Plan to build....steam!!

[Steamchick]

Green Twin. I know you to be a very competent modeller. Expert in my view. I certainly am not in the same league. But I trust you are a certified welder and understand the precision required in setting up, size shape etc. Of weld preps, control of rods, current etc. Start and finish of weld on tabs etc. As per regulations (which are simply the best guide to what is best practice).
I can weld. But NOT pressure vessels, etc. Like being a tightrope walker. I have seen it done properly, but only by an expert. I don't try it.
I have employed welders, examined and sectioned and polished welds, destructively tested welds and passed and failed welders on routine tests. But I don't weld pressure vessels.
I'm sure yours would be OK.
But for the benefit of those who don't know, in the world away from your little workshop, only certified welders make boilers.... "By Law" in many countries.
But silver soldering does not need a certified coppersmith. Just a careful, trained and skilled operator.
Faults happen, as in Blondiehacks' videos, but can be easily rectified.
I reckon your local club will have an expert to advise and help if you ever choose to make a copper boiler.
K2

 

[Maxjon]

lagging is insulation material that goes into the void around the cylinder between the two end flanges. You then fit metal or wood cleading or cladding over that to keep it in place.

It would help a little with heat loss and reducing condensate but on a small 5/8 bore engien that is not really going to do work and even if it did efficiency is not really a consideration then it is just as easy to go with a solid cylinder.

Yes 3/32" wall would be fine, that Simplex engine I posted the two videos of has 2.5mm wall. Flanges at the ends are 3mm thick. The simple solution would be to make the OD the same as the width of the port face (13/16) then it would be quite simple to cut with say a 6mm cutter with 1mm corner radius which would leave an internal fillet to make it look more like a casting if you decided not to fit cleading.

The bed "casting" and the entablature/lower cylinder cover are good candidates for CNC as well.

I also think the angled ports would work better than the 90 degree, right angled ones on the larger JDW design..?

 

[GreenTwin]

I reckon your local club will have an expert to advise and help if you ever choose to make a copper boiler.

I agree with what you are saying.
The person I mentioned that purchased the pre-welded certified steel boiler I think is the way to go, if someone really wants a functional steel boiler.
I have the step-by-step process in photos of how to build a certified steel boiler, and I could definitely build one; I have been welding for 60 years, but for now my focus is on IC engines and foundry work.

There are no local clubs in these parts unfortunately.
My "local club" are the good folks here who so generously share their information.

Edit:
Typically the folks who would purchase a pre-welded certified steel boiler would be the steamboat folks, but I have seen stationary folks also purchase this type of boiler.

.

 

[Maxjon]

This is the only beginner vertical I have plans for.
An old Raymond Yates design.
Not too complex.
This was one of the first engines my dad built.

Its a bit small, but you could put the plans on the copy machine and double them in size.

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View attachment 155953View attachment 155954View attachment 155955View attachment 155956

Silly question....what material would the piston be? Brass, or steel?
Thanks....MJ

 

[GreenTwin]

I can give you my preferences.

I generally avoid brass because I have some boat shaft brass/bronze, and I used it for bearings, and the stiction is basically 100%, and so the engine would not turn, even though the bearings were the correct size, well oiled, etc.

Many here that use brass (regular brass, not boat shaft brass) and they say it wears ok in a model, and it will not corrode, so not a bad choice for a piston. Brass fittings should be avoided for boilers/boiler fittings, since the metal can de-zinc under heat and pressure.

Bearing bronze makes a better wearing material, but is more difficult to find for me.
Bearing bronze has excellent wear characteristics and no corrosion.

Many make piston rods from stainless steel, to avoid corrosion.
I am not sure about a stainless piston, as to whether you would run into stiction issues or not.

Steel is my last choice if you intent to run a steam engine on steam, since steel corrodes very quickly inside a steam engine if you don't get all the moisture out after each run with WD40.
Steel is very strong, easy to machine, and generally readily available most places.
If you will run your engine on air, then steel is a good choice, but I would still add a bit of WD40 after each run.

They sell cast iron rod, and I have used a lot of that (Class 40).
Gray cast iron will corrode slowly, but it is not really a problem in steam engines.
The expression is "Nothing wears like iron", and I have to agree.
Gray cast iron will run against most other metals well, and will run against other gray iron well too.
And gray iron machines like a dream, although there are those who object to the dust that machining generates.
You do need the WD40 treatment with gray iron, as I found out the hard way with a siezed steam engine that had a gray iron piston.

So I would say brass if you will run on steam, and steel if you don't run on steam.
Again, my preferences only, and opinions vary greatly.

.
Edit:
I have purchased a lot of metal types from Speedy Metals.
They sell small quantities of all sorts of metal.
I think "Online Metals" is another seller that I have seem model engineers use.
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[Jasonb]

Pat. A lot depends on where in the world you are as to what is acceptable with a welded steel (or copper) boiler for models.

Here in the UK and also in Australia where the OP is they either need to be welded by a coded welder that is someone who has passed tests for that particular type of welding. Or on the very odd occasion you may get away with having your welds non destructively tested and submitting those to the boiler inspector. How else is the inspector to know the welds and their prep are of sufficient quality and soundness? The only one I know of that was done with own weld tests was welded by a retired coded welder so he was more than capable. Just because someone has a cheap welder and can do a few welds that look reasonable from the outside does not mean they are coded or can make a certified boiler. Also someone who is coded for say structural steel cannot weld a boiler as they would not be coded for pressure vessels. I can weld too but could not and would not want to safely weld a model boiler.

That is why every traction engine model with a steel boiler in the UK is running on a commercially made one. There are a lot of them, far more than there are steam boats

 

[Steamchick]

I have both Brass and cast iron engines - cylinders and pistons. Never experienced your seized bearing condition though. I have had the odd steam engine with either or both piston and cylinder in cast item seize if not thoroughly dried. - Agree the Water Dispersant effect of WD40 is excellent! - followed by running on air to dry it, then lube oil (with anti-corrosive and gumming properties - e.g. very low viscosity motor oil!), before storage.
K2

 

[Steamchick]

Following Jason's post #46: Larger (7 1/2in gauge and upwards) locos usually have welded steel boilers, commercially made as the certification of materials, welders, processes (especially weld preps!) and welders costs more than you can do for a home manufacture if you expect to certify it for public insurance liability....
Only Terrorists make bombs that do not have insurance cover for public liability. A faulty boiler is simply a bomb awaiting an opportunity to explode.
K2

 

[Jasonb]

Max

What metal did you use for the cylinder? is that a brass or a bronze.

I would generally opt for a different metal so if you use a bronze for the cylinder then I would have no problems with using brass, something likeCZ121 or what ever they call it in your part of the world. You could also run bronze in bronze so something like SA660 or the off cut of that hexagon stock. There are a lot of engiens that had the parts cast in "gun metal" which is a bronze and they ran the cast piston in the cast cylinder so not an issue.

If the cylinder is brass then a bronze piston such as SA660 would be a good choice.

Other options are a piece of cast iron bar but just need to watch that it is kept free from rust after running on steam. I make a lot of engines with 6062 aluminium but as this engine has not rings would only use that for air running as there is no ring to take up the gap needed for any expansion of the aluminium when it gets hot.

Passage angles will have very little effect on such a small engine. The original drawing looks like they were cored and cast in so you will have to mill the ports and drill the passages

Pat has obviously not seen the "golden No1" built from a boat prop shaft

 

[Steamchick]

Following post #42:
For all my boilers and steam pipes, etc, I lag with a combination on insulation materials.
A boiler barrel is covered in a layer of aluminium foil, shiny side out, then a layer of insulation (corrugated cardboard, knitted wool, or cotton, Dishcloths are good if 100% cotton, etc.) followed by a layer of good paper to make a decent surface for another layer of aluminium foil, covered in Balsa wood and finished and varnished. Th 2 layers of reflective surfaces from the foil generate a radiation barrier preventing 95% of the Radiant heat from escaping (like a Dewar flask), Wool and cotton are good up to 200deg.C - which is 100psi in boiler terms. Cardboard can run a bit hotter.
This one is cooler than a coffee cup when in steam. SAFE for children to touch!

Boilers with flue gases around the outside, inside a metal containment, get too hot so I use the woven fireproof material that plumbers use to prevent blowlamp flames from damaging anything. They come in cost effective 1 foot squares. - And I still use the double-foil Dewer radiant insulation as well.
STEAM Pipework is always lagged - I used COTTON string (dishcloth cotton can be bought cheaply). wound carefully, makes a good covering, 1, 2 or 3 layers is adequate. Then painted white with domestic emulsion paint (matt) looks like proper steam plant pipework with white insulation on the pipes. It also improves the steam transfer to the engine by NOT losing all the heat in transit!
The only problem I have is when I take a steam pipe through the fire for superheating..., when too hot it turns the cotton black, then it crumbles off! But from a flue tube superheater it isn't too hot.

Cylinders usually have a small air space surrounded by steel sheet or wood cladding. This vertical engine has cladding turned from a single piece of wood, scored to look like planks, and fitted around 3 sides of the cylinder.

Non-steam pipes (water-feed, etc.) are not lagged so can be polished to look pretty. (I don't do pretty, much, though.).
K2

 

[GreenTwin]

The person I mentioned that purchased the pre-welded certified steel boiler I think is the way to go, if someone really wants a functional steel boiler.

Response to JasonB:

Yes, that is why I keep mentioning the above statement regarding welded steel boilers, ie: a pre-welded and certified boiler is the way to go if you need that much steam.

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[GreenTwin]

Pat has obviously not seen the "golden No1" built from a boat prop shaft

Yes I have seen that.
Not sure what his alloy was, but I would never make the mistake of using boat shaft bronze again for anything but static engine parts.
I may as well have applied super glue to my bearings, and I must say that really caught me unaware.

I have not see the golden run either in a video, so there is that.

.

 

[Maxjon]

Max

What metal did you use for the cylinder? is that a brass or a bronze.

I would generally opt for a different metal so if you use a bronze for the cylinder then I would have no problems with using brass, something likeCZ121 or what ever they call it in your part of the world. You could also run bronze in bronze so something like SA660 or the off cut of that hexagon stock. There are a lot of engiens that had the parts cast in "gun metal" which is a bronze and they ran the cast piston in the cast cylinder so not an issue.

If the cylinder is brass then a bronze piston such as SA660 would be a good choice.

Other options are a piece of cast iron bar but just need to watch that it is kept free from rust after running on steam. I make a lot of engines with 6062 aluminium but as this engine has not rings would only use that for air running as there is no ring to take up the gap needed for any expansion of the aluminium when it gets hot.

Passage angles will have very little effect on such a small engine. The original drawing looks like they were cored and cast in so you will have to mill the ports and drill the passages

Pat has obviously not seen the "golden No1" built from a boat prop shaft

I have some bronze bar stock, I think.i will use that for the piston...Thanks!

 

[Maxjon]

https://miniaturesteammodels.com/products/master

I wonder if this boiler will run my engine build? 25 psi ?

 

[Jasonb]

It will be fine for display but may just be a little lacking for prolonged runs under load but if you don't intend to do much of that then it will be OK. Just think of future engines that may want soemthing a little larger.

I would likely run of a coffee machine's steam pipe.

 

[Maxjon]

It will be fine for display but may just be a little lacking for prolonged runs under load but if you don't intend to do much of that then it will be OK. Just think of future engines that may want soemthing a little larger.

I would likely run of a coffee machine's steam pipe.

Coffee machine steam pipe, now you got me thinking....

 

[Maxjon]

What are people using to finish the bore of the engine, after reaming..?

 

[Steamchick]

https://miniaturesteammodels.com/products/master

I wonder if this boiler will run my engine build? 25 psi ?

That burner is probably using a no 8 jet? = about a 1.2Kw gas jet... so you won't get a lot of steam at 25psi from that. But if only a no 5 jet, that's ~0.8kW - Good for "running" a 20mm bore and stroke single DA engine with no load... but NOT fast! Maybe the 5/8" bore and stroke engine that Green Twin showed in the early posts... But a 1/2" stroke 3/8" bore DA single oscillator may be small enough to power a boat using that boiler... My Steam picket boat has a burner of that sort of size - with similar size etc. of boiler and engine - but REALLY puffs along slowly. Looks real for harbour speeds at scale... But not for the high-speed "Dash to Action" for which picket boats were designed to be capable.
If your engine is 5/8" bore and stroke, then Yes, this boiler will run it. But you won't generate electricity for more than some LED pretty lights (generators have heavy loads to push magnets around against the electrical load), but can drive a small boat (up to maybe 3 foot long if slim?) as water isn't a great resistor of motion/power at model slow speeds. - JUST at higher speeds!
To give you some idea:
A boiler on a 5in gauge Steam loco can probably burn fuel for 30kW of "heat-power"... which, converted to steam, drives an engine - 2 cylinders of 1 1/2"dia x 2 in stroke Double Acting using 80~100 psi - to generate the similar pull to an electric loco with 2kW of electric motor power. I.E. Tractive power from the engine of ~6% of the "burner power" - at best?
But possibly a small engine and boiler like the one considered could be as low as 1 or 2%...
But enough for a small engine idling on "steam" at 5psi.
OK?
K2

 

[GreenTwin]

What are people using to finish the bore of the engine, after reaming..?

I use an automotive brake cylinder hone, with oil, mounted on a drill, or mounted in the lathe, but you have to be extremely careful not to let the stones get too far out of the cylinder, else they crash, and the stones are destroyed.

You can set the carriage stops on the lathe to control the travel of the hone.
You can also purchase the stones separately, in case you damage one.

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[Steamchick]

Yup! I use one too, but in the pedestal drill, with bottom stop set, and a careful action towards the top (Never let stones project by more than 1/3rd of their length! - A limit at 1/4 length projecting is good.). But the stones should project a little, as with use, the ends of stones wear more than middles, so you need to get past the worn end zone...A very few passes are needed to reduce machining tool marks to a fine cross-hatch at the "SAME" size. Otherwise you'll be removing more material in an un-controlled manner so the bore will not be as true, parallel and straight as the machine made it. If the tool marks are 0.0002" deep, the hone should remove 0.0001" ~ 0.00015" of metal - Then there will be flat surfaces for sealing and bearing of the piston and rings, and still some surface to take and hold oil for lubrication.
When honing, if I do not have any "honing fluid" I use 50% paraffin (or road diesel fuel if no paraffin available) and light lube oil. Kept in a jar, the carborundum and old metal settle with time as a black sludge.
WASH cylinders, etc. WELL after homing, as the residue will wear everything rapidly. Wash in CLEAN paraffin or turps substitute (paint thinners), allow to dry outside in the sun, then oil with CLEAN lube oil - Modern 5W30 motor oil is fantastic!
Hydraulic stuff (like brakes, car jacks, etc.) have a precision ground surface - usually on Chrome plating or something similar with a very fine material grain - so they do NOT pass the hydraulic oil or wear the seals. - Not the same as a piston in your IC or steam engine!
K2