What pipe to us for steam connections?

[Ken WeeksParticipant @kenweeks58536]

Hi

I am making a model that to look right will use threaded pipe connectors on the steam pipes.

This will entail threading the pipe ends 5/16×27.

What is the best tubing to use brass, copper or stainless steel?

Any comments will be appreciated

Ken

[Ken WeeksParticipant @kenweeks58536]

[JasonBModerator @jasonb]

Does it have to be 5/16×27 MPT? as that requires quite a thick wall tube. I tend to use 5/16×40 ME and just thread the pipe fittings to suit . 5/16MPT is the same as 1/16 NPT so you may find the 1/16" bore very restrictive.

If its a short run of pipe just drill out some rod 3/16" or if longer a thickish wall copper tube will do say 16 or 18 gauge which takes the 40tpi thread

This is 5/16" steel rod drilled out to 7/32  and threaded 5/16×40

 

Edited By JasonB on 25/04/2013 13:22:57

[nigel jones 5Participant @nigeljones5]

I would opt for brass for ease of machining and rigidity

[Ken WeeksParticipant @kenweeks58536]

This is the first steam engine I have attem pted to build, and am a bit restricted with my equipment a Cowells 90 CW lathe and a Sherline mill, I started by doing clock cleaning and repairs.

My engineering skills also leave a bit to be desired.

5/16 x 40 is not a problem but how/where do you source the pipe fittings?

What pipe would you use size of bore etc?

With regard to brass pipe is their not a problem with zinc? leaching out?

Is it something to worry about?

I am still learning so all comments are appreciated.

[JasonBModerator @jasonb]

PM Research make sell unmachined fittings which will be easy enough to frill and thread with what you have machine wise, you may be able to get them through Forrest Classics but they have a limited range so I order them straight from PMR in the US.

If using the 40tpi thread then 16g or 18g wall thickness will be OK and readily available in brass or copper, as Fizzy says the brass will be a lot easier to thread and as you are using pipe fittings there will be no need to bend the tube. This will give approx 3/16 and 7/32 bore respectively

Brass is OK with steam, its the acutal boiler water that can affect it.

Whats the engihe you are making.

[Ken WeeksParticipant @kenweeks58536]

Thanks fro all the info.

I am making a sled mounted Dolbeer horizontal capstan logging steam donkey engine.

I am working from the patent application drawing and a drawing of a full sized engine sent to me from America.

Scale is about 1"=1' and make it up as you go along!

I was given a vertical boiler and two completed Rainhill cylinders, the boiler is is threaded 5/16" x 40 your suggestion about casting seems an o.k. suggestion.

I had looked at the PM Research connectors and was unsure how easy they were to machine.

This German site http://www.dorrington.de/en/page/home appears to stock all the PM Research parts.

Tthe explanation about the brass makes thiings clearer.

[Ken WeeksParticipant @kenweeks58536]

I have posted some photos of the type of engine I am endevouring to make

[JasonBModerator @jasonb]

If its a Donkey then the pipe fittings are indeed the right way to go for that look. There are a couple of build threads on Donkey engines, I'll dig out some links for you later.

I just hold the fittings in the mill vice, face, drill and tap then turn arond to do teh other end, some people make jigs to hold them I'll post a link to them as well.

The only fittings you may not be able to buy are the nutted unions but they hare not hard to make from a bit of hex stock, I may still have a sketch for the ones I did on this engine

J

[JasonBModerator @jasonb]

Donkey build on HMEM and another but not so scale looking

Jig to hold fittings while machining

[Ken WeeksParticipant @kenweeks58536]

Jason thanks for the links etc.

Just as a matter of interest I did contact PM Research about supplying 5/16" male/female elbows machined but unthreaded and they said they could supply and quoted a price.

Thanks to you and fizzy for taking the time to reply.

I have taken up "model engineering" as a hobby in retirement, my last real "engineering" was 3 years metalwork 1 hour a week at school longer ago than I care to think about.

One of my jobs was working out the steps to make specialised electronic cables from the drawing, and then writing the assembly procedure.

Edited By Ken Weeks on 26/04/2013 22:15:48

[Ken WeeksParticipant @kenweeks58536]

Jason

I have worked out how to convert a .pdf file to .jpg and have listed the Dolbeer patent drawing that I hope to reproduce in my photos if you are interested

[JasonBModerator @jasonb]

Always interested but unfortunately only the last one can be viewed, it may well be that you can see them on your screen though.

If you are having problems send me a PM.

Just make sure that if you do get the drille donly elbows they are drill to suit the thread you intend to use not what PMR use.

J

[Ian S CParticipant @iansc]

Ken, I can see the first 4, and the last photo, looks interesting, could make a good model. Ian S C

[Sub MandrelParticipant @submandrel]

Hi Ken,

That's an interesting prototype. post some pictures of progress when you get started.

There were some similar setups used to power steam logging and felling saws in the UK.

Neil

[Ken WeeksParticipant @kenweeks58536]

I have amended the photos I managed somehow to include four blanks.

[Author]

Posts