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Thread: Grizzly Rod upgrade

  1. #1
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    Grizzly Rod upgrade

    Lots of guys like and use the grizzly rods that Gordy developed a few years back. One of the biggest gripes and what I didn't care for, was having to hold one end in a drill chuck, mounted in the tailstock.

    My take is you have to be inducing some flex into the setup (Grizzly rod) as the bore wanders when dialing in, albeit minimal. This is due to the Grizzly rod being held somewhat rigid in the chuck on one end while the piloted end follows the bore.

    I'm not scientific, so I don't want to get involved in a lengthy, pick my method apart discussion. But I just wanted to share this because a lot of you guys do your own work, and I have had a lot of help over the years from some great smiths that were generous enough to give out info.

    What I did to remedy this was....mill out some 5/16ths ball bearing and fit them to the end of each Grizzly rod.

    This allowed me to mount that end in my Starrett No#828 wiggler, and then hold the wiggler with the chuck in the tailstock. This allows 360 degree movement of the rod at that end. Resulting in better indication.

    I used high rpm and Garr tool carbide endmills in sizes 13/64, 15/64 and 17/64ths.

    One was a press fit, the other was tight enough that I used Loctite 609. The other I used some JB weld.

    Click image for larger version. 

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    Last edited by eddief; 05-09-2012 at 04:09 PM.

  2. #2
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    Eddie, the wiggler joint is a good idea but how are you planning on keeping that ball on the crest of the land or in the bottom of the groove?

  3. #3
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    Jerry,

    The other end is in the bore with a proper fitting pilot. I just wanted a better way to hold the tailstock end.

    This just allows me to go into the throat and indicate better (in my eyes) before pre-drilling. I still go in after pre-drill and get a final direct reading on the throat with the DTI.

  4. #4
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    Quote Originally Posted by eddief View Post
    Jerry,

    The other end is in the bore with a proper fitting pilot. I just wanted a better way to hold the tailstock end.

    This just allows me to go into the throat and indicate better (in my eyes) before pre-drilling. I still go in after pre-drill and get a final direct reading on the throat with the DTI.
    So, the ball is riding in the bore of a pilot bushing? That should work.

  5. #5
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    Jerry,

    No, the other end (not shown) has the fitted to the bore bushing like the tapered PTG range rods. The Grizzly Rods aren't tapered.


  6. #6
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    Quote Originally Posted by eddief View Post
    Jerry,

    No, the other end (not shown) has the fitted to the bore bushing like the tapered PTG range rods. The Grizzly Rods aren't tapered.

    Now I get it , finally. The ball is on the wiggle joint end??

  7. #7
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    How would this method be better than say a tapered range rod? I to use a grizzly rod, and i was under the impression that we want the rod to flex. Some fellas even hang a weight in the middle of the rod to add a little extra flex. Im new to all this, with a pedigree of 4 barrels under my belt. I find these topics very interesting. Thanks Lee

  8. #8
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    Quote Originally Posted by JerrySharrett View Post
    Now I get it , finally. The ball is on the wiggle joint end??
    This is an ingenious solution to a problem that is still the problem, i.e. You are still indicating outside the bore. Not only that, the farther you extend the rod toward the pivot the more you are reducing the movement of the rod where your indicator is taking its reading.

  9. #9
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    They don't get it Jerry!

  10. #10
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    You make me laugh Butch!!!!!!!!

    It works better than deltronic pins before pre-drilling.

  11. #11
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    Don't you indicate the lands and grooves at the throat after predrilling? Predrilling allows my indicator with a short stiff probe to reach in and then indicate at the throat.
    Maybe that will give you more jollys.

  12. #12
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    Jerry,
    Wouldn't the difference between the outside and inside the barrel measurements decrease as distance from the end of the barrel to the pivot point (at the tail stock end of the rod) is increased?
    Boyd

  13. #13
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    Butch,

    Yes I do. This just allows me to go right to the throat for the initial dial in. Then I pre-drill and go in with Mituoyo DTI, take my direct reading, tweak the throat in as perfect as I can get it, and then pre-bore.

    Sounds like we are getting the same results with a little different method or jollys as you put it.

    For the record, I love the brashness and wear on my sleeve attitude around here. Makes me think back of my father and grandfather, god rest their souls. I can't stand people who tiptoe around crap and you don't know where they come from.

    I appreciate all that is shared here from you all.

  14. #14
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    I thought holding the one end fixed in the chuck allowed the bore to be indicated quite well.

    I grab very little of the rod in my tail stock chuck and I hold the pilot end down a bit when I tighten the chuck. This causes the pilot to be low in the bore. I also hang a 2 ounce weight in the middle of the rod so the pilot is held down in the bore when it is just past the throat area. My ten thou indicator measures up and down movement on the rod just outside of the chamber. I don't care what the actual movement measures, I dial it down as close to no movement as I can get.

    I was going to solder ball bearings on the chuck end of the rods but I find I can 'cock' the rod down slightly in the chuck and have no problem with this method.

    I just dialed in the crookedest barrel I have ever had from Shilen and the throat appears very concentric in the bore.

  15. #15
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    Eddie, I use Deltronic pins for my initial setup. I predrill and then use my Mitutoyo to indicate the throat. I taper bore to the throat. We are probably doing much the same thing.

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