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addjunkie
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Awful things to get to seal properly too!
slim_boy_fat
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I've just gone back through this thread and am (again) in awe of the attention to detail shown. Simply amazing! 
Brad93
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Oh yeah, and getting the big ones back together is no mean feat!
addjunkie
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There are many types, spring loaded, or with belows to avoid back pressure, pilot operated etc, all have their quirks. Nearly as big a pain in the butt as getting big fuel injectors to pop after over haul.
Safety valve over haul is often done by speacilist outside contractors who do nothing else, on large process sites
I had a rethink about making a gas burner and decided that getting a burner to work was voodoo black magic, and there were 3 parts to getting a good flame
1) getting the flame shape right
2) getting the gas mixture strength right
3)getting the gas mixture velocity right.
with the flame shape I decided that I needed just 10 small flames, with 2 on each of the water tubes. the smaller flames to prevent the larger ones weren't required as the burner would be in a enclosed space, so if one went out it would be self igniting again. I started off with my smallest Sievert burner and just taped a 3/32 brass tube to it and thought that's the shape of flame I want and all I needed was 8 of them. the previous flames I'd been playing with wern't as defined. it also shows that by playing with the gas velocity (as the tube is a restriction) it causes the mixture to richen which is indicated by the yellow tip to the flame.
so that simple test set me on the way to making a V10 burner
my method of making the burner was to start off with a round bar and drill the 10 holes that the gas jets would be silver soldered into
showing the burner blank and the jets made from 1/8 brass bar drilled 1.5mm
and ready to be silver soldered, using silver solder rings as it leaves a nice fillet. I also like jewellery grades of silver silver solder as they are annealed so eaier to bend, the engineering grades seem to be hard and springy
and machining the bore of the burner. its one of those setups that I was lucky that I got away with it. with hindsight I should have used a longer piece of brass and used the end for a mounting spigot. to begin with the burner is basically solid bar but is the centre is removed, it becomes thin walled tube (0.8mm wall thickness) , which can deflect under the clamping force of the chuck jaws and lose grip. I did start to drill the centre out but the holes for the gas jets were making the drill go off line, I was using a 6mm drill as a pilot at this stage. I then ended up boring out the first 15mm or so than then used a 8mm end mill that can cut square bottom holes, just advancing 2mm at a time then withdrawing to clear the swarf and being lucky enough that the flutes didnt bite, as it wouldnt have ended well. the end mill was used upto the depth of the drill chuck
and the first test of the burner, which was luckily a good fit in the sievert burner. and Im happy with the flame shape as its much more precise. also the flame coolour looks good (mixture strength) as you will see there isnt the orange tip to the flame as in the first pic on this thread, and the gas velocity is correct as all 10 holes are lit and have similar shaped flames.
1) getting the flame shape right
2) getting the gas mixture strength right
3)getting the gas mixture velocity right.
with the flame shape I decided that I needed just 10 small flames, with 2 on each of the water tubes. the smaller flames to prevent the larger ones weren't required as the burner would be in a enclosed space, so if one went out it would be self igniting again. I started off with my smallest Sievert burner and just taped a 3/32 brass tube to it and thought that's the shape of flame I want and all I needed was 8 of them. the previous flames I'd been playing with wern't as defined. it also shows that by playing with the gas velocity (as the tube is a restriction) it causes the mixture to richen which is indicated by the yellow tip to the flame.
so that simple test set me on the way to making a V10 burner
my method of making the burner was to start off with a round bar and drill the 10 holes that the gas jets would be silver soldered into
showing the burner blank and the jets made from 1/8 brass bar drilled 1.5mm
and ready to be silver soldered, using silver solder rings as it leaves a nice fillet. I also like jewellery grades of silver silver solder as they are annealed so eaier to bend, the engineering grades seem to be hard and springy
and machining the bore of the burner. its one of those setups that I was lucky that I got away with it. with hindsight I should have used a longer piece of brass and used the end for a mounting spigot. to begin with the burner is basically solid bar but is the centre is removed, it becomes thin walled tube (0.8mm wall thickness) , which can deflect under the clamping force of the chuck jaws and lose grip. I did start to drill the centre out but the holes for the gas jets were making the drill go off line, I was using a 6mm drill as a pilot at this stage. I then ended up boring out the first 15mm or so than then used a 8mm end mill that can cut square bottom holes, just advancing 2mm at a time then withdrawing to clear the swarf and being lucky enough that the flutes didnt bite, as it wouldnt have ended well. the end mill was used upto the depth of the drill chuck
and the first test of the burner, which was luckily a good fit in the sievert burner. and Im happy with the flame shape as its much more precise. also the flame coolour looks good (mixture strength) as you will see there isnt the orange tip to the flame as in the first pic on this thread, and the gas velocity is correct as all 10 holes are lit and have similar shaped flames.
I also decided that the complete burner adssembly would be best to be made in 4 sections
1) the gas jets
2) a method of restricting the gas velocity
3) some method of mounting the burner assembly
4) gas jet holder / air holes for combustion mixture
with my earlier testing I found that sintered bronze silencers worked well for use as a restriction, but as they could vary in consistency from one another, so may not give repeatable results., here is one being machined. the lathe tool is 8mm square.
I then thought about using a disk with holes in it again to be used a a restriction plate in the burner. here I'm drill 8 off 0.6mm dia holes on a 7mm pcd, using co-ordinate drilling. I would have used a shorter piece of bar if I had one, but did want to cut this one
and parting it off 1.0mm thick, the parting tool is 1.5mm thick and ground so it doesnt leave a pip on the part being parted off
with experimentation I found that mixture velocity and mixture strength seem to be very hit and miss and there is no rhyme of reason of how to alter them. the mixture strength is easy to alter over a limited range though as you can drill too many air holes and cover the excess ones with masking tape to restrict the air.
after swapping gas jet holders about with diffrent bores and restrictors I eventally ended up with something like this, which is where I was at the end of the last post. on the way I had flames coming out of the air holes, orange tipped flames a maximum of 6 jets being lit or if too lean, no gas jets lighting. the restriction plate needed the holes enlarging to 0.8mm to get the correct color flame, with 1.0mm holes the mixture ended up far too lean so was hard to light.
so I was happy with a burner that worked like that in free air, but under combustion the air comes from two sources, the combustion mixuture and surrounding air, but as this burner would be working in a closed environment, there wouldn't be any surrouding air to burn, so the flame can end up burning rich due to the lack of oxygen. this was tested in a 35mm dia tube to restrict the amount of free air available. after a few tweaks then went from orange tipped flames to these nice blue ones, and as long as only one flame was lit in free air, in a closed environment, they would all soon light, so Im happy with that too.
a holder was made to replace the M8 nut (rethreaded 3/8" x40) to hold the burner parts together. this was made for brass bar turned to shape on a spigot
and then clamped it a collet chuck to bore the centre out and tap it to size.
with the gas jet holder (bit with air holes in) it was necessary to recess the face that the restriction disk goes again to work, and the recess is 0.4mm deep, so the mixture has to go though a sharp 90 degree bend though 0.8mm holes, just enough to slow it down. the centre is drilled out 4.0mm
and the restrictor loose in the holder and the other ends of the burner assembly from the ends the screw into the holder
and the completed gas burner assembly, it'll just mount but 2 screws the other end of the burner will be free to flat in a 3mm hole in the boiler compbustion space.
and most of the parts that went into this small part of a small project (the final 4 parts I'll be using are at the bottom of the picture). I'd have to think this is more along the lines of experimental engineering rather than model engineering, as I don't have any plans to work to, and there are success and failures along the way, and its a big learning cure. if my thought about combustion are wrong, if there are any combustion engineers out there can you let me know, as I think Im right until I, corrected by though who actually know what they're talking about.
1) the gas jets
2) a method of restricting the gas velocity
3) some method of mounting the burner assembly
4) gas jet holder / air holes for combustion mixture
with my earlier testing I found that sintered bronze silencers worked well for use as a restriction, but as they could vary in consistency from one another, so may not give repeatable results., here is one being machined. the lathe tool is 8mm square.
I then thought about using a disk with holes in it again to be used a a restriction plate in the burner. here I'm drill 8 off 0.6mm dia holes on a 7mm pcd, using co-ordinate drilling. I would have used a shorter piece of bar if I had one, but did want to cut this one
and parting it off 1.0mm thick, the parting tool is 1.5mm thick and ground so it doesnt leave a pip on the part being parted off
with experimentation I found that mixture velocity and mixture strength seem to be very hit and miss and there is no rhyme of reason of how to alter them. the mixture strength is easy to alter over a limited range though as you can drill too many air holes and cover the excess ones with masking tape to restrict the air.
after swapping gas jet holders about with diffrent bores and restrictors I eventally ended up with something like this, which is where I was at the end of the last post. on the way I had flames coming out of the air holes, orange tipped flames a maximum of 6 jets being lit or if too lean, no gas jets lighting. the restriction plate needed the holes enlarging to 0.8mm to get the correct color flame, with 1.0mm holes the mixture ended up far too lean so was hard to light.
so I was happy with a burner that worked like that in free air, but under combustion the air comes from two sources, the combustion mixuture and surrounding air, but as this burner would be working in a closed environment, there wouldn't be any surrouding air to burn, so the flame can end up burning rich due to the lack of oxygen. this was tested in a 35mm dia tube to restrict the amount of free air available. after a few tweaks then went from orange tipped flames to these nice blue ones, and as long as only one flame was lit in free air, in a closed environment, they would all soon light, so Im happy with that too.
a holder was made to replace the M8 nut (rethreaded 3/8" x40) to hold the burner parts together. this was made for brass bar turned to shape on a spigot
and then clamped it a collet chuck to bore the centre out and tap it to size.
with the gas jet holder (bit with air holes in) it was necessary to recess the face that the restriction disk goes again to work, and the recess is 0.4mm deep, so the mixture has to go though a sharp 90 degree bend though 0.8mm holes, just enough to slow it down. the centre is drilled out 4.0mm
and the restrictor loose in the holder and the other ends of the burner assembly from the ends the screw into the holder
and the completed gas burner assembly, it'll just mount but 2 screws the other end of the burner will be free to flat in a 3mm hole in the boiler compbustion space.
and most of the parts that went into this small part of a small project (the final 4 parts I'll be using are at the bottom of the picture). I'd have to think this is more along the lines of experimental engineering rather than model engineering, as I don't have any plans to work to, and there are success and failures along the way, and its a big learning cure. if my thought about combustion are wrong, if there are any combustion engineers out there can you let me know, as I think Im right until I, corrected by though who actually know what they're talking about.
arther dailey
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staggered by the finess of the work , really enjoying this thread.
Kayos
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There are formulas for the burner but they involve knowing things like the calorific value of the gas
You have done a good job with trial and error. If you get some yellow flames when its in use that could just be flame impingement if the boiler is cold
Excellent work as ever
You have done a good job with trial and error. If you get some yellow flames when its in use that could just be flame impingement if the boiler is cold
Excellent work as ever
I thought a safety valve was a simple device which just vented off excess steam or air and then closed again when it had reduced to the opening pressure, but I can't believe how much time and effort I put into making one. this has been problem that has affected model engineers over time and someone called Gordon Smith had been there before and his work was available to see on the internet
https://www.scmes.co.uk/images/Technical Information/SafetyValves/Safety Valves Master.htm
with this one being roughly the right size to start off with
so it looks like the mild pop design was the way to go for, but I didnt get the crisp closing but I think that Im only using a low pressure of 25psi as a working pressure. I alos decided that I didnt want to use a ball in the valve as I couldn't get a perfect seal with them, even though the steam loss would be acceptable for most people and here is my first version of a safety valve using a ball
I did try and bore a recess in the body of the safety valve to retain an O ring but found that the steam pressure was going in the wrong direction so would be fine in a check valve , but just kept blowing out of the recess in the safety valve body. the machining of the recess ended up being complex as I needed to have 4 stops on my lathe to machine it accurately as I dont have a dro on my lathe, so used 4 tool makers clamps to do this
so then I thought about using a O ring on the spring guide spindle and sealing against the bottom of a drilled hole (standard 118 degrees point) and initially didnt get it to work well, so though about using a 1.5mm rubber disc so used tried a bit of neoprene rubber on the end guide spindle in a flat bottomed hole, and this was my first test and sealed well even though it looks like a less than ideal setup.
so I then ordered some 1.5mm thick viton to use as it is suitable for the temperature of steam (as the neoprene has max temperature of 85C). aparently the best way to machine viton is to do it submerged in liquid nitrogen, but somehow I dont think that was a realistic option, so I ended up supergluing it into a 3mm dia stainless steel bar and grinding it using the small grinding/milling/drilling spindle I made a while ago, and these retained in a recess in the end of the spring guide spindle
I also thought that maybe the viton could be too soft under harder spring pressure and would deform over time, so thought about using a ptfe disc, and I literally thought that the best way to part them off would be to slice the end of a ptfe bar. so I literally clamped a knife blade to the lathe toolpost.
ohh and I also decided that I needed to make some springs which turned out very easy to do with the minimum of equipment, and I did this thread about it.
https://www.mig-welding.co.uk/forum/threads/making-small-compression-springs.102521/#post-1600449
using a simple tool in the lathe toolholder
and the first springs I made
so after a while I ended with alot of test pieces or just a big pile of scrap parts, and at what stage do you decide its time to give up.
so I thought I'd best do some more systematic testing
so I had 3 test bodies, one with a flat bottom hole to use discs for sealing, one disc was 3mm dia ptfe and a 3mm and 4mm dia viton discs. the other two bodies had a 120 degree end to the hole from a drill point and the last one had a 60 degree end to the hole and this was drilled using a BS2 centre drill that has its diameter reduced to 4.5mm diameter. there are also the spring tension adjusting nut, a couple of spacers if the springs were short and an O ring to seal the body against the boiler....and finally 8 springs I made of different tensions.
so then it was down to testing and there were 40 different combinations to test and I systematically went though them one by one. I set then to vent at aprox 5psi under water using compressed air, but this equated to roughly 25psi on steam, I have no idea why but it seams to be close enough to fine tune. I used 10cc of water in the boiler and it took 2 or 3 minutes to get upto pressure, so then ran it for about 5 minutes adjusting the pressure for venting. I then turned the heat off (well the testing was done on a cooker) and seeing how long it took to get drop to 20 psi and how long the steam feathered form the valve as it closed and what pressure it completely stopped venting steam. so after going though all 40 combinations, there wasn't a perfect result but some were better than other and I then made a safety valve that would be used on the engine. at some stage you just need to move on, or Id be worrying about the safety valve closing for ever. the opening pressure and ability to cope with the volume of steam is not an issue, so nothing to really worry about.
and the safety valve assembled
https://www.scmes.co.uk/images/Technical Information/SafetyValves/Safety Valves Master.htm
with this one being roughly the right size to start off with
so it looks like the mild pop design was the way to go for, but I didnt get the crisp closing but I think that Im only using a low pressure of 25psi as a working pressure. I alos decided that I didnt want to use a ball in the valve as I couldn't get a perfect seal with them, even though the steam loss would be acceptable for most people and here is my first version of a safety valve using a ball
I did try and bore a recess in the body of the safety valve to retain an O ring but found that the steam pressure was going in the wrong direction so would be fine in a check valve , but just kept blowing out of the recess in the safety valve body. the machining of the recess ended up being complex as I needed to have 4 stops on my lathe to machine it accurately as I dont have a dro on my lathe, so used 4 tool makers clamps to do this
so then I thought about using a O ring on the spring guide spindle and sealing against the bottom of a drilled hole (standard 118 degrees point) and initially didnt get it to work well, so though about using a 1.5mm rubber disc so used tried a bit of neoprene rubber on the end guide spindle in a flat bottomed hole, and this was my first test and sealed well even though it looks like a less than ideal setup.
so I then ordered some 1.5mm thick viton to use as it is suitable for the temperature of steam (as the neoprene has max temperature of 85C). aparently the best way to machine viton is to do it submerged in liquid nitrogen, but somehow I dont think that was a realistic option, so I ended up supergluing it into a 3mm dia stainless steel bar and grinding it using the small grinding/milling/drilling spindle I made a while ago, and these retained in a recess in the end of the spring guide spindle
I also thought that maybe the viton could be too soft under harder spring pressure and would deform over time, so thought about using a ptfe disc, and I literally thought that the best way to part them off would be to slice the end of a ptfe bar. so I literally clamped a knife blade to the lathe toolpost.
ohh and I also decided that I needed to make some springs which turned out very easy to do with the minimum of equipment, and I did this thread about it.
https://www.mig-welding.co.uk/forum/threads/making-small-compression-springs.102521/#post-1600449
using a simple tool in the lathe toolholder
and the first springs I made
so after a while I ended with alot of test pieces or just a big pile of scrap parts, and at what stage do you decide its time to give up.
so I thought I'd best do some more systematic testing
so I had 3 test bodies, one with a flat bottom hole to use discs for sealing, one disc was 3mm dia ptfe and a 3mm and 4mm dia viton discs. the other two bodies had a 120 degree end to the hole from a drill point and the last one had a 60 degree end to the hole and this was drilled using a BS2 centre drill that has its diameter reduced to 4.5mm diameter. there are also the spring tension adjusting nut, a couple of spacers if the springs were short and an O ring to seal the body against the boiler....and finally 8 springs I made of different tensions.
so then it was down to testing and there were 40 different combinations to test and I systematically went though them one by one. I set then to vent at aprox 5psi under water using compressed air, but this equated to roughly 25psi on steam, I have no idea why but it seams to be close enough to fine tune. I used 10cc of water in the boiler and it took 2 or 3 minutes to get upto pressure, so then ran it for about 5 minutes adjusting the pressure for venting. I then turned the heat off (well the testing was done on a cooker) and seeing how long it took to get drop to 20 psi and how long the steam feathered form the valve as it closed and what pressure it completely stopped venting steam. so after going though all 40 combinations, there wasn't a perfect result but some were better than other and I then made a safety valve that would be used on the engine. at some stage you just need to move on, or Id be worrying about the safety valve closing for ever. the opening pressure and ability to cope with the volume of steam is not an issue, so nothing to really worry about.
and the safety valve assembled
Ive now remade the gas valve so that its got finer adjustment, I also decided that that I needed to have the gas pipe from it to be easy to remove without spanners and to be gas tight, so decided to use a swivel joint with an O ring to do the sealing. I know people use tailstock die holders, but I never use one, I just use a normal die holder and use a drill chuck for support. I also use a mandrel handle (for tapping too) as is easier to count the number of threads you're doing.
so this is the start of the centre of the swivel union, and for scale its a 1.2mm drill
and machining the 2.5mm AF hexagon on the other end so that it could be screwed into a housing etc. and 2.5mm fits nicely into a 3.0mm hole
and boring out the 3mm hole it goes into on the valve body
and machining the valve spindle, the threads on this are M1.6 and M2.5
and turning the 10 degree taper on the other end. the last valve I did was 20 degree.
and the parts of the valve and union before assemble (and silver soldering the body together)
and making the taper in the body using a carbide engraving bit
and the completed assembly, I have to say that I prefer the feel to the fluted surface, it feels and looks better that a knurled finish to me.
if anyone has wondered what I use for sealing the threads, my choice is loctite 243, because
1) I had some
2) its not to thin and is easy to apply to the thread with wooden cocktail stick
3) its very easy disassemble fasteners, so Im not going to snap them or round the heads off bolts etc
4) it gels almost instantly (I've used things under pressure within a couple of minutes)
5) it doesn't need a perfectly clean surface to work
6) its operating temperature is 150C
https://www.henkel-adhesives.com/uk/en/product/threadlockers/loctite_243.html
so this is the start of the centre of the swivel union, and for scale its a 1.2mm drill
and machining the 2.5mm AF hexagon on the other end so that it could be screwed into a housing etc. and 2.5mm fits nicely into a 3.0mm hole
and boring out the 3mm hole it goes into on the valve body
and machining the valve spindle, the threads on this are M1.6 and M2.5
and turning the 10 degree taper on the other end. the last valve I did was 20 degree.
and the parts of the valve and union before assemble (and silver soldering the body together)
and making the taper in the body using a carbide engraving bit
and the completed assembly, I have to say that I prefer the feel to the fluted surface, it feels and looks better that a knurled finish to me.
if anyone has wondered what I use for sealing the threads, my choice is loctite 243, because
1) I had some
2) its not to thin and is easy to apply to the thread with wooden cocktail stick
3) its very easy disassemble fasteners, so Im not going to snap them or round the heads off bolts etc
4) it gels almost instantly (I've used things under pressure within a couple of minutes)
5) it doesn't need a perfectly clean surface to work
6) its operating temperature is 150C
https://www.henkel-adhesives.com/uk/en/product/threadlockers/loctite_243.html
doubleboost
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Amazing work
sometimes things go wrong and then it goes right even to the point when you can say that's the way you planned it. The is what happened with the design of the gas tank and gas burner valve. From the start I decided that I was going to use a plumbing T piece as the gas tank, and for mounting it thought in would just be easiest to fasten by studs in the centre of both end plates for it. I was originally going to fit the gas valve with a vertical spindle, but found the valve was too long to fit nozzle from the lighter fuel aerosol
but turning the valve round so the spindle was now horizontal, gave enough clearance. The next issue was how do you fill it up? the best way to do this would be out of the model. this is because with the gas tank out of the boat, you can weigh it to find out how much gas there is in it, also the is no pressure on the hull from the force required to get the lpg into the tank from the aerosol. as the gas tank could rotate along is axis this would allow the correction between the valve on the the gas pipe to be disconnected. if the studs went in vertical slots the gas tank is easy to remove.....simple when you think about it, but is just how things worked out, by accident and luck, but if anyone asks I can always say it was planned this way.
so I decided to try the new valve out, but just plumbed it into the old gas valve so that the new valve could be fitted together without having the empty the gas tank each time. with the old gas valve I never planned on using the finger tight swivel fitting, and testing to see how the burner worked and the rate the valve opened
and the first extended lighting of the burner, the gas tank holds 10 grams of butane and this ran for over half an hour, but over time the flames got smaller as the tank cooled and the pressure dropped. the gas tank has only been tested to 100 psi, so Im happy with 100% butane. if I use a butane/propane mix, the pressure drop because of cooling is less so should give more consistant running. the butane/propane mix runs at a higher pressure so at this stage its better to be safe than sorry and the gas tank will need pressure testing to 400psi.
and the burner under the boiler, with two flames on each of the water tubes, this was just to test it, a proper boiler casing will be built to conserve the heat, but even like this it was up to 15psi pressure in 3 minutes, with the boiler half filled with water (10cc) of water.
and this is the full setup, may not seem to be too tidy, but a few pages ago this was but a few ideas rattling about in my head and @Carl Wilson mentioning about using a AC waveform rather than DC for detecting the water level. and as you can see things havnt always gone as planned but they have evolved.
I was lent a book today, Ive never seen it before but if you want to make small simple boilers for powering a small steam engine, its a good read with step by stem instructions for building 6 dfferent ones, I think I'll be building one of them at a later date.
if you've read though this thread I mentioned somewhere that I planned to make a steel boat hull to test the engine once its built, well the same person, lent me a plan for a flat bottomed boat that is just slightly larger than the boat in my first post on this thread, so Im thinking of reducing it in size slightly and using that as a mule. so thats my next part of this, think I'll be starting a new thread for that though as its been a while since I've done any proper sheet metalwork and welding.
and when Ive got that done, I need to design an engine, it'll still be a simple twin cylinder oscilating engine, which will be more straightforward than the boiler and its ancilliaries.
but turning the valve round so the spindle was now horizontal, gave enough clearance. The next issue was how do you fill it up? the best way to do this would be out of the model. this is because with the gas tank out of the boat, you can weigh it to find out how much gas there is in it, also the is no pressure on the hull from the force required to get the lpg into the tank from the aerosol. as the gas tank could rotate along is axis this would allow the correction between the valve on the the gas pipe to be disconnected. if the studs went in vertical slots the gas tank is easy to remove.....simple when you think about it, but is just how things worked out, by accident and luck, but if anyone asks I can always say it was planned this way.
so I decided to try the new valve out, but just plumbed it into the old gas valve so that the new valve could be fitted together without having the empty the gas tank each time. with the old gas valve I never planned on using the finger tight swivel fitting, and testing to see how the burner worked and the rate the valve opened
and the first extended lighting of the burner, the gas tank holds 10 grams of butane and this ran for over half an hour, but over time the flames got smaller as the tank cooled and the pressure dropped. the gas tank has only been tested to 100 psi, so Im happy with 100% butane. if I use a butane/propane mix, the pressure drop because of cooling is less so should give more consistant running. the butane/propane mix runs at a higher pressure so at this stage its better to be safe than sorry and the gas tank will need pressure testing to 400psi.
and the burner under the boiler, with two flames on each of the water tubes, this was just to test it, a proper boiler casing will be built to conserve the heat, but even like this it was up to 15psi pressure in 3 minutes, with the boiler half filled with water (10cc) of water.
and this is the full setup, may not seem to be too tidy, but a few pages ago this was but a few ideas rattling about in my head and @Carl Wilson mentioning about using a AC waveform rather than DC for detecting the water level. and as you can see things havnt always gone as planned but they have evolved.
I was lent a book today, Ive never seen it before but if you want to make small simple boilers for powering a small steam engine, its a good read with step by stem instructions for building 6 dfferent ones, I think I'll be building one of them at a later date.
if you've read though this thread I mentioned somewhere that I planned to make a steel boat hull to test the engine once its built, well the same person, lent me a plan for a flat bottomed boat that is just slightly larger than the boat in my first post on this thread, so Im thinking of reducing it in size slightly and using that as a mule. so thats my next part of this, think I'll be starting a new thread for that though as its been a while since I've done any proper sheet metalwork and welding.
and when Ive got that done, I need to design an engine, it'll still be a simple twin cylinder oscilating engine, which will be more straightforward than the boiler and its ancilliaries.
Screwdriver
Member
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- 10,519
Amazing, not just the skill but the sheer determination to make it work exactly the way you insist. Top job.
time for an update, and there's no need to rush these things. Although this boiler and burner has been made and worked fine, for the size of models I make it is still too heavy so wont end up in a model boat that I'll end up making. In the meantime Ive started playing with commercially made steam toys.
here is a Signal Equipment Limited (on the left) and a Wilesco steam engine that I have.
the Signal Equipment Limited engine will run forhalf and hour and when I was refitting it, I realised how light the boilers are due to the thinner wall thickness that toy engines use compare to the thickness of commercially available brass and copper tubing. I then got a smaller engine built by them just for the brass tubing that the boiler was made from. the new boiler will be using the brass tubing between the safety valve and the steam pipe with end plates and it will be silver soldered together. I could soft solder it, but dont like the way that soft soldered joints fall apart over time (this boiler will be roughly 70 years old but the bush with the safety valve is no longer part of the boiler).
and for another project I've also got an unused Stour Valley Steam marine engine that was made in the mid 1990's
and a close up of the engine
I thought I'd make another engine based on this one but 3/4 of the size (6mm bore x 9mm stroke cylinders) so that it would use roughly half as much steam. the main body of it will be lightened and steam inlet and outlet for the regulator will be in the main body. I was also given a scrap chunk of cast phosphor bronze, which was nice and free cutting.
For fueling the boiler I'll be going for something that is alcohol based because when the fuel runs out the flame stops so you use just enough fuel to run out before the boiler runs out of water. Gas is more complicated as it should use an extra valve (and servo) to turn the gas off in an emergency so that the boiler doesn't boil dry. I don't think I'll be using methylated spirits for fuel as there is a a possibility of it spiling and burning the boat the engine is in. there are a couple of alternatives to try though that are used as chafing fuels in restaurants for keeping food warm on tables. The is a gel version which can be methylated spirit and water and uses calcium acetate as the gelling agent. The other one is wick chafing fuel which uses diethylene glycol. although this is a liquid it wont burn if you try and sent it alight with a flame, it has to be on a wick to burn. I'll need to see which type of fuel has the most heat output as I expect it will be less that that of methylated spirit, but should be safer to use.
here is a Signal Equipment Limited (on the left) and a Wilesco steam engine that I have.
the Signal Equipment Limited engine will run forhalf and hour and when I was refitting it, I realised how light the boilers are due to the thinner wall thickness that toy engines use compare to the thickness of commercially available brass and copper tubing. I then got a smaller engine built by them just for the brass tubing that the boiler was made from. the new boiler will be using the brass tubing between the safety valve and the steam pipe with end plates and it will be silver soldered together. I could soft solder it, but dont like the way that soft soldered joints fall apart over time (this boiler will be roughly 70 years old but the bush with the safety valve is no longer part of the boiler).
and for another project I've also got an unused Stour Valley Steam marine engine that was made in the mid 1990's
and a close up of the engine
I thought I'd make another engine based on this one but 3/4 of the size (6mm bore x 9mm stroke cylinders) so that it would use roughly half as much steam. the main body of it will be lightened and steam inlet and outlet for the regulator will be in the main body. I was also given a scrap chunk of cast phosphor bronze, which was nice and free cutting.
For fueling the boiler I'll be going for something that is alcohol based because when the fuel runs out the flame stops so you use just enough fuel to run out before the boiler runs out of water. Gas is more complicated as it should use an extra valve (and servo) to turn the gas off in an emergency so that the boiler doesn't boil dry. I don't think I'll be using methylated spirits for fuel as there is a a possibility of it spiling and burning the boat the engine is in. there are a couple of alternatives to try though that are used as chafing fuels in restaurants for keeping food warm on tables. The is a gel version which can be methylated spirit and water and uses calcium acetate as the gelling agent. The other one is wick chafing fuel which uses diethylene glycol. although this is a liquid it wont burn if you try and sent it alight with a flame, it has to be on a wick to burn. I'll need to see which type of fuel has the most heat output as I expect it will be less that that of methylated spirit, but should be safer to use.
I recently changed the phone that I use as a camera, and thought I was taking photos, but I wasn't so there are a few missing about making some parts, although its just straightforward machining just on a small scale. Most of this engine has been made from a chunk of scrap phosphor bronze, which was cut on a bandsaw into smaller and smaller shapes, and Ive still got half of it left. the main body was made first and started off as an 11mm square piece of metal. The holes for routing the steam around it were drilled first as some of them are within 0.2mm of holes that cross them, but the holes mustn't break into one another as they are steam passages. Once that was done, I started lightening the main body.
and after a bit more lightening ended up with it looking like this. I did machine a bit more off but then stopped as it became more difficult to clamp and ran the risk of being being grabbed by a milling cutter and becoming a pile of scrap
the lower cylinder end covers that the piston rods go though were machined in two goes, the part that goes outside the cylinder was machined first
and it was then reversed in a collet chuck for machining the mounting face. I intend to Loctite the end covers to the cylinders so an 0.8mm wide grove was machined to hold Loctite. The piston rods are made from 2mm precision ground stainless steel, and needs to be as good a fit in the cylinder end covers as they can as they are under steam pressure. I have got a 2mm reamer, but that would cut fractionally larger than the rods, but I made my own reamer by filing 3 flats on the sides of the same rod that the piston rods are made from. The hole was drilled 1.9mm and this reamer was used. This works because the stainless rod is much harder that the bronze. shown below is a completed cylinder end cover in the chuck and a half made on on top of it.
the top cylinder end caps were made from offcuts of offcuts, and these were superglued to some steel bar to hold them. this was machined to 8mm O/D and then the groove was cut into it to loctite it into the cylinder.
the outside face was then machined, the section being clamped in the collet chuck is only 0.8mm wide, so a dowel was put in the other end of the collect for it to grip correctly (at both ends of the collet). the outer face ended up being 1.0mm thick
I needed to make a M1.6mm screw. my method of doing this it to turn a short length at a time (in this case 3mm) as then the metal can support itself. held in collet chuck so a few mm could be pulled out at a time and should still be held concentrically. if you are lucky enough to be able to machine a 1.6mm diameter over a 15mm length, there is no was it would be parallel, but it it it more likely that it will flex, bend and snap. ohh and I used a die to cut the thread, screwcutting is something to be avoided at all costs.
for the regulator a couple of 1.6mm wide and 1.6mm deep semi circular grooves need to be machined into a round disk, these were milled using a rotary table. I was thinking about calculating a few points using a pcd calculator and machine the groove as a dot to dot. it would have been accurate enough for this
littlemachineshop.com
and after a bit more lightening ended up with it looking like this. I did machine a bit more off but then stopped as it became more difficult to clamp and ran the risk of being being grabbed by a milling cutter and becoming a pile of scrap
the lower cylinder end covers that the piston rods go though were machined in two goes, the part that goes outside the cylinder was machined first
and it was then reversed in a collet chuck for machining the mounting face. I intend to Loctite the end covers to the cylinders so an 0.8mm wide grove was machined to hold Loctite. The piston rods are made from 2mm precision ground stainless steel, and needs to be as good a fit in the cylinder end covers as they can as they are under steam pressure. I have got a 2mm reamer, but that would cut fractionally larger than the rods, but I made my own reamer by filing 3 flats on the sides of the same rod that the piston rods are made from. The hole was drilled 1.9mm and this reamer was used. This works because the stainless rod is much harder that the bronze. shown below is a completed cylinder end cover in the chuck and a half made on on top of it.
the top cylinder end caps were made from offcuts of offcuts, and these were superglued to some steel bar to hold them. this was machined to 8mm O/D and then the groove was cut into it to loctite it into the cylinder.
the outside face was then machined, the section being clamped in the collet chuck is only 0.8mm wide, so a dowel was put in the other end of the collect for it to grip correctly (at both ends of the collet). the outer face ended up being 1.0mm thick
I needed to make a M1.6mm screw. my method of doing this it to turn a short length at a time (in this case 3mm) as then the metal can support itself. held in collet chuck so a few mm could be pulled out at a time and should still be held concentrically. if you are lucky enough to be able to machine a 1.6mm diameter over a 15mm length, there is no was it would be parallel, but it it it more likely that it will flex, bend and snap. ohh and I used a die to cut the thread, screwcutting is something to be avoided at all costs.
for the regulator a couple of 1.6mm wide and 1.6mm deep semi circular grooves need to be machined into a round disk, these were milled using a rotary table. I was thinking about calculating a few points using a pcd calculator and machine the groove as a dot to dot. it would have been accurate enough for this
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