Making a piston valve engine from mainly junk materials

[derekwarner_decoy]

Hi PD's ... & as John says....ever stop to think, and forget to start again?   that's not correct yer fool Derek

Have placed a few OFF line calls to John....turns out he has been VERY busy... the DOG is about to sit for university entrance tests & needed a BRUSH up on his maths........, the CAT sat in the paint pot & needed lots of brushing too...& to top this.....the grandson has taken back the pencil & ruler............. :ohno...its OK PD's..... I have posted another REAM of A4 paper & a few OZ pencils to John    :music

[bogstandard]

Hi all,
Back again at last. Many thanks to Derek for waking me up. Haven't got the paper or pencils yet so I have got a piccy to show you.
It shows the engine prepared for its first main run, you can tell the size of this monster by comparing it to my gorilla sized hand.
It has been assembled just from the made components with no rings, gland packing or sealant, also the timing has only been quickly done (near enough). So really this engine is leaking air from most of the joints and so is most probably only running at about 50% of its capabilities.
I will be posting soon all the components that have been made over the last week or so. Some like the spool valves I will dedicate a complete post to, like I did about the eccentrics, they are really easy to do once you get the correct machining sequence.
Anyway, have a look at the pic then go here for a quicky vid to show you that it does work.

John
http://www.youtube.com/watch?v=QwOhxvGc5VY

[Eddy Matthews]

VERY impressive John!

Will you be taking us through the complexities of making a steam regulator/throttle for the engine once you've caught up with all the other bits you've made over the last week?

How big is the video? It would be nice to have it stored on Paddleducks so it's always available here - I never trust third party sites as you have no control over them and things can go missing. Maybe you could send it to me via email and I can put it online for you? admin@paddleducks.co.uk has a 20Mb inbox.

[bogstandard]

Hi Eddy,
Glad you like it.
The video is in fact nearly 53mb, but I suppose I can get a program to reduce the size below 20mb, but you will lose quality, as it has already done so on utube.
Yes, I have got the design of the speed control valve in my head, its just a matter of getting it made and working, it isn't my design but a modified one to make it easier to produce.
It will take me about a week to catch up, but I am feeling a lot more confident now that the design has been proved.
I would like to take this opportunity to thank Sandy of ACS for the help he gave me in explaining the operation of the valve gear, which enabled me to get it all to work in unison.

John

[woody]

Very nice what boiler does it use ?
Regards Woody

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, 03 Jul 2007 19:54:42 +0100

Hi all,
Back again at last. Many thanks to Derek for waking me up. Haven't got the
paper or pencils yet so I have got a piccy to show you.
It shows the engine prepared for its first main run, you can tell the size
of this monster by comparing it to my gorilla sized hand.
It has been assembled just from the made components with no rings, gland
packing or sealant, also the timing has only been quickly done (near
enough). So really this engine is leaking air from most of the joints and
so is most probably only running at about 50% of its capabilities.
I will be posting soon all the components that have been made over the last
week or so. Some like the spool valves I will dedicate a complete post to,
like I did about the eccentrics, they are really easy to do once you get
the correct machining sequence.
Anyway, have a look at the pic then go here for a quicky vid to show you
that it does work.

John
http://www.youtube.com/watch?v=QwOhxvGc5VY

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






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[Eddy Matthews]

you can tell the size of this monster by comparing it to my gorilla sized hand.

Notice the knarled fingertips - Definately the hand of a borne engineer!

[bogstandard]

Hi Woody,
No thoughts on making a boiler, but a commercial 3.5" one should power it ok. I said in an earlier post that if I was designing this without the limitations on material sizes I would most probably make it with a larger bore. The physical size of the engine is rather large compared to my twin cylinder oscillators which use the same bore and stroke.

Eddy,
I wouldn't call them gnarled, just well used. Thats what hands were made for, its just that people use them in different ways :nose
Tried to send a resized vid to you last night, and it was returned because it said your box was full. I have resent this morning, see if that fairs better.
I will be drawing up some bits today so will most probably post tonight about the spool valves.

John

[derekwarner_decoy]

OK PD's.......it is easy for me being 20,000 km away  & :post ... the  machined & assemblied engine is  :no1  &  :kewl .... however don't give up the day job John... as your 1/8" copper temporary pressure inlet source looks     in need of a STRAIGHT/STRAT/STRAIT piece of tubing....you know what I mean  :hmph

[bogstandard]

What do you mean Derek, 1/8" copper temporary. This is finished product, all my pipework looks like this, gives it a 'used' look.
And now, the 'easy way' to make your spool valves. This is a rather lengthy post but it goes thru step by step how to get useable spool valves.
The first thing to do before anything else is to look at pic 1. Put two pieces of close fitting rod thru the two steam port holes. Now measure close to the block, to the outside of both rods on each side and take a mean measurement, that is if one side measures 18.96 and the other 18.98 the mean is half way between the two 18.97mm.
I decided from my four readings to go for 19mm, on no account go for anything shorter than the largest of your mean reading. This is going to be the distance between the ends of your spool valve.
There is no picture of the next step. Cut a length of bar to 46mm and just face both ends. While the bar is still unmachined and rigid drill the two end holes one 24mm deep by 3mm diameter and the other 10mm deep by 2mm diameter, and tap the 10mm end out to 2.5mm.
Put the untapped end into the chuck (I would recommend making a split brass collet to protect the finish on the bar) leaving about 28mm protruding from the chuck. Using VERY sharp tooling turn down the end for a length of 26mm to a diameter of about 4.05mm, the last job with the cutting tool is to face the end closest to the chuck, these corners must be kept really sharp and if need to be deburred use only very worn emery or fine steel wool.
Finish down to size with fine emery (if you look at pic 9 they look rough as old boots but in fact they are totally smooth like the one laying horizontal).
Now remount the rod with the 4mm end in the chuck (again protect if possible) with enough of the 4mm end protruding so you are able to get your measuring device on comfortably, as in pic 3. Now very gently face off the end until you get to your measurement in pic 1.
While still in the chuck get a felt tip and mark off 3.5mm in from the end of each spool face. If you look at pic 4 it shows my spools marked up and in the background are two grooving tools of the type I used, you could use a right and left turning tool if you are careful. The land between the two spools is not critical and can be any size from 4.5mm to 5mm, and the surface finish just isn't critical. Push the large end of the rod right up to the chuck to give as much support as possible and rough out between the spools to the marks you made as in pic 5.
Remount the spool again to have it protruding for getting in with your measuring instrument as in pic 6 and very carefully face the end of the spool until you reach the 3mm required. Push the spool you have just done right up to the chuck and carry out the same on the spool at the other end. Deburr as mentioned before. The spools are now finished, now just have to put in a steam transfer port.
The hole for the steam port is drilled just below the bottom port face, see pics 7 & 8. Make sure you don't touch the edge of the bottom spool and touch on with a small centre drill to give you a drilling detent, then drill right through with a 1.5mm drill, turn the spool thru 90 degrees and drill another cross hole the same size. Carefully deburr the holes and you should now have finished spool valves as in pic 9.
It has most probably taken longer to write this post than actually make them. I would like to thank Sandy of ACS for the design of this type of spool valve, it has saved hours design time.
Next time we will be making the bits to join the spools to the eccentric.

John

[Eddy Matthews]

I'm going to have to read that little lot about a dozen times to really start to understand it!

I suppose it doesn't help that I don't have a clue how these things work, but no doubt that will become apparent as we move through the next stages?

[bogstandard]

Hi Eddy,
The way I wrote the last post was supposed to make it easy, just follow it step by step and you should end up with a good spool valve.
The easiest way I can explain the operation is that the two 3mm wide bits (the spools) act as small gateways, blocking two holes, one to the top of the cylinder and one to the bottom. The eccentric to which they are connected say moves down, because there are two they open two holes at the same time, the top one say lets steam into the top of the cylinder so pushing the piston down, while the bottom spool at the same time connects from the bottom of the cylinder to exhaust. As the eccentric moves thru 180 deg it then does the opposite and lets steam into the bottom and connects the top to exhaust and because there are two cylinders at 90 deg apart there is always a cylinder on power stroke and because of this the engine should always self start and run in reverse if the inlet and exhaust are swapped over.
Now you have gone cross eyed do you really want me to carry on, or will you just believe me that it works.
Just a little update on the monster that is running. It has now been on air for over 10 hours and hasn't missed a beat as far as I know in this time, I check every hour and it is still running. I have fitted a restrictor in the air line and it ticks over very slowly indeed, and it runs better in one direction than the other which suggests the timing is out. I will finish the runs tonight and carry on with building a speed control for it.
BTW still couldn't upload vid. says your box hasn't enough room even though the vid is only 15mb.

John

[Eddy Matthews]

That helps a lot John, thanks.... At least I now understand the basics of how the valves work.

I'm sure my grey matter will figure out the finer points as it comes together. If not I'll ask!

[crash93]

Does ths help at all
If you click on it it runs

Peter

[bogstandard]

Hi Peter,
As they say about a picture. That explained it a lot easier.
Its nice to get input from other people to help me out or even prove me wrong, or hints and tips, it helps everyone

Thanks

John

[sandy_ACS]

 

Hi PD's

John: -  work my friend, you can be proud of yourself.

Just a little update on the monster that is running. It has now been on air for over 10 hours and hasn't missed a beat as far as I know in this time, I check every hour and it is still running. I have fitted a restrictor in the air line and it ticks over very slowly indeed, and it runs better in one direction than the other which suggests the timing is out.

There are many reasons for an engine to run slower in one direction than the other and, certainly, valve timing is one of them.
Another, and a very important one, is.... steam/exhaust passage port dimensions... specifically the cross sectional area.

I did a few quick sums on your ports John and I would like to suggest the following: -

Your main steam ports are 3mm dia = 7.097 sq mm cross section area.

Turning to your PISTON VALVE (Spool valve as you call it).... a couple of changes would be beneficial.....

1,  The bore through the valve( to feed steam to the bottom port) is 2mm dia  = 3.161 sq mm cross section area

This bore should be increased to 3mm dia.

2, The 1.5 mm cross hole has and cross section area of only 1.935 sq mm
so, since this goes right through, this would total only 3.87 sq mm.

Increase this cross hole hole size to 2.3 mm dia. (4.1 sq mm cross section area x 2 = 8.2 sq mm total)

In order to accommodate these changes the reduced dia  (4mm) will need to be increased to 4.5 mm or the wall thickness may be a little thin.
In the cross hole area, and to avoid changes to the bottom gland, the increase in dia need only be long enough to accommodate the cross hole... the rest can stay at 4mm, hopefully this will still leave length to allow the spindle through the gland and with enough length for movement.

OK... if you think about what is happening... when the piston valve moves downwards, thus opening the top port, then the steam has direct access to a 3mm dia port.... on the other hand, when it goes to the top of its stroke, uncovering the bottom port, then the steam must first pass through the restricted centre bore, then through the restricted cross holes, before it gets to the 3mm  bottom port..... QED less steam in a given time.

When you reverse the ports (for reversing) then the steam is entering via the centre area (between the spools) and has equal access, and ample cross sectional area to move through... thus no restriction to the incoming steam.

A similar issue occurs with the exhaust side if you think about it... and the same really should apply as far as port/passage cross section area.

Incidentally, making the reduced OD 4.5mm instead of 4mm will still give approx 13sq mm cross section area between the spools... so no problem here.

One thing I forgot to mention, when I sent you the valve info John.... the piston valve should really be lapped into the bore to give a very close running /sliding fit since this is how the steam is prevented from bypassing the spool and disappearing up the exhaust... tricky with a blind bore... I agree.

This type of valve was developed for steam locomotive use, and the full size ones are hollow to permit steam transfer between the ends, however, they are fitted with sprung rings to seal the bore.

Ok John... thats my 1 pence worth.... hope you find it helpful....  just observations and suggestions.  :respect2

Eddy.... the next installment of the STEAM AND STEAM ENGINES series will contain a complete section on how these valves work... along with lots of diagrams..... It is on hold at the moment whilst I get the galley finished..... not going a well as hoped :rant   , but then does it ever?

Best regards to all.

Sandy.   :computer