The Steampunk Forum at Brass Goggles
October 24, 2017, 03:15:34 am *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with username, password and session length
News: Support BrassGoggles! Donate once or $3/mo.
 See details here.
 
   Home   Blog Help Rules Login Register  
Pages: [1] 2   Go Down
  Print  
Author Topic: Building a steam engine from scratch (need advice)  (Read 15472 times)
MaxLibra
Gunner
**
United States United States

Gravatar

Maximilian Libra

http://twitter.com/steamp
WWW
« on: May 14, 2010, 03:25:02 pm »

Greetings fellow artisans and mad scientists! I wish to build a small steam engine from scratch, but would like some advice and a few questions answered, if at all possible.

The workload of the steam engine will be very modest for this first project: I wish only for it to successfully turn a turbine, in a similar vein to the popular Jensen model:



My general idea is to use an aluminum can, or food tin, as my boiler. For fuel, I thought to use the easy-lighting charcoal tablets people use in hookahs or to burn incense with, if you know the kind I'm talking about:



The general idea would be to create a little minature insulated oven just big enough for the tablet, insulated with some heat-reflective material on the sides and bottom, so that the majority heat is channeled upward (that which doesn't leak out of the door). The rest is really just standard steam engine principles, really.

However, this brings a couple of very important questions that I hope to ask of the more experienced steamers amongst you:

  • Will those charcoal tablets produce enough heat to boil water in the conditions I mentioned?
  • Can you recommend a good, cheap, heat-reflective material that won't burn up by the charcoal? For now I'm just assuming brick or clay.
  • Will soldering hold the boiler together and make it water-tight? Should I use lead or copper solder? I'm assuming copper, but I'm lead to understand it's more of a pain to work with.
  • Considering the small size of the steam-engine, and the low heat to be generated, I expect the risk level to be minimal. However, I would like to know if there are some particular things I need to be cautious of.
  • Any tips you can provide to save me time or headaches would be greatly appreciated as well.

Thank you in advance.
Logged

-Maximilian Libra, Gentleman Technosmith
http://twitter.com/steampunkforge


MechanicalMouse
Zeppelin Captain
*****
United Kingdom United Kingdom


A tall mouse with huge cogs!


« Reply #1 on: May 14, 2010, 04:08:03 pm »

Its a pleasant relief to see someone coming at a project like this at the right approach.

I'm sure some here has made a tin can boiler, and I believed they used a copper based solder. I'm not sure if he used a softer solder for the pipework. From my own experience with hard solders, the most important part is making sure the metal around the join is nice and hot before applying the solder. Though there are those with more experience out there on this.

The main thing I would think of is make sure you have a safety valve installed. Not sure where you can get one, maybe you can get a spare from a Jenson supplier.

Basic clay should be ok for the firepit. Not sure about how heat reflective it would be, I think it will absorb some of the heat.

Really looking forward to seeing how this pans out.
Logged
Winston Smith
Gunner
**
United States United States


Looking down the Garw Valley, Christmas 2008


« Reply #2 on: May 14, 2010, 08:54:08 pm »

There are numerous model engineering magazines, most have some information or articles on building steam engines (plus dedicated steam modeler mags)
 There is a real danger from boilers exploding, even if you 'intend' a low pressure system.
 you need to do some proper research before you start

Logged

Pirate by day, Ninja by night
I dabble in rocket science, when I'm not picking my nose
akumabito
Immortal
**
Netherlands Netherlands


Mundus Patria Nostra!


WWW
« Reply #3 on: May 14, 2010, 10:09:40 pm »

Use pre-made safety valves from Mamod or any other model steam manufacturer, they can be bought new for a few bucks.. you'll want two of those on your boiler..
Logged

Hardwick Steam Impl. Co.
Gunner
**
United States United States


You can find me in the lab...


WWW
« Reply #4 on: May 15, 2010, 06:24:21 am »

There are several vendors of steam engine kits and parts on ebay. Worth a look, I'd say. The search term "live steam" should be a good start
Logged

Dr. Emiel Kozlowski, at your service.
Reckless Engineer
Snr. Officer
****
United Kingdom United Kingdom



« Reply #5 on: May 15, 2010, 06:51:20 pm »

To be honest youd be alot better off using brass or copper pipe for the boiler,this will save maaive headaches to come!

Soft solder is fine for the boiler as long as you do not let the boiler run dry! For this you will need to ensure that a set amount of fuel will burn out just before the water will do. Unless you fancy a bigger chalenge and install a sight glass and boiler feed pump.

Which ever fuel you use it needs to burn cleanly, charcoal tablets will soot up the bottom of the boiler creating an insulating layer on the boiler.

I recomend buying building simple steam engines by tubial cain if its your first steam engine it has plans and instructions for about 10 simple steam engines.

Logged
sidecar_jon
Snr. Officer
****


« Reply #6 on: May 15, 2010, 08:54:02 pm »

"...My general idea is to use an aluminium can, or food tin, as my boiler..."
 Aluminium will melt and at tin can thickness wont stand any pressure, neither will a normal food can, it'll blow up like a metal balloon! One could use a pressure vessel of more substantial thickens, say a empty gas bottle. Probably simpler to make one as per Tubal Canes very good book. Find a copper pipe of substantial diameter and work with that? And do use that safety valve, its paramount. Small bore copper pipe can be bought at model shops etc and copper is easy to solder ...
Logged

elShoggotho
Guest
« Reply #7 on: May 15, 2010, 10:04:53 pm »

http://www.echtdampfwelt.de/echtdampf-zubehoer/messingrohr-fuer-kesselbau-o-650-mm.htm

That's a link to a German vendor specialized in supplies for that very purpose, building working steam engines. Use aluminium or tin cans if you want some massive problems. You -NEED- brass.
Logged
Reckless Engineer
Snr. Officer
****
United Kingdom United Kingdom



« Reply #8 on: May 15, 2010, 11:39:06 pm »

Copper is the best material but brass will suffice. You cannot solder brass bushes ect into an aluminium can! As for thickness well a standard mamod boiler is only 0.20mm thick brass and i have presure tested them upto 30-40psi without problems.

My stuart 504 boiler has a wall thickness of 1.5mm and has held 120psi no problems under steam and has been mechanically tested upto 160psi! As with any boiler making test it then test it again and again before you light anything underneath it!

Id also be tempted if making your own engine work out what the steam consumption would be and at what working pressures and work out your heating area needed to produce ample steam.

As for a safety valve,alot of small marine steamplants dont have a safety valve as such they just use rubber pipe for the steamlines so if the pressure gets to high they just pop off of the boiler(good for small presures less than 20 psi.
« Last Edit: May 15, 2010, 11:41:08 pm by Reckless Engineer » Logged
sidecar_jon
Snr. Officer
****


« Reply #9 on: May 16, 2010, 07:42:44 pm »

Brass is less forgiving if harder solders need to be used. Brass melts pretty close to the solder melting points or the harder grades.
Logged
chainmailleman
Deck Hand
*
United States United States


« Reply #10 on: May 16, 2010, 08:57:17 pm »

If your using hookah coals, I recommend a water-tube boiler. It will take too much time to heat a large volume of water with a fire-tube design.
Logged

KJ6GOT
MaxLibra
Gunner
**
United States United States

Gravatar

Maximilian Libra

http://twitter.com/steamp
WWW
« Reply #11 on: May 17, 2010, 07:53:42 pm »

Ladies and gentlemen, thank you for your assistance, referrals, and regards for my safety. Please allow me to assuage your concerns a bit: I'm an engineering student and also somewhat obsessive compulsive when it comes to preparation and safety (former Eagle Scout). So you may rest assured I am not foolishly diving into this without several layers of research, precaution, and materials testing. That said, I do not remotely pretend to know all, and am grateful for the site, book, and materials references. I believe they will be invaluable in the coming weeks/months.

I have completed both the initial draft for what the boiler will look like, as well as materials testing. If you care to read the results, I have posted the entire experiment in detail here.

If you simply want the quick and dirty rundown:
  • Two charcoal tablets are sufficient to boil water in the tin at about 185F / 85C, under a pressure of about 8-9psi.
  • The engine I want to build to test this with should supposedly work off of less than 5psi.
  • Previously recorded safe pressure tolerance for a tinplate-steel can has been established on other sites at about 30psi, though I will not need near that much pressure, and intend on using an air compressor to test the average burst-tolerance of a food-tin.
  • The boiler and engine will be built in such a way that should it exceed  the safe pressure tolerance, it will shunt pressure automatically, and pressure itself will be monitored via a gauge.
  • The boiler itself will be built in such a way that if the tin becomes unsteady or too oxidized from coal smoke, I can recycle it and braze a new one together, should it even require brazing.
  • Brazing most likely will not be required, as lead-solder has a melting point of 361.4F / 183C, and my boiler design appears to only reach 185F, though further testing under work conditions will be necessary to establish the max temperature.
  • As water loss from pressure boiling and open-can on heat resulted in only 1/6th out of 1/2 cup of water, loss being at 33% and heat from coals begins declining at roughly 45 minutes, with an average 1-hour total burn time, I do not expect the engine to run dry so long as only one load of 2 coal tablets are ever used at once, though again, more testing will be necessary.

Further tests that will be run before I ever assemble the boiler and engine together and fire them up:

  • Compressed air-pressure test on tin cans to test pressure tolerance.
  • Water-loss test on test boiler in working conditions.
  • Vapor-pressure test on boiler in working conditions to determine if vapor pressure will exceed pressure tolerance of boiler.
  • Engine test on compressed air to see if it runs at all.
  • Engine test at differing pressure levels to test performance.
This first experiment was great fun. It was quite enjoyable to be doing hard science again, rather than just cosmetic changes to things and research. It was also educational. I'll post more once I finish the next test.
Logged
agent036
Gunner
**
United States United States



WWW
« Reply #12 on: May 17, 2010, 08:54:18 pm »

I'm an engineering student and also somewhat obsessive compulsive when it comes to preparation and safety (former Eagle Scout).

I applaud you gusto and wish you the best in your endeavor. I only wish to point out that one is never a "former" Eagles Scout, the rank is earned for life. Alas I never achieved that lofty goal myself (1st class and patrol leader) but am always a boyscout at heart.
Logged
Narsil
Immortal
**
United Kingdom United Kingdom



WWW
« Reply #13 on: May 17, 2010, 10:14:45 pm »


If you pressure test your cans it's much better to use water or oil rather than air. If a pressure vessel fails when it's full of liquid it will leak, if it fails when it's full of compressed gas it will explode.
Logged







A man of eighty has outlived probably three new schools of painting, two of architecture and poetry and a hundred in dress.
Lord Byron
MaxLibra
Gunner
**
United States United States

Gravatar

Maximilian Libra

http://twitter.com/steamp
WWW
« Reply #14 on: May 18, 2010, 03:49:12 am »

Yeah, even almost 20 years later, I still feel like a boy scout most times. I guess I say "former" so people don't automatically group me with the kids. I'm 34. Still a kid to some, I suppose...heh. But it was definitely the most useful thing I ever completed.

As for the pressure test, the advantage to air-testing is that my compressor will tell me exactly at what point the failure is with minimal setup. The fluid-pressure test I'm pretty sure would require more work per can and I need to test a good number of cans to have a safe threshold range. The grill I have should provide enough protection in the event of an explosion provided I removed the propane tank first. It also has the benefit of letting me tell when it failed even when the can itself is not visible. Whereas the liquid one would have to be visible for me to tell, which would require the purchase of a lexan shield or something, I would think. Do you have  some suggestions for how to pressure test easily using liquids?
Logged
Angus McCarthy
Officer
***
United States United States



« Reply #15 on: May 18, 2010, 04:24:44 am »

Very glad to see you've worked in a relief valve even in the prototyping phase here. It's not hard to imagine what may transpire if one were to leave out the most important bit...

But just in case some of use don't have very good imaginations:
Spoiler (click to show/hide)
Logged

Train up a moustache in the way it should go, and when it is old it shall not depart from it.
MaxLibra
Gunner
**
United States United States

Gravatar

Maximilian Libra

http://twitter.com/steamp
WWW
« Reply #16 on: May 18, 2010, 11:30:37 am »

Pardon my French, but WTF were they thinking!?!?!?! Using a blowtorch to quick-heat a tank and not having a pressure gauge to monitor or an auto-release safety valve? They're lucky it didn't kill someone! The obvious downside to using a torch to heat the tank too quickly is the amount of noise it produces makes it impossible to hear the water come to a boil, the stressing of the tank (or the engine if something is amiss). With no audio clues and no visual clues to determine at what point the water was boiling or how high the pressure had gotten, I can definitely see it exploding like that. And don't even get me started on the fact they had no safety-shield around the thing and they were holding the torch by hand, and not even a glove on the hand. Good lord... I'd make a comment about the Darwin Awards if that was how evolution actually worked. Thank you for the video. It made me mad at the kids doing the experiment, but vindicates my paranoia.



I drew up a quick and dirty visual for my safety measures built into the device (not to scale). My boiler unit itself will be behind a shield, since it will not require refueling. Presumably at this stage, it will not require a water refill, but I want more tests before assuming this risk. Note the emergency release valve is within the shield, so if it pops off like a rocket, it doesn't put out an eye or break something. The shield itself is baffled both because the coal will require oxygen and to vent gasses in the event of a boiler explosion. The tube exiting the shield has a visual pressure gauge that I'll be monitoring as well as a manual valve I can open or close as needed to build steam or send it to the engine. I may add a third, redundant release valve to shunt pressure from the entire system manually if the engine cannot work off the pressure fast enough to avoid critical pressure.

(edit to add: Also, the tubing going to the valves will be rubber, not metal, providing another safe "breaking point" should things go wrong)

The fuel itself does not appear to burn hotter than 200F, though it does boil the water at 185F (85C), giving me about 8psi in the initial test even with a leaky system. I expect a range of 15-25psi in the end, though again, more tests are needed. Assuming others work is valid, the tin can should easily hold 30psi if I drill it rather than cut the seal, but again, more tests will be needed. I may end up going for the copper tubing and brazing after all is said and done, just for my own peace of mind as well as the durability. Even with all the safety measures, if my boiler explodes, that's not only embarrassing, it's more work I have to do before its next run, assuming no harm was done. The main reason I've been focused on a tin-can boiler is a combination of desire to recycle rather than further consume, if possible, considering the tiny workload of the engine.


« Last Edit: May 18, 2010, 11:44:49 am by MaxLibra » Logged
johnny99
Snr. Officer
****
United States United States



« Reply #17 on: May 18, 2010, 04:02:40 pm »


As for the pressure test, the advantage to air-testing is that my compressor will tell me exactly at what point the failure is with minimal setup. The fluid-pressure test I'm pretty sure would require more work per can and I need to test a good number of cans to have a safe threshold range. The grill I have should provide enough protection in the event of an explosion provided I removed the propane tank first. It also has the benefit of letting me tell when it failed even when the can itself is not visible. Whereas the liquid one would have to be visible for me to tell, which would require the purchase of a lexan shield or something, I would think. Do you have  some suggestions for how to pressure test easily using liquids?
     The problem is, that you don't want to just test to see if the can will withstand the arbitrary pressure that you have calculated. But atleast 2x the max pressure that it is capable of achieving.  Which means you are probably intentionally setting up a pressure explosion. Never assume that an open grill will contain it.
     Narsel is correct, do a hydro test!  There are several options to do this easily. the High pressure air gun guys do it using a pressure washer. even a cheap one will generate a few thousand psi. of water.  Since you don't need anywhere near that much pressure, you can do it easily enough with your air compressor. If it were me I would do it in the following manner.
     place a five gallon bucket ontop of a larger shallow pan, and level the rim on all sides. Fill your preasure vessal completely full of water Dyed with red food coloring. (note the exact volume of water necessary to fill.) Atatch air hose, set the test vessel in the bottom of the bucket. Fill the bucket exactly to the rim with water.  establish a lexan shield between yourself and the test. apply pressure to the test vessal. Any leaks will be easy to note, due to the dye, and if you meassure the volume of water that spills over the lip of the bucket and into the shallow pan, you will be able to calculate how much the pressure vessel stretches as it comes under pressure.

     Fyi, the reason that for the testing with water, is that air  is compressible, and acts like a spring. When your test vessel fails, all that energy is released at once. Water is for all intents uncompressible. Hence very little energy gets stored.
Logged

We have enough youth. How about a fountain of smart!
MaxLibra
Gunner
**
United States United States

Gravatar

Maximilian Libra

http://twitter.com/steamp
WWW
« Reply #18 on: May 19, 2010, 01:39:52 am »

Ahhhh, I see now. I misunderstood before. So I would still be applying pressure with my air compressor, and have the gauge to tell me at what pressure the vessel will leak, but the vessel itself will be filled with water. There are a couple of questions this brings up, however. It seems like I would get a false reading because if the air will compress far more than liquid, then I should reach a much higher pressure in the tanks and feed-tube (from the air) than I would from the boiler (which will be full of water). This will presumably give me a false read on the pressure gauge of the compressor itself. However, this can most likely be overcome by going ahead and installing the additional pressure gauge and manual turn valve.In this way, I can test the pressure coming from the opposite side of the water from the air compressor. The reading still won't quite be accurate to "critical fail" pressure, but should at least give me a good guideline for the component parts.

Of course if I'm already going to that much effort, it seems like I might as well go ahead and build the copper boiler rather than the tin can test ones, as it will withstand far more rigour.

This may sound like a stupid question, but will an air pressure gauge serve equally well as a water pressure gauge for these purposes?
Logged
Reckless Engineer
Snr. Officer
****
United Kingdom United Kingdom



« Reply #19 on: May 19, 2010, 03:25:56 am »

An air guage is no good for water or steam.

Have you concidered using an  existing boiler to start with? It would make life easier when building an engine.

http://www.mamodparts.com/spares-Mamod-Boilers.asp
Logged
Narsil
Immortal
**
United Kingdom United Kingdom



WWW
« Reply #20 on: May 19, 2010, 12:35:46 pm »

Ahhhh, I see now. I misunderstood before. So I would still be applying pressure with my air compressor, and have the gauge to tell me at what pressure the vessel will leak, but the vessel itself will be filled with water. There are a couple of questions this brings up, however. It seems like I would get a false reading because if the air will compress far more than liquid, then I should reach a much higher pressure in the tanks and feed-tube (from the air) than I would from the boiler (which will be full of water). This will presumably give me a false read on the pressure gauge of the compressor itself. However, this can most likely be overcome by going ahead and installing the additional pressure gauge and manual turn valve.In this way, I can test the pressure coming from the opposite side of the water from the air compressor. The reading still won't quite be accurate to "critical fail" pressure, but should at least give me a good guideline for the component parts.

Of course if I'm already going to that much effort, it seems like I might as well go ahead and build the copper boiler rather than the tin can test ones, as it will withstand far more rigour.

This may sound like a stupid question, but will an air pressure gauge serve equally well as a water pressure gauge for these purposes?


If you ramp up the pressure pretty slowly then the whole system pressure should be more or less the same, the compressibility of air won't affect this as long as you're dealing with approximately static pressures. It would be  adifferent matter if you were concerned with work and energy in a hydraulic system but since you;re only interested in pressure mixing liquid and gas won;t affect the static readings.
Logged
MaxLibra
Gunner
**
United States United States

Gravatar

Maximilian Libra

http://twitter.com/steamp
WWW
« Reply #21 on: May 19, 2010, 03:04:28 pm »

Have you concidered using an  existing boiler to start with? It would make life easier when building an engine.

Indeed, it absolutley would, but I Would learn very little in the process. If I were to simply want a steam engine I could fill with water, turn on, and watch it spin merrily, I'd just save my pennies till I could buy the Jensen model above. But I wouldn't learn anything in the process. By building the materials from scratch, I am forcing my five senses to work hands-on in applied engineering, as opposed to merely reading about it. It makes a world of difference, and also keeps the subject interesting for me. So I guess I've voluntarily signed up for the hard way.


If you ramp up the pressure pretty slowly then the whole system pressure should be more or less the same, the compressibility of air won't affect this as long as you're dealing with approximately static pressures. It would be  adifferent matter if you were concerned with work and energy in a hydraulic system but since you;re only interested in pressure mixing liquid and gas won;t affect the static readings.

And if I just go straight into building the copper boiler, and skip the food tins, I will almost certainly end up allaying the biggest safety concern: that of the food-tin not being able to withstand the modest pressure of a 2-coal boil. Though certainly the safety tests will still be executed, of course.

Thank you all very much! I hope to get at least a little practice brazing done this weekend, and maybe have the boiler built and liquid-tested within the next couple of weeks.
Logged
johnny99
Snr. Officer
****
United States United States



« Reply #22 on: May 19, 2010, 03:09:38 pm »

Ahhhh, I see now. I misunderstood before. So I would still be applying pressure with my air compressor, and have the gauge to tell me at what pressure the vessel will leak, but the vessel itself will be filled with water. There are a couple of questions this brings up, however. It seems like I would get a false reading because if the air will compress far more than liquid, then I should reach a much higher pressure in the tanks and feed-tube (from the air) than I would from the boiler (which will be full of water). This will presumably give me a false read on the pressure gauge of the compressor itself. However, this can most likely be overcome by going ahead and installing the additional pressure gauge and manual turn valve.In this way, I can test the pressure coming from the opposite side of the water from the air compressor. The reading still won't quite be accurate to "critical fail" pressure, but should at least give me a good guideline for the component parts.

Of course if I'm already going to that much effort, it seems like I might as well go ahead and build the copper boiler rather than the tin can test ones, as it will withstand far more rigour.

This may sound like a stupid question, but will an air pressure gauge serve equally well as a water pressure gauge for these purposes?

Short answer, don't worry about it. The water will for all intents be under the same amount of  pressure as the air, It just doesn't "squish" (pardon the technical term) down like the air does. your compressor should be rated for somewhere above 120psi. you're trying to hydrotest to probably 60 psi or so. you're boiler is liable to be the week link in the chain. the air fittings will all easily hold the max air pressure that you're compressor will produce.
Logged
Reckless Engineer
Snr. Officer
****
United Kingdom United Kingdom



« Reply #23 on: May 19, 2010, 03:27:56 pm »

I know what you mean about the hard way lol. IO did the same!!!

What kind of engine are you going to make? ocilator,slide valve ect
Logged
jringling
Time Traveler
****
United States United States


convicted Rogue and Vagabond…long story…


WWW
« Reply #24 on: May 19, 2010, 03:31:10 pm »

I have read this thread with interest and have afew thoughts...

I agree with the comments on safety, but you should also keep in mind the scale we are talking about... The boiler is going to hold 1 or 2 cups of water and be fired by some sort of slow burning solid fuel... If the pressure builds to a critical level, it will first leak and then split... not explode with tremendous force...

I am playing with the idea of  building a small boiler as well and figured I would use standard copper plumbing and fittings. Copper plumbing is soldered everyday and installed in houses. It is not uncommon for static water pressure to be up to 85 psi with surges to 100 psi. Most building codes require a 120 psi test, sustained for 24 hours, so copper fittings should be able to holdup to the steam pressure. Thick walled pipe can be easily drilled and tapped for fittings.

@MaxLibra - If you are interested, I have a short length of brass pipe, @2.25" diameter and a short length of thick walled copper, @ 6" diameter, that I would be willing to trade... send a PM if you want specific details...
Logged

Pages: [1] 2   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.20 | SMF © 2013, Simple Machines Valid XHTML 1.0! Valid CSS!
Page created in 0.306 seconds with 15 queries.