Machining bolt lugs ?
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    Default Machining bolt lugs ?

    I'm interested in how they used to machine lugs on bolt action rifles , especially the Lee Enfield bolt that has a lug running almost the whole length of the bolt body, did they plane them, grind them or what ?

    How do you produce a partially round bar without turning ?

    How would you machine the round areas between the lugs say on a two lug bolt ?

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    I think in the early days they started life and forgings and were subsequently machined then finished.

    I have purchased a few 1898 new old stock Krag bolts. Few of the original machining marks are left. The working surface of the locking lug shows mill marks were it was finished almost everything else shows abrasive polishing marks. It is real hard to figure out there machining order because of this. even harde when picking up an worn bolt.

    They did some complex fixturing back then with multiple cutters ganged on horizontal milling machines. I have seen photos of receivers and other parts of guns being machined. The reason you see no photos of bolts being machined, perhaps they were secretive about it.

    boltdings2rs.jpg

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    The profile is a fairly simple milling and turning job....more complex is how the angled pitch locking surfaces were machined,and matched to a tolerance of .001".....The firearms industry were the first to use what Henry Ford later applied "One operation done in one machine".........One other point with the Lee Enfields.....the thread indexing in the barrel tenon was maintained from 1871 until 1957....and much later in India ....I screwed a 1961 made Lithgow SMLE barrel into a 1874 made Martini Henry action,and the barrel indexed exactly to put the sights in the proper position.

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    perhaps the bolt is held and machined in a circumferential manner, such as when a part is held between centers under a surface grinder, and rotated so that the surface grinder makes it a cylinder. Except the radius of the wheel would limit how close adjacently you could come to the lugs and the bolt handle on either side at the common axial distance.

    Alternatively what about a shaper running axially, and the part rotated under it, with different depth stops based on the angle. Because the two lugs are at different angles you would have a clear line to all surfaces so long as you put the part in one way for one operation then back in the other end first for another.

    Then the lugs are cleaned up somehow, perhaps tapered facing with interrupted cuts. Or maybe they are taper faced as bands, then cut down into lugs with a shaper chiseling them off.

    But the real question is what about the bolt handle, is that a separate fabrication that is welded on afterwards, or were the parts rough cast / forged then finish machined without the bolt handle getting in the way somehow, because I can't imagine they started from stock with a wide enough radius for the handle, or even off center with a wide enough diameter for the handle even. Too much material waste.

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    That is the "secret" of the Mauser rifles ...the design seems more complex than a Lee Enfield ,but every part is carefully developed to make manufacture simple and fast ......whereas the Lee Enfield was always a difficult rifle to make,and considered impossible by several US makers in 1914......The foregoing is the reason the British decided to adopt a Mauser design in 1912....unfortunately the whole idea was caught up in WW1 ,and the rifle was never widely adopted ,despite over a million of them being made in the US.It was judged the best military rifle of WW1 ,but no one ever liked them .Except gun nuts ever since. '

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    Quote Originally Posted by woodstove View Post
    perhaps the bolt is held and machined in a circumferential manner, such as when a part is held between centers under a surface grinder, and rotated so that the surface grinder makes it a cylinder. Except the radius of the wheel would limit how close adjacently you could come to the lugs and the bolt handle on either side at the common axial distance.

    Alternatively what about a shaper running axially, and the part rotated under it, with different depth stops based on the angle. Because the two lugs are at different angles you would have a clear line to all surfaces so long as you put the part in one way for one operation then back in the other end first for another.

    Then the lugs are cleaned up somehow, perhaps tapered facing with interrupted cuts. Or maybe they are taper faced as bands, then cut down into lugs with a shaper chiseling them off.

    But the real question is what about the bolt handle, is that a separate fabrication that is welded on afterwards, or were the parts rough cast / forged then finish machined without the bolt handle getting in the way somehow, because I can't imagine they started from stock with a wide enough radius for the handle, or even off center with a wide enough diameter for the handle even. Too much material waste.
    This whole thread is an example of how far we as a country have gone down the toilet. These basic manufacturing techniques were figured out 150 years ago, and though were “high tec” at the time.. well, that was a OVER A HUNDRED YEARS AGO. How is it “professional” metalworkers are just making ridiculous wild ass guesses as to basic manufacturing methods that were taught in high school for over a century? Because we stopped thinking it mattered to learn these basics. Now we are paying the price, this is why China is eating our lunch.

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    Quote Originally Posted by john.k View Post
    That is the "secret" of the Mauser rifles ...the design seems more complex than a Lee Enfield ,but every part is carefully developed to make manufacture simple and fast ......whereas the Lee Enfield was always a difficult rifle to make,and considered impossible by several US makers in 1914......The foregoing is the reason the British decided to adopt a Mauser design in 1912....unfortunately the whole idea was caught up in WW1 ,and the rifle was never widely adopted ,despite over a million of them being made in the US.It was judged the best military rifle of WW1 ,but no one ever liked them .Except gun nuts ever since. '
    I'm no expert but from memory the Brits had the mk1 in WW1 and went to the Mauser designed P14 . . . . . And then went back to the Enfield design that was still in-service up until the 50s. If the Mauser design was better and easier to make why would they go back to the Enfield design?

    I used to be a big fan of Mauser and for a hunting rifle I would choose one over an Enfield any day but as a battle rifle. . . . .after owning both . . . . I have been swayed to the Enfield design.

    10 shot mag that can be removed or topped off with 1x or 2x 5 round clips (mag doesn't need to be empty) cock in close is very fast and smooth, heavy but well balanced and have hand guard on barrel with good sights and accurate enough. The cock on close is the thing that helps because all the force / momentum is going on one direction and it's in line with the bore. The Mauser you need to cam the bolt open to cock a heavy spring and potentially extract a tight round in the same motion. The Enfield does work better when full of sand and mud.


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