Making a piston valve engine from mainly junk materials

[bogstandard]

Please Note[/size]

This entire series of posts by John (bogstandard) and others, has now been recreated as a series of pdf files by Floyd (TFL45). They can be found in our "Downloads" section at the following link:

http://www.paddleducks.co.uk/forum/dlman.php?func=select_folder&folder_id=231

Our sincere thanks to John and Floyd (and all the others who contributed) for all their hard work!



Having carried out a full site poll, half way down a topic somewhere and having immense response, 1 really, I have decided to show how I build my engines from scratch (and junk), hopefully to inspire at least one person to have a go.
This opening post will be to try and convince you that making is not too difficult or overly expensive if you just have a few basic engineering tools.
Its always nice to have a fully equipped workshop, but even by buying a cheap lathe, Arc Eurotrade do one for just over £100 with maybe another £50 for some basic bits to go with it, can work wonders for your modelling, not just engineering, you can make most of your metal, wood and plastic fittings yourself.
A small vertical slide to fit the lathe will allow you to do not only basic milling but more complicated things as you get used to it, in fact what I do is use the machines to make more bits for the machines. An el cheapo drill press is a worthwhile investment, and can be obtained everywhere for just over £30.
For basic hand tools I use an engineers square, a little gizmo for finding the centre of roundish thingies, its actually called a centre square, again you can buy sets of these from somewhere like Chronos for just over £25 (this is great, spending someone elses money).
A selection of files, scriber, a good six inch rule, centre punch, hammer, the list goes on, but most people have the neccessary things already, you can buy purpose made deburring tools, but I use a stanley knife, by scraping the sharp edges at 45 deg, instant deburr, just change the blade every couple of months.
A flat surface and a sheet of very fine wet & dry takes care of lapping any faces, I used a piece of plate glass until recently, in fact it was the platen glass out of an old photcopier, (it only needs to be about 12" square), I had used it for about the last ten years, not just for lapping but anytime I needed a flat surface, just scrape the glue off before using it to lap. Unfortunately, glass, big lumps of metal and fumbling fingers don't mix.
Please bear in mind, with the machinery I have I can easily remove 5 or 6mm at a time, with a very small lathe or miller you will be lucky to remove one tenth of this, so you have to do a lot of small cuts. Usually the larger the machine the better, what will do a lot will also do a little, but not the other way round.
I am not saying that you could build an engine like this on the small lathe that I mentioned, but I would love you to prove me wrong. That was just to show that it needn't cost a fortune to start in engineering.
Now a few of my famous drawings showing the basic setup for calculating what is needed. This engine will not be a good looker by any stretch of the imagination, it looks very spindley, that is because again I have gone for the same bore and stroke 10X20 long stroke.
The next bit I submit will be even more long winded than this, because I want to mention a little about safety in a workshop environment. It needs to be done, and I promise, only the once. I have picked up more body parts from people alive and not so alive than I care to remember, so I can talk thru experience.
Digest this lot if you can, will do the next post either late tonight or early tomorrow. It will get better.

[Eddy Matthews]

I'm with you so far John, so you can't be explaining it that badly!

You mentioned the cheap Arc lathe - Is it accurate enough to do what we need? I know cheap drill presses will drill any angle you want except 90 degrees! Though I have to admit that half the problem is probably caused by the drill bit itself wandering...

As I've said before, I'm not into working with metal (but I hope your article will change that), so what accessories will be needed for the basic lathe? Tools, chucks, etc etc.

[bogstandard]

Hi Eddy,
If you read my post you should have noticed that I stated that this little lathe most probably wasn't up to the job for this article. The main problem is getting a vertical slide to fit something this small. That is the key to using a lathe to do milling, and also square drilling. Using the lathe chuck as though it was a milling chuck to hold the cutters or a drill chuck to hold drills so you could in fact get away with not needing a pedestal drill. The C2 or the C3 would be even better as good vertical slides can be obtained for these units, and they are more powerful and rigid.
I would suggest you let me get a bit further into the article before jumping in at the deep end and spending a lot of money. You might decide that machining isn't for you.
By the way, it pays to advertise to other members that you are looking for a lathe, they might have something suitable second hand and you usually get the extras included for a lot less than the cost of a new machine. All my machines were bought second hand.

John

[Eddy Matthews]

Don't worry John, I had no intention of leaping out of bed in the morning and buying a lathe!

I need a lot more convincing that I can handle things before I go flashing my chequebook around - My bank manager would never forgive me, or my wife for that matter!!

[bogstandard]

Before I go any further, the most boring bits, but the most important. Ignore the warnings at your own peril!!! If you can't follow the basic rules, you shouldn't be anywhere near this post!!!!
From now on alcohol is banned from the workshop. Well thats got rid of 99% of the readers, we'll just carry on without them. In fact I'm most probably writing this post to myself.
Safety is a must, the eyes need careful protection, without them your modelling days are over, get a pair of safety glasses, AND USE THEM!!!!.
Machinery has no feelings, it will take your fingers off just as easily as it removes metal. Keep your bodily bits away until the machine has stopped. Long hair and shirt cuffs have an affinity for moving parts. Remember, don't become another piece of your latest project.  
Metal that has been machined produces heat, and a lot of it. When I'm cutting some tough stuff it actually glows. Let it cool down before you touch it, and for goodness sake don't drop hot metal into water to cool it down, you might find that the metal has become hard as glass and you won't be able to do any more machining operations on it.
When metal has been machined, very sharp edges are produced, it will cost you a fortune in plasters. Don't put away a piece of metal until it has been properly deburred. In fact I deburr after every operation, if you don't, aside from the safety aspect will, if put against a datum face, will throw all your machining calculations out of the window.
It seems mundane, but getting splinters of metal in you skin can have drastic repercussions. Get a piece of brass embedded in your skin and leave it for a few days, the puss filled, weeping, gory open festering wound will wish you had got it out with a pair of tweezers as soon as it got in there. Remember there will be minute bits of metal everywhere, keep your hands away from it, sweep it up or better still get an old vacuum in there and suck it up as often as needed.
If you can add any more please do, I can't think for everyone, it is up to you to keep yourself safe and healthy, no-one else - YOU!!!. In fact in industry you can be prosecuted for having an accident, lose your fingers, get prosecuted, what a bummer. But you only do it the once.
Lecture over, it does get better, but it had to be said.


The Main reason you are reading this.
Project - To build a twin cylinder slide valve steam engine with the same bore and stroke as my previous oscillator, namely 10mm bore x 20mm stroke. This will allow parts designs from my previous engine to be used with this one. This will save a lot of time having to design new parts. All measurements are metric. Hopefully there will be no 'bit' measurements, I will try to keep everything to the nearest 1/2mm. I am also building in a few adjustable bits for those of us who are not quite as accurate.
Please be aware that I design and make as I go along, aided by a few sketches. If anyone wants to build one you will have to strip it down and measure it up, and give me a copy of the drawings.
Or else ask and I will post what workings sketches I have.
I will be building two engines in parallel so if you see two of everything don't worry, I am hopefully going to make one horizontal, and not by drinking alcohol.
Most of the raw materials for this build will come from the yard of many skips, or have been donated freebies from people that say "give it to that nutter John, save us having to take it to the tip". Little do they know about the cost of raw materials.
95% of my raw materials for building are not the correct size or shape, you have to go with an open mind and envisage what is in there trying to get out. I expect this engine excluding fasteners to cost me less than £10 in raw materials. Your local scrapman will become your best friend, slip him a couple of quid and he will be happy to hack old material into smaller bits, it will save hours in the workshop trying to cut it down yourself.
Throw no materials away. If while machining say a bit of brass and you cut off a 10mm long piece to get to size, don't throw that piece away, if you cut a bolt down, anything you cut off over say 6mm long, save it, great for making studs and joiners, saves time as well. Nothing is truly done for until it can no longer be used for anything else. It is people that don't follow these rules that get me all the raw materials from the scrapman.
The one thing that I do invest in is good quality fasteners, and I get them from here - http://microscrews.easywebstore.co.uk/  
If it is not on the site just give them a call, only about 10% is shown on the site but they stock everything in stainless screwed fasteners, but only in metric I think, up to 4mm, and very reasonably priced as well.
By the way I have no affiliation to these suppliers, other than being a very satisfied customer
What I do is during the build I use any old crappy screws that I have lying around, and when the engine is up and running I put shiny new ones in.

Now to start (and hopefully finish)

Metal for the main block or 'How to hopefully recycle a useless bit of metal into a bit of metal with a use'

Picture 1 - The scrapmans moll, gently eased apart to show the tempting secrets within.
Picture 2 - With even more teasing further treasures are revealed.
Picture 3 - After an hours hard fumbling the sheer beauty is revealed, silky smooth, soft to the touch and a delight to fondle (I must stop reading the wifes girlie mags).
Picture 4 - Hacking off the outer skin to get a nice square block.
Not bad for a lump of scrap cast iron from the scrapyard that cost 30p (35mm cast iron bar, over £10 if bought from a metal supplier, over 90p per inch), will be able to get about 6 engine blocks (5p each) out of one sash weight and is most probably up to a hundred years old and you won't get much better seasoned material than that.
This has been a long haul post but it sets things into the correct frame of mind, just to reiterate, safety first and foremost, clean and deburred, get to know your friendly scrapman, don't be put off if you bodge it up, if it can be put right it was never wrong in the first place.
The next posts will be nowhere near as bad as this one.

[bogstandard]

Lay back a little.
Metal doesn't just up and run away out of your chuck or vice (unless of course you didn't tighten up enough then it will chase you round the workshop), so take your time, the world won't end if you don't get the bit machined tonight, go and have a pint, be nice to the missus for a change. It is when you rush, get tired, fed up or whatever that accidents and mistakes happen, it will still be there in the morning. You are not in a production environment, unlike Sandy, who has to get things out on time otherwise his employees don't eat. Get to enjoy yourself, because if you don't enjoy it you shouldn't be doing it.
I don't use tolerances (this is a designed figure that you can work to, and if kept within the figures will ensure that the mating parts will fit together and carry out their designed function). Because these engines would be classed as prototypes, I make everything to fit individually. If you go slightly over or under on the bores, make the pistons to fit, the grim reaper won't call just because one bore is 0.02mm bigger than the other. So I try to keep to exact size, but I don't worry if not.


A few general notes for machining.
To get an idea of using a vertical slide on a lathe, when you see a picture of my milling setup, swing the picture thru 90 deg and imagine the cutter being in your lathe chuck and the vice as being the vice on your vertical slide, you can do everything I can do with my miller, maybe not as quickly, but as mentioned above, why rush.
Use a dial test indicator for setting the fixed jaw of your machine vice totally parallel and square to the cutting action of the cutter. This can be done without a DTI just by machining a piece of metal and measuring the results.
The fixed jaw of the vice now becomes your datum face, don't move it unless you really have to. After you have been doing any heavy cutting, check it again, just in case it has moved.

To get square out of round. Put material in vice, and face off the side. Then clean off the swarf, deburr both cut edges and remount into vice putting the now flat face against the datum jaw. Take a cut across the face, this will give you two sides square to each other, again clean and deburr.
The face you have just cut goes down into the vice with the same datum face that you used before against the fixed jaw. I set my piece onto parallels and tap the material onto that until it just grips the parallels, that way I know that everything will be square and parallel. But if the jaw is square to the base of the vice you should be ok.
Now machine the third side down to the required thickness, again, as usual, clean and deburr.
Put the first machined side down into the vice with one of the now machined and parallel sides against the fixed jaw, tap down the material and then cut the fourth side down to required thickness.
If all is well you should now have a piece of bar that has opposing faces parallel and square to adjoining faces.
If you can get this right everything else is almost easy.

Forgot to mention, a cheap digital vernier is a very good investment. Last one I bought was about £9 from Aldi.

Here is a website to give you a few basic instructions in metalworking, and explains things a lot easier than I can - http://www.nmri.go.jp/eng/khirata/metalwork/index_e.html
There is some pigeon english but most of it is understandable.
If there is anything at all that you don't understand, just go to Google and type in what you want, ie 'using a vertical slide' or 'how to use a boring bar in the lathe', most questions will give you all the info you require and just add the sites to your favorites for later reference.

The first picture shows a lot more than you think.
I have already faced one end of the cylinder block, now is the time to get it to the right dimension.
At the bottom left and right of the picture are two of my most useful bits on the lathe. The right hand one is the saddle clamp that locks the saddle solid, the left hand one is a saddle stop that I made for this lathe, it doesn't have to be this complicated but it can stop you ruining your lathe.
It stops the toolpost going too far and hitting the chuck, usually with irreparable damage. This is usually a fairly simple thing to make and you will wonder how you ever lived without it. The way I use it for facing is bring the saddle to it and lock the saddle, then I can use the top compound slide to give very fine cuts without having to worry about the saddle being pushed back by the pressure of the cut.
I am using my four jaw chuck to hold the material, the material doesn't have to be centralized when end facing, in fact with a little bit of ingenuity the whole block could have been machined in the four jaw.
I am a stickler for a good surface finish, and will spend hours lapping and polishing, so you will notice that I have used a bit of cut up drinks can (I prefer Pepsi Max, but almost any will do) between the jaws and the material, this is to protect the surface finish, chuck jaws are very hard and will mark most materials.
On the metal sticking out of the jaw, near to the cutting tool, you can just notice a felt tip mark near to the end. This allows me to rough cut up to that mark, leaving me about 1/2mm to go to length. Then I take a very fine facing cut (maybe 0.02mm , 0.001"). Then remove the piece from the chuck and measure the length. This will tell you how much you have left to come off to get to size. Remount in chuck with Pepsi Max, bring the tool to just touching the face then take your cuts, the last one being like before, very fine. You will find that you should have now a piece of material to the correct length.
The last bit in this picture is rather indistinct, that is the cutting tool itself. I started using one of these so called 'profile' tools about 5 years ago, and it is one of my most prized possessions in getting my own back against lumps of metal. They are obtainable from a lot of places but here is about the cheapest - http://www.rdgtools.co.uk/cgi-bin/sh000001.pl?REFPAGE=http%3a%2f%2frdgtools%2eco%2euk%2f&WD=profile&PN=INDEXABLE_LATHE_TOOLS%2ehtml%23a13086#a13086
Go to the bottom of the page and all will be explained. I bought five tips for it when originally purchased, I am just on the last one now. The beauty of these is that when the tip wears you just turn it a few degrees and you have a brand new cutting edge, and the surface finish is superb. About £3 a year running costs, not bad, and it is used daily for facing, reducing to size and of course a little bit of profiling.

The second pic is the blocks finished to size, blued up (this is not really necessary, but you don't have to scribe such a deep line to see it) and marked out for the job tomorrow, namely putting the big holes in.
Oh! and a little message for Eddy, here is the first wart (or pimple), the block was a bit tight to get out of the rough cast material and is in fact 0.15mm (0.006") too short on the height, but as I said, don't worry, all I will do is take the same measurement off the top of the piston and all will be right with the world.

John

[sandy_ACS]

 

Hi PD's,

John......Looks good so far, however, just a couple of additional tips for everyone.....when using a milling vice...

The face you have just cut goes down into the vice with the same datum face that you used before against the fixed jaw. I set my piece onto parallels and tap the material onto that until it just grips the parallels, that way I know that everything will be square and parallel. But if the jaw is square to the base of the vice you should be ok.

This will only work well providing your milling vice, or vertical slide vice, are of high quality...cheap vices are just not true enough....The inside (datum) face of the fixed jaw must be absolutely vertical (90 deg.) to the top face of the vice base, which in turn must be set truly parallel to the cutter. Ideally, the top face of the fixed jaw should also be absolutely parallel to the top face of the vice base (if not then use the top surface of the base as your second datum), but on anything but a high quality, or toolroom standard milling vice, it is highly unlikely that any of these requirements will be the case.

There are other methods, using an angle plate, parallels and suitable clamps, but I will leave it to John to enlarge on this for you, should he choose to do so...after all it is his article.

Oh! and a little message for Eddy, here is the first wart (or pimple), the block was a bit tight to get out of the rough cast material an is in fact 0.15mm (0.006") too short on the height, but as I said, don't worry, all I will do is take the same measurement off the top of the piston and all will be right with the world.

I would not be to concerned about 0.006" after all you have got, or should have, approx 0.031" clearance volume at each end of the bore...if you adjust the con-rod length (the big end or piston will I assume be screwed on) you can make this -0.003" at each end of the stroke...no worries.

BTW John, I hope you got the gist of my explanation on eccentric location/orientation...if not then let me know and I will try to explain it in a different way...sorry if it confused you, but it is an important detail.

As for standard direction of rotation....on single screw vessels the majority would have clockwise prop rotation when looking towards the bow from astern.

On twin, or multi screw vessels then Port side screws would turn counter-clockwise and Stb screws would turn clockwise...again looking from astern.

This is known as outward turning...in other words the topmost blades turn outwards, away from the rudder/s

Keep happy.

Regards to all.

Sandy.  :computer  

[bogstandard]

Hi Sandy,
Many thanks for the comments, all duly noted.
Hopefully the article will not now be as long winded, I just wanted to get across the basic understanding of machining metal and what is involved, and put over how I cope with the odd situations.
The eccentric bit did confuse me because you switched ends half way thru. The way I see it now, is that when viewed from the output end (the end connected to the shaft), engine going in a clockwise direction, with the nearest piston in the fully upstroke position, the eccentric  will be 90deg to the right,  the rear piston is on its downstroke and its big end at 90deg to the right (the same position as the front eccentric)  and its eccentric 90deg fwd of that at full bottom stroke, or should the rear piston be on its upstroke and it's eccentric be at the same position as the front pistons big end? Or doesn't it matter.
When I asked about direction of rotation of props, as far as I'm concerned, on the full size it is pointy bit at front, blunt bit at back, don't know whats underneath, can't see it unless I get wet. On models as far as I was aware, you always went for the safety factor and a single screw always went anticlockwise when viewed from the rear, so the shaft was screwing the prop on tighter (the same as the port side setup when viewing a twin output).

John

[derekwarner_decoy]

Hi PD's & I do agree with the......quote by Sandy....

On twin, or multi screw vessels then Port side screws would turn counter-clockwise and Stb screws would turn clockwise...again looking from astern.

I think Sandy really means being astern & looking FWD  :twisted:

.....however what happens in a triple engined vessel :?: ... from memory   the above is true & also minimises cavitation...but the middle prop shaft in early British war ships & was in fact a shaft within a shaft complete with CONTRA rotating propellers

No one really liked this too much  :ohno     & just prior to the GREAT WAR [WWI] triple engines vessels gave way to twin or quadruple engined vessels

Twin turbines were also used into one gearbox & propeller in merchant vessels

The US designed Doyle class FFG vessels [guided missile frigate] [4000 tonnes] [still servingi n the Australian Navy]  have twin GE250 LM gas turbines through one gear box to one constant speed variable pitch propeller

[bogstandard]

Now to get back on track.
I will sometimes mention a couple of words that need a bit of explaining and they are related. These are CONcentric and ECcentric.
Concentric means in our situation that the outside diameter has the same centre as the inside diameter, a good example is a well made washer.
Eccentric means the outer and inner diameters have different centres, like the holes on a button, stick it on a shaft and spin it and it wobbles up and down.

Found this site today - http://www.jjjtrain.com/vms/library.html
Almost everything you need to know about using the things and operations I use on the lathe and milling machine can be found here.
Be very careful though, if you are just starting out in machining the hours will fly by while surfing on this site. Vids and all sorts on here.

When drilling holes bigger than 2mm you should always if possible use a centre drill, if drilling large holes say of above 6mm, eg 10mm. Start with the centre drill, then use something like 4mm followed by one around 7mm, then 9mm and finish off with the 10mm.
You will find that the holes will be a lot more accurate than stuffing a 10mm straight in.
For sheet metal drilling I find that cone drills do a wonderful job, they don't snatch when breaking through.
The first picture shows centre drills and cone drills (another great buy from Aldi).

The second pic shows the steps I will use to drill the bores through the main block. I will finish off with a 10mm reamer, but if doing it on a lathe you can bore the holes or just drill them either mounted into a four jaw chuck or vertical slide, but you must make sure that you don't drill into the holding chuck or vice.
Two other things to note on this picture. The first is showing block sitting on parallels to allow drills to penetrate right thru without doing any damage. The other is that just behind the block is what is called a back stop, this allows me quickly to flip the block around and without having to remeasure, drill the second hole.
Backstops are also used on a lathe, I will point it out when I come to use one.

Third pic shows cylinders bored and reamed. The surface finish in the bore looks really grotty, but in real life they are like a mirror.

Work has now finished on the blocks for the time being, the next bit is to make and fit the pistons and rods.


John

[Eddy Matthews]

I still can't get over the fact that I'm actually managing to follow this without any problem!

I can see that I'm going to have to talk one of my club mates into letting me have a go on his lathe, then I can see if this sort of thing is really for me before parting with the hard earned!

However, should I decide that it is for me, and i go out on a spending spree - Where should I send the bill John? After all it will be your fault, so I think that's only fair

[bogstandard]

Hi Eddy,
Glad you can still understand it.
When people come round to my house to learn how to do things I usually get them to make something simple, like the picture below. There are dozens of people with one of these in their sailing jackets, it reminds them of the first thing they ever made on a lathe. Many of them now are craftsmen in their own right, not just machining but using metal for other things.
But be careful, using a file to profile needs to be done under supervision to show where not to put your digits.
Send the bill to Decoy, he seems to have a very good lifestyle that costs him very little, he can afford it.

John

[sandy_ACS]

 

Hi All,

John .....

The way I see it now, is that when viewed from the output end (the end connected to the shaft), engine going in a clockwise direction, with the nearest piston in the fully upstroke position, the eccentric will be 90deg to the right, the rear piston is on its downstroke and its big end at 90deg to the right (the same position as the front eccentric) and its eccentric 90deg fwd of that at full bottom stroke, or should the rear piston be on its upstroke and it's eccentric be at the same position as the front pistons big end? Or doesn't it matter.

Sounds like you have got the gist of this....from a model point of view it does not really matter...either is correct for running, however, on full size engines the NORM is for number 1 cylinder/crank to lead the number 2 crank by 90 degrees....so if you term your rearmost cylinder number 1 then when it is at TOP DEAD CENTRE the other one should be on it's up-stroke.

Just to add to the confussion  :twisted:  :twisted:  : ...He He....on real ships, number 1 cylinder is always nearest the bow (pointy bit to you). :music  :hmmm  :hmph

As for prop rotation...yes, on model ships/boats the general trend was to use anti-clockwise rotation on single shafts...this stems from the earlier times when IC engines were more the norm and these always run/ran anti clockwise.

On real ships, the prop is pretty well always keyed, or splined, to the shaft and the retaining locknut/s were always cross pinned or had keyed locktabs on them to prevent them unscrewing, sometimes they were threaded to be opposite the direction of rotation (left hand thread for clockwise rotation), or even both methods were used.

DEREK....yes I did mean ASTERN looking FWD...    :hmmm why didn't I say that.....

I must admit, I have never seen a British capital ship with contra-rotating centre shaft props....but that does not mean they did not exist....and I can imagine the operational problems they would present.

Some of the WW2 German capital ships had 3 screws...TIRPITZ, BISMARK and SCHARNHORST...to name but 3....and their centre shaft followed normal practice as for single shaft ships...i.e they turned clockwise....same as the STB shaft....apparently this did give some problem with stearage when going full ahead on all shafts.....hence the reason for most British Naval ships to either have 2 or 4 shafts.

Interestingly though....a lot of earlier twin screw tugs had/have inward turning props since this does give better rudder authority at low speed.


Keep Happy.

Best regards.

Sandy. :twisted:  :  :music    :computer  

[derekwarner_decoy]

deleted   & reposted in the correct folder - Derek

[bogstandard]

Sandy,
Thanks for the info again Sandy, I've got something right at last.
Did a few calculations last night, dog helped me, he's better at maths than I am. This is sure going to be an ugly engine, and because I am limited to height because of the size of raw material on the block it caused me a bit of concern, I would have liked about another 5mm on height but the dog and I have solved it all and still keeping to the 20mm stroke. A bit tight but definitely do-able. If its wrong the dog gets it.

Derek,
It was my birthday yesterday, and was treated to a pack of paper, no stopping me now, the only prob is, I don't know which way up the sheets are supposed to be, there are no markings on them.

John