Making a piston valve engine from mainly junk materials

[bogstandard]

Hi Peter,
Don't worry, just getting my hand working again, doing all the drawings today. So should be posted later.

John

[bogstandard]

Here is the second part of the control block build.
This one is a bit of a long haul.
The major point on here is the recess for the 4mm bore by 1mm cross section viton o-ring (purchased from Blackgates Engineering).
This o-ring stops steam leakage thru the control arm hole. The recess is bored 0.9mm deep, refer to picture 1, to allow for an 0.1 mm crush on the o-ring.
This area can be machined to suit if you have o-rings of different sizes, but you must remember to alter the spindle size and the clamp hole size.
Anyway, back to the making and building, this is done in stages to allow the correct fitting of parts.
The first bit to be made is the spool. Turn your bar down to fairly tight fit in the main bore of the block, for a length of about 30mm. Then turn down the 15mm long by 4mm spigot on the end. Part off the spool leaving it about 8.5mm length on the main spool. All shoulders on this spool valve need to be kept fairly sharp and square, so no heavy deburring.
Refer to pic 2 shows what the spool should look like, and it should be fairly tight in the bore. Next hold the spool by the spigot of your chuck, and put a bit of metal polish, t-cut or chrome polish (raid the garage, you might find a very mild abrasive substance in there) and start up your lathe on the slowest speed possible. Refer to pic 3. Being very careful about keeping your hands away from the chuck ( I used my collet chuck because it is safer for me because I have to work left handed), gently feed the bore onto the rotating spool, get ready to let go just in case it galls up and starts spinning (galling is where the materials lock together, usually it is caused by the materials being the same or one is very soft). If this happens turn off the machine and try to unscrew the bits apart, if not remove the lot from the chuck and gently tap apart using a piece of wood to protect the surfaces.
If all goes as planned the spool will go all the way thru the block, move the block up and down the spool a few times and it should feel nice and smooth and free. Don't overdo it. Take out of the chuck and give everything a very good clean, you don't want abrasive running around inside your new engine. Put a bit of oil (I use multigrade or 3 in 1), on no account use WD40 anywhere near this engine, this was mentioned by both Sandy and myself a few posts back, it ruins certain types of o-ring seals, and put the bits together and turn them, they should be silky smooth with no rock between the parts. If you've got rock, you've either been to the seaside or you have overlapped the parts. Make a new spool and start again, don't worry about the bore, we make everything to fit that.
This takes you to pic 4, showing the bits together.
Put the spool away safe for now and refer back to picture 2. We now make the top and bottom covers. Start with the bottom cover, remembering from the sketch that this has a thicker flange to allow for threading to 2.5mm. The spigot on it is machined for a good fit in the bore. The top cover is like the spool, done in stages to keep everything in line. Turn the 7 mm spigot first and part off from your main bar.
Remount in your chuck by holding onto the 7mm spigot. If you haven't already done it turn down the od to 22mm. Now turn down the flange and the spigot for the bore, don't worry too much about the 1mm depth for the bore spigot, close enough is good enough, that goes for the bottom cover as well, as long as the total thickness of the flange and small spigot together add up to the total required on the drawing all should be ok. At this stage bore your 4mm hole. Next cut your recess. If you are worried about getting a boring bar to do this, let me know and I will show you how to do the job with a throw away one that only takes 10 minutes to make.
Now you have got your two covers, pick up the holes from the main block and drill and tap all the holes. Then go and have a coffee and or a fag, cos the next bit is going to take ages.
Now you are refreshed and remember how I told you to make the 10mm diameter spool longer than required. Put the spool in the bore, pop the bottom cover on followed by the top (no need for o-ring until final assembly), no need for bolts yet. Hopefully the covers don't touch the faces of the main block, if they both touch, make a new spool, just a bit longer this time. Put the assembly on a flat surface, bottom down and push on the block, this will seat the bottom cover and raise the top cover away from the block. This is the amount we need to remove from the length of the spool. Do a rough measure and remove a smaller amount from the bottom of the spool, try again, if it is getting very close, just remove 0.02mm at a time, until you are so close put a couple of screws in the covers and see if it still turns (don't tighten down until the later stages), continue until you can just turn the spool with the screws tightened, with no up and down movement. When you get very close, rather than turning any off, try emery on a flat piece of wood to just to remove minute amounts. It took me about twenty disassemblies to get them perfect. Now to hack out the slots in the spool
Refer to pic 5. The slot is central on the spool depth. If you haven't got a 3mm cutter a 1/8" will suffice. Cut down to 3mm depth. Before you take out of the vice, scribe a line parallel to your cut across the face of the 4mm spigot, this is to show you where the control faces are after it is assembled in the block.
Now go to pic 6. You have to mount the spool so your cut is parallel to the first one, I don't have a narrow enough parallel to sit inside the previously cut slot, so I improvised and used the blade on my engineers square. Machine the same position, size and depth of the first slot. Job nearly done.
Only deburr by slight scraping of the edges. You will most probably find that it will now not fit into the bore, but just put a bit more metal polish on to the spool, and do a very gentle relap.
Clean down again and assemble, using some sealant on the face joints, but this time put the o-ring in, this will cause a slight bit of drag but nothing to worry about.
Make the control arm, fit it so that it is at right angles to your scribed marks and you should have a non leaking control valve.
All the bits for the assembly are shown in picture 8.

John

[bogstandard]

Almost there, the last component for the engine.
I have made here a fairly large lubricator, should get a good session out of this.
Three bits on the sketch, the fourth you have made previously, the longer of the two steam pipes.
Picture 1 shows the three parts to be made plus the long tube with a hole drilled half way along in line with the mounting bolt holes, the hole only goes in one side, mine is 0.7mm diameter, but you can use up to 1mm. If it underlubricates I can always open up the hole, but if it lets too much thru it is difficult to make smaller. The bit of text pointing to the cap is if the cap won't tighten down fully, just put a small recess to the bottom of thread depth and that should cure it.
The o-ring is 8mm bore by 1mm cross section viton (the same as the piston rings), the one shown here is in fact a used one from running in my oscillators, it is only worn on the outside edge so why pay another 47p for a new one, as I said before, nothing is thrown away until it can't be used any more.
Pic 2 shows the bits silver soldered up. I soldered up the chamber and top first, then put it in the lathe to be cleaned up, then I soldered in the copper pipe. When soldering this in make sure that the flange is in the up/down position otherwise you will have trouble filling the lubricator, but not emptying it. I put the hole on mine facing up, so if it does get blocked it can be cleaned out.

ONLY USE CORRECT STEAM OIL IN THIS LUBRICATOR. For the rest of the engine almost anything except steam oil or WD40. I use multigrade.
You might have to make a few extended tools to fit these two pipes correctly, but that is the price you pay for having no bends.

I will try to get the timing sorted by days end, but no promises.

John

[bogstandard]

The final bit of the build, getting it to run efficiently.
First look at the photo, it shows the position of the parts I will be referring to.
It is easier to set up if the top and bottom are not joined at the start, as it is easier to adjust the crankshaft timing, but can be done with things built up.
First you have to make a decision whether you want the engine timed to run clockwise or anticlockwise as viewed from the flywheel end of the engine, it shouldn't matter, it should run the same in both directions, but due to machining errors it is not always the case. If it doesn't work well one way, try the other.
I have given you the view for both on the sketch.
To start, set the two cranks either side of the crankshaft centre bearing block at 90 degrees(or very close) to each other and tighten up, these will not be moved again.
Viewing from the lubricator end of the engine, set up No 1 crankshaft to a horizontal position as shown in the sketch, depending on direction chosen. Slacken off the screw in the crank nearest to the eccentric and turn the eccentric until the marked line (you did remember to put the line on) is at 90 degrees to the crank and lock up the screw. If you didn't mark the lines on you will have to use a DTI and find the point of highest lift and mark that.
Turn the engine round so you are viewing from the flywheel end and carry out the same procedure on crank 2 and eccentric 2.
That is the bottom end timed. From now on nothing should be moved on the bottom end.
Assemble the top to the bottom and carry on with the sketch about timing the top end. Leave the bore top caps off, and the piston valve end covers, but put screws or nuts on to hold the piston valve block in the operating position.
We will totally complete the piston 1 and valve 1 first.
Always turn your engine now in the direction you set the bottom up on, there should be no difference but you never know in this world.
If you read the sketch it explains everything, after you have finished the number 1 end, proceed to the other end and carry out the same procedure.
You should now have a fully timed engine. But because we all have different tolerances and fits no two engines are ever the same, so might need a little bit of timing tweaking on the piston valves, only minute, opening slightly earlier or later, but at least you can now always set to basic.
Mine was a fair way out all round when I retimed it today, but my vids show that even being out on that, the engine will still run fairly well. It took me about half an hour to retime mine, and seal the plates.

If I have made any mistakes on here please let me know and I will put it right.

John

[derekwarner_decoy]

Hi PD's.... still a brillant build John   & you say.... made from scrap...but that is only a SMALL part of the story we PD's have experienced...you have explained relatively simple machining techniques that people like Eddy or myself can understand & produced the   results for our own eyes - however I still see years & years of experience behind the concepts & notes {& Bandits mathematics}  :music

So the only two questions I ask .......

1) after the timing has been set & established...do you provide further match marking... then the engine down to pieces.... spray with Loctite 7471 primer & the reassemble with a Loctite stud lock material?

2) you have used M4 &  M :?:  tappings & used  stainless steel socket head cap screws... are you going to nominate a torque setting for the respective fastners  :?:

[bogstandard]

Hi Derek,
Glad you have enjoyed the build as much as I have, as you know I have a bit of a problem and doing this has forced me over the last couple of months or so to remain active both physically and mentally, so the build hasn't just been for the people that have been following it but for myself as well. That is why I take on projects that last a couple of months, I know that I can get that far before I have to put on my slippers and watch soaps on the box for a few days.
Now for your two questions.
With reference to marking, stripping down and rebuilding. This engine has to be stripped because there are a few things that need to be done, like the flats on the packing glands for the piston valves, but I won't do any more marking, just keep each end of the engine separate. On rebuild, I always use Hylomar jointing compound for all sealed joints, this acts like a mild threadlock for the holding bolts and screws. For the bits that might  be forced to unscrew, the pivot pins on the joints for the eccentric to piston valve spool and the crosshead to conrod joint will get a drop of nutlock on the threads. By using stainless fasteners, not just for corrosion resistance, but also they have a bit of a 'grab' factor when tightened, so with the low vibration levels on this engine I don't expect to have anything come loose.
That brings me onto the second question about torque loading. Normally for larger sized bolts, a big shifter and white knuckles would do it, but for these small bolts, I don't think it is required and it would just complicate things. In fact I am having a bit of trouble with this area myself. I am trying to convert to being left handed and I just haven't got the 'feel' yet and am occasionally stripping out the hexagon heads of the screws so maybe I should get a small screwdriver torque wrench.
There is one thing I forgot about and that is the packing of steam glands. What I do is unwrap the 'string' into smaller threads, wrap it around the shaft I want to seal, then push it into gland with a thin piece of rod ( the one on piston valve is a bit tight but can be done), tighten up the nut until you have a gap of about 1mm between the nut and the gland and you can feel the friction being applied to the shaft, if too much friction just undo about 1/4 turn, if it can tighten all the way up, you need to put some more packing in.
I would like to add it is not just yourselves that have learned new things on this post. I have found out how to use my camera a lot more efficiently, plus all the related bits that go with it, like using the computer for graphics manipulation and video. How helpful people on this site are and their willingness to share information, not just with me but with everyone.
One disappointment is the feedback, I was expecting loads of questions, but very little materialized. Either I have explained well enough so questions were not needed, or it was totally above their heads and were afraid to ask because it might make them look silly. As I have said before, there is no such thing as a silly question, just a silly sod for not asking.
There have been a fair few hits on this posting, and looking by the number of times the pictures have been viewed there must be about 50 contemplating building, which is well above my wildest dreams, I was expecting four or five with an interest. Another way to look at is that next year the country will be flooded with far eastern made piston valve steam engines.
Now I have to find something else to make, this one is a none starter for horizontal conversion, it is just too long. Any suggestions will gratefully accepted, and I do mean that.
I want to do a final vid just to show how well the control valve works, but I want to do it outside in a different setting, but every time I try to set it up it starts raining. Maybe later today.

Thanks all, and keep the questions coming.

John & Bandit the Brain

[sandy_ACS]

   


Hi PD's,

I think we all owe John a huge amount of gratitude for this series of posts.

What a magnificent effort.

 :no1  

It just shows what can be achieved with very small budget and a bit of lateral thinking.

John's design should be easily achievable by others, even with only small/modest machines available. All this really means is that some elements of machining would take a little longer (lighter cuts), or perhaps require a slightly different method of work holding to suit the available equipment.


If I may, I would like to add a few notes regarding timing...... It Sure beats building kitchen units....    

The biggest problem in all timing is finding the TRUE DEAD CENTRES.

On the surface, this may appear simple, but one thing, in particular,  should be taken in to account..... Namely, LOST MOTION, and it's effect on angular rotation.

When the piston is being driven down by steam pressure the crosshead is being pushed, and hence the thrust is applied to the crankshaft side of the crosshead small end pin/bearing.
Conversely, when the piston is being driven in an upwards direction, by steam pressure from below, then the crosshead is being PULLED, as a result the thrust is now taken by the opposite side of the crosshead pin/bearing.
The same applies to the big end/crankpin/ bearing.

Whilst this may only amount to a small dimension (especially in a new engine, and assuming careful machining), it is, however, inevitable in any running bearing, and it creates the LOST MOTION I refer to.

Every time the piston changes direction, some piston motion is used up taking up the slack in the bearings (albeit a very small amount) without any actual motion of the crosshead and/or crankshaft. This is LOST MOTION.

It can, especially where large running clearances are involved (or in a worn/well used engine), make quite a large difference in angular position of the crankshaft when locating the TRUE DEAD CENTRES.

I attach a drawing and some text explaining how to find the true dead centres, taking into account any lost motion.

Once marked up, then it is easy to find the true dead centre positions for the crankshaft rotation.

It is well worth performing this task prior to attempting to set the eccentric angles and valve timing.

Incidentally, there will also be some LOST motion in the eccentric/eccentric strap bearing surface and the pin/bearing at the connection with the spool valve...... this must be minimised by close running tolerances, and allowed for in the valve setting.

One final point..... when setting the position of the valve spools (at TDC) it should be just about to open..... any actual open amount will reflect as a non-open amount when the piston is at BDC.... think about it..... which means the crank will need to pass BDC before the lower port opens.

For this reason alone, it is important to get the length between the spool lands dead right...... i.e. the same as the distance between the outer edges of the steam ports.

Ok PD's, That's my small contribution..... so AGAIN, very well done John and thanks on behalf of all PD's.          :respect2

So whats next?..... a true scale Titanic engine perhaps?..... Although this will mean the CAT will have to go to college and get a degree in maths as well...... you don't want to see the valve gear calculations involved....    

Best regards to all.

Sandy. :computer    :vacat

[crash93]

Yes thanks John, I look forward to each Instalment

Peter

Ps. for those who like this sort of thing I have been following another build over the last few years

http://mokei-jouki.hp.infoseek.co.jp/e-Wiltop.htm

[woody]

John
I have followed your build with great interest,having not used a lathe
since I left High school,55 years ago. I found your packing instructions the
same as I would use to pack or repack steam rods on a pump or valves, lots
of graphite to lubricate them. Great site.
Regards Alex

From: "bogstandard" <livesteam@paddleducks.co.uk>
Reply-To: livesteam@paddleducks.co.uk
To: livesteam@paddleducks.co.uk
Subject: Re: Making a piston valve engine from mainly junk materials
Date: Tue, 17 Jul 2007 12:52:18 +0100

Hi Derek,
Glad you have enjoyed the build as much as I have, as you know I have a bit
of a problem and doing this has forced me over the last couple of months or
so to remain active both physically and mentally, so the build hasn't just
been for the people that have been following it but for myself as well.
That is why I take on projects that last a couple of months, I know that I
can get that far before I have to put on my slippers and watch soaps on the
box for a few days.
Now for your two questions.
With reference to marking, stripping down and rebuilding. This engine has
to be stripped because there are a few things that need to be done, like
the flats on the packing glands for the piston valves, but I won't do any
more marking, just keep each end of the engine separate. On rebuild, I
always use Hylomar jointing compound for all sealed joints, this acts like
a mild threadlock for the holding bolts and screws. For the bits that might
be forced to unscrew, the pivot pins on the joints for the eccentric to
piston valve spool and the crosshead to conrod joint will get a drop of
nutlock on the threads. By using stainless fasteners, not just for
corrosion resistance, but also they have a bit of a 'grab' factor when
tightened, so with the low vibration levels on this engine I don't expect
to have anything come loose.
That brings me onto the second question about torque loading. Normally for
larger sized bolts, a big shifter and white knuckles would do it, but for
these small bolts, I don't think it is required and it would just
complicate things. In fact I am having a bit of trouble with this area
myself. I am trying to convert to being left handed and I just haven't got
the 'feel' yet and am occasionally stripping out the hexagon heads of the
screws so maybe I should get a small screwdriver torque wrench.
There is one thing I forgot about and that is the packing of steam glands.
What I do is unwrap the 'string' into smaller threads, wrap it around the
shaft I want to seal, then push it into gland with a thin piece of rod (
the one on piston valve is a bit tight but can be done), tighten up the nut
until you have a gap of about 1mm between the nut and the gland and you can
feel the friction being applied to the shaft, if too much friction just
undo about 1/4 turn, if it can tighten all the way up, you need to put some
more packing in.
I would like to add it is not just yourselves that have learned new things
on this post. I have found out how to use my camera a lot more efficiently,
plus all the related bits that go with it, like using the computer for
graphics manipulation and video. How helpful people on this site are and
their willingness to share information, not just with me but with everyone.
One disappointment is the feedback, I was expecting loads of questions, but
very little materialized. Either I have explained well enough so questions
were not needed, or it was totally above their heads and were afraid to ask
because it might make them look silly. As I have said before, there is no
such thing as a silly question, just a silly sod for not asking.
There have been a fair few hits on this posting, and looking by the number
of times the pictures have been viewed there must be about 50 contemplating
building, which is well above my wildest dreams, I was expecting four or
five with an interest. Another way to look at is that next year the country
will be flooded with far eastern made piston valve steam engines.
Now I have to find something else to make, this one is a none starter for
horizontal conversion, it is just too long. Any suggestions will gratefully
accepted, and I do mean that.
I want to do a final vid just to show how well the control valve works, but
I want to do it outside in a different setting, but every time I try to set
it up it starts raining. Maybe later today.

Thanks all, and keep the questions coming.

John & Bandit the Brain

------------------------
Ever stop to think, and forget to start again?

 Post generated using Mail2Forum

[bogstandard]

Sandy,
Many thanks for the compliment and the help you have given in the areas I didn't understand or fully able to explain, but as I said before I get enjoyment from this, and that is all the thanks that are needed.

Alex,
Start turning again, it keeps you going.

Peter,
I followed this fellows great efforts, well beyond my scope of doing things.
I look for shorter term projects.

John

[Eddy Matthews]

I have to agree with everyone elses comments - An absolutely superb series of posts by John which just goes to show that even idiots like me have the ability to make their own steam angine with the guidance given in this series.

I think the reason for the lack of comments is twofold, firstly everything has been explained extremely well, and secondly, a lot of questions would probably only come about when you actually started to make the unit. It's one thing reading a series like this, it's another thing entirely to take it as the basis of making your own engine - Only then would a lot of questions really start to become apparent.

I still hope to have a go at something like this, but having just parted with almost £5000 for a car, it may be while before I can afford to start building up the required machinery etc. Though as a secondary point, it is good to know that you don't need to spend anywhere near as much as I had first thought! You need to buy good quality yes, but you can get away with not having some machines by using some of Johns techniques and a bit of lateral thinking.

Once again, my sincere thanks to John and to everyone else that contributed to such an unusual and well presented thread.

[crash93]

,


Peter,
I followed this fellows great efforts, well beyond my scope of doing things.
I look for shorter term projects.

John

John
 I don't think you would have any problems matching his work. And on your bender you said you "may" need a rotary table to build it ,any other way to do it ? and how do I get a set of the plans of you  OR can you post a fer more pictures of it , Or even a nice new next build .

thanks again  Peter

[bogstandard]

Hi Peter,
Because the plans are from a magazine article I don't want to infringe any copyright laws by doing a build on here as the build is already in the article.
The reason for the rotary table is to cut the grooves in the rollers using standard milling cutters, otherwise you have to grind lathe tools to a perfect semi circle of the correct size.

I don't want to turn this site into a model engineering one and I am sure everyone else doesn't, just want to show how basic model engineering can help people to achieve what they want in the pursuit of making model paddlers, and maybe offer advice on how to do it.

There are a lot of other sites dedicated to model engineering and I subscribe to a couple of those, but they are 'look what I have done' type sites, and don't seem to be geared towards the support of the kind I have received here.

John

[bogstandard]

Here at last is my final video.
http://www.youtube.com/watch?v=gTuET23TkaI

I said before that the control valve was not as good as I expected. I have now changed my mind on that one. Being outside without all the compressor noise in the background I was able to hear the speed changes on the engine rather than having to rely on visual changes, and it does now come up to my ideal for a fairly easily made control valve, with no leakage.

John

[crash93]

Ok John what are you Building Now ?? and how about some pictures . I miss getting up to what happened last night on the engine ,In fact I started staying up for the next instalment.

Peter