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Thread: Engine turning

  1. #1
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    Default Engine turning

    Anyone know anyone doing engine turning?

  2. #2
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    When I was younger no problem. Now their just too darn heavy.

  3. #3
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    Quote Originally Posted by troyboy50 View Post
    Anyone know anyone doing engine turning?
    I've no firsthand experience with anyone currently doing that, but if your inquiry is firearms related, I think you'll expand your results when doing an internet search if you also search "jeweling" or "bolt jeweling".

    FWIW, back in the day I jeweled hammers and triggers using a drill press and Cratex abrasives. A cross slide vise is helpful for accuracy.

    Brownells sells Cratex rods: https://www.brownells.com/tools-clea...abrasive-rods/

    Regards,
    Greg
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  4. #4
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    I've used a pencil with a good eraser and polishing compound or lapping compound in a drill press. It's no doubt slower and not as effective as the cratex which is a fine idea I never thought of but it worked.
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  5. #5
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  6. #6
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    Quote Originally Posted by gb6491 View Post
    FWIW, back in the day I jeweled hammers and triggers using a drill press and Cratex abrasives. A cross slide vise is helpful for accuracy.
    Brownells sells Cratex rods: https://www.brownells.com/tools-clea...abrasive-rods/
    The other option from Brownells is a wire Engine Turning Brush. Those work well but "too much pressure" on the brush can make the 200th push (push "down" onto the surface you're turning on) larger than the 1st one -- but I easily solved that by wrapping a fine wire around the bristels of the brush only allowing so much flex, and it worked well.

    I did the bolts on my Marlin Cowboy, Browning BLR and Ruger MkII by making a jig which fit on my drill press. The jig allowed the bolts to be turned 1/8" (rotated around center) or so, to make the pattern.

    To make the jig work on the side-to-side movement (down the length of the bolt) I simply taped grid paper to the drill press table and held the jig in alignment with that; I put a witness mark on the jig and could align that with the grid as I moved the bolt left or right.

    There is a "trick" to making it look GREAT and not just good -- will try to explain it...

    You do not want the circles to be side by side like this OOOOOOOO

    You want them to overlap -- which I can't type here!!

    But I'd suggest you practice on a scrap piece of steel; I think the best pattern I came up with (and there are others which also look good) is that the 2nd circle (or swirl or jewel-mark, whatever you call it) overlapped 1/3 of the 1st circle, then the 3rd overlapped the 2nd by 1/3, then continue making overlapped (by the SAME amount) on all the circles on that row.

    Then, when you rotate the bolt to the next row (or if it's the flat of a hammer, it's the next row, but it's not rotated), you overlap 1/3 of the above row, then finish that row.

    The jig I made was a piece of wood, with (2) 2" right-angle braces attached, and I used bolts and nuts to secure the bolts -- I recall having to grind a sharp point on the bolt to secure it to the firing pin hole at the front of the bolt -- after confirming that "it was centered".

    Hope this helps.

    Old No7
    "Freedom and the Second Amendment... One cannot exist without the other." 2000 DTH

  7. #7
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    Quote Originally Posted by Old No7 View Post
    I did the bolts on my Marlin Cowboy...
    Look at what I found -- this was posted over 13 years ago on the Marlin Forum -- this should be helpful too!

    Cheers!

    Old No7

    A "right of passage" in my family was when you turned 16 years old, you got to go with Dad to drill the bank vaults. Sure, we could have made much more money by doing it at night in really big vaults! But we only did it during the day on small safe deposit vault doors -- always under the watchful gaze of an armed guard -- so we only made a decent living doing it. Funny thing is, our Dad always did the drilling, we were just the "lumpers". But we did get to learn some useful skills once the doors went back to the shop to be rekeyed and finished. Dad taught us how to do engine-turning, aka "jewelling", which is how we would disguise where the door had been drilled and pinned. I've done maybe 5 or 6 bolts for my guns over the years, so I decided it was time to tackle the plain-Jane bolt of my 38-55 Marlin Cowboy.

    Here you see the bolt mounted in a homemade (but effective) jig, and it's been highly polished with NEVR-DULL to prep the surface. I think that results in a better/more even finish later.
    SEE PIX #1

    The Brownell's engine-turning brush has been wrapped with light wire and secured with black tape. Sometimes I don't do that, but for this bolt I wanted nice tight swirls -- almost like fishscales -- and I didn't want the brush to open up too much under the pressure of the drill press' quill. You can see the 600-grit valve lapping compound that I paint on the bolt, along with the straight-edge clamped to the table and the graph paper aligned to that, so I'd have a grid to follow. You do NOT want to do this job by eye, as it's very tedious doing dozens & dozens of "move, quill down, count to 3, quill up, move..." repetitions. You do have to align the bolt with the brush and paper too. Having a solid setup, a good jig to hold the bolt level and with enough tension to prevent it from turning on you, and consistency on the quill pressure are the keys to this job.
    SEE PIX #2

    Here's the finished bolt still covered with the compound, along with the Brownell's brushes used. On every other bolt, I would always rub off some compound to "see how she looked" but this time, I was feeling pretty good about the pattern in the "goop" so I wanted to see if I could do it all without wiping. (That sounds wrong, but just go with it...)
    SEE PIX #3

    So without further adieu, here she is... I like it! And I'm really happy with the smaller pattern that I was trying to achieve, although some of my other work does look good with a larger pattern of swirls.
    SEE PIX #4

    Here's the bolt installed in the receiver, with the bolt open:
    SEE PIX #5

    Just in case you're curious, this is not just done "for looks", although that's a big part of it for sure. I've been told the swirls "hold lube" better. Whether that's true or not, I'm not sure, but maybe a trained machinist/gunsmith can weigh in on that.
    Attached Images Attached Images
    "Freedom and the Second Amendment... One cannot exist without the other." 2000 DTH

  8. #8
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    Phenomenal work and thanks for the write up. I hope to one day tackle this and do some triggers, hammers and barrel hoods on a few handguns.

  9. #9
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    Quote Originally Posted by troyboy50 View Post
    That works. Is it DIY?
    Regards,
    Greg
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