Silver soldering rod for boiler

[Steamchick]

Krypto, did Blondihacks demonstrate a design that can be certified by a Boiler inspector, so the local club will let you run engines on live steam on show days? I. E. Give you cover within their insurance? That is my need for calculations for boilers ... I would not make another boiler without a comprehensive set of calcs, as it would be a waste of time as I could not use it in public places. Sounds good that the video covers failures, and presumably the countermeasures?
Making a boiler right first time is not easy, depending on size and complexity, and repairing leaky joints without melting everything takes a bit of skill.
I should watch this video.
K2

 

[Lloyd-ss]

This is quite an interesting thread, wandering back and forth from the original question about brazing filler rods. I personally have never built a boiler and probably never will, but I am learning a lot anyway. By the very nature of this forum, I would think that everyone here is reasonably smart, has a fairly good mechanical intuition, and is fully aware when they are about to make a dumb mistake. So nobody is totally right and nobody is totally wrong (unless they are trolls). So all I (we) can do, for our own personal sake, is read and learn and make what I (we) think is the best decision for us personally. That's my philosophy anyway.
Thank you for all contributions to our knowledge base. Learn something new every day.
Lloyd

 

[Steamchick]

I should learn diplomacy... according to 40 years of annual reviews at work!
K2

 

[packrat]

"Did Blondihacks demonstrate a design that can be certified by a Boiler inspector"
Yes, Blondihacks boiler will be certified so she can run it at a club track...You should watch all the series on the boiler making.

 

[krypto]

Good, we have some experience here.

I think it would make it easier to follow in this thread if we separate the boilers into two camps, the small <30 PSI stationary boilers used to power the steam engines that Nikhil mentioned in his original post and larger >30 PSI boilers used in ride able locomotives.

Quinn already built the stationary boiler and completed the boiler first for the A2 switcher locomotive build. As packrat stated, she already talked to the people with the club track before the build was even started and they were OK with the design of the engine. You would have to be nuts to start a loco build without consulting with the club people first as the old men have the final say on whether you can steam at the track or not regardless of your research or what you think will work. Kozo's A2 design is not new and many have been successfully built and working.

Back on the stationary boiler, Quinn pressure tested her boiler to 90 PSI although she was running that engine at ~30 PSI on the gauge. As far as getting a boiler certified for publicly showing live steam stationary engines, I've never seen stationary boilers running at a show. One of bigger shows on the east coast, Cabin Fever, always has all the stationary steam engines running on air. Internal combustion, yes, external combustion, no. They do have a track layout for the small butane-heated steam locomotives and maybe a steam boat or two in the pond.

 

[Steamchick]

Hi Krypto.
Interesting that no-one bothers with live steam for stationary engines. Such a variety from small - and not so small - Oscillating engines to turbines, and larger mill engines, boat engines, compounds, etc.
I regularly steam a 3inch dia. horizontal, 4 inch or 4 1/2 inch dia. vertical boiler (ceramic gas burners) to power a compound twin - built by apprentices in the 1930s. Not perfect, but needs 20psi (Steam) to run until hot when the secondary cylinder kicks-in and the pressure can be dropped to 10 or 12 psi.... - I use it to demonstrate to Joe Public all the aspects of steaming engines, managing the fire (gas valve), water (hand-pump), and condensate (Oily stuff in a condenser at the exhaust that kids love and parents hate!).
I also run a 2in. vertical with scotch yoke engine that has a generator and street lamp fitted. To run on air is simply boring.... but I do run a half a dozen small engines on air to show their (valve) workings... and explain differences and applications of the "engines that powered the Industrial revolution". Adults and kids enjoy aspects/stories of our history. (We have a lot of history in the UK).
But steaming attracts all and sundry. Try it and see...
In the UK there is a division between "regular" models and "small boilers" at 3 bar-litres. Above that there must be 2 independent water feeds, below that only 1, or none if a shop model with boiler capacity for steaming determined by the size of fuel charge. (solid fuel tablet or spirit). Any boiler with a fuel supply potentially larger than the limited quantity of boiler water must have a water gauge and 1 feed pump (min). ALL must have safety valves. (Must be similar in USA, Australia, N-Z, Europe, etc?).
BUT the small boilers must still comply with drawings, calculations, etc. to meet the same engineering standards as larger boilers, for certification and insurance cover at open days, etc. (Club Public display).
Hope that helps?
K2

 

[Steamchick]

Curious:
Just watching Blondiehacks - post #3 video - I noticed a practice that I was taught to avoid during milling.

Simply, the first pass kept the workpiece driving against the line of tangent of rotation of the cutter, so the lead screw retains full contact all the way.
The reverse pass (shown) does the opposite. The workpiece is travelling with the tool, so each cut of the tool is trying to un-seat the traveller nut from contact with the main screw, so this can develop chatter - depending on the machine quality, wear, maintenance, materials cutter sharpness, speeds and feeds, and friction in the whole traveller. - Something to avoid (in my workshop).
What I was taught I think was basic practice for all cutting machines. Has anyone else come across this?
Perhaps "self-taught" people may not be aware of the effect of cutting forces on their machines and how to avoid "issues"?
What is "best practice"?
K2

 

[Steamchick]

Hi Lloyd, Nikhil, FYI. Just back-tracking on this thread (I am enjoying this one! - Thanks to Nikhil for asking his initial question!):
Here are a couple of documents I refer to from time to time... and a picture of how I set-up for silver soldering ends of boilers.

Note the use of 2 pre-heating blow-lamps - Their fuel tanks partly shielded from the radiant heat from the hot boiler. The main blow-torch is the propane torch that is hand-held during soldering. Leather welding gloves, sleeve, apron and safety glasses are worn for protection. This is immediately next to the open garage door - for fumes (or me!) to escape.
Test codes for small and larger boilers for UK.
Brazing notes/tables

Hope these help?
K2

 

[krypto]

...
The reverse pass (shown) does the opposite. The workpiece is travelling with the tool, so each cut of the tool is trying to un-seat the traveller nut from contact with the main screw, so this can develop chatter - depending on the machine quality, wear, maintenance, materials cutter sharpness, speeds and feeds, and friction in the whole traveller. - Something to avoid (in my workshop).
What I was taught I think was basic practice for all cutting machines. Has anyone else come across this?
Perhaps "self-taught" people may not be aware of the effect of cutting forces on their machines and how to avoid "issues"?
What is "best practice"?

It's called conventional milling versus climb milling. Apparently Quinn is well aware of the difference as she talked about it in-length at the beginning of this tutorial video from several years ago:



Climb milling is very handy for cleaning-up and getting a good finish after a heavy cut, you just need to understand your machine's limitations and stay within it's parameters for safe operation. In the video you mentioned it was probably a useful technique when working with gummy copper, but I've never done much with that material.

 

[Steamchick]

Thanks Krypto.
Learn something new every day!
I have experienced many machines, but nothing "modern" with "backlash removal". So I'll stick to conventional milling with my machines.
My view of "Hobby" machines are lower cost, so do not have such luxuries as CNC control, backlash removal, digital readouts, and the other significant technical introductions since I was a lad... (Great developments for Industrial "low cost, High Quality", fast output.).
Being retired, I have time and my brain needs activity, even though my body is less able. My machines need time, brains and skill to operate correctly, which suits me. I am not into a "do it all automatically" machine where I just drop in a lump of material and out pops a finished article. I want to know "I made it". - The machine simply did the had work. I even refer to graving, or the use of hand tools - because I can. Though not for the "perfect" straight line or circle.
Call me old fashioned. - You are correct. My drawings are just that - Made with pencil on paper. Calculations made with slide rules and real worked-out sums. - Even when using a calculator, I single enter every number and operation, because that's what "tickles my neurons". Or I write a computer calculation in Excel - line by line - as I want to see the numbers developing. Sorry, to those who are too "modern" to appreciate the "beauty" of watching "an idea develop into an egg, that needs nurturing to become a chick, then on to become a fully fledged something that flies". You are missing something of the beauty of creativity, IMHO.
Or am I a dinosaur? A dead-end of evolution? I simple want to be "Master of the machines", not have them take away the "humanity" of my models.
Back to Silver solder:
Johnson Matthey: who sell Phosphorous copper brazing rods for pure copper. recommend:
"Specific Issue: Sulphurous Atmospheres at Elevated Service Temperatures Recommendations:
Phosphorus containing filler metals should not be used in cases where they will be exposed to sulphurised gases at elevated temperatures, for example in model engineering boilers.
I hope that clarifies the view from experts.

K2

 

[Peter Twissell]

Hi k2, I regularly climb mill on my (manual) machine. I just nip the gib clamps enough to prevent the cutting load from snatching the job. Climb milling generally gives a better finish than upcut milling. Also, because the cutting load is pushing the tool away from the job, it gives a more accurate and repeatable dimension.
Just don't try it with slitting saws!

 

[trlvn]

I have experienced many machines, but nothing "modern" with "backlash removal". So I'll stick to conventional milling with my machines.

Did you perhaps bail out of the Blondihacks video before she finished? She quite clearly says that for hobby machines conventional milling is the safest route with the most predictable results. BUT, she points out that climb milling ought to leave the best surface finish simply due to cutter geometry. SO when you want a really nice surface finish, mill almost all the material away with conventional milling and then take a very light climb milling cut to achieve final dimension. Gives the best of both worlds.

Even an old dog can learn a new trick with the right motivation, eh?

Craig

 

[Steamchick]

Old habits die hard - for me. I dare to admit it, It was just a bit conflicting with a lifetime of experience, and to learn something new, I.E. when to change and when not, is more risk to my work than what I do already.
Thanks for all the help though.
Back on thread, here's a brochure I have been trying to send....
K2

 

[ninefinger]

I'm a bit surprised that 3 pages into the subject nobody has suggested the Australian Miniature Boiler Safety Committee's document for boilers, though it is quite well hidden on the internet and hard enough to find where to acquire it.
AMBSC Code Part 1 - (various issues - Issue 8 - 2012 is the most recent) https://www.aals.asn.au/ambsc-code-part-1-index-only/
available here: AMBSC Boiler Codes
For a non-engineer its a simplified guide to ensuring that a boiler is of sound design, using tables to set out the requirements.

I consider it quite complete and sufficient for the purpose of ensuring a safe boiler. At least the Australians do...
It addresses things such as min shell thickness for various operating pressures, plate thicknesses, stay diameters and pitch spacing, brazing materials, etc.
Its not perfect but is a very good guide and a basic boiler built using it as a guide will be safe.

As and example using the code I can determine the following:
For a 2-1/2" boiler up to 400kPa the shell should be 1.6mm according to the above mentioned code. The end plates will generally depend on if there is any form of staying - if stayed on a 19mm pitch with 3mm stays then 1.6mm as well. Unstayed end plates would need to be unreasonably thick (a material thickness for a stay pitch of the boiler diameter in effect is "off the charts - i.e. above 6mm thick). And end plate 3mm thick with a single central stay of 6mm diameter would be ok for a 2-1/2" boiler.

They also have a Part 2 for steel boilers that I don't have but I am interested in getting...copper is so expensive...

 

[Steamchick]

That's great! - Curious how it appears to need more copper in the ends - and stays - than my calculations for ASME. - I had thought they were the effectively same standard. But you live and learn.
K2

 

[ninefinger]

I also realized they have a standard for "sub miniature" boilers, and as I did not know where a sub miniature boiler ends and a "regular" (to me) boiler starts I did a search, and found this very helpful description on another forum:
https://www.tapatalk.com/groups/modelandtoysteamforum/aussie-boiler-codes-t1402.html

Copying the text from there (i.e. these are not my words) I'm including here for convenience - as its directly related to the initial discussion on a small boiler ~2-1/2" of ~ 30psi.

The code that will effect most members will be the SUB - MINIATURE BOILERS so i will start with it.

The code is to help modelers with design requirements and operation of model steam boilers up to 3 inch OD, have an operating pressure of less then 75 psi and a water capacity of 1 litre or less.

There are two classes in this code, LOW PRESSURE and MEDIUM PRESSURE

LOW PRESSURE boilers have a maximum working pressure of 29 psi, can be constructed from Brass or Copper and can be Soft Soldered or Silver Brazed, if constructed from Brass the boiler can not be over 2 inch in dia, most commercially produced LOW PRESSURE boilers ( Mamod, Wilesco etc ) may not need to be inspected or issued with a certificate for steaming in a public place.

MEDIUM PRESSURE BOILERS can have a working pressure of up to 75 psi, must be constructed from Copper, bushes from Gunmetal, Bronze or Copper, the Silver Brazing Rod must contain 15% or more Silver and comply with the thickness requirements for the barrel, end plates and stays were necessary, on commercially produced boiler a serial number should be attached and build certificate should be issued by the manufacturer showing the materials used and the relevant ID number. Non commercial boilers should be inspected by AMBSC Club Inspector if they are going to be steamed in a public place.

 

[Raygers]

Curious:
Just watching Blondiehacks - post #3 video - I noticed a practice that I was taught to avoid during milling.
View attachment 149858

Simply, the first pass kept the workpiece driving against the line of tangent of rotation of the cutter, so the lead screw retains full contact all the way.
The reverse pass (shown) does the opposite. The workpiece is travelling with the tool, so each cut of the tool is trying to un-seat the traveller nut from contact with the main screw, so this can develop chatter - depending on the machine quality, wear, maintenance, materials cutter sharpness, speeds and feeds, and friction in the whole traveller. - Something to avoid (in my workshop).
What I was taught I think was basic practice for all cutting machines. Has anyone else come across this?
Perhaps "self-taught" people may not be aware of the effect of cutting forces on their machines and how to avoid "issues"?
What is "best practice"?
K2

Hi Lloyd, Nikhil, FYI. Just back-tracking on this thread (I am enjoying this one! - Thanks to Nikhil for asking his initial question!):
Here are a couple of documents I refer to from time to time... and a picture of how I set-up for silver soldering ends of boilers.View attachment 149860
Note the use of 2 pre-heating blow-lamps - Their fuel tanks partly shielded from the radiant heat from the hot boiler. The main blow-torch is the propane torch that is hand-held during soldering. Leather welding gloves, sleeve, apron and safety glasses are worn for protection. This is immediately next to the open garage door - for fumes (or me!) to escape.
Test codes for small and larger boilers for UK.
Brazing notes/tablesView attachment 149863View attachment 149864
Hope these help?
K2

Do you leave the blow-lamps on when soldering using the propane torch or do you turn the off?

 

[Steamchick]

Yes, the pre-heating is applied to get the whole boiler hot relatively uniformly, but the wet fuel blowlamps are only around 2 ~ 2 1\2 KW each in effective heat. The Propane blowlamp is another 4 to 5 kW and more intense so locally gets the copper red hot for silver solder to melt and penetrate the joints. The actual red hot zone where the solder is molten is only 1 to 2 inches diameter. If the wet fuel blowlamps were extinguished the boiler would suck the heat away from the soldering zone too fast for the soldering temperature to be achieved. Total heating is about 10 kW for a 3 in diameter boiler 8 inches long. A 5in loco boiler could take twice this heat - or more - and bigger boilers need huge amounts of heat.
K2

 

[Steamchick]

Just been checking costs....
A litre of petrol costs £1.52.
A litre of paraffin costs £4.50-ish...
6kg of propane costs £35 - or over £5.20/litre: + cost of £70~100 for the cylinder, - which is returnable, at a fee.... so an additional £5/litre? - (Guess!).
Maybe I'll buy another bigger petrol blowlamp? Swedish ones are best! easy to light, use and maintain, (mine is 45 years old - still OK) BUT you need to protect the fuel tank from overheating when using close to a large red-hot boiler! A shield of aluminium foil is a good idea... 2 or 3 layers of crinkly helps reflect the radiant heat.
K2