shinny from the rear of the barrel and the front of the action are just clearance. Every time you install and tighten a barrel and remove it, that stepped thread chews away at the action thread.

    Cutter angle, grind, tool angle, tool height, rigidity, in-feed tool angle , number of passes, number of cleanup, spring passes. and about a dozen more, if I really wanted to list them all.

    Single point threads are not the holy grail, especially when most learned how simple it is from the pros available anywhere on the WWW.

  3. #18
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    Feb 2003
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    Quote Originally Posted by TRA View Post
    More than likely you are cutting your threads in too few coarse steps. When there is no allowance for failure, most cut lathe threads with the least passes possible. ......


    Single point threads are not the holy grail, especially when most learned how simple it is from the pros available anywhere on the WWW.
    Something to be aware of too is that on most lathes while on the cross slide dials the graduations move the tool half of the indicated amount while the compound dial moves the tool the actual indicated amount.

    i.e. moving the cross slide dial 0.010" takes 0.010" off the diameter while moving the compound dial 0.010" takes 0.020" off the diameter.

    .


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  4. #19
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    Feb 2003
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    Tennessee
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    Quote Originally Posted by Tim Singleton View Post
    I have a couple Pandas and bought a Borden with the spacer to be able to test barrels
    The 1.060 I had been using for the pandas was to tight for the Borden
    I've started making them all 1.057
    Remember too you only want an unthreaded diameter that is about 80% of what a sharp thread diameter would be. Look on most thread gages and they give the double depth of the thread as 80%.


    .

  5. #20
    Join Date
    Jun 2003
    Location
    Milwaukee, WI
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    104
    Well I pulled the old barrel off and found a couple interesting things. It is right at 1.061 / .062 for the major dia, but it was a very smooth fit. The recess at the end of the action is 1.062 and you can see the OD dia of the thread cut into it so it would seem that this action would accept a full 1 1/16th thread. I've not measured over wires yet, but I will. The tenon is .020 longer than recommended, but the cone is deeper from the end about the same amount. Not sure why it would be done that way but the bolt nose clearance is maintained and the only thing you can see is there is essentially no flat at the OD of the cone. I think I will stick with the recommended dimensions, other than the thread major dia.
    I had my barrel dialed in but pulled it to make a sleeve to measure the headspace with as well as a bronze "wedding ring" with 1/8" diameter radius to go over the barrel shank for the four adjustment screws to bear on. I didn't like the feel of the copper wire I was using, squishing under the screws as tightened up. Now I think I have all the tools made up, including a reamer mic and reamer pusher so time to dial it back in and get it done.

  6. #21
    Join Date
    Feb 2004
    Location
    Austin, Texas
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    199
    Quote Originally Posted by mwezell View Post
    Curious, what type of cutter and do you feed the cutter straight in or with the compound. If with the compound, what's it set on? Has the cutter ever been sharpened?
    I use threading bits from ThinBit by Kaiser, on this particular case I threaded with the compound and brand new bit. Used the cross slide for additional 0.001 after done with compound.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  7. #22
    Join Date
    Feb 2003
    Location
    Belgium
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    112
    somthimes the tip of the cutting tool is not sharp enuff so it does not cut deep enuff you can have the right dia. and cutting depth with the 3 wire methode and it still does not fit
    do not ask how i now LOL

  8. #23
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    Feb 2003
    Location
    Tennessee
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    Another thing too for those using factory carbide threading tools. For example a positive rake (TPMG) will take those final cuts more predictable than a neutral rake (TNMG) tool.

    Keep in mind too, while you can feed aggressively on the first few passes since the tool isn't under much load the last 3-4 passes must be much lighter since the tool is cutting a full load. And too, these little tool room size lathes most of use will "spring back" and not cut accurately under that full load.

    .

  9. #24
    Join Date
    Jun 2003
    Location
    Milwaukee, WI
    Posts
    104
    Update.
    I've finished chambering the barrel in question. I think it turned out very nicely. The bronze wedding ring worked, but the screws still flattened the radius I put on it which would affect the barrel's ability to pivot, so I think I'll try steel the next time. The reamer cut on size at the base (a .471 pin would just start) and chamber is round with no runout or chatter. I nearly screwed the pooch when I bumped the cross slide handle between cuts on the cone, it's supposed to stay put and carriage controls depth. The next cut started MUCH deeper than expected but I had far enough to go that it cleaned up. Torqued the barrel to 40 lb-ft. I ended up with .008" bolt nose clearance and the stripped bolt drops on the GO gauge but will not close with a .002" shim on the back, so I'm happy. Crowned at eleven degrees with a light 45 degree kiss on the inner radius. Made a brass driver pilot for the muzzle, padded with two cleaning patches and then spun it for a while at 400 rpm while I ran a green Scotchbrite pad on it. Hope to see how it shoots this weekend. I appreciate the wise counsel that was shared.
    Greg

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