Building a Boiler for a 3 1/2" Gauge Locomotive

[sbwhart]

Thanks Nick that would be useful

Stuart

Thats a good point about the seal I've bin thinking that screwing the joints up tight mite not be the right way to go to get a seal, the hollow stay has to take the loading from the boiler pressure on the tube plate, so any additional load from tightening is not a good idea, I was thinking of using bosswhite or somesuch sealant, how does the copper slip work does it need to harden off with the heat from the boiler ?.

Thanks very much all for your input.

Stew

[NickG]

Stew,

I was thinking the same last night when I took mine out. (sorry no pics yet) It's designed to seal on the screw thread itself rather than up to a shoulder I think so it doesn't need to be tight and as you say, it could make it worse when it's compounded by the boiler expanding longitudinally.

I measured mine as best I could and it's 5/32" OD and I measured 0.098" ID so probably 22g the same as you had. it seemed fairly robust when I was screwing it in hand tight into the front tube plate bush - I think it should only be hand tight, you just need some sort of sealent.

Is your tube soldered into the valve at the backhead end? Mine is.

Been thinking about it again and hopefully when the new boiler inspector sees it, he'll agree to leave it unsoldered as it would be handy to be able to get it out if it ever gets blocked. Otherwise I think I may to a solid stay and route outside. I had problems once with an old 5" engine I had with the hollow blower stay being bunged up.

Cheers,

Nick

Thanks,

Nick

[sbwhart]

Thanks for that Nick

I've just had delivered a 5/32 solid stay but I'm thinking of having one more go with a hollow stay with some sort of sealant.

I wasn't thinking of soldering the valve our boiler inspector doesn't seem to concerned if its soldered or not.

Cheers

Stew

[lordedmond]

Stew

boss white will do but copper slip will enable you get the threads in they will be 99.9999999% of the time out of phase that in its self will ensure a seal


but as I said use a solid one with a  a pipe out side , a hollow stay will not add that much strength anyway


BTW my chassis and boiler are going to Myfords open day and to the Warwick show on the NSMEE stand

[sbwhart]

Thanks Stuart:- I'm going to try copper slip,  I was thinking of going over to the Myford show I under stand they have lots of kit for sale recovered from workshop clearances, If I go I'll look out for your loco, will you be their ?.

Well today i took delivery of a solid stay, it didn't break but a I still had difficulty getting the threads to seal I tried ptfe tape but the joints just kept weeping, next try I'll use copper slip.

But I did get it up to 160 psi a couple of times and it held pressure long enough for me to check out all the soldered joints and they were all good, I'm now going to cut off the spikes and book the boiler in for a test with the inspector.

 




Happy Stew

[NickG]

Well done stew, my solid stay is soldered in, as long as you get a good seal don't suppose it matters.

[Dean W]

Looks good on your home hydro test, Stew!  I'm sure you'll be all flying colors on the big test day.
Best of luck!

Dean

[Stilldrillin]

Stew, you lost me a little while ago..... 

That was when a piece of pipe went ping, and you started talking of stays, wet headers, to solder, or not to solder, that is the question!

GOOD LUCK, for the test day! 

David D

[NickG]

Yep, good luck Stew - you don't need it mind you!   

When  if I ever get mine ready for testing I'll have to leave my regulator in as the two screws that hold it in need to go into something. Suppose could seal with nut underneath or something and bung regulator up as that is likely to cause leaking?

Cheers,

Nick

[sbwhart]

Thanks Guys

I repeated the test this morning using copper slip to seal the threads it worked great.



I then cut off the spikes and cleaned the boiler up with a brass wire brush.

Then I couldn't resist seeing how it looked between the frames



Starting to look like a proper loco know.

Stew

[NickG]

Stew, looks amazing, boiler looks like a bought professional one, loco isn't too bad either!!!   

[Stilldrillin]

By 'ek lad..... That's beautiful! 

David D

[Bogstandard]

No flies on you Stew, that really does look like a boiler should, and now the pressure test, and everything should be fine.

John

[Brass_Machine]

 

Very very nice Stew!!!

I like that.

Eric

[Dean W]

Stew, when you mention "copper slip", it that some kine of metal paste, like never seize, or do you mean some
kind of a mechanical fitting?

Thanks,

Dean

[AdeV]

 

I aspire to be as good as you, Stew. I think it will take me many years. Beautiful work.

Dean - Copper slip is a coppery grease which allegedly ensures that a screw once done up, can always be undone again at a later date; but, in my experience, it is most often used to glue spark plugs into car engines...

[sbwhart]

Thanks for you kind comments Guys

Dean as Adev said "copper slip" is a coppery grease I think it helps getting a seal by letting the threads slip over each other more easily so you get things tighter, and they can be undone again so I guess it must be like never seize.

Thanks you all again

Stew

[Divided he ad]

Stew,


        



Top looker you got there. You're going to have a lot of fun when it's finished I'll bet?


Copper slip/copper easy.... Gluing spark plugs in?  Better than steel to aluminium without lube of any sort!! Usually over tightening causes the issues doesn't it?  But now way  Sorry Stew.



Again, looks great and as Ade says "I think it will take me many years. "  to get to the stage where that will be possible or at least have the patience required 






Ralph.

[Powder Keg]

I just read through this entire post. Super job!!! I would like to build a traction engine one day. Maybe as soon as I finish a couple projects I'll start on one? Thanks for posting pictures they are great!!!

[sbwhart]

Thanks Wesley

Seeing all the engines running round the track at the club Gala last week stiffened my resolve to crack on and get the engine finished, but before I do that I've got a few other jobs to complete.

I've a liking for Traction Engines, and done quite a bit a research into building them, collected drawings for a few of the smaller 1" and 1 1/2" /ft, the biggest problem is having the machine capacity to make the large diameter rear wheels, and for the larger scales, 2" and above, builders seem to prefer steel boilers I think because the boiler supports the weight of the engine.

Cheers

Stew

[Bogstandard]

You have a largish lathe at your disposal right here Stew. Or you might even be able to roll them on that 3 in 1 I have in the back room.

John

[shoey51]

Just got back from my overseas jaunt
catching up on things here
must say Stew that looks lovely well done mate

[NickG]

Stew, was just thinking the other night about the problem you had with the water gauge / clack clashing together so had to come and skim through your build log again first thing this morning! How did you solve the problem in the end, Did you change the design, you seem to have a bush on top of the boiler now instead of that curved bit soldered onto the top but where is the water gauge bush on the backhead? 

Cheers,

Nick

[sbwhart]

Nick

yes thats what i did the guys at the club recon that a screwd bush is better than that curved thing shown on the drawing, I also moved the position of the clack valves to the front of the barrel just behind the smoke box, the guys reccon its better to feed the cold water into the front rather than at the back onto the fire box.

[metalmad]

Looking fantastic Stew 
 
Pete