B
Bogstandard
Guest
Bernd,
Thanks.
Done.
John
Thanks.
Done.
John
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B
Bogstandard
Guest
Another short post again, but did manage a couple of hours on it.
You might be wondering why I have stopped doing the sketches. The reasons being are that what I am doing with the casing ends and bearing caps can be made to whatever you want, as long as it does the correct job, has some sort of ball races in there, and they are made to very tight tolerances. The only real critical bit was the rotor and casing, these bits can be made by looking at how I am doing them.
I finished the last post with basically, it is not what is on the outside, it is what is within that is the critical bit.
All the operations in this post are done from beginning to end without removing the part from the collet chuck. The second part is done the same way. This ensures all the critical bits of the machining are in perfect concentricity (they all have exactly the same centre), and everything is square to each other.
-----------------------------------------------------------------------------------
The first stage is to get the part as true running in the chuck as possible.
The face was cleaned off to the depth that was required to get it down to 1/8" thick. The outside bit of the part doesn't matter if it is a couple of thou out, that is there for cosmetic reasons and tolerances that small won't be noticed on a 'blinged' part.
This out of focus shot shows me setting up the grooving tool (my flywheel recess tool) exactly square to the face of the job. You could use a normal boring tool, it is just that I prefer this method to get my recesses to perfect depth and squareness.
In this shot I have already drilled thru the part with a clearance drill for the rotor shaft, it will be the ball races taking the bearing load, not these bearing caps. But from the outside it will look like the cap is the main bearing.
I then bored down, to a width slightly larger than the OD of the inner race of the bearing and about 20 thou deeper than the thickness of the bearing flange (if it was plain ballraces that were being used, it would be bored to a depth of 20 plus the amount the bearing was protruding from the casing cap). This is to ensure nothing interferes with the free running of the inner race.
The recess for the flange (or bit of the bearing sticking out) is now bored. It is bored to the depth of the flange minus 1 or 2 thou, and a very snug fit on the outside of the flange. The reason for not going to full depth is that when the bolts are tightened down on these end caps, the bearings will be physically trapped against the casing end, this will stop them moving in any way or form. As good as loctite, but easier to remove when needed.
This picture shows how far I got in just over two hours. Precision takes time. Never rush it, or make do. If it isn't right do it again. That is why, in this picture is another bearing cap blank, just in case. This time, it wasn't needed.
If you look at the bearing cap with the bearing on it, you can see the smaller recess put in to allow the inner race full clearance.
At the back is what it will look like when assembled (with bolts of course).
If I don't get my expected engineering visitor, I will get back into the shop and get these to a stage where they bolt together. Then it is just a matter of knocking up a few nozzles and a couple of internal bearing spacers and we should be ready for the initial vid of it running.
John
You might be wondering why I have stopped doing the sketches. The reasons being are that what I am doing with the casing ends and bearing caps can be made to whatever you want, as long as it does the correct job, has some sort of ball races in there, and they are made to very tight tolerances. The only real critical bit was the rotor and casing, these bits can be made by looking at how I am doing them.
I finished the last post with basically, it is not what is on the outside, it is what is within that is the critical bit.
All the operations in this post are done from beginning to end without removing the part from the collet chuck. The second part is done the same way. This ensures all the critical bits of the machining are in perfect concentricity (they all have exactly the same centre), and everything is square to each other.
-----------------------------------------------------------------------------------
The first stage is to get the part as true running in the chuck as possible.
The face was cleaned off to the depth that was required to get it down to 1/8" thick. The outside bit of the part doesn't matter if it is a couple of thou out, that is there for cosmetic reasons and tolerances that small won't be noticed on a 'blinged' part.
This out of focus shot shows me setting up the grooving tool (my flywheel recess tool) exactly square to the face of the job. You could use a normal boring tool, it is just that I prefer this method to get my recesses to perfect depth and squareness.
In this shot I have already drilled thru the part with a clearance drill for the rotor shaft, it will be the ball races taking the bearing load, not these bearing caps. But from the outside it will look like the cap is the main bearing.
I then bored down, to a width slightly larger than the OD of the inner race of the bearing and about 20 thou deeper than the thickness of the bearing flange (if it was plain ballraces that were being used, it would be bored to a depth of 20 plus the amount the bearing was protruding from the casing cap). This is to ensure nothing interferes with the free running of the inner race.
The recess for the flange (or bit of the bearing sticking out) is now bored. It is bored to the depth of the flange minus 1 or 2 thou, and a very snug fit on the outside of the flange. The reason for not going to full depth is that when the bolts are tightened down on these end caps, the bearings will be physically trapped against the casing end, this will stop them moving in any way or form. As good as loctite, but easier to remove when needed.
This picture shows how far I got in just over two hours. Precision takes time. Never rush it, or make do. If it isn't right do it again. That is why, in this picture is another bearing cap blank, just in case. This time, it wasn't needed.
If you look at the bearing cap with the bearing on it, you can see the smaller recess put in to allow the inner race full clearance.
At the back is what it will look like when assembled (with bolts of course).
If I don't get my expected engineering visitor, I will get back into the shop and get these to a stage where they bolt together. Then it is just a matter of knocking up a few nozzles and a couple of internal bearing spacers and we should be ready for the initial vid of it running.
John
B
Bogstandard
Guest
I will just explain something. When you design an engine like I am doing here, on the run, and not using cad, but using experience and little sketches as you go along, you have to be about four or five moves ahead in your mind. A hole put in the wrong place now, can cause havoc later on.
That is why sometimes I stall on putting up posts, I sit down in the shop for a few hours going thru the build in my head. I find, even with these time outs, I can knock out a working engine a lot quicker than trying to get it all down on paper first.
--------------------------------------------------------------------------------------------
Another post full of holes.
I can't believe how long it has taken me to get all the bolt down holes done. But I did have a bit of a slip up last night and managed somehow, to get an hole, half an hole out (well the centre drilling was), but I fixed that after mulling over how to do it overnight, and got it fixed with no more than a redrill with the centre in a different position (the correct position) and by the time the hole was drilled and tapped the mistake had been machined out. Saves having to make new parts.
So this post is all about getting 20 little screws into the right position.
I started off bluing up the areas that needed marking.
The first job was to get a corner to corner line on the main chamber, and find a position at one corner, on the line, that a hole could be drilled in all eight corners safely, without interfering too much with the other holes in the block. A position was found, and a measurement taken from the outer corner, to the hole position.
A chamber end was put onto the chamber and two opposing corners were scribed onto the back of the disc. These corner marks on the disc were duly joined by using a centre square, and by measuring from the scribed corner, down the centred line, the position of the required hole was pop marked in one position only. Only one disc needed to be done. Explanation later.
The hex caps were stood up on one of the faces and using a vernier height gauge, the centre line between two opposite points was found, this was done on each in turn. A good position for a mounting hole was found and duly marked and centre popped on each cap.
The pop marks can be seen in the pic.
Now onto the rotary table, set up in the vertical position.
There is no need to centre it under the drill chuck, but the chuck on the RT has to be perfectly centred on the RT table. Mine is spigotted to the centre hole and clamped down.
Now to drilling. The cap was mounted into the self centering chuck, the RT was set to '0', then the centre in the drill chuck was put directly over the pop mark on the cap by moving the x & y table controls. Once it was perfectly over the mark, the table locks were tightened.
Then it was a matter of drilling the hole, fwd 60deg on the RT and drill the next, and so on until all six were done. The new cap was put in the RT chuck, but the chuck was only just 'nipped' up. Now the cap was turned in the chuck jaws until the pop mark was directly under the centre drill. RT chuck fully tightened up, and the holes were drilled as before.
The marked up chamber cap was mounted, RT to zero, and centre drill located as before, hole drilled, move 90 deg, next hole, continue until all four holes are drilled.
Notice here that the locating spigot is facing upwards, as that was the side the markings were on.
Now comes the later explanation. Because thefour holes can be anywhere on the PCD (pitch circle diameter), I can just drill the four holes without going thru the set up procedure, I just used the same drilling position as the previous one. Notice that the outside face is being drilled first.
Because the outside face was drilled, I now put an end mill into the chuck, and duly made a recess for the cap screws on all four holes. Once they were finished I put the drill back into the chuck, put the first casing cap into the RT chuck, with the outside face upwards, and duly relocated the cap into the same drilling position by locating the drill in a hole and tightening up the RT chuck. The recesses for cap screws were then machined. That was how the twenty holes were drilled, now to get the screw holes drilled and tapped in the right positions
Casing was blued up, and put into a large v-block. Using the height gauge again, the exact corner to corner height was found, and duly marked on all eight corners.
The end caps were fitted, and eyballed down the holes so that the centre lines run exactly thru the eyeballed centre of the holes. Without disturbing the position, a fillet of superglue was put between the casing and end cap to hold them together.
Once the glue was dry, I put a transfer punch (these are bought as sets and come in very close sizing to get the right size for the hole, and consist of a hardened rod with a centre point on the end) down the holes and made a pop mark onto the end face of the casing. The opposite end was done in the same manner. Once all eight marks were in position, I went to the drill press, centred and drilled to depth all eight holes (it was at that point I made my mistake). They were then tapped for the fixing bolts.
The scribing marks you see on the ends were made by me as a double check that they were in the correct position.
Casing ends are bolted on , the bearing caps are located, with the bearings in positon, the top face was levelled while the casing was on a totally parallel spacer. Once double and treble checked for being level, the superglue was used again to lock the parts together. This was done on both ends. Once everything was dry, the holes in the caps were spotted thru with a drill. Everything was then disassembled, and the casing ends were drilled and tapped to take the bearing cap screws.
Here are all the bits ready to go together.
The whole lot that have been made so far. Only three nozzles and two rotor spacers to be made. So getting a definite run tomorrow, and see if all the hard work and planning was worth it.
It might seem that this post was a total waste of time and energy. But to the novice, it does show that with a few basic tools, and a little bit of thought and forwards planning, holes can be put in components fairly easily and accurately.
Wacked out John
That is why sometimes I stall on putting up posts, I sit down in the shop for a few hours going thru the build in my head. I find, even with these time outs, I can knock out a working engine a lot quicker than trying to get it all down on paper first.
--------------------------------------------------------------------------------------------
Another post full of holes.
I can't believe how long it has taken me to get all the bolt down holes done. But I did have a bit of a slip up last night and managed somehow, to get an hole, half an hole out (well the centre drilling was), but I fixed that after mulling over how to do it overnight, and got it fixed with no more than a redrill with the centre in a different position (the correct position) and by the time the hole was drilled and tapped the mistake had been machined out. Saves having to make new parts.
So this post is all about getting 20 little screws into the right position.
I started off bluing up the areas that needed marking.
The first job was to get a corner to corner line on the main chamber, and find a position at one corner, on the line, that a hole could be drilled in all eight corners safely, without interfering too much with the other holes in the block. A position was found, and a measurement taken from the outer corner, to the hole position.
A chamber end was put onto the chamber and two opposing corners were scribed onto the back of the disc. These corner marks on the disc were duly joined by using a centre square, and by measuring from the scribed corner, down the centred line, the position of the required hole was pop marked in one position only. Only one disc needed to be done. Explanation later.
The hex caps were stood up on one of the faces and using a vernier height gauge, the centre line between two opposite points was found, this was done on each in turn. A good position for a mounting hole was found and duly marked and centre popped on each cap.
The pop marks can be seen in the pic.
Now onto the rotary table, set up in the vertical position.
There is no need to centre it under the drill chuck, but the chuck on the RT has to be perfectly centred on the RT table. Mine is spigotted to the centre hole and clamped down.
Now to drilling. The cap was mounted into the self centering chuck, the RT was set to '0', then the centre in the drill chuck was put directly over the pop mark on the cap by moving the x & y table controls. Once it was perfectly over the mark, the table locks were tightened.
Then it was a matter of drilling the hole, fwd 60deg on the RT and drill the next, and so on until all six were done. The new cap was put in the RT chuck, but the chuck was only just 'nipped' up. Now the cap was turned in the chuck jaws until the pop mark was directly under the centre drill. RT chuck fully tightened up, and the holes were drilled as before.
The marked up chamber cap was mounted, RT to zero, and centre drill located as before, hole drilled, move 90 deg, next hole, continue until all four holes are drilled.
Notice here that the locating spigot is facing upwards, as that was the side the markings were on.
Now comes the later explanation. Because thefour holes can be anywhere on the PCD (pitch circle diameter), I can just drill the four holes without going thru the set up procedure, I just used the same drilling position as the previous one. Notice that the outside face is being drilled first.
Because the outside face was drilled, I now put an end mill into the chuck, and duly made a recess for the cap screws on all four holes. Once they were finished I put the drill back into the chuck, put the first casing cap into the RT chuck, with the outside face upwards, and duly relocated the cap into the same drilling position by locating the drill in a hole and tightening up the RT chuck. The recesses for cap screws were then machined. That was how the twenty holes were drilled, now to get the screw holes drilled and tapped in the right positions
Casing was blued up, and put into a large v-block. Using the height gauge again, the exact corner to corner height was found, and duly marked on all eight corners.
The end caps were fitted, and eyballed down the holes so that the centre lines run exactly thru the eyeballed centre of the holes. Without disturbing the position, a fillet of superglue was put between the casing and end cap to hold them together.
Once the glue was dry, I put a transfer punch (these are bought as sets and come in very close sizing to get the right size for the hole, and consist of a hardened rod with a centre point on the end) down the holes and made a pop mark onto the end face of the casing. The opposite end was done in the same manner. Once all eight marks were in position, I went to the drill press, centred and drilled to depth all eight holes (it was at that point I made my mistake). They were then tapped for the fixing bolts.
The scribing marks you see on the ends were made by me as a double check that they were in the correct position.
Casing ends are bolted on , the bearing caps are located, with the bearings in positon, the top face was levelled while the casing was on a totally parallel spacer. Once double and treble checked for being level, the superglue was used again to lock the parts together. This was done on both ends. Once everything was dry, the holes in the caps were spotted thru with a drill. Everything was then disassembled, and the casing ends were drilled and tapped to take the bearing cap screws.
Here are all the bits ready to go together.
The whole lot that have been made so far. Only three nozzles and two rotor spacers to be made. So getting a definite run tomorrow, and see if all the hard work and planning was worth it.
It might seem that this post was a total waste of time and energy. But to the novice, it does show that with a few basic tools, and a little bit of thought and forwards planning, holes can be put in components fairly easily and accurately.
Wacked out John
Brass_Machine
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Bogstandard said:
Woah woah wait a second there John. Posts like this are never a waste of time. At the very least they are inspiration to some of us. So keep them coming.
Eric
Divided He ad
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Hi, as an ultimate newbie I am going to have to say this is so far from a waste of time it's not even measurable!
you may remember me a little? I was the one who recently commented on the grin I had when I saw your single turbine running on the "Tube" and then had a great fasination with the two treadle engines....(Thank you for your suggestion of this site) I have started my simpler one already
This tutorial has inspired me so much i am going to attempt something similar (I will add my own flair!! ;D) as soon as I have finished my current one.
Thank you for this very well put together and selfless undertaking. :bow:
Ralph.
P.S. You gotta have "BLING" ;D
you may remember me a little? I was the one who recently commented on the grin I had when I saw your single turbine running on the "Tube" and then had a great fasination with the two treadle engines....(Thank you for your suggestion of this site) I have started my simpler one already
This tutorial has inspired me so much i am going to attempt something similar (I will add my own flair!! ;D) as soon as I have finished my current one.
Thank you for this very well put together and selfless undertaking. :bow:
Ralph.
P.S. You gotta have "BLING" ;D
B
Bogstandard
Guest
Ralph,
I definitely remember you, and welcome to the site.
It really pleases me to hear that my offerings have inspired someone to have a go.
Why not introduce yourself in the welcome section, and let everyone else know you are about, I am sure you will get a good welcome.
If you are contemplating making a turbine, keep it simple and keep it safe. Bearings will be your limiting factor, so make sure you bury them deep and rigid, so no one gets hurt if one does decide to blow.
My next post will be about the very simple, but most important part, the converging nozzle.
John
I definitely remember you, and welcome to the site.
It really pleases me to hear that my offerings have inspired someone to have a go.
Why not introduce yourself in the welcome section, and let everyone else know you are about, I am sure you will get a good welcome.
If you are contemplating making a turbine, keep it simple and keep it safe. Bearings will be your limiting factor, so make sure you bury them deep and rigid, so no one gets hurt if one does decide to blow.
My next post will be about the very simple, but most important part, the converging nozzle.
John
B
Bogstandard
Guest
I lied, it is not the nozzle this time, but the rotor spacers.
These sit either side of the rotor between the rotor and bearings.
I machined them to allow a side to side movement of 0.002" of the rotor, this was to allow the rotor and shaft to expand slightly, without putting any side loads on the bearing races.
A couple of these pics are a bit blurred, must be old age setting in.
On this first one I have turned a bit of bar down to couple of thou smaller than the centre hole in the casing cap. I also turned on the end of the bar, a small spigot, 20 thou high and just larger than the centre race on the bearing. This is to allow it to turn with the bearing but only ever be in contact with the inner race part.
The end cap was put onto the bar, and pushed on until the bar touched the bearing. A mark was put on the rod to show the rough length it needs to be.
Here is the next shaky one. What I have done, in the area that the spacer will fit inside the casing cap, I have turned 4 grooves, 15 thou deep and 50 thou apart. What I am hoping, if any steam does get into the bearing area, water vapour will be trapped in these grooves, and due to centrifugal force, be thrown out of shape to form like a series of liquid o-rings, thus preventing any large amounts of liquids reaching the bearings. When the end caps are eventually squared off, I might drill down with a fine drill, form a small drilled reservoir at the top and put a bit of oil in there, might be a bit better than trying to seal with water.
It was parted off just a bit longer than needed.
Not shown was that a second one was made the same as the first. Holes the same size as the main shaft drilled thru them, and the parted end cleaned up. Both were then made exactly the same length, by taking material off the parted ends.
To work out how much was needed to bring them to correct length, I put both end caps on (without the rotor installed) and measured the overall length of the motor.
The spacers were put on the rotor, and that was then put into the casing. One end cap was alredy bolted to the chamber, so the other one was put onto the central shaft and pushed towards the casing as though I was going to tighten it on. The spacers actually stopped the cap going all the way, so I then took the overall measurement again, in the same position that I took it from the first time. A 0.026" difference. This told me take take off each spacer 13 thou, plus 1 thou for clearance. 0.014" was duly taken off the parted off end of each one.
The whole lot was reassembled, and spun over by hand. Perfect.
To keep my word, I knocked up a very basic converging nozzle, fitted it to the centre (fwd) rotor and wacked some air thru this little monster.
This vid shows the results.
I actually turned my compressor off before I started, just to keep the noise down (little chance of that with this thing running), but what it meant, on the second runup, there wasn't enough air left in the tank to get it on the boil.
Enjoy it.
[youtube=425,350]YpcQ4JinhzI[/youtube]
Deaf John
These sit either side of the rotor between the rotor and bearings.
I machined them to allow a side to side movement of 0.002" of the rotor, this was to allow the rotor and shaft to expand slightly, without putting any side loads on the bearing races.
A couple of these pics are a bit blurred, must be old age setting in.
On this first one I have turned a bit of bar down to couple of thou smaller than the centre hole in the casing cap. I also turned on the end of the bar, a small spigot, 20 thou high and just larger than the centre race on the bearing. This is to allow it to turn with the bearing but only ever be in contact with the inner race part.
The end cap was put onto the bar, and pushed on until the bar touched the bearing. A mark was put on the rod to show the rough length it needs to be.
Here is the next shaky one. What I have done, in the area that the spacer will fit inside the casing cap, I have turned 4 grooves, 15 thou deep and 50 thou apart. What I am hoping, if any steam does get into the bearing area, water vapour will be trapped in these grooves, and due to centrifugal force, be thrown out of shape to form like a series of liquid o-rings, thus preventing any large amounts of liquids reaching the bearings. When the end caps are eventually squared off, I might drill down with a fine drill, form a small drilled reservoir at the top and put a bit of oil in there, might be a bit better than trying to seal with water.
It was parted off just a bit longer than needed.
Not shown was that a second one was made the same as the first. Holes the same size as the main shaft drilled thru them, and the parted end cleaned up. Both were then made exactly the same length, by taking material off the parted ends.
To work out how much was needed to bring them to correct length, I put both end caps on (without the rotor installed) and measured the overall length of the motor.
The spacers were put on the rotor, and that was then put into the casing. One end cap was alredy bolted to the chamber, so the other one was put onto the central shaft and pushed towards the casing as though I was going to tighten it on. The spacers actually stopped the cap going all the way, so I then took the overall measurement again, in the same position that I took it from the first time. A 0.026" difference. This told me take take off each spacer 13 thou, plus 1 thou for clearance. 0.014" was duly taken off the parted off end of each one.
The whole lot was reassembled, and spun over by hand. Perfect.
To keep my word, I knocked up a very basic converging nozzle, fitted it to the centre (fwd) rotor and wacked some air thru this little monster.
This vid shows the results.
I actually turned my compressor off before I started, just to keep the noise down (little chance of that with this thing running), but what it meant, on the second runup, there wasn't enough air left in the tank to get it on the boil.
Enjoy it.
[youtube=425,350]YpcQ4JinhzI[/youtube]
Deaf John
zeusrekning
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Holy **** man !!! Pardon me, but this was one of thoses projects I just didn't seem to have intrest in. But John's in depth write up kept drawing me in. I had no Idea at all what you were building to start with. I'm facinated! I love the sound it makes. I'd could listen to that whine all day.
Very impressive. Not I get to start at the beginning and read no stop start to finish.
P.S. You don't write with a british accent.
Very impressive. Not I get to start at the beginning and read no stop start to finish.
P.S. You don't write with a british accent.
DICKEYBIRD
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Noice...very, very noice indeed. Luv it!
So, I may have missed an earlier mention of it but are you building the speed reduction gearbox as well?
Fabulous! ;D
Cheers,
Milton
So, I may have missed an earlier mention of it but are you building the speed reduction gearbox as well?
Fabulous! ;D
Cheers,
Milton
B
Bogstandard
Guest
Milton,
What you saw on the vid isn't anywhere near its output. I ran it up for just a little bit longer before I shot the vid, and all of a sudden it hit its power band, and started to run away. A quick shutdown was called for.
The thing this runup did show was my static balancing had worked, and very little vibration showed up. But I did notice that the bearings really need a grease repack. I can easily make a little tool to do that without having to take the shields off.
I will be coupling it to a variable speed gearbox (if it can take the speed) to work out what is required to get the motor running at optimum speed and giving the required revs. Then make a basic gearbox, based on the results.
That is a fair way off yet, and won't be shown on here, except at the final stage. Other projects are starting to rear their ugly heads, and customers are starting to look forwards to delivery.
John
What you saw on the vid isn't anywhere near its output. I ran it up for just a little bit longer before I shot the vid, and all of a sudden it hit its power band, and started to run away. A quick shutdown was called for.
The thing this runup did show was my static balancing had worked, and very little vibration showed up. But I did notice that the bearings really need a grease repack. I can easily make a little tool to do that without having to take the shields off.
I will be coupling it to a variable speed gearbox (if it can take the speed) to work out what is required to get the motor running at optimum speed and giving the required revs. Then make a basic gearbox, based on the results.
That is a fair way off yet, and won't be shown on here, except at the final stage. Other projects are starting to rear their ugly heads, and customers are starting to look forwards to delivery.
John
B
Bogstandard
Guest
Dave,
I am sorry about that, but that is what happens when you catalogue a live build. You are seeing it after a couple of hours of it being done.
I have to design the next bit, only then can it be made.
Body and mind (plus unwanted visitors, like over the Easter weekend, and again in half an hour) all contribute to the delay.
But hopefully between my medico meetings this week I can get a lot more done.
Lost John
I am sorry about that, but that is what happens when you catalogue a live build. You are seeing it after a couple of hours of it being done.
I have to design the next bit, only then can it be made.
Body and mind (plus unwanted visitors, like over the Easter weekend, and again in half an hour) all contribute to the delay.
But hopefully between my medico meetings this week I can get a lot more done.
Lost John
zeusrekning
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John, that is one of the most amazing parts, maybe even more than the work you do.
It is so hard to design on the fly while also being able to document procedures you may not have already proven out. I've noticed with the project that I'm working on that there is alot of ,"let me see if this is going to work", before I even take pics. Plus with my Patience level and memory it is hard to stop working for fear I might miss that needed revelation.
Keep it up! :bow:
Tim
It is so hard to design on the fly while also being able to document procedures you may not have already proven out. I've noticed with the project that I'm working on that there is alot of ,"let me see if this is going to work", before I even take pics. Plus with my Patience level and memory it is hard to stop working for fear I might miss that needed revelation.
Keep it up! :bow:
Tim
B
Bogstandard
Guest
I was going to do such a lot in my shop this evening after getting rid of the unwanted, then just as I was walking out, my mentor turned up, wanting to know what I had been doing to poor defenceless bits of metal. So it wasn't a very productive evening after all.
So here is one of the most boring posts yet.
Just a sketch and one pic. But it might explain the direction I am going in.
I will just show you what I am doing with this sketch. A converging nozzle is required to speed up the pressure coming in, whether it be air or steam. In an ideal world the nozzle would be similar to the one at the top. The air/steam comes in from the RHS, and squeezes down to go thru the small central hole, thus increasing the velocity as it goes thru the smaller hole (the same happens when you press the plunger on a syringe). Just past this small hole the nozzle starts to open out slightly to the finished size of nozzle (this area where it squeezes down and then opens up again is called a venturi). As the gas starts to expand again into this slightly tapered up area, it speeds up even more (the gas is trying to get out of the restriction and so speeds up to do it all the quicker). I hope I have explained this enough in laymans terms, just so everyone can understand the principle. In fact it is all to do with increase and drops in pressures.
So the next part of the sketch shows how I have tried to replicate the principle. I could spend hours grinding up very fine D-bits to get it spot on, but in this case, what I am doing works, not quite as well, but good enough. I am using the drill point to give me the taper for the lead ins and outs.
I could have showed machining the outside of the nozzles to size, and then drilling holes of different sizes thru them, but I thought that would insult your mentality, because I am sure you are all capable of doing those operations.
So what I have done is taken a very exciting pic of a finished nozzle held in my gnarled old gripper. This is a real treat for you, not everyone gets to look at a bit of stepped brass in an old farts hand.
I would have shown you all three that I made, but I thought that might be a bit too overwhelming for a few of you.
It's the bits that you can't see that are important.
Now that bit is over and done with, I promise, after I get back from the clinic tomorrow, I will do something a bit more exciting, maybe watching paint dry.
John
So here is one of the most boring posts yet.
Just a sketch and one pic. But it might explain the direction I am going in.
I will just show you what I am doing with this sketch. A converging nozzle is required to speed up the pressure coming in, whether it be air or steam. In an ideal world the nozzle would be similar to the one at the top. The air/steam comes in from the RHS, and squeezes down to go thru the small central hole, thus increasing the velocity as it goes thru the smaller hole (the same happens when you press the plunger on a syringe). Just past this small hole the nozzle starts to open out slightly to the finished size of nozzle (this area where it squeezes down and then opens up again is called a venturi). As the gas starts to expand again into this slightly tapered up area, it speeds up even more (the gas is trying to get out of the restriction and so speeds up to do it all the quicker). I hope I have explained this enough in laymans terms, just so everyone can understand the principle. In fact it is all to do with increase and drops in pressures.
So the next part of the sketch shows how I have tried to replicate the principle. I could spend hours grinding up very fine D-bits to get it spot on, but in this case, what I am doing works, not quite as well, but good enough. I am using the drill point to give me the taper for the lead ins and outs.
I could have showed machining the outside of the nozzles to size, and then drilling holes of different sizes thru them, but I thought that would insult your mentality, because I am sure you are all capable of doing those operations.
So what I have done is taken a very exciting pic of a finished nozzle held in my gnarled old gripper. This is a real treat for you, not everyone gets to look at a bit of stepped brass in an old farts hand.
I would have shown you all three that I made, but I thought that might be a bit too overwhelming for a few of you.
It's the bits that you can't see that are important.
Now that bit is over and done with, I promise, after I get back from the clinic tomorrow, I will do something a bit more exciting, maybe watching paint dry.
John
John,
Excellent build and documentation. I have added quite a few mental tools to my arsenal.
A question: Would the nozzle design parallel a NACA duct in round mathematically? I.e. a 1 to 3 ratio of rise to run? http://www.revlimiter.net/mods/duct.html shows an example.
I have always been interested in aerodynamics and this seems to be a common theme with regards to intakes.
Just wondering,
Sean
Excellent build and documentation. I have added quite a few mental tools to my arsenal.
A question: Would the nozzle design parallel a NACA duct in round mathematically? I.e. a 1 to 3 ratio of rise to run? http://www.revlimiter.net/mods/duct.html shows an example.
I have always been interested in aerodynamics and this seems to be a common theme with regards to intakes.
Just wondering,
Sean
B
Bogstandard
Guest
Sean,
It is nearly 40 years since I got my qualifications in aeronautics and aerodynamics, so the answer to your question has to be, I have no idea, sorry. The theory would be way out of date by now any way, and dementure is setting in fast.
What you are showing in the URL is in fact (when I was into things that flew) a standard low drag intake. But I am sure with all the latest gadgets available, the aerospace people have come up with a more efficient design. Maybe trolling around modern day fighter pics and searching for say 'diverging intake design' would give you an idea of the shapes they are using nowadays. But some of the stuff that comes up, especially in the aeronautical side just might be a bit hard going. I have trouble myself nowadays, understanding stuff that is too technical, whereas at one time I could soak it up like a sponge.
Those intakes work in the opposite way to the nozzle principle except where it comes out of the nozzle. The way they work is by taking high speed air and slowing it down to an acceptable level to be used inside the engine bay, otherwise if it was the other way around (like the nozzle works), the hood would be blown off in seconds, caused by pressure build up once a respectable speed was reached. One thing I do know is that in a converging/ diverging nozzle, if the calculations are way out, you can reach the point of a mach1 shock wave, in which case everything goes pear shaped.
John
It is nearly 40 years since I got my qualifications in aeronautics and aerodynamics, so the answer to your question has to be, I have no idea, sorry. The theory would be way out of date by now any way, and dementure is setting in fast.
What you are showing in the URL is in fact (when I was into things that flew) a standard low drag intake. But I am sure with all the latest gadgets available, the aerospace people have come up with a more efficient design. Maybe trolling around modern day fighter pics and searching for say 'diverging intake design' would give you an idea of the shapes they are using nowadays. But some of the stuff that comes up, especially in the aeronautical side just might be a bit hard going. I have trouble myself nowadays, understanding stuff that is too technical, whereas at one time I could soak it up like a sponge.
Those intakes work in the opposite way to the nozzle principle except where it comes out of the nozzle. The way they work is by taking high speed air and slowing it down to an acceptable level to be used inside the engine bay, otherwise if it was the other way around (like the nozzle works), the hood would be blown off in seconds, caused by pressure build up once a respectable speed was reached. One thing I do know is that in a converging/ diverging nozzle, if the calculations are way out, you can reach the point of a mach1 shock wave, in which case everything goes pear shaped.
John
B
Bogstandard
Guest
Giles,
Rather too costly I am afraid, so I stuck with some standard bearings that I know the details about.
Because these ones have old grease in them, they do feel and sound a bit rough. But as I said, I know how to make a dead easy tool for recharging them with grease, and I will show how to make one after this is finished. Then it should run a lot smoother.
I am hoping this will hit a power band around 30-35k RPM, so bearing selection should be easy. But from my trials with it, I just might knock up an ali rotor, to see if the lower mass will allow a faster acceleration. As I said, this is a proto, so will be played about with. But as built, it is giving a nice running turbine, very close to my expectations.
I must get a proper tacho on it when it is finished, mine only goes up to 29K, it was designed for model aero engines.
John
Rather too costly I am afraid, so I stuck with some standard bearings that I know the details about.
Because these ones have old grease in them, they do feel and sound a bit rough. But as I said, I know how to make a dead easy tool for recharging them with grease, and I will show how to make one after this is finished. Then it should run a lot smoother.
I am hoping this will hit a power band around 30-35k RPM, so bearing selection should be easy. But from my trials with it, I just might knock up an ali rotor, to see if the lower mass will allow a faster acceleration. As I said, this is a proto, so will be played about with. But as built, it is giving a nice running turbine, very close to my expectations.
I must get a proper tacho on it when it is finished, mine only goes up to 29K, it was designed for model aero engines.
John
I have heard of guys puting bearings in a container containing oil, then vacuum all the air out of the container. Once you remove the vacuum, oil gets sucked into the space once occupied by air in the bearing. Is that how your tool works bog?
E
E
B
Bogstandard
Guest
AT,
Nothing as complicated as that.
It will be a quickie make, manual jobbie, to be used with a grease or pressure oil gun.
A couple of hours work and a bit of metal. You will be able to make them to fit almost any bearing within reason.
I won't go into details yet as it will distract me too much from this post, and I need to get this little thing up to speed first.
John
Nothing as complicated as that.
It will be a quickie make, manual jobbie, to be used with a grease or pressure oil gun.
A couple of hours work and a bit of metal. You will be able to make them to fit almost any bearing within reason.
I won't go into details yet as it will distract me too much from this post, and I need to get this little thing up to speed first.
John
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