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P-W 900 coil spring.. purpose?

Discussion in 'Shooting Related Threads' started by Unknown1, Nov 22, 2010.

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  1. Unknown1

    Unknown1 Well-Known Member

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    Nov 5, 2009
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    I own 4 P-W 900 reloaders. Each has broken the same coil spring at least once: the big coil spring on the finish knockout tool. The first one I replaced with a factory spring, the second with a hardware store spring and the last two, well...

    I am at a loss to understand the purpose of the coil spring and the finish knock out housing on the final station of these loaders. <center>
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    I didn't replace the last 2 springs that broke and I removed everything from that tool station except the knockout shaft and the button on the end. The loader functions perfectly without the spring and housing and the shells show no evidence of being mistreated. The only difference in machine operation that I noticed is that the missing spring provided a bit of an assist to help lower the bottom cross head and now that's gone.

    I'm wondering if anyone really knows why the spring and housing were hung on that tool station in the first place. No speculations if you don't mind.

    MK
     
  2. Ahab

    Ahab Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    3,650
    I never heard of that coil spring breaking.

    My old 800C loaded 500,000+ shells and never broke that spring!

    That spring is to clamp the finish knockout housing around the shell to keep the knockout ram from distorting the rounded taper crimp ... if there is a tightly stuck shell is in the die.
     
  3. cubancigar2000

    cubancigar2000 Well-Known Member

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    Idaho
    Been using mine for almost 10 years, no broken spring??
     
  4. Unknown1

    Unknown1 Well-Known Member

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    Yeah... it seems that some springs last a long time and some springs don't. I had one break because the allen screw that locks the shaft wasn't tight and it wore a weak spot in the spring.

    The last one broke right in the middle. I looked at the break under magnification and could see where the top surface of a coil had been nicked at one time creating a stress riser that lead to the failure.

    These springs are probably just made of piano wire and I don't think they're stress relieved in any way after they're wound. A little sloppy heat treating or careless handling at the plant... it happens.

    MK
     
  5. Whortle

    Whortle Member

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    Jul 17, 2010
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    Mine broke after 6 yrs of use on an 800+.

    Got a new one on the way from ID.
     
  6. phirel

    phirel TS Member

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    Jan 29, 1998
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    9,556
    The knock out housing centers the knock out plunger directly over the die. It is pushed up as the shell is ejected. The spring pushes it back down. I did break one once and they are easy to replace. Whiz told me that I did need the spring and I never question his wisdom.

    Pat Ireland
     
  7. whiz white

    whiz white Strong Supporter of Trapshooting Banned

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    Either you simply had some bad luck with coils, OR the center shaft for that housing is loose.

    It is to be tightened all the way in until you run out of threads, and THEN tighted (not over-tighten) the set-screw which should prevent the shaft from loosening up.

    Many times you can get residen buildup under the lower cap. I recommend removing the center shaft, and then remove the small Allenhead screw in the very center on the underside, and thoroughly clean the whole appratus.

    WW
     
  8. Unknown1

    Unknown1 Well-Known Member

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    The shaft and the screw definitely weren't loose when I removed them. I'll make sure the threaded bore is clean all the way in when I replace them.

    I do the reinstall the way you described: I use a half of an 8d nail as a lever in the hole in the shaft to run it up until it stops then lock it down. They feel rock solid when they're tight.

    The shaft inside the spring that just broke had an area near the threads where the housing had worn into it. The housing had an oval bore and was a little wobbly. The assembly was free of residue. I ordered replacement parts from Bruce only so that the loader is complete if I want to sell it.

    I'm going to de-burr the edges of the housing bore and try lubing the new shaft with NECO "Moly-Slide"; 60% solids moly grease for guns... rub it into the metal until it disappears and it leaves a non-sticky film of M<sub>2</sub>SO in the metal (use it on pistol slides, hammer sears and to pre-condition rifle bores for moly-bullets).

    Thanks for the advice.

    MK
     
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