Is it possible to make this simple, small steel cone?
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  1. #1
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    Default Is it possible to make this simple, small steel cone?

    My knowledge of machining is just short of pathetic; I'm a software engineer and this question actually comes from a personal project, nothing professional.

    I'm been kind of surprised at how hard it is to find the right resources on the Web to fabricate this part exactly the way I've spec'd it. I guess true cones are a little difficult... I understand that spinning can be done in such a way that there's a point with no hole--but I still haven't been able to find precisely what I'm looking for.

    Here's what I need:

    cone-4.5-detail.jpg

    Any guidance from the forum would be greatly appreciated!

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    Of course can that be made. Spun it will perhaps not be as straight as you imagined or the tip not sharp enough. Drawn it will require a large press and the forms. Cast it will demand a good sand shaper. It can be hammered by hand on a wooden tip. Some closer specs would help, say, surface finish, roundness, such.

    x, y, and z you specify down to tenths. Okay, it must be turned then, a precision job. No, wait, no precision because no tolerances

    Do you understand?

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    The final application has a lot of how you want to make it. 1/16" wall with a 4 1/2 base diameter will be somewhat prone to distortion. If you can stand a joint, the easiest way would be to lay the part out in the flat and roll it into shape. Then solder or weld the joint followed by final shaping and cleaning up the joint by grinding, sanding or whatever. The rolling part could be done by a series of small creases with a press or a wooden cone cut to be slightly smaller than the inside of shape of the sheet metal cone. A series of hoops, like a barrel could be used to force the sheet metal to conform to the wooden form and be used to hold it in place while the joint is made.

    It could also be spun but there would be a ring like surface finish.

    Tom

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    [QUOTE

    Any guidance from the forum would be greatly appreciated![/QUOTE]
    In our world 1/16" doesn't equal .0625" due to implied tolerance.
    The print in front of me gives +/- .06" for fractional dimensions.
    .063" has a tolerance of +/- .010".
    .0625" would be even more costly due to the need to hold an even tighter tolerance +/-.0002?
    What does the part do?

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    Drawing is in error. If h is 2.25, x & y are nearer 3.18 - assuming you would like to keep the 45 degrees

    Sort of important since that would be the radius of any flat pattern (such a flat pattern would be a "PIE" shape with the 3.18 odd radius and and arc length of 254.56 degrees. Just looking at such a thing immediately shouts at you the difficulty of coming up with a nice pointy end if forming from the flat)

    Any guidance from the forum would be greatly appreciated!

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    Quote Originally Posted by johnoder View Post
    Drawing is in error. If h is 2.25, x & y are nearer 3.18 - assuming you would like to keep the 45 degrees
    The sine of 45 degrees is .7071. Multiply that by 4.5 and see what you get. A real CAD program would get the right answer.

    And the end points of either h or z are drawn wrong.

    If the tolerances are sloppy enough, an approximation of that part could be made. But it will not be "picture perfect" or "exactly the way I've spec'd it."

    Larry

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    Quote Originally Posted by L Vanice View Post

    And the end points of either h or z are drawn wrong.

    [/COLOR]

    Larry
    What are the endpoints of z?
    The ID of the big end,the OD, or the theoretical sharp points of x and y where they intersect z?

    I hope the OP knows even with liberal tolerances these are x00 $ parts. If it is a wave-guide and
    needs the tolerances implied?
    x000$ parts.

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    Quote Originally Posted by Toolroomguy View Post
    What are the endpoints of z?
    The ID of the big end,the OD, or the theoretical sharp points of x and y where they intersect z?

    I hope the OP knows even with liberal tolerances these are x00 $ parts. If it is a wave-guide and
    needs the tolerances implied?
    x000$ parts.
    We may be talking different items, but a wave guide will have an opening on at least one end for the signal to travel thru...

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    Quote Originally Posted by Mike1974 View Post
    We may be talking different items, but a wave guide will have an opening on at least one end for the signal to travel thru...
    Right you are, it was the first thing that came to mind that needs stupid tight tolerances.

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    Quote Originally Posted by Toolroomguy View Post
    Right you are, it was the first thing that came to mind that needs stupid tight tolerances.
    Ya I work in that industry and we are often adjusting things by tenths to get signal loss within range and such!

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    I sent the OP an email with an offer to help, we'll see if he takes me up on it. This sounds like it needs some design intent resolution first, before worrying about what the manufacturing methods and tolerances are. Not to mention final geometry...

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    Quote Originally Posted by Mike1974 View Post
    Ya I work in that industry and we are often adjusting things by tenths to get signal loss within range and such!
    My first job when I moved to MA in the mid-70's was making microwave rotary joints for civilian and military radar systems. We used to adjust waveguide performance with a ball peen hammer to get coupling right. Ah, the old days...
    Last edited by Milland; 10-24-2019 at 05:17 PM.

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    Quote Originally Posted by Toolroomguy View Post
    Right you are, it was the first thing that came to mind that needs stupid tight tolerances.
    Aye. Anyone looking for simple but very pricy small parts to make? These are about 1/2" parts 1000usd per piece mass-produced
    https://www.pasternack.com/1.0mm-fem...pe45403-p.aspx
    Internal Error

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    To OP:
    Don´t state how to make a part !
    Unless and until You have experience and Big $$$.

    So asking for rolling/spinning etc. with exact dimensions below 0.01 mm,
    is a terrible idea.

    Asking not to use a solid is a terrible idea !
    Your print must have a defined wall thickness, and some form of tolerance for radius.
    After that, You should care less if a solid piece was used to make it.

    Explanation:
    Machining from solid would be dead easy, fast to do, and very accurate.
    Cheap.
    It´s a 20$ part, machined from solid, you buy for 60$, in qty many, from endless suppliers here with decent lathes.

    1.1
    For qty 2 you might get 2 for 400$.
    But 360$ of that is setting up, and dealing with the one tiny order.

    1.2
    For qty 2, if You need spinning for some weird reason, You might be looking at paying 2000$, or more, for 2, accurate to typical cnc shop standards of 0.02 mm +/- all-around as-dropped - sans distortion.

    A part that is spinned, formed, whatever, will likely need final machining in a special fixture, You buy and pay for with the first order of 2 parts.

    And may still need multiple cycles of heat treat, stress release, final machining, if you expect it to be anywhere near as accurate as a part machined from a solid piece.

    2.
    "Accurate" is very expensive, especially for 2, most especially where You specify "not solid".
    I understand as not made from a solid billet.

    3.
    Always add details.
    Explain what needs to be accurate, why, and how accurate.
    Don´t say *everything*, it makes a 60$ part cost 20.000$.
    Yes it does.

    4.
    If You want a part to be made fast, cheap, in the future, in high quantity, state so.
    But spinning is not a cheap and accurate production method.

    5.
    Endless high-tech finishing methods can make extremely accurate parts, very fast, very very cheaply, on some features of the part.
    They generally have setup costs == 5000$, which is not much compared to the 2 prototypes at 2000$+ each, via spinning/multiple secondary ops.

    5.1.
    E:
    So a cone external or internal surface could be extremely accurate, vari-form (aka have complex shape),
    made in 9-15 secs cycle time for the final op,
    to about 0.01 mm final accuracy, +/-, or even better to a few microns if needed, for 30 secs cycle time and a bit more setup/tooling.

    It´s called a rigid hone, aka custom diamond plated hone.
    Cost == 3000$ custom made, last 3000.000 parts in one year, used a lot to make engine cylinder holes to spec.

    6.
    You cannot get a cheap accurate proto part cheaper by asking for "spinning" or whatever.

    Ask for the cheapest way to make this in steel, of suppliers choice.
    Ask what makes the part expensive to do.

    7.
    To get 2 excellent parts, offer money.
    Offer say 700$ for 2, with needed guidance included on how to make them easier to make, cheaper to make, why.

  19. #15
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    Somehow I don't think the OP is actually wanting parts, just testing the waters.

    Tom

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    I could see that part being spun to near net, then ground on the inside (The apex would be a byt##)

    Mounted on a formed mandrel to finish grind the outside.

    Not too bad, maybe a $700 part in qty 2. Depending on the blending requirement of that inside apex and the "tightness" of form specs. Distortion could be a fun hunt.

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    Hi all,
    So I got an email with a much more complete description for use of the cones, as well as an illustration. Basically the cones are to be cover caps on risers for the outlets of a smoker (for meats, one presumes), and given the actual purpose and the cost constraints I strongly encouraged the OP to find the best option from the off-the-shelf cones made by the company linked to in post #16 (good find, bikebuilder).

    I did also suggest a recheck of the geometry given in #1 as it doesn't work as drawn, but again, NBD now that we know the purpose. There's a decorative aspect to the cone design, but I think that cost and common sense will win out.

    If the OP wishes to update he will. Be nice...

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  25. #19
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    Thank you very much for your response. The representation of precision wasn't a good choice on my part; this is not a precision job, hence no tolerances. I just figured the more info the better, but I don't work in the machining industry so forgive me for that. Surface finish would be "unfinished" I would say... In other words, for rolled steel the finish of the original material is fine for the finished product. It will be sanded and painted. No need for roundness at the lip of the cone; square edges suffice. Attached is a diagram that puts this in context. Again, thank you for taking time to respond to such a minor request.smokestack-weather-guard.jpg

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    Thanks for that. Here's additional info regarding the final application. It doesn't have any significant requirements regarding tolerances or finish.smokestack-weather-guard.jpg


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