A small boiler

[firebird]

Hi

Just a half hour shop time today, long enough to make a jig that will hold and support the boiler end plates when I get to drilling the holes. 2 pieces of scrap. A piece of 12mm ply and a piece of 18mm MDF. The photos should be self explanatory for this.

cheers

 

[firebird]

Hi

Whats the best/easiest way to find the centre of a circle? I'm referring to the boiler end plates

Cheers

 

[Bogstandard]

Just pop them into your outside jaws on the lathe, and just touch on with a centre drill.

John

 

[firebird]

Thanks John

Easy when you know how aint it.

Cheers

 

[firebird]

Hi

I was somewhat disappointed with the burner trials the other night so had another go at it tonight. The following photos show the mod. It consists of an additional wick as a pre-heater. The tank had another hole drilled in it close to the mushroom outlet and a brass bush tapped 3/16" x 32 soldered in. A short length of 3/16" brass drilled through 1/8" and threaded one end. The mushroom had its brass tube removed and a longer one soldered in. I drilled the sixth hole in the brass cap next to the broken in drill. The pre-heater tube has just one strand of cotton wick. The wick material by the way I bought at a local market in the form of a mop head for the princely some of £1.00. Should be enough there to last me a while.

The following four photos show the burner being lit. The pre-heater wick lit easily and within 30 seconds the jets had self ignited giving a nice flame.

I then changed the brass cap with its 2mm holes for the copper cap with its 1mm holes. It still lit very easily but note there seems to be more of a blue colour to the flame and looked to be burning better. Maybe more efficiently with the smaller jets?

Over all a much better trial than the previous one. I will be adopting this type of burner for the boiler. I think the mushroom head could do with being a little larger so that the pre-heater is not on the edge. This rough drawing shows the type of thing I will make.

I'm happy with tonights results. Progress is being made.

Cheers

 

[SandyC]

;D

Hi Firebird,

You are on the right track with the added pre-heater. As you say, a marked improvement.

Might I suggest, if you are going to build a new burner, to make the jet holes smaller (say No 76 (0.5mm) or even No 80 (0.35mm) dia) and use more of them....say 18.
Also, if you can keep the wall thickness of the mushroom sections down to around 0.020" (0.508mm)then I think you will get a better evaporation of the Meths and a better flame pattern.
You may also find that you can reduce the pre-heat flame level a good bit....i.e.shorten the exposed wick, this will have the advantage of lower overall fuel consumption.

If you look at the version you are trying to emulate, you will see that he has a large number of smaller holes on his burner.

The overall plan for your new, two headed, burner looks good and should work well, possibly with the above additions included....the only thing you will need to be carefull of is that the Meths level in the main tank should not be higher than approx one third - half way up the pre-heater tube, otherwise you may find the meths expands to much in the pre-heater feed tube and will overflow....not good.

I am sure you will eventually find the correct combination.

Returning to your boiler...... I would suggest that you mark a vertical centre line on your end plates (if you have the vee attachment for your combination square you can use this to find the centre of the disk) and then take one end of the mark round the flange (make this the top) and make a good heavy mark on the flange bend.

If you also (using your combination) mark the top centre of the barrel, on the edges, again make good heavy marks, then you can easily line up the end plates with these marks when you fit them.
This will be important, since you need to keep the STAY holes aligned at both ends of the boiler...or you will have a lot of trouble fitting the stays.

If you don't have the vee fitting for your combination, then you can use the same method as for finding the centre...i.e. put it on the lathe...but use a sharp lathe tool to scribe a line across the plate.
Extend this round the flange edge using a scriber, or a stanley knife blade.

To mark the barrel....fit one end plate (just pushed in) and mark one end of the barrel in line with the flange mark.

Place the barrel on a pair of vee blocks with this mark roughly in the horizontal position and lightly clamp it so that it cannot move.
Set a height gauge (or scribing block) to the height of the mark and lightly scribe along the outside of the barrel and round the opposite end.
Enlarge the end marks with a stanley knife blade so that they are easily seen and dont get rubbed off when you come to clean the copper for soldering.

The line marked on the outside of the barrel will become the top centre line along which you can mark the positions for your Dome (if fitted) and safety valve bushes.
Hope this is clear and helps a bit.

Keep up the stirling work.

Best regards.

SandyC ;D

 

[firebird]

Hi Sandy

Again many thanks for the invaluable help. After I had posted last nights results it did occur to me that the brass mushroom might be a bit heavy and would be better fabricated from brass/copper sheet. I see what you mean regarding the level of meths in the tank. When I get to the final design I may make the tank shallower or the pre-heater tubes slightly taller. Your method of marking out makes good sense as well. I doubt my small V blocks will be big enough to hold the barrel but we'll see. I hope to get in the shop for a while over the weekend.

Cheers

 

[firebird]

Hi

I have a couple of questions.

Dickeybird mentioned radii in an earlier post. it has just occurred to me that when fitting the dome and safety valve bush into the top of the boiler barrel they don't have the same radii. Does this matter? Does silver solder have gap filling properties? The sketch below shows what I mean.

I understand its best to use distilled water in the boiler. We sell de-ionised water at work for topping up car batteries, is that the same as distilled?

Cheers

 

[SandyC]

Hi Firebird,

No problem, just thought a few pointers would help, as it is your first boiler.

If your v-blocks are to small, you can always try sitting the barrel on your miller table (in the rear tee slot) this will keep the barrel level (which is the point of the exercise) and you can lightly clamp it from the same tee slot., just sufficient to prevent movement.

You can then use your surface gauge on the remaining surface of the table.... VEE HAV ZEE VAYS.

The need for a radius is not necessary for these items, the silver solder (easyflo 2) will run round the joint and form a good fillet.

As for boiler water...NO DO NOT use de-ionised water, especially that sold for batteries (some of these can contain small amounts of sulphuric acid).
Even if it does not contain acid, being de-ionised (by ion exchange resin methods) it will attempt to recover lost ions by extracting the required ones form any bronze and or copper in the boiler (which is most of it) and also from the silver solder.(Which can damage/degrade the solder)

The same can apply to water from a domestic filter/softener, since these often contain ion exchange resins either before or after a carbon element. (BRITA etc).

The best water to use is pure distilled water (obtainable from your local chemist, but can be pricey), failing this you can use REVERSE OSMOSIS water (try your local tropical fish store, they often use for partial water changes in the show tanks (they generally produce it themselves)), next best is well filtered rain water or water recovered from a de-humidifier(domestic) and lastly....cooled, well boiled tap water.

Best regards.

SandyC  ;D ;D
 

 

[Florian]

By the way:

For the steam dome, its better to make some small holes into the boiler tube than one big hole. This prevents the water to be carried along with the steam.

Florian

 

[firebird]

Hi

Thanks to Sandy and Florian.

Today I made one end on each of the three stays that will be used in the boiler. The method is described in the PDF attachment from Sandy in one of the above posts. Briefly though anneal the end of the 3/16" dia. phosphor bronze, hold in a collet in the lathe and tap over with a small hammer. Clean up with a file.

Next job is marking out the end plates. Hold in the 3 jaw and lightly mark the centre with a centre drill. Make sure the tool is at centre height and scribe a line across the end plate.

Mark a line along the boiler barrel. Sandy has suggested another method as well but I hadn't read it so this is what I came up with. Hold the barrel in the lathe and mount the scribe in the cross slide.

I have an adapter that fits into the rotary table that my myford chuck screws onto. Centre drill a bit of scrap. Unscrew the chuck from the lathe and screw onto the rotary table. Its now easy to centre the rotary table under the mill chuck using the centre drilled hole in the bit of scrap. Lock the table in this position.

Screw the face plate onto the rotary table. Mount the end plates into the jig. Using the centre drilled mark on the end plates centre one end plate under the chuck. then clamp the jig to the face plate.

Now move the cross slide over to the required PCD and using the rotary table drill the 3 stay holes. Move the crosslide again and drill the 2 water guage holes. The drawing by Sandy shows another hole for the water injector. I Haven't fully decided yet whether or not to fit a water feed sytem onto this boiler so I haven't drilled that hole yet. Move the table across and centre under the second plat and drill just 3 holes for the stays and counter sink with a centre drill.

Finally I made 2 phospher bronze bushhes drilled and tapped 1/4" X 40 for the water guage.

Cheers

 

[firebird]

Hi

Question time again.

Do you anneal phosphor bronze the same as for copper?. Thats how I did it, heat to red and quench but the phosphor bronze rod was still quite hard.

Do you think the bar I used for the bushes is phospher bronze? The gentleman that sold it to me assured me that it was but it has a colour almost the same as brass. How do you tell?

Florian has suggested drilling small holes for the steam dome but Sandy's plan shows one large hole with a dome machined from solid phosphor bronze?

 

[Bogstandard]

FB,
That is phos bronze, the usual giveaway is the spiral dark marks down the bar, something to do with how it is cast or drawn.

If I may, I will give you a couple of tips on fitting your water gauge, if Sandy already hasn't told you.

The first is the bushes. Screw each fitting into its respective bush with its little soft copper washer and give them a tweak to tighten. Put a small pop mark on each bush then put the bush and fitting into its respective hole. Turn the fitting and bush in the hole in the direction of tightening until you are about 1/16 of a turn from the required fully tight position. Put a tiny pop mark on the end cap adjacent to the mark on the bush. When you silver solder the bush in, line up the pop marks and solder in that position. Doing that you will be very close to the correct position for putting the fitting in for alignment. After soldering, when you eventually put the fitting in, if it won't tighten all the way to the required position, it is then just a matter of flatting down the copper washer slightly until, when tight, it is in line. Do not overtighten. Also, before final fitting, re anneal the copper washer.
The next tip is measure up your sight glass for diameter and then put it away somewhere safe, Find a bit of rod the same diameter as the glass and use that for all playing about and alignment. The rod should be a nice sliding fit into the two fittings.

Personally I would forget about the top up fitting. When you get a bit more experienced with hand and engine driven pumps, then start to make boilers with top up fittings and clack valves.

It is a few years since I made my last boiler, but it seems that everything is still the same, except for material and fittings costs.

Hope that this has been of use.

John

 

[SandyC]

;D ;D

Hi Firebird, John and Florian,

I would say that was SAE660 which is continuouse cast (in a rotating mould, hence the spiral markings) not straight PB102, which is normally solid drawn, and generally much more copper coloured.
Much easier to machine .... and exactly what I use for my bushes etc.

The method John has described for lining up your water gauge bushes prior to soldering is a very good one and his advice about using a piece of rod instead of the glass, when finally aligning the fittings is one I use myself. Gauge glass is all to easy to break and the fittings must be perfectly lined up before attempting to fit the glass...if not...the glass will most certainly break..... TAKE YOUR TIME when performing this task.

You are making excellent progress on your boiler FB, and am pleased you found another method for your marking out...lots of different ways....well done.

I would drill for, and add, the extra bush for a non-return valve, it can always be fitted with a capping plug if you don't use it immediately and is not much extra work at this stage..... but a PITA to add latter.

Florian,

yes I agree that a set of small holes under the dome would be of help in reducing water transfer and is the more standard way, especially for high output, higher pressure boiler such as for a traction engine or a loco, where the steam would also be possibly passed to a superheater before finally entering a cylinder, in such a case, the minimising of carried over water is much more of an issue, however, 2 reasons I have not mentioned it up to now....

1. this is FB's first attempt at a boiler and keeping it as simple as possible is probably best.
To go down the small holes route would certainly make the manufacture and fitting of the dome a great deal more complicated, and I think FB has enough to get his head round already. MAYBE for the next, more powerful one!!!.

2. For smaller low pressure boilers, with a relatively small dome inner bore I don't really feel it would be of any great advantage, since it is running at low (35psi) pressure and wet steam is going to be the output.
Providing the max water level is not made to high then transfer should be minimal, even with the single hole.

Most of my smaller marine boilers use this method and I have yet to have any complaints on this score.... my higher pressure ones, or water tube boilers (high rate) such as the Scott (see my Avator) use multi small holes and/or internal perforated steam pickup tubes.


Keep up the great work FB.

Best regards.

SandyC ;D ;D

 

[firebird]

Hi

Some more good tips from John and Sandy, thanks.

I've managed to sneak an hour in the shop this morning and checked out the water guage bush alignment. Because the radii of the flange is not as tight as it could be the holes I drilled for the bushes are a little close to the edge the bushes don't sit flat enough so I made this little jig to hopefully hold them square. 2 pieces of equal length 1/4" dia steel. Thread one end 1/4" X 40 to fit bush and drill 3/32" holes in the other end to accept a length of 3/32" stainless steel rod. I will try and mount the fittings in the bushes and mark their positions as you suggest John. I found this company Maidstone-engineering.co.uk who supply a pack of 1/4" copper washers 5 of each size .005 .010 .015 .020 for £3.12, so I think I will get some of those.

There is still one unanswered question from above, how to anneal phosphor bronze?

Cheers

 

[SandyC]

FB,

Annealing.....You have already done just that, when you did your stay heads.

Heat to dull red and let it cool, or can be quenched in clean water.

It will, just like copper, work harden again when worked.
The material you used for the stays are genuine PB102...you can see the colour difference as compared to the bush material.

The stuff you have used for the bushes (I suspect as being SAE 660 leaded bronze) does not need to be annealed, just turn it using a sharp tool.

After you have cleaned up all the bits with wire wool etc and just before you Silver solder everything, chuck all the bits in the pickle bath for a few minutes to get rid of any grease etc....rinse in clean, cold water....no need to dry them, then flux, assemble, add more flux as required and solder up.

That little jig you have made up should work just fine, but be sure not to over insert the screwed parts into the bushes, they may get stuck with all the heat.
And remember to remove them before you put the boiler in the pickle after soldering...else they will go BLACK and GUNGY and possibly ruin the pickle bath.
One possible small addition to the jig would be to add some small screws in the top to allow you to lock the cross bar once the bushes are correctly aligned....else it may slip whilst heating.

Looking good so far.

Best regards.

SandyC ;D

 

[CrewCab]

Nice work on the jig FB ;D ................ this is a really interesting thread and your doing a great job with the boiler imho .......... please keep it coming 8)

CC

 

[Bogstandard]

I am really glad that Sandy, our resident boiler expert, has deemed to pick up on this post, and give good, knowledgeable & expert advice.

I have seen so many boilers in the past, made from suspect or totally wrong materials. Rather than flanging the ends, I have see them just butt soldered onto the ends of pipes, with no stays to give even a bit of safety. I have seen people testing them to over 100psi using air, with the boiler stuck in a bucket of water to detect leaks. They don't realise just how dangerous these little beasties can be, if not made from the correct materials and using the correct building and testing methods.

So it is nice that there will only be good methods and materials used on this post, and a good guiding light to those who would like to build one.

Nice one gents.

FB, I noticed that the burner you intend to use was soft soldered. When put into the enclosed area under the boiler, the soft solder might not be able to take the build up of heat. Better to be safe than sorry.
Maybe now would be the time to start gathering the bits together to make your own little brazing hearth and suitable propane torch (I personally wouldn't recommend oxy/acet).
I made my own hearth out of a bit of angle iron and a few firebricks, and is a perfect size for these types of boilers. If you want I can take a few piccies and give dimensions if needed. Much cheaper than buying a ready made one.

John

 

[Circlip]

And don't forget,the radiants from an ex "Gasmiser" are superb for resting the bits on. The pointy bits allow heat to get under the target and also reflect heat.
Regards Ian.

 

[firebird]

Hi Sandy, John, Ian

Sandy, Yes a couple of small screws to lock the bar would be a good idea. The further down the road I get with this project the less erors that are allowed to creep in the better.

John, The burner is just an experimental piece but yes the real thing will be silver soldered. I have a propane torch and oxy/acet. Being in the motor trade I have 30 years experience of handling oxy/acet so it holds no problem for me although I intend to do most of the silver soldering with propane. I have a cast iron hearth from an old bar b q that I thought would make a brazing hearth, approx 12" X 18". A couple of pics of yours would be great so I have an idea of how to build.

Ian. "the radiants from an ex "Gasmiser" ? More info please.

Question time again

Is it best to anneal copper/phospher just prior to working it or once annealed does it stay in its annealed state until worked?

I used citric acid in my pickling bath. The sort home brew enthusiasts use for sterilising bottles. It works well but after about 4 weeks it seems to have some slimey stuff in it now. How long does the pickle normally last?

Cheers