Author Topic: How to cut cones for steam fitting unions.  (Read 2017 times)

Offline Bangkok Mick

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How to cut cones for steam fitting unions.
« on: August 09, 2013, 08:26:37 AM »
Hi,

I am making some inline water/steam pipe coupler fittings with a threaded collar and union to create the seal. I have bored out the female cone using a standard center drill to counter sink the cone shape. I now need to cut the male cone onto the matching piece.

My plan is to set the compound on the lathe at the same angle as the center drill to cut the matching cone with a normal cutting tool. Can anyone tell me what angle center drills counter sink at so I can correctly set the compound.

Alternatively is there another way to machine matching cones for this purpose and what is the best angle to machine the cones for best seal.

Cheers Mick

Offline vtsteam

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Re: How to cut cones for steam fitting unions.
« Reply #1 on: August 09, 2013, 08:53:58 AM »
I believe from memory it's 60 degrees -- take with a grain of salt therefore.
I love it when a Plan B comes together!
Steve
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Offline vtsteam

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Re: How to cut cones for steam fitting unions.
« Reply #2 on: August 09, 2013, 08:57:18 AM »
Whatever angle you choose, you could cut your male cone and also a piece of drill rod at the same setting, and make the drill rod into a reamer by fluting. Then you'd have a very good match.
I love it when a Plan B comes together!
Steve
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Offline Bangkok Mick

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Re: How to cut cones for steam fitting unions.
« Reply #3 on: August 09, 2013, 09:14:53 AM »
Thanks VT steam


Offline vtsteam

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Re: How to cut cones for steam fitting unions.
« Reply #4 on: August 09, 2013, 09:28:16 AM »
Check this out for dimensions of various standard fittings:

http://www.lenzinc.com/filedownload.php?filename=pdf_49d7f998771f6.pdf
I love it when a Plan B comes together!
Steve
www.sredmond.com

Offline David Jupp

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Re: How to cut cones for steam fitting unions.
« Reply #5 on: August 09, 2013, 01:48:39 PM »
In very high pressure fittings, a 60 degree female cone (standard centre drill) is mated with a 59 degree male cone - this gives a line contact where the male and female meet, resulting in a high contact pressure.

I'm not suggesting you need to follow this principle, but if any uncertainty about the angle of the male cone, it's best to aim for a touch under 60 degrees, rather than allowing it to exceed 60 degrees.