It is sometimes worth polishing the displacer rods with metal polish, or even very fine wet and dry paper, say 1200 grit, be sure to polish them length wise.
You might solve the leak with RTV silicon, it has a bit more bulk that the gasket compound.
Ian S C
2-cylinder Gamma - project
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Triangle.Stirling
- Posts: 133
- Joined: Mon Sep 09, 2013 8:29 am
Re: 2-cylinder Gamma - project
Thank you for your answers!
@Ian S C
I know i can use RTV silicone, and i have it at home, so i could do that, but i don't like to use that, because then the engine can't be disassembled easy.
The rods are perfect, it's stainless steel. If you compare them with other rods, they're very smooth. they can fall down under their own weight, that shouldn't be a problem. I don't think that polishing can make them smoother.
@ tomostre
We have tried parts without the crankshaft connected. At the moment it is also not connected. When i pull the diaphragm up and down, you can feel the air leaking from under the top plate, that is the problem. We started to test it, but it won't run. When we searched for the reason, we discovered the air leakage.
We have a few solutions we can try to get the engine sealed without using silicone stuff, we will try that first, otherwise we will use the silicone.
Does anybody now if the silicone will attach to the rubber or the wood? I'd like to keep it clean, so it can be easily taken apart.
When the engine is running, there will surely be a video!
@Ian S C
I know i can use RTV silicone, and i have it at home, so i could do that, but i don't like to use that, because then the engine can't be disassembled easy.
The rods are perfect, it's stainless steel. If you compare them with other rods, they're very smooth. they can fall down under their own weight, that shouldn't be a problem. I don't think that polishing can make them smoother.
@ tomostre
We have tried parts without the crankshaft connected. At the moment it is also not connected. When i pull the diaphragm up and down, you can feel the air leaking from under the top plate, that is the problem. We started to test it, but it won't run. When we searched for the reason, we discovered the air leakage.
We have a few solutions we can try to get the engine sealed without using silicone stuff, we will try that first, otherwise we will use the silicone.
Does anybody now if the silicone will attach to the rubber or the wood? I'd like to keep it clean, so it can be easily taken apart.
When the engine is running, there will surely be a video!
Re: 2-cylinder Gamma - project
I don't know where I saw it, but someone used wax paper to make custom silicone gaskets that would release on one side. Might be worth trying.
Bumpkin
Bumpkin
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Triangle.Stirling
- Posts: 133
- Joined: Mon Sep 09, 2013 8:29 am
Re: 2-cylinder Gamma - project
quick update: We managed to seal the cylinders air-tight. We used an extra sealing from silicone rubber, that is used for baking cookies or something like that.
It is the material that is also be used for cupcake forms ect.
When we decided to test, we saw the crankshaft was not good. We secured the different parts with loctite, but due to increased stress from extra compression, it's not in the right form now.
I'm going to disassemble the crankshaft tomorrow, and my fahter's going to weld al the spots were now the glue is. Then it's time for anther test.
Stay tuned!
It is the material that is also be used for cupcake forms ect.
When we decided to test, we saw the crankshaft was not good. We secured the different parts with loctite, but due to increased stress from extra compression, it's not in the right form now.
I'm going to disassemble the crankshaft tomorrow, and my fahter's going to weld al the spots were now the glue is. Then it's time for anther test.
Stay tuned!
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Triangle.Stirling
- Posts: 133
- Joined: Mon Sep 09, 2013 8:29 am
Re: 2-cylinder Gamma - project
have done a great lot after my last reply, trying to get the engine to work.
Welded the cranshaft, and it broke again. Bad welds. Rewelded it (careful for the bearings) and this evening it broke again...
We were testing with chafing dish alcohol burners. Sometimes the engine wil maken 2 or 3 revolutions on its own, then it stops.
Tested one cilinder with a bigger gas-cooking burner, and sometimes is runs 10 rounds or so. The cylinder is then red-hot.
What could be wrong that the engine won't run?
there are two things i'm uncertain about:
1 Wat should the flywheel weigh? Tested differents weight, but doesn't seem to make that much sense.
2 When i disconnect everything from the crankshaft, and slide the displacer rod up and down, the diaphragm moves a little. Should this be so, or is the displacer to tight, and must it be more loose?
Any answers are really appreciated, we must show it next week, and it would of course be nice to show a running engine!
Greets,
Krijn
Welded the cranshaft, and it broke again. Bad welds. Rewelded it (careful for the bearings) and this evening it broke again...
We were testing with chafing dish alcohol burners. Sometimes the engine wil maken 2 or 3 revolutions on its own, then it stops.
Tested one cilinder with a bigger gas-cooking burner, and sometimes is runs 10 rounds or so. The cylinder is then red-hot.
What could be wrong that the engine won't run?
there are two things i'm uncertain about:
1 Wat should the flywheel weigh? Tested differents weight, but doesn't seem to make that much sense.
2 When i disconnect everything from the crankshaft, and slide the displacer rod up and down, the diaphragm moves a little. Should this be so, or is the displacer to tight, and must it be more loose?
Any answers are really appreciated, we must show it next week, and it would of course be nice to show a running engine!
Greets,
Krijn
Re: 2-cylinder Gamma - project
I'm just going to have a guess or two. With the diaphrams, are they fully extended at the extremes of their stroke, there should be some slack remaining. Crankshaft, maybe a bit light. It must be straight, the shaft must spin freely in the bearings, perhaps you can disconnect the clips that hold the conrod bearings, you could test this. I suspect that your crankshaft is too light, for a motor that size I would use 6 mm or more, you can get this from an old printer, or scanner. The flywheel, if you make it say 150 mm dia., it could be 6 mm to 8 mm thick, a large diameter, and light weight is a good combination, read up a bit on flywheels, you will find that the important weight is the weight at the rim. You might need 300 to 500 gms.
When you reassemble the motor, only attach one displacer rod and power piston rod, and try it as a single unit, if this runs, disconnect it and connect the other two, with any luck if that goes, it will rotate in the same direction as the first half, if not you will have to modify the crankshaft, but that's too obvious, though not impossible. Its a bit hard trying to think what is wrong with the motor, this is what industry calls research and development, its never a mistake, keep going you will get it. Ian S C
When you reassemble the motor, only attach one displacer rod and power piston rod, and try it as a single unit, if this runs, disconnect it and connect the other two, with any luck if that goes, it will rotate in the same direction as the first half, if not you will have to modify the crankshaft, but that's too obvious, though not impossible. Its a bit hard trying to think what is wrong with the motor, this is what industry calls research and development, its never a mistake, keep going you will get it. Ian S C
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Triangle.Stirling
- Posts: 133
- Joined: Mon Sep 09, 2013 8:29 am
Re: 2-cylinder Gamma - project
Hi Ian, thank you for your suggestions!
The diaphragm is right, there is a bit slack remaining, i think that's good.
The crankshaft is actually 6 mm, maybe it could be 8 mm, but when welded properly, it should do. It can spin freely with the parts disconnected.
The flywheels are about 300 gms each, so total 600 gms.
I tried one cylinder, while the other was disconnected. It wouldn't hardly run. Sometimes it will, but then the underside was red-hot, and it was barely running. Get a second burner tomorrow, then i can test with two cylinders.
What do you think about my second question ? I think i need to look at the displacers, they're a bit 'closed' ( don't know the word) maybe air can't go through it, and also not so good at the sides of the displacer. In this way the air can't be displaced that well, wich can cause problems.
Could this be so ?
Greets,
Krijn
The diaphragm is right, there is a bit slack remaining, i think that's good.
The crankshaft is actually 6 mm, maybe it could be 8 mm, but when welded properly, it should do. It can spin freely with the parts disconnected.
The flywheels are about 300 gms each, so total 600 gms.
I tried one cylinder, while the other was disconnected. It wouldn't hardly run. Sometimes it will, but then the underside was red-hot, and it was barely running. Get a second burner tomorrow, then i can test with two cylinders.
What do you think about my second question ? I think i need to look at the displacers, they're a bit 'closed' ( don't know the word) maybe air can't go through it, and also not so good at the sides of the displacer. In this way the air can't be displaced that well, wich can cause problems.
Could this be so ?
Greets,
Krijn
Re: 2-cylinder Gamma - project
The displacer should have a gap around it, say 1 mm to 1.5 mm, it should be free too move when detatched, but without too much leaks around the shaft, and no leaks in the displacer its self. Yes if you move the displacer up and down, the diaphragm should move. Red hot is not bad. Ian S C
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Triangle.Stirling
- Posts: 133
- Joined: Mon Sep 09, 2013 8:29 am
Re: 2-cylinder Gamma - project
Good News!
Got it running last saturday, the first of March.
Made bigger flywheels with a diameter of 30 cm's, instead of 12,5 cm's.
The engine then first ran on the heat of the burners. Got a RPM of 270 then.
The flywheels were at that moment 600 gms each. Total of 1.2 Kg.
Made the flywheels lighter by making holes around the middle of it, now they're 500 gms each. Think they can be made lighter. They are made of 12 mm plywood
Today we had the presentation at school. We were able to let it run 3 times, for about 15 minutes a time. Then the upper side of the cylinder reached about 100 degrees Celsius. Cooling was only with a wet strip of cloth. In total we ran it for 45 minutes today, during a 2 hour 'presentation market'.
Talked with very much people. Many people liked the engine. They al liked the silent running of the engine. This can be made better, because there is a 'plop-plop' sound from one diaphragm. It is not perfect, so when i make a new one, it should be better.
Also many people were asking if the Stirling engine is being used today.
In the last run i got it to 500 rpm's, and that was not with the burners at 'full speed'. around the 500 rpm. the engine started to vibrate, mainly because the crankshaft is not 100% straight.
We will be upgrading the engine over the time, on the list are:
- improved cooling (closed circuit), any ideas on this? We are thinking about copper pipes, and a little water reservoir, working with the thermosyphon effect.
- shielding the heat from the upper parts of the engine. Heat is going up along the cylinders, i think we have to make a plate between there, but that's hard to make in the right form.
- maybe another crankshaft
- experimenting with flywheels
Of course there will be a Youtube-video soon, don't worry about that.
Got it running last saturday, the first of March.
Made bigger flywheels with a diameter of 30 cm's, instead of 12,5 cm's.
The engine then first ran on the heat of the burners. Got a RPM of 270 then.
The flywheels were at that moment 600 gms each. Total of 1.2 Kg.
Made the flywheels lighter by making holes around the middle of it, now they're 500 gms each. Think they can be made lighter. They are made of 12 mm plywood
Today we had the presentation at school. We were able to let it run 3 times, for about 15 minutes a time. Then the upper side of the cylinder reached about 100 degrees Celsius. Cooling was only with a wet strip of cloth. In total we ran it for 45 minutes today, during a 2 hour 'presentation market'.
Talked with very much people. Many people liked the engine. They al liked the silent running of the engine. This can be made better, because there is a 'plop-plop' sound from one diaphragm. It is not perfect, so when i make a new one, it should be better.
Also many people were asking if the Stirling engine is being used today.
In the last run i got it to 500 rpm's, and that was not with the burners at 'full speed'. around the 500 rpm. the engine started to vibrate, mainly because the crankshaft is not 100% straight.
We will be upgrading the engine over the time, on the list are:
- improved cooling (closed circuit), any ideas on this? We are thinking about copper pipes, and a little water reservoir, working with the thermosyphon effect.
- shielding the heat from the upper parts of the engine. Heat is going up along the cylinders, i think we have to make a plate between there, but that's hard to make in the right form.
- maybe another crankshaft
- experimenting with flywheels
Of course there will be a Youtube-video soon, don't worry about that.
Re: 2-cylinder Gamma - project
That's excellent, top marks. These motors seem to go faster as they get run in, don't worry too much if it vibrates, often there is a point as they speed up that they bounce around a bit, then as the revs go up, they settle down. One or two of my motors need to be clamped to the bench just in case the revs get to the critical point when I'm not looking, it's not good if the motor drops off the table, onto the floor. It's worth taking the motor up to full speed, just to see what is possible, you might be surprised! Ian S C
Re: 2-cylinder Gamma - project
Hey guys, post the video please! You promised!
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Triangle.Stirling
- Posts: 133
- Joined: Mon Sep 09, 2013 8:29 am
Re: 2-cylinder Gamma - project
@Ian,
Ok, thank you for your answer! I will try to push the engine to higher speed, but i'm a bit anxious to destroy the crankshaft, but is will see. It is running very smooth, so i believe it's possible to go above the 600 rpm. mark.
Also thank you for your help with the building, the tip about the flywheel diameter was the last thing we knew to improve, and it worked!
@Tomostre,
Video's will come soon, but i'm busy with school, that comes first. Hope to have it uploaded this weekend, but i can't say for sure. There will definitely be video's, i promise that, but i can't say exactly when, just remain patient ;)
Ok, thank you for your answer! I will try to push the engine to higher speed, but i'm a bit anxious to destroy the crankshaft, but is will see. It is running very smooth, so i believe it's possible to go above the 600 rpm. mark.
Also thank you for your help with the building, the tip about the flywheel diameter was the last thing we knew to improve, and it worked!
@Tomostre,
Video's will come soon, but i'm busy with school, that comes first. Hope to have it uploaded this weekend, but i can't say for sure. There will definitely be video's, i promise that, but i can't say exactly when, just remain patient ;)
Re: 2-cylinder Gamma - project
Tomostre, don't mind me, I work on the theory that if you don't break something, your not really trying hard enough, you then modify the part that broke, then push it harder. Now days I usually find that expirence with previous motors means that I have few if any problems. Ian S C
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Triangle.Stirling
- Posts: 133
- Joined: Mon Sep 09, 2013 8:29 am
Re: 2-cylinder Gamma - project
@ Ian S C, i agree with that theorie, but because i spent so much time on the crankshaft, i'm a bit cautious with it, but i will try harder, no doubt.
First i glued it with loctite, that broke. Then it was welded, with a chance of burning the bearings. Then there were a few bad welds, that are now fixed.
Does anybody know a better way of making a crankshaft, i'm not a huge fan of bending crankshafts, it is very, very hard to make it straight, specially with our size, and another problem is the strength. I now use a 6 mm crankshaft, but when i have to re-do it, i'll use 8 mm.
For the curious ones out there, still nog video of the engine actually running, till that time a teaservideo, to keep you quiet :P
[youtube]http://www.youtube.com/watch?v=dupM2auNsdI[/youtube]
First i glued it with loctite, that broke. Then it was welded, with a chance of burning the bearings. Then there were a few bad welds, that are now fixed.
Does anybody know a better way of making a crankshaft, i'm not a huge fan of bending crankshafts, it is very, very hard to make it straight, specially with our size, and another problem is the strength. I now use a 6 mm crankshaft, but when i have to re-do it, i'll use 8 mm.
For the curious ones out there, still nog video of the engine actually running, till that time a teaservideo, to keep you quiet :P
[youtube]http://www.youtube.com/watch?v=dupM2auNsdI[/youtube]
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Triangle.Stirling
- Posts: 133
- Joined: Mon Sep 09, 2013 8:29 am
Re: 2-cylinder Gamma - project
I'm afraid it will take a little more time before the running-video will be online.
wanted to make a nice video, beginning with startup from the engine. Last friday i had the camera set-up, and then the engine won't run.
Have tried today(saturday), but the engine will not run.
The last time the engine ran was thursday, at the presentation. That was inside, 20 degrees C, and it has run for about 3 times 15 min.
Nothing happened from thursday to friday, but it will not run. (10 degrees C)
What could the problem be? everything seems to be ok. I think maybe it are the displacers? You can hear them a little 'scraping' in the cylinder, but they were free to move.
Maybe they are bigger now, due to the heat?
Does anybody know the problem, or know a possible solution? Thanks!
wanted to make a nice video, beginning with startup from the engine. Last friday i had the camera set-up, and then the engine won't run.
Have tried today(saturday), but the engine will not run.
The last time the engine ran was thursday, at the presentation. That was inside, 20 degrees C, and it has run for about 3 times 15 min.
Nothing happened from thursday to friday, but it will not run. (10 degrees C)
What could the problem be? everything seems to be ok. I think maybe it are the displacers? You can hear them a little 'scraping' in the cylinder, but they were free to move.
Maybe they are bigger now, due to the heat?
Does anybody know the problem, or know a possible solution? Thanks!