Prototype three rotor steam impulse turbine

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Al,

A lot of questions to be answered there

I am talking about on this build about a total loss impulse turbine, compared to maybe a reaction turbine that you were involved with. In my impulse design the steam (or air) is totally finished with within about 3/4" from the injection nozzle and the propellant is scavenged out of the case fairly quickly. With a reaction turbine, the steam is continuing to work thru the whole blade system of the engine (just like an aircraft gas turbine). There is also a big difference when working with small engines such as this.

The boiler system I am leaving to the boat builder. He has suggested he will try a standard boiler system first and if not enough volume to keep the engines going, he will then go to a flash boiler. In my trials it will be carried out with a standard gas fired vertical boiler.

The nozzles for the forwards part will be fed simultaneously, so giving , in practice 36 pockets at 10 degree spacing, whereas the single reverse rotor will be working on 18 pockets at 20 degrees apart. The change of direction will be caused purely by switching steam from fwd to rev and vice versa. I am hoping this will give about a 4 second delay from switching to spinning in the opposite direction, slight faster when going from rev to fwd.

Any collected moisture with be automatically blown out of a small drain at the bottom of the case. There will be slight leakage of steam thru the bearings, hence the use of stainless, but this will not be an issue as far as I am concerned. In larger engines, galleries and seals can be introduced to prevent this sort of steam transfer, but in a model of this size and non complexity, it is not a viable proposition. but hopefully a sytem of collection grooves will be used that fill with water to form a spinning o-ring type seal, similar to oil grooves on a steam engine piston.

I too worked with full sized turbines, but the aircraft engine variety.

I hope this has explained what I am trying to achieve. This is a proto after all.

John



John
 
Bog,

You have all the bases covered as I suspected you would, as I said I was only trying a bit of devil's advocacy.

Thinking back is the impulse type of rotor called a 'curtis wheel'?

Thanks for taking the time.

Al
 
Great tutorial Bogs. Even I learned something there.

I don't want to hijack this thread,so I'll make it short. If anybody wants to hear the full story I'll relate it in the General area. That lead hammer reminds me of a story my dad told me about the new apprentice that they sent to the heat treat room to have a lead hammer heat treated because it was to soft. I'm sure you all know that he came back with just the handle. :big: :big: :big: :big:

Bernd
 
Al,
I have no idea of what a Curtis wheel looks like,and after a quickie search on the net I am none the wiser.
Mine works on a Pelton wheel basis, but mine are machined as small pockets, unlike the one shown here, this one is being driven very inefficiently.

[youtube=425,350]tFiFBbMJsfw&hl[/youtube]

John

 
This is going to be one of those long boring (sorry about the pun) bits of text about how to put great big holes in a defenceless lump of metal. Putting it on a slimming regime from the inside out.

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First off, we've got to find where we are going to be putting the hole and mark it up so we can find it again when we come to put the holes in it.
This first pic shows some of the tools than can be and are used to get the centre position marked (this is where I want it, in the centre, if you want to put it in another position you can use the same sort of techniques).
First off, put something on the metal so you can see the markings as you put them on. I use marking out blue, but coloured broad tipped permanent markers do just as good a job. I use a blue marker for covering up mistakes on my marking out, rather than redoing the full face.
I tend to use either a height gauge or a centre square for this type of job, so I will concentrate on those two bits of kit.



rotbore1.jpg


A height gauge is one of the most important bits of kit IMHO that is needed in the shop, either digital for the lazy ones, or a manual one like this for people that won't spend the money for the other type. Both do an equally good job of putting lines on bits of metal in the right place. They can also be used as very good precision hammers (just joking of course, I use my digital verniers for that job). But if you can read a vernier, there is really no difference between the two. On this job, where all sides are perfectly equal, the side length was measured, divided by two, set the vernier to that figure and scribe a line across the blued face, turn the job thru 90 deg and repeat the marking, to double check I went round all four sides, and as you can see, they all line up perfectly.
They really need to be used on a totally flat surface. My marking out table is a genuine cast iron one that I also turned into a tapping stand, isn't it great, dual purpose machinery. But a sheet of plate glass does just as well. For many years I used the platen glass out of an old photocopier, until I dropped a lump of the heavy stuff onto it. Steel and glass don't mix.


rotbore2.jpg


The other bit of kit is called a centre square, another piece of essential equipment.
These are really designed for finding the centre of round bar, but if you are using perfectly square bar, it will do the job admirably. They are usually fairly cheap to buy and are a worthwhile investment if you are building up a stock of tooling.
I have shown how they are used, just scribe a line along the blade, and you can see that the centre matches up perfectly with the one done with the height gauge. So either method could be used in this case.


rotbore3.jpg


So we have the centre. Now that centre mark has to be made into something that can be used to locate things into it.
I will just bring up a point here. Basically there are two types of point on a centre punch. One at 60 degrees and the other is 90 degrees. We need to use the 90 deg type, no arguments on this one, the 60 deg is for marking out edges of things, like edges to be filed to, the 90 deg one is made that way so that it accepts the 90 deg points of other tooling.
That out of the way, how do we get that point exactly on the centre as marked. I will explain the method I use. Your centre punch should be sharp pointed, blunt and rounded over is no use at all. Put the tip of the punch into one of the first lines that were scribed on the face, and drag it down the line (you will find, if sharp enough, that it will follow the line with ease) towards the centre marking, as it reaches the centre you will feel it hit the later scribed lines. Lift it upright without moving the tip and give it a light tap with a hammer. Get a loupe or magnifier and look at the dimple you have just made. You can almost guarantee that it is near the crossed centre, but not exactly there. So what you do now is gently move the mark until it is spot on where it is needed. This is done by using the hammer and punch and drive the spot towards where you want it to go. Do not be heavy handed, just a gentle tap. Eventually by looking at the magnified image you will see when the dimple is exactly in the right place. Put the punch into this dimple, totally upright, and give it a good wack with a hammer. You should end up with what is in the pic.


rotbore4.jpg


It took all that effort to get just one little spot marked on the end of a bit of metal. If it was done wrong, then everything that follows will be out. As experience is gained that spot can be within 0.001" of where it should be, and tolerances that tight are acceptable.
I will just tell you now, a few days ago I would not have been showing you how to do this using a four jaw on the lathe, it would be being bored using the miller and a boring head. It is now I can use both hands that this is possible.
So, lets introduce the metal to the four jaw. Mount it up as shown, a thin parallel at the rear of the block (more on this later), a piece of soft shim between the jaws and the job (no drinks can again, but this is a bit of soft ali litho plate). Tweak up the jaws but not too tightly.


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Unless your are very lucky and the sun shines out of you know where, the centre punch mark will be way off centre when the chuck is turned.
There are many varied ways of doing the next stage, with all sorts of weird and wonderful gizmos and dingdongs, but the one I will show is the generally accepted method of doing it here in the UK (we've been at it a bit longer than the colonials, and we don't accept new methods lightly).
The reason for this method is that there is usually one of these centres knocking about the place, so why not use it, save your money, this is just as accurate. I have tried all sorts, wigglers with points, pointed edge finders, play dough with pins in, spring loaded doodahs with bells etc. I always come back to this.
Set up as shown, and by tweaking the jaws (slackening on one, tightening the opposite) on the chuck get the runout to as low as possible. I class 1/2 thou as acceptable.
Take all the setting up gear away, remove the parallel from the rear of the job (more on this later). You are now nearly ready to start cutting metal.


rotbore6.jpg


Put a big centre in the end of the metal, and wack thru with the largest drill you have got. I must invest in a set of blacksmiths drills, I love putting big holes in things.


rotbore7.jpg


The next two pictures go hand in hand. You always use the largest boring bar you have that will do the job. So you may not have set it to correct height yet. If you use a QT toolpost it is dead easy. Get your favourite facing tool that is already set to height, lock your spindle if you can, if not, do this very gently so the spindle doesn't move. Using the facing tool, scribe a small line on the metal as shown in the first of this pair of pics.


rotbore8.jpg


Mount your boring bar into its tool holder and bring the height up to the line marked on the job. Perfect tool height achieved in seconds. I always have trouble with my biggie bars if doing it by normal methods, because the tips are angled downwards. doing it this way solves the problem.


rotbore9.jpg


Again the next pair of pics are linked.
I have a home made saddle stop fitted to my machine, the square lump with bolts sticking out, to the left of the saddle. If you have one of these, use it to stop the boring tool going too far thru the job and hitting the chuck. If you haven't got one of these fitted, be careful, and expect some time in the future to cut some nice circular bits out of your chuck. Go to the next pic.


rotbore10.jpg


This is a close up shot of what I was on about, with the stop set, the tooling cannot hit the chuck.
I will now mention 'more on this later'. The boring bar has to penetrate all the way thru the job, if there wasn't a space caused by the thin parallel, the boring bar would hit the chuck as soon as it got to the end of the hole. This is a safety area for the tool to run into. It is needed if the hole being bored is larger than the hole thru the chuck.


rotbore11.jpg


Now the best bit is here, metal to be cut.
All safety spaces have been created, everthing is set to length. Now start boring thru. As much as the machine will take at this stage, finer cuts later on. As you start to get to finished size, take finer and finer cuts. On this job it doesn't matter about a good finish until the rotor fits into the hole. On my very very expensive set of boring bars (kindly donated by a rep, for recommending them to the boss), they have holes going right thru them, so cutting fluid is fed into the back and emerges just behind the replaceable tip. A real neat idea, but in this case not used, after each boring run, I just stopped the machine, cleaned out the curly swarf and painted in some of my 'ali mix', then carried on until I was at the right size for the rotor to fit snugly into the hole.


rotbore12.jpg


The rotor, nice and snug in its future casing. But this is no use to me, I need about 5 or 6 thou running clearance to allow for expansion of different materials while being powered with hot steam.


rotbore13.jpg


The final cut to give me this clearance was duly keyed in and run back and forward thru the hole a few times at the same setting. This not only gives a nice finish, but also takes out the remaining metal left behind by 'tool springing'. So you end up with a nice shiny parallel bore.


rotbore14.jpg


JOB DONE.

rotbore15.jpg


Next will be putting the rest of the holes in the casing, and maybe making the converging nozzles.

John

PHEW!!
 
Sorry I never put the expected post up yesterday.
With my new found mobility I actually burnt myself out in the shop, so yesterday I just took it easy, surfed a bit and slept a lot.

What I would like to suggest, is that as I am doing this post showing how I do the things I do, if anyone else has a different or better or easier method of doing what I am showing, please do a small write up post in the tips and tricks section, and pop a link to it in this post. That way people will be able to choose the method that serves them the best, with the equipment they have.

I am not perfect, I do things that are my way, to achieve what is needed, and in no way am I trying to influence people how to do things. I can only suggest.
No animosity will be shown to anyone who does this, in fact I condone it, I might be able to learn a few tricks as well. There is a mass of untapped knowledge amongst the members on this site, so if you can, set it up, take a few piccies, do an easily understood write up (so even I can understand it), and pop it in a post. You never know, you might start to enjoy doing it, as I do. The main plus side is that newbies will have a chance to learn how to do things, and so won't have the stigma of being a newbie for any longer than is necessary.

John
 
I am starting to get very lazy, two days behind with this project, must get my a**e into gear and start moving.

Today it is getting the smaller holes into the rotor chamber to feed steam/air in and get rid of it as soon as it has done it's work. The energy in this design I am making will only be playing on the rotor for half an inch of movement at the most, then it is discarded. So you will see with the first sketch that the steam will be fed in, hit the rotor, move it a bit, then it will be straight out of the first exhaust. If a bit gets past this first one, I am hoping that the second one will scrape most of the remainder away. What I don't want to happen is to get a build up of pressure in the chamber.

inexsketch1.jpg


This next sketch shows the position of the holes required. I have left the chamber at 2" long to allow me to work from a central point, the chamber will be reduced to correct length after all this work is done.
For the second set of exhaust holes the datum is moved 3/8" towards the centre of the chamber, then the required 20 degree angle is put on to give me the tangential exhaust to hopefully scrape away the left over steam.


inexsketch2.jpg


Theory over, time to get it done. As you can see from the next two pics I have blued up and marked where all the holes are positioned. I still do this even though I use DRO on my mill. It is a double check to make sure that I am drilling or machining in the right place, and is a good practice to get into. You never know when your DRO might go down and you have to do it manually. A lesson here. Before all the whizzbang stuff came along, this is how it was all done, if you can learn to do it manually, it will stand you in good stead. Gizmos make life easier, and if you want to go down that route, do so by all means. But don't forget how to manually do things.


inex1.jpg



inex2.jpg


This is a standard drilling setup to put the holes in for the nozzles. I first drilled into the chamber with a 1/8" drill, then using a 3/16" end mill I milled down for 0.200" to give a stop for the nozzles to be made and to allow for a grub screw to be fitted from the top to allow the nozzle to be held in position.
While I was in the vice I turned the job thru 90 deg and popped a small (0.020") into the centre of the chamber on the base to make a small drain hole, just to get rid of any water that might condense out.


inex3.jpg


Switched over to the RT in horizontal mode. I squared it up basically with an engineers square to the table edge (this is only near, and relies on the base of the RT being totally square). Then the RT was set to zero, inside jaws fitted to the chuck and the block mounted on using a square to get it near.


inex4.jpg


This is where you get everything spot on. DTI in the drill chuck, bring the Y axis into play and get a reading on the clock. Now track left and right using the X axis and tap the RT base (with a soft hammer) until you get no deflection across the whole face. Now using the quill, take the DTI up and down and get the job perfectly upright by slackening slightly on the chuck jaws and very gentle tapping on the job to get it tracking perfectly up and down. Tweak up jaws and recheck.
Now the exhaust holes were drilled (making sure I didn't hit the chuck jaws as the drill penetrated into the chamber).


inex5.jpg


Now I went back to the first hole drilled, moved 3/8" towards the centre and rotated the table 20 degrees to give me the correctly positioned hole. This is repeated for the other two holes. The two fwd holes will be the same direction on the RT, the reverse will require you to turn in the opposite direction. It all depends which way round the block was first mounted as to which way the RT has to be turned.


inex6.jpg


Inlet jet side


inex7.jpg


Exhaust side


inex8.jpg



This shot shows the chamber on the inside, you can see the tangential exhausts and nozzle inputs. If you look carefully on the bottom face you can just see the small drain hole and grub screw holes.


inex9.jpg


I have put the rotor in the casing to show how it will work. If you look carefully you can see the inlet nozzles on the far side. The pressure comes in, hits the uprights on the pockets and pushes the rotor forwards, it only travels a very short distance before the next face is in position to have pressure on it. It goes just over TDC and starts to escape thru the first large exhaust, the second exhaust port catches any that was missed (I hope).
The bluing is to show me which end 1/8" has to be removed to get everything spot on and tight.


inex10.jpg


The next stage for this job is to fit the end plates. Normally I would make square ones and just wack them on. But because I lost all my pictures a while back about making flywheels out of plate, I am going to do the same sort of thing for making the end plates, just to show the technique to people who haven't had the chance to see it done.

John
 
Bog - your photo's and documentation on your build are OUTSTANDING !! Please keep it up - I'm sure I speak for many here - we're learning tons !!

Mike
 
Thanks Mike,
Glad you are enjoying it and hope it is explaining things in a different light.
You just might like this one.

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I will just explain what I will be doing on this post.

I will be showing how to get a circular disc out of a lump of plate. Round bar can be fairly expensive in the larger sizes, but if you don't mind putting a bit of work in, they can be made almost any size you want. Ideal if you want to make a flywheel. The reason I am showing this, is that last year I did almost exactly the same post about getting flywheels from plate. But unfortunately I lost all my pictures on photobucket, and didn't have a backup to replace them. It can't happen now, I have a full backup in two separate places now.
The other reason you might be asking is, why make round endplates for a square engine. There is method in my madness. The rotor on this engine has only 0.003" between it and the outer casing. So by using a round disc, it can be loaded onto the lathe and concentric holes and spigots can be machined to much finer tolerances than if it was square and put either into a four jaw or the milling machine. After the disc is machined, it will be a fairly easy operation to make it square to fit the engine.
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So rather than beating my gums any more, lets get on with it.

First pic, shows rotor casing and a chunk of plate that was rough cut from a bit of a jig a mate gave me.


endcap1.jpg


In this next one I have already blued up, done a rough scribe around the casing, found the rough centre, and using calipers, scribed a line so that it encircles the square and popped a small centre into the rough middle. If you were making a flywheel, you would scribe your diameter (slightly oversize) and put the centre in. The rest of this is relevent to all.

endcap2.jpg


I could have just cut between the two circles and ended up with a couple of squares. But to save time and stress trying to do large interupted cuts on the lathe, I did a rough cut out on the bandsaw, a few minutes doing this saves a lot of minutes and anguish on the lathe.


endcap3.jpg


Flip 'em over and stick some masking tape on the back, to the nearest thou, just as I have done. This is going to be the friction pad between the chuck and the job.


endcap4.jpg


Now to set up the lathe.
Put a piece of stock in the chuck jaws, and push it into the jaws as shown. The size of stock that is required is that when the jaws are tightened up, the outside of the jaws should be a bit smaller than the finished diameter of the disc, nothing special, near enough is good enough. Tighten the chuck jaws.

endcap5.jpg


This will only work if you have a rotating centre as in the pic, don't attempt this with a solid centre. There is a bit of a trick to the next bit, but it is simple if followed correctly.
Bring the tailstock towards the head but leave enough room for the saddle to be able to be moved to give the cut across the side face of the job. Lock up the tailstock and wind forwards, as you get near to the chuck feed the centre drilling in the job onto the rotating centre, and carry on winding forwards on the tailstock until the job is gently trapped between the centre and chuck jaws. Turn the chuck, the centre should turn with the job and there should be no wobble on the tailstock ram. If there is a bit of wobble, retract the ram and repeat. Once all is running true, put some pressure onto the job using the tailstock ram. When you turn on, the centre should be rotating and the ram should have no wobble.
This technique is called friction turning, and is safe. I have turned items up to 2ft in diameter and weighing many pounds, but not on this lathe, I have a max of 10" diameter.


endcap6.jpg


Mount up your favourite tool, and set it so that it can cut across the whole side face plus a little bit and not go too close to the chuck, just put the saddle in the position you will end up at, and rotate the chuck by hand to make sure nothing will foul. I use my saddle stop in this situation, but if you haven't got one, be very careful as you will be working in areas around the chuck you don't normally go.
If doing an interupted cut, 10 thou is OK, if the job stops turning, take a bit of cut off and come in again, but a bit slower feed. This is the reason I trim mine down. From the outset I can take a cut of 20 thou with no problems.
Machine down to your desired size. You can even polish the edges if you want to, but keep your knuckles away from the chuck.


endcap7.jpg


Down to size, a quick deburr with an emery block and it is ready for making a flywheel or WHY.


endcap8.jpg


These are the plates being used for mounting the bearings into, and also the engine will be supported on these end plates, so they have to be fairly substantial. In this shot I have already removed 1/8" from the length of the casing by mounting it into the four jaw and facing to length.


endcap9.jpg


The next job will be getting these end plates to accept the bearings.

John
 
This post will be about how I obtain very close tolerances on large round bits using my lathe.

As mentioned before, the engine I am designing and making is made to fairly tight tolerances in places, in some cases no tolerance at all, it has to fit together perfectly.
So I will let you into my little world to show you how I do it.
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This first picture shows what maybe a few of you have never heard about. They are called soft jaws. They are bought as extras for your self centering chucks. Not all chucks are supported, so when I buy a new chuck, if soft jaws are not available for it, I go for one that has. All my self centering chucks have soft jaws, from this four jaw one to the 3" one I use on my rotary table. These, as far as I am concerned, are one of the most important parts of the precision turning arsenal that I possess.


endcap1-1.jpg


So, how are they used?
The jaws are not like your normal very hard ones, and are usually made of free cutting steel. This allows you to machine them to hold the circular parts that you have.
The jaws are tightened down onto a bit of bar stock, as shown. The bar stock is selected on size to allow you to either bore a new recess on a clear bit of face, or modify an old recess slightly, to allow a good fit for the part to be machined. By tightening down onto the bar stock, your are basically locking the whole jaw and scroll set into a solid mass and at an exact position. So when the part is tightened into the recess, it again locks everything together, in exactly the same position as the boring was done, so perfect concentricity is retained. They don't need to be very deeply bored, because the surface area contact is a lot more than normal. It is not recommended to use these soft jaws as you would normal ones, the machining on the pointy bits is not usually very accurate, and besides, with the metal being soft, it cannot grip too well just on the points.
After boring the machined area must be deburred very well. This is the part that takes the time.
A set like this would last, if old borings are modified to suit the job, very many years, most probably the life of the chuck. The jaws are usually longer than standard sets, so when the face becomes full of all sorts of borings, you face them all off and you can start all over again.


endcap2-1.jpg


Now back to making the high precision ends for my new motor.
The previously machined plates were put into the custom bored recess in the chuck jaws. The centre drill was taken up another size, just in case the friction turning was slightly out, and followed thru with a 3/8" drill.


endcap3-1.jpg


The disc was skimmed very lightly both sides, just to clean them up and get them totally flat. I am not worried about the thickness of these discs, as fine tuning takes place a bit later.
The centre hole was then bored out until it was just a little smaller than the ID of the outside race on the bearing.
The discs have to have a spigot machined on them that fits into the rotor casing. If this was done before the bearing housing was machined the soft jaws would need to be rebored to take account of the spigot, so the bearing hole has to be done first.


endcap4-1.jpg


I am using flanged bearings, so they are not too critical on boring depth, anything that is either to length or just over will do. If standard bearings were to be fitted, they would be bored to a depth of 3/4 of the width, this would allow the bearing to produce its own sticky out spigot, just like the ones I am using.
The holes were very finely bored until the bearing was a finger push fit in the hole. Too slack or too tight is not what is wanted on this engine.


endcap5-1.jpg


The bearing fits perfectly.


endcap6-1.jpg


Bearing removed, disc flipped over in the chuck and a 0.050" high spigot is machined on the face. This has to be machined, yet again, very precisely on its diameter, to a 'wringing' fit in the bore of the rotor casing.


endcap7-1.jpg


This is what it should look like if done correctly.
Now make another one exactly the same for the other end.


endcap8-1.jpg


This little beastie is starting to look menacing.
So I took a chance, because there are no internal spacers yet, and put a bit of air onto it. In fact more than a bit, and it ran almost exactly as I wanted it to. But without all the other bits and full bearing rigidity no definite results.
Very promising is all I will say.


endcap9-1.jpg


The next job will be getting the bearings and end plates fixed into their correct positions.

Then it might start flying.


John

Footnote.

After double checking this post, I noticed that I showed boring to depth for the bearing and putting the spigot on, I had used replaceable tipped tools.
This sort of tooling usually has a very small rad on the tip, so doesn't cut a totally square corner. For bearings it doesn't usually matter, they are most often made nowadays with slightly rounded corners to cater for the rounded corner holes. But in the case of the spigot, I had to make sure that the large hole in the rotor casing had a good chamfer on the edge to allow for the non square corner. If you are using ground up tooling with sharp points, this problem would not occur.

I mentioned this because, if ever you are using replaceable tipped tooling to make your little engines and something just won't sit down tight, face to face, it just might be a matter of making a little chamfer to cater for this radius.
 
I don't understand why the soft jaws are more precise than hard jaws. Doesn't it all boil down to how well the part is dialed in ?


 
SmoggyTurnip said:
I don't understand why the soft jaws are more precise than hard jaws. Doesn't it all boil down to how well the part is dialed in ?

Smoggy, it looks like its a 4 jaw self centreing chuck he's using, not a four jaw independent. in a four jaw independent, you're right, wouldn't matter. dial in with a 10ths indicator and all is good. in this case i can see the advantage of the soft jaws, he creates not only axial concentricity, but also the way the jaws have been machined creates a radial step to set the short pieces on, like a built in spacer.
 
Thanks for that Mcgyver, I should have mentioned that it was a four jaw self centering. People automatically assume it is an independent four jaw, just because of the number of jaws.

I would like to add that Smoggy is right, you can just redial it in with an independent. But with soft jaws you can take the job in and out and flip it over without having to redial each time, also, because you don't have the gripping area too deep, and if you are careful with the depth of cut, you can work on fairly thin jobs on both face and sides in relative safety, without fear of the chuck 'letting go'.

John
 
This is only a short post tonight, a bad case of the lazies got to me today.

I will just explain what I am going to be doing.

In the last post I got the end caps onto the casing and the bearings a nice concentric snug fit into them. To stop the bearings popping out or rotating in their recesses, I am going to make a cover that tightly fits over the protruding flange, plus I want to make the recess for the flange very slightly shallow (only 1 or 2 thou) so that it 'grips' the flange between the rotor end cap and the bearing cap, to lock it into place, I could use a bearing lock product, but I want to get the bearings out fairly easily, as I expect this engine will go thru them at a fair rate if it is used a lot.

I have decided to pep the look of the engine up a bit, as it does look a bit sparse.
I know Marv doesn't like the word B***G, so in an act of respect for a very knowledgeable man, and just for this post, I will call it visual enhancement.
Ali and brass give a very nice looking contrast, so for this engine I am going to make the bearing cap a little over the top, but it should look right when it is finished.

To start off with I mounted a lump of large hex bar into the 3 jaw.

bearcap1.jpg


The end was faced across, and a spigot 1/2" diameter by 1/4" long was machined on the end using a round profile tool, just to put a bit of curve onto the engine.


bearcap2.jpg


This was duly parted off leaving a hex flange on the part just over 1/8" thick. A second one was made straight afterwards.


bearcap3.jpg


This gave me two rough part bearing caps. They were duly put into my collet chuck, gripping on the spigot and the hex end was faced across, so that I could measure the thickness.


bearcap4.jpg


Two caps, faced off, showing roughly how thick the mounting flange should be.


bearcap5.jpg


These are the end caps, with a dimension on them that is the amount of material required to be removed to get the mounting flange to the correct thickness of 1/8".


bearcap6.jpg


You might ask, why didn't I drill the hole thru for the shaft before I parted it off. This will be explained in the next post, all I will say is that what is not seen is the critical bit, visual enhancement can look after itself.

John
 
John,

Aw, go ahead and use 'bling' as much as you like. Just remember, though, at the first mention of rhinestones, I'm outta here. ::)
 
mklotz said:
John,

Aw, go ahead and use 'bling' as much as you like. Just remember, though, at the first mention of rhinestones, I'm outta here. ::)

Aha, the Liberace of the model steam set.

BW
 
Bogstandard said:
a bad case of the lazies got to me today.

Everyone is entitled to a day off, with your output your lazy day doesn't even equal my most productive.

Regards
 
Al,

I am not at work at the moment, so I use the shop to kill time and stop my brain going addled. When I eventually get back to work, I will be just like the rest of the members, grab a bit of time here and there.

John
 
John,

I went back and checked how you wrote up the use of soft jaws. Might want to mention why a piece of stock was used to clamp the jaws on. I know why, but thought you would explain it better. I think some of the members have never seen this method used and what the procedure is and why you clamp on a piece of stock while boring out the jaws.

Regards,
Bernd
 

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