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Thread: What is "Trochoidal venting"

  1. #1
    Boolit Master

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    What is "Trochoidal venting"

    What is Trochoidal venting and what does it have to do with bullet molds?? Sorry I'm just a high school graduate and spent my time in junior college majoring in sex and beer. Trochoidal venting sounds like a medical disorder!!

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  2. #2
    Boolit Master

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    Seen this on another site. Apparently it's crosshatched pattern shown in the closeup.
    Click image for larger version. 

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  3. #3
    Boolit Master
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    Knew what it is but to me it does sound sorta like a volcanic event, really... "St. Helens is Trochoidal venting and we expect another huge eruption soon" as in...

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    Boolit Master

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    THX Omega, I need another mold like I need another X-wife but I thought it might make a good plinker for my Rossi 38/357 carbine with 38 Special loads. Sorry Mr Lee have to pass on it, remain $38 richer and continue to send bare bottom 38156's downrange cast two at a time.

  5. #5
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    https://fsreloading.com/index.php?_r...309-113-f.html

    Lee molds feature trochoidal venting on the mold face and sprue plate mating surface.This unique venting allows consisstent and effortless fill out. The mold cavities are CNC machined for unmatched roundness and size control. Most bullets from Lee molds can be used as cast without sizing.


  6. #6
    Boolit Master
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    Don't they still hob around a titanium core after matching a sub caliber chamber?

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    If you axe me it's a simple way of adding vent grooves using a face mill or a flycutter.
    But it looks cool and it works.
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    It's Lee's $2.00 word for the .25 cent curved vent lines they use....sounds really high brow don't it !
    Supposed to impress us high school graduates!
    Since the mould does not have "trochoidal " venting I'm betting it has no vent lines just smooth blocks.
    I haven't had to vent a mould in a long time . Some of my old plain faced Ideal (no vents) 1 and 2 cavity moulds cast just fine....don't know about 6 cavity.
    Last edited by gwpercle; 01-06-2018 at 12:31 PM.
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    If I know Lee, Like I think I know Lee, I'd say, Trochoidal = fastest, cheapest way to cut vent lines using a CNC.

  10. #10
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    Quote Originally Posted by JonB_in_Glencoe View Post
    If I know Lee, Like I think I know Lee, I'd say, Trochoidal = fastest, cheapest way to cut vent lines using a CNC.
    Yep we have a winner.

  11. #11
    Boolit Master Grmps's Avatar
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    My uneducated assumption to Trochoidal-venting is interconnected vent lines/tubes as in air for molds and lava in volcanoes.

  12. #12
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    Marketing 102 - 'If you can't dazzle them with brilliance, baffle them with B.S.'

    Comes right after 'A sucker is born every minute.'

    Watch Your Top Knot!

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    Boolit Master 15meter's Avatar
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    Quote Originally Posted by Jim_P View Post
    Marketing 102 - 'If you can't dazzle them with brilliance, baffle them with B.S.'

    Comes right after 'A sucker is born every minute.'

    A trochoid (from the Greek word for wheel, "trochos") is the curve described by a fixed point on a circle as it rolls along a straight line.[1] The cycloid is a notable member of the trochoid family. The word "trochoid" was coined by Gilles de Roberval.

    Sounds like hip boot time!

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    Quote Originally Posted by jdfoxinc View Post
    Don't they still hob around a titanium core after matching a sub caliber chamber?
    I believe they still make the round ball molds by compression around the carbide ball mandrel, but I believe they've gone to CNC cutting the other types of cavities if I'm correctly recalling the conversation I had with one of their engineers several years ago.
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  15. #15
    Boolit Master NoAngel's Avatar
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    Quote Originally Posted by JSnover View Post
    If you axe me it's a simple way of adding vent grooves using a face mill or a flycutter.
    But it looks cool and it works.
    You’re exactly right.
    Crank up the feed rate so the tool drags on the back cut. They slap a fancy name on it and viola!
    When I was machining I would get fired for turning in poorly finished parts like that but leave it to Lee to make it work FOR them.
    When dealing with islam one should always ask themselves: "What would Leonidas do?"

  16. #16
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    "No finer molds can be purchased at *any* price."

    While I have a drawer full of Lee molds, I have to laugh when I see or hear this Herter'sesque proclamation,,,,,,,.
    More "This is what happened when I,,,,," and less "What would happen if I,,,,"


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  17. #17
    Boolit Master NoAngel's Avatar
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    I laugh as well Hamish.

    Lee molds remind me of Ruger firearms. They are the finest “Preassembled Do It Yourself” kit on the market.
    When dealing with islam one should always ask themselves: "What would Leonidas do?"

  18. #18
    Boolit Master
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    Hertersesque LOL

  19. #19
    Boolit Master

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    The big reason for the new vent line style is more manufacturing then anything. The older production machines had feed rates up to around 20"-30" a minute at the fastest. so an engraving type cutter was used to cut the vent lines on at a time. long and slower doing them this way as each vent line might require 2-3 passes. A hob mill could be ground to cut them on each face, an expensive cutter extra fixture or set up. The new CNC machines have feed rates as high as 600"-900" a minute so a simple fly cutter with the proper carbide insert faces the blocks then cuts the vent lines Saves a tool change custom tools and special set up. Even with a tool changer on the machine the saved tool change and dual use of the cutter saves one trip to home and a spindle start and stop. Saved time equals saved money in manufactureing. Saved custom tooling is a big plus also. Cutting those fine vent lines is a slow process due to the fragile tooling required.

  20. #20
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    I like the new vents line, they seem to be less sensitive to damage and don't clog up as much.

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