Scotch Type Marine Boiler

[Diversion900]

Nice work Pete.

A couple of questions......

it seems like a large diameter circle for the super heater, I thought it would've been better to double it back up top instead of going round the outside ?

and how come the exit points to the ground ?

Cheers, Neil

 

[doubletop]

Well spotted; it’s a rough copy of the sketches in the KN Harris book and after I’d done it I had second thoughts. I may pull it out over the weekend and make a copper block V type that comes straight down from the steam dome and then does a hard right out of the exit hole with the V over the end of the burner tube

The reason the exit curves downwards right now is the shape it took up when I was threading it in it. It’s annealed and will straighten up OK. It’s going to get shorted considerably.

 

[doubletop]

Latest drawings can be found here. A few more bits of detail and the main boiler plates reversed to help in construction.

http://www.homemodelenginemachinist.com/index.php?action=tpmod;dl=item285

There are undoubtedly errors in these drawings but they give you the general idea of how it goes together.

Pete

 

[doubletop]

Done the final bits and bobs

• Made the door handle and latch
• Made the funnel cap
• Painted the detail on the mounting feet
• Changed the super heater to be a copper block rather than the coil. Fortunately the door was big enough to get the assembly installed without having to solder it up in situ.
• Gave a a bit of clean up with a small rotary wire brush in the pillar drill.
• Installed the fittings

Sorry the photos are a bit blurred the flash wasn't giving me the results I wanted.

I may strip it down again and do one last pressure test and then it may be time for its first steaming over the weekend.

Pete

 

[tel]

It's really looking the part now Pete - ONYA!

 

[Diversion900]

Great job Pete.

Let us know how the extentions for the level guage go, if they cause any drama's or not.

On another note, a visit to my local scrapyard yesterday had me returning home with a 12" length of 6" diameter copper pipe with 2mm wall thickness. ;D would you believe $20 and it was mine.

I may have to re think the dimentions of my new boiler !

Cheers, Neil

 

[zeeprogrammer]

That looks great Pete. I hope a video is being considered. ;D

 

[doubletop]

Thanks again everybody.

The promised firing happened to some degree of success yesterday with wisps of steam coming from the flue. Which is always a gratifying moment.

And you can tell there's a "However" coming next.....

• The burner wasn't stable it would go out or flare and was making a pulsating noise. I spend some time trying different combination of jets, air hole sizes but did have some success with a simple blow torch I have, which my burner is based on so I am in the process of making a newer more exact copy of the original torch.
  
• The wisps of steam didn't stop which indicates there's a leak somewhere and not just a bit of dampness drying out.
  
• The pressure gauge didn't indicate which needs investigating. There was plenty of steam when I opened up the steam valve (no engine connected yet.)
  
• The camping gas cartridge I am using ran out of gas so I need a new cylinder

Things are a bit slow today as I went to a 60th birthday party last night - Mine. So no shop time today

Pictures and videos are de rigueur so will be provided in due course

Pete

 

[Blogwitch]

Happy belated birthday Pete.

Don't worry too much about having a leak, there is a rescue if you can't get the boiler up to silver soldering temp in a local area.

Have a search for a product called Comsol. This is a silver bearing soft solder with a temp range of around 300° C, and is normally used for sealing small areas of leaking silver solder jointing, where you can't get the area up to the high temps required for a silver solder repair.

In the early days, boilers were completely assembled with this stuff, but now, I think it is used just for doing small repairs.


John

 

[tel]

Well, 'appy birthday for yesterday Pete - I turned 63 yes'dy as well.

 

[doubletop]

John

I think it is the superheater. But it can be no more than a dribble as I got steam pressure OK. I had also done a pressuer test to50psi with all the fittings in place and it held that OK. I'll see if I can source so Comsol, I'm now sourcing my solder products direct from the NZ wholesaler that supplies BoC so I'll start with them.

'appy birthday to you as well Tel. The 'real' day was last Monday but Saturday was the best day to celebrate. The All Blacks were also playing South Africa in town so the whole place was in a bit of a party mood. Which led to a late night after we all left the restaurant.

Pete

 

[Diversion900]

Happy Birthday Pete.

Sorry to hear about the problems, might be worth bypassing the superheater and testing that way.

Cheers, Neil.

 

[doubletop]

Neil

Thats the plan. I've got a spare port on the steam dome where I can put the steam valve and I can blank off the super heater port.

First job is to get this new burner working

Pete

 

[Maryak]

Happy birthday Pete and Tel :bow: :bow:

Good luck with the leak and the bummer pressure gauge.

Best Regards
Bob

 

[Diversion900]

I've been looking into those mini hiking burners with the ceramic type burner......

Not sure yet, so still thinking.

Now that I have this piece of 6" pipe, I think the burner could be a lot bigger than the ones I have been looking at by the time I re-design the boiler layout.

Cheers, Neil

 

[doubletop]

Tested the presssure gauge and it may have just been a bid of crud in the syphon U bend. Anyway it works now

I've just spent the evening trying out the burner again. What worked Saturday decided it wasn't going to work today. Fiddled about with diffrent combinations of jets, gas valves, and burner heads, jet postions, air hole sizes and I eventally got it going and managed to raise 10 psi in about 3 mins.

It has a degree of ferocity and instability that would indicate that if you put this setup in a boat it would most probably emulate a Viking funeral pyre by the time it got to the middle of the lake!! As it stands what I have at the moment is on the brink of being OK for this through flue boiler, but for now I can't turn it down without it going out. As a pair with a figure 8 water tube flash boiler it would be brilliant.

Anyway I'll persevere and get something sensible working in due course. At least I'd hope to. I've now got so many combinations of gas valves/regulators, jets, adaptors, burner heads, sheets of ceramic and they are all cross compatible that something should work.

On that; I've realised that the pressure for a ceramic type burner is lower than that for a torch type burner, also most of the ceramic burners I've seen have a jet between 5 and 10. Does anybody have any basic rules for these things e.g gas pressure, jet size, head type etc. ????

Pete

 

[Diversion900]

Sorry Pete, can't help on this one.

The only ceramic heater I have is in my trusty butane soldering iron.... ;D

These ceramic burners are all new to me, by what Ive been reading they sure put out some heat though.
I am yet to find out if they will work when placed inside a tube, or if they need to be spaced back from the entrance a bit in order to get air?

I have only ever used metho on the little pot boilers I have made, this is my first multi-tube.

Cheers, Neil

 

[doubletop]

I’m back after three nights of going around in circles with various combination's of burner parts trying to get something to work. At the end of last night the gods were not looking down on me and I couldn’t get anything to work. Even burners that had worked fine in the past just wouldn’t light up. I parked everything and gave the evening up as a bad job.

Tonight I came home and started again.

First burner I’d made perfect; Poker burner, perfect, Old gas torch working again. Out came the calipers and drill rod to measured bores, fits, whatever they were all very similar. So the only variables I had were size 5, 10, 12 and 15 jets and two gas cylinder valves that had different flow rates. I systematically went through all the jets with my first gas valve and found the combination that worked on the original burner and then the poker. Back to the old gas torch got that going again. Tried my two copies of the torch and they both worked. Tried all three on the boiler and one of the new ones cut out once it was inserted the other worked to some degree. I adjusted the air vent adjuster and got it going fine. I was back at the burner I’d made in the first post of this thread. Explain that!! Actually it’s about being methodical, logging results, analyzing trends and being thorough. Too many variables adjusted in the wrong order and you’ll never get there..

Anyway, as I had it going it was time to connect the engine steam it up and see what happened. Then you guys get the obligatory video.

[ame=http://www.youtube.com/watch?v=xLdz6jHvYi8]http://www.youtube.com/watch?v=xLdz6jHvYi8[/ame]

It took just under 3 mins to get to 20psi when about 3/4 full (up to the top of the guage) and water straight out of the tap. There was a bit of heat in the copper from a previous attempt but that was it.

(I'll come clean here; As its only running at 20psi I coupled the engine to the boiler with a bit of plastic tubing. The jump in the video is where the pipe blew off and I had to re-connect it)

The boiler is looking a bit sad right now after three nights of throwing heat at it. But now I know it works, and pretty well if I say it myself.

I'll go and strip down tonight and get it cleaned up ready for mounting on a piece of wood with the engine. I'll do some photos when I get that finished.

Pete

 

[Blogwitch]

Pete,

That is absolutely great, both engine and boiler in perfect harmony.

I don't know if you have steam lube in there or not, but I would recommend you get something in there before running too much.

Also, by the amount of steam you have around the engine, it looks like you could turn the feed pressure from the boiler down some, these engines really will run very nicely on about 10 to 15 psi of steam, any more and it is just a waste of gas and water.

Very well done indeed, a case of perseverance paying off in the end.


John

 

[doubletop]

Thanks for your support once again John.

Yes I had oil in the "Bogs Oiler" and only a few drops were left at the end of the run. Running on steam it ran really quietly, as you'd expect. That's why I shut the burner down at the end just to hear how quiet it was.

There are a couple of engine leaks but I've now got some Viton 'O' rings so going to take the pistons out an put in an O ring groove. And do the glands with O Rings (another Kozo article convinced me it was the way to go.)

I'm pleased I can make more steam than the engine can use. With the vertical boiler it just couldn't make enough steam even with the little single cylinder engine. But I do also have a new ceramic burner for that which I ran up at one point but haven't installed yet. On the last count I'm on my eighth burner, and some of those have gone through a but of an metmorphis over time. That was so frustrating the other night I've made so many gas burners that mostly worked pretty well first time and then nothing worked. I thought I was loosing it .

Pete