Model Engine Maker

Supporting => Engine Ancillaries => Topic started by: smfr on August 19, 2012, 06:01:15 AM

Title: Flanged pipework
Post by: smfr on August 19, 2012, 06:01:15 AM
I wanted some nice flange-joinged pipes for my Stuart No. 4, so I've been playing around with making pipe flanges, and thought folks might be interested, and have useful feedback for me!

I got some copper pipe from the hardware store (the type used for refrigerator waterlines), in 3/16", 1/4", and 5/16" diameters (that's an external diameter) to play with.

My first problem was knowing how big to make the flanges, and I underestimated on my first, "freehand" attempt. So some internet research on full-sized flanged fittings suggested that the diameter of the flange is about 2.5x the pipe diameter. Using half that diameter for the diameter of the central "boss" where the pipe screws in seemed about right. The boss ended up with a length of about half the pipe diameter, and I guesstimated the flange thickness as about 75% of that.

Here's one flange underway, turned from some 3/4" brass bar. I've turned the back side, and now I'm drilling for the tap:

(http://farm8.staticflickr.com/7273/7812656254_bd0ccbc438.jpg) (http://www.flickr.com/photos/smfr/7812656254/)

I'm using 26TPI BSB taps. After threading, it's parted off, leaving a flange of the right thickness:

(http://farm9.staticflickr.com/8439/7812656978_c5921d90e2.jpg) (http://www.flickr.com/photos/smfr/7812656978/)

I finished the parting with a hacksaw (taking care not to mark the flange face). Here's my first attampt at flanges for 1/4" pipe before cleanup:

(http://farm9.staticflickr.com/8298/7812657534_1cbc0377f7.jpg) (http://www.flickr.com/photos/smfr/7812657534/)

To cleanup the mating faces, I threaded the end of a bit of 1/4" brass rod and used that as a mandrel:

(http://farm9.staticflickr.com/8282/7812658088_a5ca6a6a66.jpg) (http://www.flickr.com/photos/smfr/7812658088/)

After turning, the part can get pretty stuck on the mandrel. Here's my new favorite shop accessory, a bit of non-slip rug pad material which is great for unscrewing slippery parts :D

(http://farm9.staticflickr.com/8296/7812658626_d285724e48.jpg) (http://www.flickr.com/photos/smfr/7812658626/)

Threading the pipe, which is held gently in the 3-jaw?but not so gently that it revolves under the threading force, leaving nasty gouges (ask me how I know):

(http://farm9.staticflickr.com/8289/7812659172_21d44e9fa9.jpg) (http://www.flickr.com/photos/smfr/7812659172/)

Progress so far: 2 sizes, 1/4" pipe at the top, and 5/16" pipe at the bottom. Top left flange was not threaded deep enough.

(http://farm9.staticflickr.com/8425/7812659552_dc92a385ef.jpg) (http://www.flickr.com/photos/smfr/7812659552/)

I'll silver-solder the flanges onto the pipes, after drilling holes for bolts. I think I'll use 6 bolts on each. I did struggle with a 10BA die today trying to make some studs for this, but making 24 teeny nuts will drive me crazy so I ordered some 8-10BA nuts and bolts to give me a size range to play with  :D

I guess I should trepan a groove for an O-ring on the faces (any tool suggestions for doing that?).

Simon
Title: Re: Flanged pipework
Post by: Bogstandard on August 19, 2012, 06:52:14 AM
Simon,

O-rings don't scale well at all to the sizes you are making, and you could be letting yourself in for a lot of unnecessary work.

The easiest way of all, and still retain the 'look' is to use a small ring of gasket material. I would use PTFE sheet, but paper gasket would do a similar job.

Just make up gasket washers by the dozen using easy to make tube punches, so the gaskets sit inside, and held in the correct position by your ring of bolts. Once tightened up, no one will ever know how you sealed the joint.

See C-o-C at the bottom.


John
Title: Re: Flanged pipework
Post by: smfr on August 19, 2012, 07:27:28 AM
Thanks for the tip, John!

Simon
Title: Re: Flanged pipework
Post by: derekwarner on August 19, 2012, 07:37:27 AM
Sorry  :Doh:...I had forgotton this is a make it yourself WEB...... :hammerbash: but for others like me.......  :Argue:

Guys......Winfried Niggle..... http://www.modellbau-niggel.de/ manufactures a range of minature flanges

His range indicates o-ring sealing only for 2 bolt SAE style and gasket sealing for 4 or 5 bolt styles

Winfried is a great person to deal with & has manufactured 4 & 5 bolt o-ring flanges for 1/8" & 5/32"OD tube  :agree: for me

The last image shows 5/32" OD tube & flanges...I am comfortable with the scaling of both the flange & the bolt size......

Derek

Title: Re: Flanged pipework
Post by: Bogstandard on August 19, 2012, 08:18:55 AM
You are quite right Derek, Winfried does make some very tasty bits and at very reasonable prices as well.

I think we discussed him many moons ago, when I was making a few bits for you.

BTW, I have fixed the link to his site, to save members having to search him out.


John
Title: Re: Flanged pipework
Post by: tel on August 19, 2012, 08:39:56 AM
6 bolts? You are a real glutton for punishment Simon - 4 is plenty to do the job and look OK and makes for far less fiddling.

(http://inlinethumb47.webshots.com/43310/2754525070105506259S500x500Q85.jpg) (http://entertainment.webshots.com/photo/2754525070105506259Pgshga)
Title: Re: Flanged pipework
Post by: steamer on August 19, 2012, 12:07:58 PM
Simon,

The other bit to keep in mind with a screwed connection is getting the bolt holes to line up.  You may want to consider a slip in soldered connection to the flange so that you can position the flange rotationally to align the bolt holes

The tubing will twist a bit once silver soldered as it is locally annealed once brought up to red heat.

Dave
Title: Re: Flanged pipework
Post by: smfr on August 19, 2012, 05:35:48 PM
I chose six as a compromise. Peter Tarn's model (which is a constant inspiration to me) has 8 on the steam inlet pipes!

(http://farm1.staticflickr.com/53/118962508_0a0c4feb16.jpg) (http://www.flickr.com/photos/79633815@N00/118962508/)

Some good tips here, folks, thanks!
Simon
Title: Re: Flanged pipework
Post by: Jasonb on August 19, 2012, 05:47:21 PM
4 or 8 are the normal configuration that way any valves or fittings can be mounted vertically or horizontally. Full size flanges to the BS hole patterns are made that way with 12 holes on flanges for pipes over 12" dia.

J
Title: Re: Flanged pipework
Post by: Dan Rowe on August 19, 2012, 06:05:59 PM
Simon,
6 bolt flanges are not really very common. I have made a bunch of gaskets like the ones John posted a sketch of and they work fine full scale.

Here is a link to pipe and flange sizes for several pressure ratings.
http://www.engineeringtoolbox.com/flanges-bolts-dimensions-d_464.html

Dan
Title: Re: Flanged pipework
Post by: mzt on August 28, 2012, 09:58:43 AM
I've sharpened one end of a compass to a blade and used it to cut gaskets from thin cardboard (no better gasket material at hand) which I later soaked into thin oil.
(http://i1226.photobucket.com/albums/ee403/mzetati/_steamEngines/WIP01-Bernay/39/63_IMG_1001.jpg)

As for the flanges, my mistake was not making them large enough to fit studs and nuts. They're OK with SH screws, tho.

Marcello