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Thread: Barrels

  1. #91
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    I thought the second Youtube

    was interesting in that the presenter emphasized STRAIGHT, making sure the barrels were straight. We all have seen some that weren't.

    Pete

  2. #92
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    Quote Originally Posted by Pete Wass View Post
    was interesting in that the presenter emphasized STRAIGHT, making sure the barrels were straight. We all have seen some that weren't.

    Pete
    The questions I would have for them would be....

    Is the steel coming in stress relieved to begin with? I ask because it's a very important question and will relate to my last question......

    How are they measuring the straightness of the bar? What's the tolerance they are running with?

    Are they checking for straightness after drilling?

    After reaming and rifling?

    What/how are they measuring the straightness of the hole?

    After stress relieving? And.....After contouring?

    Again if they are straightening weather it be the bar or the contoured rifled barrel either way I'll guarantee they are inducing stress into the barrel.

    I won't name the maker but we inspected several barrels in a AR profile/contour. We had to do a before and after process inspection. The barrel maker was claiming that the finishing companies for finishing process (this came from the finisher to us) was causing the bores to change size and it was the finishing companies fault so they wanted the finisher to eat the cost on the barrels. The thing was where ever the barrel changed contour size the bore and groove dimensions had already changed from the machining during contouring. There fore there was no uniformity to begin with. When the finish was applied and heat treated (basically the short version of the process) the bore and grooves where yet changing again because the finishing process was relieving residual stresses in the finished barrel. So after seeing this and my opinion being asked as to why it would do that both ways.....my only guess is the steel wasn't stress relieved as it came from the mill. I told the finisher to get a copy of the material inspection report. The bore dimensions changed again during the contouring process and changed yet again after the finishing process. The dimensions varied an easy +.001" in different areas in the barrels.

    Also checked some hammer forged barrels by a well known firearms manufacturer a few years back. Again no consistency in bore and groove dimensions over the length of the barrel.

    Happy New Year to all!

    Later, Frank
    Last edited by Frank Green; 12-29-2017 at 03:44 PM.

  3. #93
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    Quote Originally Posted by FBecigneul View Post
    I like the way you do it Frank.
    I've won more with Bartlein Barrels than with any others.
    Thanks FBecigneul!

  4. #94
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    Question Frank,

    Is it possible to begin with stress free bar stock and keep the stress out as the process goes along and end up with straight barrels with concentric holes through them on purpose, not just by accident? Lets say a straight blank 1" in diameter. Is stress free stock even or ever available?

    Thanks,

    pete

  5. #95
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    Quote Originally Posted by Pete Wass View Post
    Is it possible to begin with stress free bar stock and keep the stress out as the process goes along and end up with straight barrels with concentric holes through them on purpose, not just by accident? Lets say a straight blank 1" in diameter. Is stress free stock even or ever available?

    Thanks,

    pete
    Off hand I'm going to say no. Again you cannot measure for it per say at this point in time that I'm aware of. Some information was just giving to me on this subject but have to check it out.

    If the steel mill could make and guarantee us stress free material what would all of be willing to pay for it? I'm sure it would come with a cost. If our costs go up the product cost is going to go up as well.

    Again the most stress free way to rifle a barrel is by the single point cut rifling method. The only real place I possibly see us inducing stress/or relieving stress in the blank is during the contouring operation. If it happens there one it's before reaming and rifling and second we throw the blank away so it never makes it to rifling to begin with.

    Later, Frank

  6. #96
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    Yea Pete

    Quote Originally Posted by Pete Wass View Post
    with a Kostyshyn barrel on it that was whopping big bore except for the two inch tight choke a the muzzle and it was a hammer. Only 30 Cal barrel I have ever seen made like that but it shot superbly. It's a shame Craig didn't hang in there. I have sold high mileage rifles that have won Nationals and one set at least one record but much of that was driver dependent, no question in my mind.

    Regarding the observations we can provide is any match for what someone who is testing with sophisticated measuring equipment along with testing can provide. Many of us have seen exceptions to all the rules I think but if straightness is a guarantee, why wouldn't anyone want to be there?

    I really don't think anyone is seeking the crookedest barrels they can find, Do you?

    Pete
    but even richard petty couldn't win a race behind the wheel of a Pinto.

  7. #97
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    Quote Originally Posted by Pete Wass View Post
    Is it possible to begin with stress free bar stock and keep the stress out as the process goes along and end up with straight barrels with concentric holes through them on purpose, not just by accident? Lets say a straight blank 1" in diameter. Is stress free stock even or ever available?

    Thanks,

    pete
    Pete, most of the irregularities you see in a Barrel's ID are the result of the initial drilling operation. Despite the great strides that have been made through the years, the act of getting a 100 percent true and straight hole through something like a Rifle barrel is still a great challenge. Every other operation, the reaming, the rifling, and the lapping will tend to follow this initial drilled hole.

    Figuring out why Gun drills seem to take a mind of their own and drift off of their initial course has always been a source of aggravation. Often, the hole might end up true with each end, but found to wonder off in different directions as it courses through the material.

    The culprit might be a small difference in RC hardness encountered by the drill as it advances. It could be a small buildup of shavings that for whatever reason did not flush properly.. In simple terms, there might be a few things that would cause a gun drill to follow a predetermined true path through a blank, and a multitude of things that would cause it not to.

    The truth is, I am amazed at how truly straight the ID's of barrels that come from our top quality manufacturers are.

    Stress will cause a piece of material to change when subjected to a certain actions after all of the finished machining processes have been performed. Heat is the first one to come to mind, but strain and vibration can also be a contributing factor.

    We deal with this on a constant basis at my shop. When machining long shafts, you get a first hand view as to the amount of stress that can be induced into a piece of material through machining, and the amount that can be released. We are constantly having to straighten them throughout the entire marching steps, so that in the end, we end up with a long shaft that is truly straight.

    But we rarely have to deal with an ID. 95 percent of the shafts we machine are solid. On occasion, we will have a shaft that has a hole through the center for a control rod or hydraulic system to operate a variable pitch Propeller system. We generally have these holes Trepanned and Reamed with the hope it will end up somewhere in the middle and be reasonably straight with it's self.
    Last edited by jackie schmidt; 12-31-2017 at 01:34 PM.

  8. #98
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    Thanks Jackie

    Quote Originally Posted by jackie schmidt View Post
    Pete, most of the irregularities you see in a Barrel's ID are the result of the initial drilling operation. Despite the great strides that have been made through the years, the act of getting a 100 percent true and straight hole through something like a Rifle barrel is still a great challenge. Every other operation, the reaming, the rifling, and the lapping will tend to follow this initial drilled hole.

    Figuring out why Gun drills seem to take a mind of their own and drift off of their initial course has always been a source of aggravation. Often, the hole might end up true with each end, but found to wonder off in different directions as it courses through the material.

    The culprit might be a small difference in RC hardness encountered by the drill as it advances. It could be a small buildup of shavings that for whatever reason did not flush properly.. In simple terms, there might be a few things that would cause a gun drill to follow a predetermined true path through a blank, and a multitude of things that would cause it not to.

    The truth is, I am amazed at how truly straight the ID's of barrels that come from our top quality manufacturers are.

    Stress will cause a piece of material to change when subjected to a certain actions after all of the finished machining processes have been performed. Heat is the first one to come to mind, but strain and vibration can also be a contributing factor.

    We deal with this on a constant basis at my shop. When machining long shafts, you get a first hand view as to the amount of stress that can be induced into a piece of material through machining, and the amount that can be released. We are constantly having to straighten them throughout the entire marching steps, so that in the end, we end up with a long shaft that is truly straight.

    But we rarely have to deal with an ID. 95 percent of the shafts we machine are solid. On occasion, we will have a shaft that has a hole through the center for a control rod or hydraulic system to operate a variable pitch Propeller system. We generally have these holes Trepanned and Reamed with the hope it will end up somewhere in the middle and be reasonably straight with it's self.
    Very well stated. Doesn't take away much of the frustration of knowing that though. Would air gauging be able to see the hole wasn't straight before reaming begins if the test was done?

    Happy New Year,

    Pete

    P>S>

    I have watched a number of videos of Keith Fenner straightening shafts. Pretty interesting how he is able to straighten them and how little heat is required.
    Last edited by Pete Wass; 12-31-2017 at 06:01 PM.

  9. #99
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    Quote Originally Posted by Pete Wass View Post
    Very well stated. Doesn't take away much of the frustration of knowing that though. Would air gauging be able to see the hole wasn't straight before reaming begins if the test was done?

    Happy New Year,

    Pete

    P>S>

    I have watched a number of videos of Keith Fenner straightening shafts. Pretty interesting how he is able to straighten them and how little heat is required.
    Pete, we straighten shafts at room temperature. The American Bureau of Shipping, (ABS), does not allow heat quench straightning.

    We straighten shafts and bent rudder stocks up to 13 inches. Here are four pictures of a 9 inch diameter Rudder stock that we straightened. The first is with the straightening rig in place, getting ready. The next two are the actual straightening, the last, the finished job. Keep in mind, there are quite a few "hits" in between as you work the bend out.

    The straightening rig has a 500 ton hydraulic ram. If you look behind the big Lathe, you see our largest one in it's cradle. It has a 750 ton hydraulic ram.

    We designed and built these rigs ourselves. They are constructed from T-1 plate. We also have smaller ones for smaller applications, one at 150 and another at 300 tons.

    We do this sort of thing on a regular basis.

    http://benchrest.com/attachment.php?...1&d=1514783143

    http://benchrest.com/attachment.php?...1&d=1514783256

    [url]http://benchrest.com/attachment.php?attachmentid=20531&stc=1&d=15147833 44[/url}
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    Last edited by jackie schmidt; 01-01-2018 at 01:30 AM.

  10. #100
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    Quote Originally Posted by jackie schmidt View Post
    . Here are four pictures of a 9 inch diameter Rudder stock that we straightened. The first is with the straightening rig in place, getting ready. The next two are the actual straightening, the last, the finished job. Keep in mind, there are quite a few "hits" in between as you work the bend out.
    That's really impressive. It would be hard to believe it's the same shaft if it weren't so distinctly 'charactered'. So, when you're chambering in that lathe, what do you do with the muzzle end? ;-)

    GsT

  11. #101
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    I thought maybe it was the barrel from the "Quest for 5000 fps" thread.
    It's always interesting seeing the stuff Jackie works on.
    Joe Hynes

  12. #102
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    Jackie. Keep the pictures going.....That is some awesome stuff.....

  13. #103
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    Jackie... couple of questions

    What kind of tolerances are you allowed on the shafts and what are the propeller diameters? I've had 8" shafts bent in hammermill crushers before, tend to vibrate a bit. Especially when running 1,000 rpm with several hundred pounds of hammers swinging around from the shaft.

  14. #104
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    Quote Originally Posted by Dave Coots View Post
    What kind of tolerances are you allowed on the shafts and what are the propeller diameters? I've had 8" shafts bent in hammermill crushers before, tend to vibrate a bit. Especially when running 1,000 rpm with several hundred pounds of hammers swinging around from the shaft.
    Dave, the majority of the Propeller Shafts we work on are 7 inch diameter to 10 inch diameter. The typical length is around 24 to 30 ft.

    When either new or repaired, we strive to keep all of the criticle fits within a few thousandths running truly straight. That includes the Bearing and seal surfaces and the prop and coupling taper fits. The area in between is machined true for balance.

    As for Prop size, most of the Inland Tugs we work on are twin screw, 1800 to 3600 HP. An 1800 will typically swing a 72 inch diameter wheel, a 2600 will swing about a 82 inch wheel, and a 3600 will swing a 92 inch wheel on each shaft. On occasion, we will have a larger shaft and wheel come in. One of our customers is G&H Towing, who have a fleet of Harbor Tugs that's handle ships on the Houston Ship Channel. Included in their fleet are six 3500 HP single screw boats which have a single 13 inch shaft and a 12 ft prop.

    Here is a picture of one we repaired the shaft and fit the prop for.

    The other pic is a 3200 HP Pushboat we did all of the machine shop work for last year. It has two 3512 Catepillar diesels and 8 inch shafts swinging 84 inch wheels.

    http://benchrest.com/attachment.php?...1&d=1514864956
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    Last edited by jackie schmidt; 01-02-2018 at 12:20 AM.

  15. #105
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    Jackie

    your straightening rig, are the tow arms the shaft is in old engine connecting rods? --Greg

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