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[MONAHAN STEAM MODELS]

I had a little bit of free time at the shop today so I decided to have some fun and make a small light weight Vertical boiler. The O.D. is 2 5/8" and the height of the pressure vessel not including the stack is 5". It's designed for operating pressures up to 100psi. It has 10 Galloway or water cross tubes in the main flue and a few extra blanked off threaded bushings for optional items to be added later. I will post more pictures as the project progresses.

Nick

[boatmadman]

A little free time and that is the result?

Most of us couldnt produce the likes of that with weeks of work!

Nice boiler.

Ian

[MONAHAN STEAM MODELS]

Thanks Ian!

In all fairness though, the only bits and pieces I had to make and machine today were the copper components. The bronze threaded bushings as well as all the brass fittings I had already made and had in inventory. The next step will be to paint it and lag it. Then the burner will need to be made. So far the total weight of everything is only 27 ounces.

Nick

[gondolier88]

I would swear you were a genius, if I didn't know you!

Thats a really fantastic little boiler- is this a prototype for a production run?

The water gauge is beautiful- is this to be put on your webstore too?

Oh, and by the way, how the devil are you???

Greg

[Bunkerbarge]

Lovely job Nick and just goes to show the quality of the products you produce.  You realise now of course that you are going to have to produce an equally small engine to go with it?!!

[Neil]

Boatmadman, a week? Wow, you are that fast?
It would take me a week to build up the confidence to start.

I'd like to know how you bore the holes so close together, Nick, without distorting the wall. I can't, I've tried, and given up. There's another photo on another posting, looking down the top of the vertical boiler, without the chimney, that looks a bit like a fan shape in a way. How did you do that? WOW! Maybe that's the difference between an amateur, and a professional? 
I can only dream of such ability, (a bit late now though, I'm way too old.  ).
Neil.

[boatmadman]

Neil,

You missed a critical letter in my last post, an 's', I said weeks!

Nick, how do you make sure the bosses for the sight glass are properly aligned when you soler them?

Ian

[benjaml1]

Very nice indeed.... 

[MONAHAN STEAM MODELS]

Thanks for all the great feedback! 

This has been a really fun project thus far. Well I managed to make some time today to get a little bit more done. The boiler was hydro tested to 200psi and passed with flying colors. Maximum operating pressure will be 100psi although I doubt I'll ever need to operate at that pressure. The main pressure vessel and smoke stack were both primed and painted in stoved enamel then baked for a half hour at 160C. I stole some of the already varnished mahogany wood slates out of inventory and cut them to the proper length then installed them on the boiler. The brushed stainless steel bands were also pillaged out of inventory and modified to fit the smaller diameter of this boiler. So far the total weight is up to 29.4 ounces. Total water capacity is pinch just over 300ml.  I still need to make a burner for it then I can fire it up and see how it works. Here's a few more pictures of how it looks now.

Greg,

It's great to hear from you! I hope all has been well. I'm not sure if this particular boiler design will become a product or not. Right now I'm just having fun building a one off while simultaneously testing a new experimental flue design. Thanks for your compliment on the sight glass. I may make them available on the website.

Richard,

The next part of the project will be the smaller engine to go with it!

Neil,

Thank you for you thoughtful compliments.  I'll be happy to explain some of the processes I went through making the parts in further detail tomorrow morning once I've had some rest.

[Engineman]

Wow! That's a speed! I could hardly imagine for myself to use some free time so effectively... A very nice small boiler indeed. I have a small and smart brass engine to be fitted to it  .

[MONAHAN STEAM MODELS]

Ian,

I've seen and used a few different methods to get the sight glass bosses properly aligned. One method which is fairly common is to make a 3 part fixture. Two of these parts are short metal dowels that are threaded at one end and have a cross hole drilled through the opposite end. The third part is just a piece of round material that passes through the cross holes in the first two parts after they have been threaded into the bosses that are to be soldered into the boiler. However the method I used on this boiler was much less sophisticated.  I laid the boiler's shell on it's side with the two sight glass bosses pointing straight up so that gravity would hold them down. I fluxed both bosses and areas around their holes and began applying heat from the oxy/acetylene torch. I welded the first boss to the boiler shell and then moved the heat to the second one. Moving the heat away from the first one allows it to cool enough to become fixed into place. Once the second boss and boiler shell around this area was hot enough to weld I then applied the silver solder. While gently holding torch's heat around this area keeping the silver solder at a liquid state I simply applied a piece of machined flat stock across the faces of both bosses which instantly aligns them. The piece of flat stock is removed immediately to allow the silver solder on the second boss to cool properly. 

Neil,

You are correct that the water cross tubes that are situated in the vertical flue are in a fan or helix type pattern. This is to allows the surfaces each copper cross tube to be exposed to the hot gasses rising up through the flue. The cross tubes are 1/4" O.D and the spacing between their centers is 5/16" allowing a 1/16" gap between them. On this particular boiler each cross hole is drilled 30 degrees from the next. Normally on production boilers I machine almost all the parts on our CNC equipment because it reduces time which reduces final costs. However on this particular boiler I machined all the parts on manual equipment because spending hours writing the machining programs and making fixtures just did not sound appealing. 

On CNC equipment there are a few ways to go about drilling holes close together. To explain just a couple, the first method is to simply use a center drill to make a pilot hole then a drill to finish the hole to the final size. The second method is to center drill then drill the hole undersized. Then you can use an end mill to circle interpolate the hole to the final size. Since all the holes and machining on this boiler's components were done on manual equipment with limited time available I simply center drilled everything then uses a brand new sharp drill bit to do the cutting. On some parts I used step bits. Copper is a very abrasive material which dulls cutting tools quicker than cutting brass or bronze. It's best to use sharp drill bits and proper cutting speeds as well as feed rates to drill holes in copper otherwise you have to force the drill bit into the material which causes large nasty burrs or can cause the drill bit to grab the material and mangle it. It's best to take your time and be patient. To properly orientate all cross holes in the boiler shell, top cap, and flues I used a small manual rotary indexer set up in the manual mill.

It's on to making the burner now!

Nick

[gondolier88]

Hi Nick,

All has been good thanks- many things are afoot though...

I wonder if maybe an engine with joy valve gear or something like that would look good with that boiler...?

Greg

[MONAHAN STEAM MODELS]

More progress was made today on the boiler but only after I got done doing the things that pay the rent!

Today's work was all about the burner. My original idea or design for the burner was going to require a lot of machining which was going to consume more time than I had available today so I decided to make a simpler burner for now which uses a standard copper plumbing reducer for the main body. The design is similar to what I think most of you have probably seen before. I'd say it's closest cousin would be a Cheddar Puffin type ceramic burner, however the plumbing reducer used to make this one is smaller in diameter by almost 3/16 of an inch. So the design that I came up with today is a bit simpler than it's Cheddar cousin too. Oddly enough because of the simpler design I was able to use a slightly larger ceramic element than the ceramic element used in the Puffin type burner.

After deciding on the burner design to make the first step was to machine a brass adapter bushing to press into the boiler's flue. The inside diameter of the bushing needed to be machined so that the copper plumbing reducer would have a nice snug interference fit so that the burner can't fall out while the boiler is in use. The next step was to drill the small diameter secondary air holes in the plumbing reducer around the circumference. This was done in the mill with a rotary indexer. While it was already in the indexer I drilled a larger cross hole for the fuel mixing tube which exits the smaller diameter portion of reducer at 90 degrees. I then machined the brass mixing tube and a end cap to plug up the smaller end of the reducer. Everything was silver soldered then painted in stoved enamel. With the end of the work day insight, I was now beginning to grow impatient and wanted to see if the fruits of all that labor was going to pay off. So I quickly made a ceramic element to place inside the now cooling freshly painted and baked burner. Once it had cooled enough to touch with out screaming ouch and accidentally tossing it across the shop I place the ceramic into burner housing. Almost immediately following that a fuel jet holder with a fuel line already attached to a gas cartridge was quickly inserted into the burner's mixing tube and then Houston we have ignition!!!!  Woohoo!!!!! It works!!!

Tomorrow I will try to raise the first head of steam!

Nick

[MONAHAN STEAM MODELS]

So the final weight so far is now 32 ounces right on the money.

[Bunkerbarge]

Nick, I just wanted to add my thanks for sharing this build with is.  Lovely job and deserves to go into an open launch where it can be seen at it's best.  I can't wait to see what sort of engine is going on the end of it!

[kiwimodeller]

Nick, it has been great to read your answers to the various questions, I always like to know why people do things in a particular way. I would very much like to hear your thoughts on burner design. I have been exploring the relationships between area of ceramic, jet size, distance from the jet to the ceramic face, number and area of primary air holes and number and area of secondary air holes. Latest experiment is an alloy burner housing that fits over the flue instead of in to the flue. I was trying to find if 24 secondary air holes of 2mm worked better than 16 2.4mm holes and putting the burner over the flue gave me a bit more circumference to fit the 24 holes in. It also meant the ceramic could be the full diameter of the flue. I am only measuring time to raise steam as a performance indicator but intend to look for a good digital thermometer when next I go to the city. An old and experienced friend once told me that the best boiler and burner combination was the one that had the hottest temperature at the flue inlet and the coldest temperature at the outlet as it was then burning well and transfering all heat to the water. I am also interested in your "liquid" burner as I have been playing with the Kovea plumbers torches one of which has the feed pipe passing through the flame so it can be used upside down but I will leave that discussion to the other thread. Thanks for all your time posting on this forum, regards, Ian.

[Circlip]

 Are you REALLY sure you've used enough Silver Solder on this boiler Nick??  

  It's such a delightful change to see one done correctly, as despite all the instructions, many seem to think that you need to "Caulk" the joints.

  Messrs Johnson Radley ain't going to be holidaying in the Bahamas with your frugality/CORRECT use of their "Glue"

  Thanks for the pikky.

  Regards  Ian.

[kno3]

That's a very nice little boiler Nick. If you ever make more of them, I'd suggest placing the threads for the sight glass on both sides of the boiler, that way one can move it to suit the installation and you also can use the other 2 for a pressure gauge and check valve.
The weight is still significant though, at over 900 g. What copper thickness did you use?

[MONAHAN STEAM MODELS]

Kiwimodeller,

Burner design is an interesting topic. I've spent a lot of time trying various designs using numbers of different materials and configurations. I've come up with designs which have worked so well that in the hands of the village idiot they would be dangerous! Burner design is half science and half black art form. Although this topic has been discussed many times I'm sure already on this forum, perhaps we can start a fresh discussion about this topic. One thing I can tell you though for now is that just one advantage with many smaller diameter secondary air holes verses lets say four larger holes significantly reduces how loud a burner is. I've run experiments using a decibel meter trying out different secondary air hole sizes and numbers and have found on average that 24 roughly .060dia. holes opposed to 4 .156dia. holes will reduce the burner's sound by almost 15 decibels depending on the design.

Circlip,

LOL, I thought I had already used way too much Silver Solder on this boiler!    The joint fits are an extremely important part of the puzzle for both strength as well as not overly "caulked" joint welds. Me wants to use the saved money on silver for vacation anyways! 

Kno3,

Thanks Calin for you thoughtful suggestion. I had originally thought about adding a few sight glass location mounting options to the boiler but every threaded boss and blanking plug adds weight, labor and cost. I thought it was important however to leave a few extra bosses on the top of the boiler for other items to be added later such as possibly a steam whistle, gas attenuator take off, water level sensor or anti vacuum valve. The extra blanked off port on the lower portion of the boiler next to the burner is for a one way check valve. This boiler was designed to be light weight but also capable of operating at high pressures allowing for numerous engine options to be used. Also total water storage capacity was another huge design factor. According to my strength calculations for the final operating pressure of up to 100psi and what is also required by the standard boiler making codes the copper thickness on this boiler is 1.6mm or .062". I do plan to make another version of this boiler which will use the same new flue design but the total height of the boiler will be much shorter which will significantly reduce weight.

Bunkerbarge,

Thank you. 

As far as engines go, I have three different small engines in mind for use with this boiler. Eventually I plan to make all three, but soon I will soon begin posting pics of the first one and possibly the second one simultaneously. The progress of the engine builds depends on how much free time I have to devote to them. I wish I could spend all day everyday building new fun stuff, but at least it gives me something to look forward to when I do have the chance.

Best Regards,
Nick

 

[MONAHAN STEAM MODELS]

Carried out the first steam test today.

Temp. inside the shop was 57 degrees F
Temp. of boiler 57 degrees F
Temp. of water 56 degrees F
Temp. of Fuel canister also approx. 56 degrees F
Boiler filled with 250ml of water
Safety Valve set to 80psi

Below are the results.

3 min 52 sec to 20psi
5 min 20 sec to 30psi
6 min 15 sec to 40psi
6 min 55 sec to 50psi
8 min 15 sec to 60psi
8 min 50 sec to 70psi (safety valve beginning to lift)
9 min 25 sec to 80psi (safety valve lifted relieving pressure, boiler maintaining 78psi)

So far I'm happy with these results but I would like to run some more tests and try playing around with the air/fuel mixture to see if I can get a couple more BTU's from the burner. So far the burner seems to be getting darn near close to full combustion since there's hardly a smell of raw fuel exiting the smoke stack. The real test for this boiler will be to see how it preforms with an engine connected to it consuming steam. Judging by the amount of steam being released from the safety valve and the boiler holding firmly at 78psi my feelings are positive at the moment.

Nick

[Underpressure]

Nick.

You raise an interesting point about burner noise. Some of the Cheddar ceramic burners are incredibly loud and I also remember that many of the Proteus burners used to 'whistle'.

Is it worth experimenting by adding a few smaller holes to an existing burner in order to reduce the noise or in an effort to rid a boiler of the whistle?

BTW, that is a great boiler and I am filled in equal measure with admiration and jealousy at your skill 

Neil

[kno3]

Hi I have a question: why are secondary air holes needed on a ceramic burner, or indeed on any gas burner that already has air holes where the jet is located?

[gondolier88]

Secondary air holes make a less turbulent atmosphere for the flame making it quieter, they also mean any miscalculation in primary air volumes are not a problem as unburnt fuel can combust after the burner.

However they can chill the flame causing incomplete combustion and they will also always make the combustion chamber cooler than a fully sealed burner unit.

Has anyone here made a fully sealed unit-perhaps with either a positive or a negative pressure fan?

Greg

[kno3]

That's the way I use my burner in my compact steam plant. I have closed the opening of the boiler with a brass plate. OK, it's not 100% airtight, but I put it there precisely because I thought that extra air drawn in would cool the inside of the firebox.
But I wasn't sure if that's the best thing to do or not.

[MONAHAN STEAM MODELS]

Here's a long overdue update on this post.

So I finally managed to get the final burner design made as well as the final sight glass design. I feel that the new sight glass is more to scale with the size of this boiler than the previous one that I borrowed off the Belmont boilers.