Making a piston valve engine from mainly junk materials

[bogstandard]

Hi Sandy,
Many thanks for your input, its nice having someone on the team who is a specialist in this field. As you know, I make things to work and put fixes in along the way. This afternoon I will try your mods on a spare valve I have made and make the adjustment to drawing and prose to suit. I think that the 2.3 dia at the bottom should be meaty enough around there to do without changing the diameter, but I will reassess when I have carried out the mods.
The valves were tight in the bores as was and I lapped them in with a bit of t-cut (not as coarse as metal polish) and I have no leakage to talk about.
Many thanks for your input yet again, with all this help we should get a very good running engine.

John

[bogstandard]

Mods all done, except rather than 2.3 hole at the bottom I have used two cross drilled at 1.5, 90 deg apart. This only gives a slightly lower reading but it does allow it to be modded without having a larger diameter.
I took the opportunity to seal the engine up whilst doing these mods so all packing glands are packed and piston rings are in, all mating faces are Hylomar sealed, no leaks at all
Now to the results.
Tried both directions, now both the same operationally even down to the raised tickover (but this is due to the engine being tight because of rebuild and rings). The speed is unbelievable on 40 psi, much faster than my oscillators, I think this must be because of a slight increase in efficiency, and maybe a little less friction.
So Sandy, you were right yet again, I am running out of thanks very fast.
Vid of modified engine - http://www.youtube.com/watch?v=I8UCWr_BeqE

John

[Eddy Matthews]

The new video looks good John, it's starting to sound like a little sewing machine - Perfect!

I have to say that for a very basic engine that (almost) anyone could build with fairly simple equipment, it looks very impressive!

I can still see that next year could see me in the market for a secondhand lathe and other odds and ends!

[bogstandard]

Glad you like it, but it still isn't finished.
Hopefully two or three more posts will see it done.
Hit a bit of a problem yesterday, came to get all the junk and bits to make the speed control and the o-rings I thought I had, I hadn't. So ordered some from my supplier - http://www.blackgates.co.uk/body_index.html
they should be here today or tomorrow, then I can carry on.
Will be posting sometime today about the eccentric straps & related bits as shown in the pic.

John

[sandy_ACS]

 

Hi PD's,

Just a quicky.... got to go and do more KITCHEN UNIT assembly..... :twisted:  :rant  :sob

John,
 
Happy to assist with a few small suggestions that may/would improve things, so no credit due my friend, you are the one that must take all of that for your great build.

My input is given, in the true spirit of PD's, i.e... one modeller helping another.

I must admit, I never thought of using 2 crossed holes of 1.5mm,   "silly old Scotsman"....   .

I took a look at the video on U-Tube, however I am unable to get a very good viewing, very jerky and broken up, I believe this has more to do with the STEAM computer at this end though, but it served to show the beast in action.

One point.... now that you have fitted the piston rings and steam glands.... don't run the engine to much on compressed air, since this is very abrasive and the o-rings will wear very quickly. Better to run on low pressure steam, with a suitable displacement lubricator in the line... these also don't work on compressed air.

Best regards to all.

Sandy.  :computer

[bogstandard]

Sandy,
Thanks for the reply.
When running on air I always fill up the engine with diesel multigrade by injecting into the airline just downstream of the engine at least once an hour. I have to pull you up on the use of a displacement lubricator with air, my compressor produces so much water it is like running on cold saturated steam anyway (just joking of course).
With this post I should be up to date with the build.
The two sketches show what is needed to connect the eccentrics to the valve blocks.
They look complicated but as usual I think that this is my sketch that is causing the problem, if you refer to the pics all becomes clear.
Pic 1 shows the block sizes required for the eccentric straps. You will notice that there is a measurement change on them. These pictures were taken before the large holes were bored. I actually lost two of these sets because my boring was very slightly out and I broke into the joining screw holes. So I increased the width just slightly to give a bit more room for error.
The corners of the top blocks are removed purely for cosmetic effect, it will make no difference if you leave them on, but they will look a lot more bulky.
You will see on pic 2 that the plates are screwed together. Mark them up so that they stay as pairs and always go together the same way. Tighten them up really well and put on a flat surface and welly them with a gert big yammer an' a bit o' protective wud, to make sure they are nice and flat toogever.
Now measure your diameter of eccentric at the bottom of the groove, as in pic 3. Mine were all the same at 13.95 (I had used the same setting on the lathe for the depth of all of them). This worked out perfectly for me as I wanted 0.05mm running clearance. So this gave me 14mm exact. I don't have a 14mm machine reamer so the thought of boring six holes didn't enthuse me at all. Then a bright idea hit me, remember a bit back about the step drills I bought from Aldi. One of the sizes was 14mm. So out with a bit of scrap plate and duly wacked the drill thru. 14mm exactly, not 14.02 or anything else. 14mm bob on.
All six holes were drilled in less than ten minutes, all spot on, except for the fact I had drilled two slightly off centre and broke into the screw holes, so it pays to make a couple extra, just in case.
So in pic 4 you end up with half the metal gone. On the sketches it isn't too clear but there are two holes in the top of the plates, one (3mm) is for joining to the joint block and the other is an oiling hole for the eccentric, and thru use it has shown to work very well.
The joints don't need much explanation, just make as is. One thing you might like to try is to cut the 4mm wide slot in a slightly wider piece of metal then bring it down very gently to 1mm either side. The reason for this is that unless you can support all the side to full depth it will spring apart at the top of the cut and you will end up with tapered width sides. Even if you do get full support, when you take it out of the vice it will spring apart. A little later you will be silver soldering the length 2.5 screwed rod into the top of this fork, after the rod is screwed to the bottom of the tapped hole. After soldering the fork will be soft, just put the matching block into the slot and GENTLY squeeze together in a vice, this will realign the sides.
On pic 5 it shows the blocks joined to the eccentric straps. This is done by silver soldering (I will go into silver soldering maybe on the next post, some people think it is a black art and expensive, no such thing, just wait and see) the 18mm tube or rod between the block and the strap (after it has been fed into the two holes). What I did to stop it all falling apart before soldering is to squeeze the tube at the ends in the vice to make them slightly oval and tight in the holes, this will also give the required joint width for the silver solder to penetrate correctly,then put the assembly on a flat surface and get the strap and block level on the same plane. I will explain why I used brass tube (or rod). This is to give me a bendy, twisty, straightening fiddle just in case your measurements when you make the top and bottom parts of this engine were just not quite spot on. For a short time after silver soldering this tube will be fairly soft and can be fiddled to get this top block perfectly in line with the fork which is attached to the bottom of the piston valve rod. I didn't need any on mine, maybe I was lucky.
The design of the joining pin is the same as the one used for joining the conrod to the crosshead but slightly smaller. I designed them this way because bolts have a nasty habit of tightening up by themselves, and if this was to happen it would lock up the forked end, you can drill right thru the forked end and put a bolt thru but you must make sure that the bolt is free to rotate, has a smooth portion as a bearing surface and the nut is locked.
Now onto the second sketch, which shows hopefully all the dimensions required. As for the glands used on the piston rods, they are made in the same sequence. The screwy in bit is made first, then the bottom bit of the top bit is drilled and tapped. The two bits are assembled and the 4mm hole is bored thru them both (keep as matched pairs). Then the top bit is parted off, the screwy bits are put in the chuck and the top bit of the top part is turned to fit the piston valve hole. Two mounting holes are drilled in the positions as shown.
This brings us onto pic 6. The reason for only two mounting holes is because of all the cross drilled holes in the block it will be attaching to. Look at the pic and it shows the position of the two screwed holes. Stick as previously done to the bottom of the valve and spot thru with a drill. These holes can be drilled until they penetrate the cross drilled holes used for mounting the piston block to main block, and tap out to 2mm.
So now you have all the bits to assemble and run this engine if you want to, and this is as far as I have got. The next post will only be a small one, about making flanges and silver soldering. If I have got all my calculations right we will only have to bend one little bit of pipe, the rest will all be straight (like the ones Derek picked me up on before).
I suppose you lot will also want a displacement lubricator as well (get your tiny drills ready).

John

[Bill Hudson]

Sandy,

Here in Oregon, live steam is not allowed at model shows and most all model steam engines are run on air.  To combat the lubrication problem I placed a 1/4 pipe T in the air line. To the top of the T I installed a drip oiler.
To prevent the air from blowing back into the oiler I soldered a piece of tubing, in the end of the inlet hose fitting, so that it extended past the bottom of the oiler. I drilled a very small #60 hole in the tube just before the oiler just to allow a very little air to blow the oil into the main stream.  I thought about building a vortex but was afraid it might suck all the oil out of the oiler.

Bill

[bogstandard]

I have been looking at the pipework and came to the conclusion 1/8" pipe would be a little restrictive in the bore, so have decided to use 4mm (5/32") instead. But this entailed a redesign of the steam flanges plus a change of material to give the strength to couple it all together, and of course I designed the control valve around the smaller pipe. So sorry no posts for a couple of days at least.
And I was hoping to get the whole lot finished within the next week

[bogstandard]

I will be splitting this post about the steam flanges over two posts, the main reasons are that there are a lot of small operations to be done and the other reason, I haven't totally finished the machining yet.
I will post the sketch on the next one because there are so many pics to get thru.
First off is what we want to avoid, pic 1 shows the dreaded bent pipes and the little machine you use to do it. If you haven't got one of these, doing pipework can be a bit of a nightmare. If you want to make one, I can help, PM me, this one only took about half a day but really requires, unless you are a great tool grinder, a rotary table with a mounted chuck.
The good news is that I have now got it so that no bends will be required at all.
Picture 2 shows the reason for the delay, the brass flange, because of the thin wall on the waisted portion just wasn't strong enough to take the rigours of machining and I didn't think it would be able to support the weight it would be carrying. So I have decided to make them out of a space age product called EN1a, otherwise known as free cutting mild steel, obtainable everywhere and CHEAP.
Because I didn't want to be continually changing tooling, I decided to set it up like a production line, so I cut off billets to make one on each end and the bit that was left from the middle would make the second type of flange required. The billets in the pic have already been turned down to 12mm diameter and are about 45mm long.
Pic 3 shows turning one end of the bar down to 12mm long by 6mm diameter, once one end is done, turn bar round and do the other end the same. Do this until you have enough for your engine, 4 required but I would make 6 just in case.
The next op as shown in the shaky pic 4 is to turn down a waisted portion for 7mm long by 4mm diameter,using the same method as was used for the spool valves. The diameter of 4mm is fairly critical, too much larger and your bolts won't fit, any narrower and you will be weakening the structure of the flange.
The components in picture 5 is what you should end up with at this stage. The end marked in red is a reject that will be discarded. In the background is a little book called a ZEUS book. If you are doing any machining especially if your are making metric bits on an imperial machine (as I do) or vice versa, this is an instant help, because it gives you direct conversion charts plus loads of info like drill sizes for tapping etc. I use mine all the time. I've had this one for 25 years and is getting worn out, but being so tight I don't want to shell out the £4:75p that a new one will cost. Buy one now if you haven't got one.
There is no picture for the next bit, but all the operation is that each part is parted off, and the flange ends machined to a thickness of 2mm, DO NOT DRILL THE MAIN HOLE UP THE MIDDLE YET, if you do the part will not be strong enough to go thru the next machining procedures. The bit that is left from between the components is used to make the 3mm thick plain flanges, that takes us onto pic 6.
Rather than boring out the soft jaws I use on my chuck I decided to make a split bush to hold the small discs. All this is is a piece of soft metal that has a thru hole (I made mine 9mm). Then bore to a depth shallower than the component part to a diameter where the part only just pushes in. Then mark one of your jaws with a marker and physically mark the bush adjacent to this jaw. Now mark the bush at a position half way between two jaws. Remove the bush from the chuck and where you marked between the jaws cut all the way thru with a hacksaw or bandsaw. Clean off any burrs, put your component into the bored bit of the bush and remount into the chuck, aligning the mark on the bush with the marked jaw. You can now face and drill to your hearts content, as long as you always realign the mark on the bush and chuck jaw, all should be ok. Discard the bush after use because it cannot be rebored to use again.
You should end up with what is on the last pic. These took me about 3 hours, being new to it if you can make half this qty in that time you will be doing well.

John

[derekwarner_decoy]

Hi PD's.... & John says

'pic 1 shows the dreaded bent pipes.... If you haven't got one of these, doing pipe work can be a bit of a nightmare' ....well I do agree with this

'and the little machine you use to do it' & I  do agree with this too

Well...PD's... the real point here is that the design difference of the tube bender set produced by John & the set of Dub-RO American tube benders I purchased

Johns version will display roller to roller clearance 0.0005" [1/10 of the thickness of a sheet of A4 paper I posted to John] & the true U shaped valley in each roller would be 0.0625" depth...+0.0005/- zero

The roller set in my Dub-RO has 0.002" clearance between rollers so my 1/8" bends in brass have a convoluted effect & subsequent thinning of the wall thickness off axis  :rant

My Dub-RO set for 5/32" od tube is """"better"""" & the degree of convolution is greatly reduced

Having said this...my latest plan is to use my version of "DUO-Core" but in brass tubes .....

1/8" OD brass tube soldered with COMSOL within  5/32" OD telescopic brass tube... then bend     the DUO-Core tube set &  

[bogstandard]

I gather from your post Derek is that you approve of the tube bender.
As promised here is the sketch, I think I have got everything on there.
Picture one shows the flange base being drilled. Centre the flange to the chuck and use machine offset to locate the two 2mm mounting holes.
Once you have the two mounting holes you can then do as I have done in pic 2. Put two pieces of rod thru the holes and locate them down to the top of the vice, then machine down 2mm. Turn it over and do the same to other side. Be careful, only nibble away downwards not from the side, otherwise it WILL lift the piece out of the vice.
In pic 3 I show that I have used the flange face resting on a parallel to keep the hole square to the flange. First I centre drilled, then went down with a 3mm drill to a depth of 4.5mm, then followed up with the 4mm required to the same depth. This is the stage at which the brass flanges failed, they couldn't take the pressure applied by the vice and duly buckled.
After the last stage, remount into the lathe and drill up the centre of the flange with a 2.8mm drill( the internal size of the copper pipe) to join into the hole for the pipe at the top.
Picture 4 is how I get bent tubing straight again. The annealed tube is rolled like a using a rolling pin between two hard surfaces.
Make sure your copper tube is squared at the ends and deburred on inner and outer faces.
All the finished bits are shown in picture 5, for the copper pipe you will require 4 off 4mm (5/32") by 30mm long, one off same diam by 60mm long and one off same diam by 90mm long.
In pic 6 it shows all the bits assembled for silver soldering. I need to point out here that for silver soldering to work correctly the parts should NOT be a tight fit together, there must be a very slight gap for the solder and flux to penetrate into to form a good joint. If you use a 4mm drill for this pipework all should be ok as 4mm is very slightly larger than the 5/32" pipe being used. The way I get the bits to hold together while handling is to slightly flare the end of the tube, so that the tube is held in the hole by the flare but still allows solder flow.
To put my mind at rest I silver soldered one of the rejected parts after drilling the main centre hole in it to a bit of copper tube and tried to break it by putting the flange in a vice and using mole grips to try to put enough force by twisting the pipe to break either the waisted portion on the flange or the copper/steel joint. As you can see in pic 7, I failed miserably on both counts, but at least it proves that the flanges are strong enough.
Just a word about failure rate, I started to make 12 flanges, one was rejected after turning, one was used to set up the drilling stages, the third got damaged during drilling because I hadn't tightened the vice enough. That is a 25% attrition rate, so always make a few spares.
Next time, a post about silver soldering, then onto the control valve , which I am just making and proving.

John

[bogstandard]

I wanted to get this out of the way so that I can concentrate on getting the control valve done. These only came out of the pickle bath an hour ago.

SILVER SOLDERING
A lot of modelmakers think that silver soldering (from now on SS means silver soldering) is a black art that they try once, make a mess of and don't do it again, or just think it is too expensive to gear up for.
I will tell you now, I am tight as a ducks a**e, and that's watertight when it comes to SS, once you have the intitial bits the running costs are minute. I showed on the last post how strong the joints produced by correct SS can be, many times stronger than soft soldering or glue.
Now I will refer to the pics of my bits and bobs.
Pic 1 is my collection of soldering things, I do have a proper home made brazing hearth but it was too heavy to set up here, and you wont need one anyway. The last time I used it and the big propane gas torch shown here was when I made boilers a few years back. The ones connected to disposable cans are a standard plumbers blowtorch, which I use for the large bits, and a can adaptor to allow me to fill the two small blowtorches with butane/propane mix.
The little orange one is what is now called a 'Chefs' blowtorch is what I use the most, while the little pencil one I used to use for building railings while they were still attached to the model boats.
The next bit in the lineup is my 'mobile SS hearth', in other words a couple of firebricks from a builders merchants, if you go there and ask if they have any broken ones they might even give them to you. DO NOT use household bricks, when they get hot small bits can shatter off them and fly in all directions. I use this all the time and move it about my workbenches to where needed, as long as you don't get them too hot and keep away from flammables they are ok.
The big bucket is a recycled (nothing goes to waste) popcorn bucket that is filled with my quenching water and is normally next to the mobile hearth. The one on top that looks like someone has piddled in is my acid pickling bath for removing flux and for cleaning the pipework. The contents of this is explained in the next paragraph.
The items in picture two are now going to be explained in an easy to understand manner.
Steel wool, this is used to clean the parts before joining. Any oil or grease or sometimes even fingerprints can stop the joining of metals with SS. So degrease first, then a rub over with wire wool (cabinet makers if possible, some others are treated with oil to stop it going rusty), then assemble the bits together. Be careful with wire wool around heat, it catches fire very easily and is usually a pig to put out.
Citric acid, used to be able to get this anywhere but now only readily available from chemists. When you go in, go in filthy like you have been under a car for a week and explain to them that you need it to make a pickle bath for soldering. You will get some weird looks and whispering between the staff, the dispensing chemist will usually be called to have a word with you but as soon as he sees how filthy you are he will let you have some just to get you out of his shop.
The reason for this is because citric acid is a main component in the use of heroin based drugs. We use it as a pickling bath and I mix it about four teaspoons to half pint of water. In a sealed container I find it lasts for many months, and I only throw it away when the things growing in it get to look a bit dangerous.
The thing next to it marked flux does in fact contain, yes, you guessed it, flux, but in an emulsified state. It normally comes as a white powder, and should be mixed with water to a consistency of thick cream. Again I find that putting it into a small sealed container (film canisters are ideal) it will keep for months, just stir it up just before use. The purpose of flux is to stop oxides forming on the surface of the metal and clean at the same time, allowing the SS to bond into the surface of the metal.
There are many types of silver soldering fluxes but I would go for one of the tenacity ones. I use tenacity 4a, which is really for stainless steel and is fairly aggressive, or the most popular of its type is tenacity 5, designed for use with normal steels. What these fluxes have over the other general purpose ones is that they can still do the job of cleaning the metal at much higher and prolonged temperatures than the general purpose ones, but as I said before they are slightly aggressive and need to be cleaned off before it thinks your copper pipe is muck and starts to eat it away.
It is just applied to the local area to be joined with a small brush.
Next we come to the most confusing bit, the silver solder itself. It comes in all shapes and sizes, melting points and even as pastes (but these do have a fairly short shelf life). The reason for the different temperature ranges is to allow multiple parts to be SS onto a construction at different times. You would use a high temp one to begin with, then with each subsequent addition you would use a lower temp than the previous one. But for our purpose we will stick with general purpose or bogstandard easyflo.
Most people go for the 1.5mm rods costing up to about £3 per rod, and end up filing most of it off the job they have just SS. It is just too large for what we want to do. I use 0.5mm silverflo wire, as you can see it costs 82p for a 3 foot length, and would do all the joints on at least ten of these engines, for slightly bigger joints it also comes in bigger sizes.
You will notice at the front of the pic are what look like springs, they are in fact coils of SS wire. I wrap the wire around the next size down of tubing that I will be using, and about 2/3rds of one coil is enough for one pipe joint.
Onto pic 3. On here I have assembled the parts and put one coil onto each joint, all that is left to do is paint a small amount of flux around the joint and stick some heat onto it. You will notice that I have protected my table because of the flux.
It isn't worth taking pictures of the process because the time you reach the temperature it is all over but I will explain the principle.
If I was doing one of the stand off flanges, I would start by heating up the flange itself to a very dull red, you can only just see the red, at this point the flux has dried up and started to turn to a liquid. Because the copper is a better heat conductor than the steel I will let the copper take its heat from the steel so I will move up towards the joint, as you do you will notice that the flux is cleaning the area and all of a sudden the silver solder will melt and flow into and around the joint, once this stage has been reach take away the heat, if you reach a distinct bright red colour, you've already overcooked it.
Pick the bit up with a pair of pliers (they get very heavy if you use your fingers) and drop it into the quenching water. This will knock most of the flux off, but to do a good job transfer the bits to your pickling tub, I have left bits in this for more than a week and they were still ok when I took them out. A couple of hours usually does a good job. One point to mention, if you are SS silver steel or any of the high carbon types, let the article cool down before dropping it into quenching water, otherwise you might find the component has gone glass hard and very brittle.
Now onto pic 4. Here are the bits straight out of the quench, you will notice on the standoff ones especially the bright silver area on the steel and the clean area on the copper above the joint, this is the flux doing a great job.
You will notice no big blobs to clean off, just nice clean fillets. Just a quickie pickle and polish then ready for the next stage.
Piccy 5 is out of the pickle after an hour, and just started to clean them up.
Not a very good pic 6 but you can see how this method produces lovely fillets with absolutely no wastage, and very little clean up, just a quickie polish and they are done.
And now one for Derek, here he is back from uni with a new degree under his collar (excuse the pun) trying to get me to make the next bits, so won't be back until its done and dusted.


John

[derekwarner_decoy]

Hi PD's & thanks John for this......from my trials [see attachment]...I think I was suffering 2 or 3 faults  :rant & poor results.......

1) I should use more air cored brick work to support & minimise heat loss
2) maybe preheat the complete tube set with the larger Primus gas torch
3) use a pickling solution over & above the BORAX flux paste
4) use 0.5 diameter pre formed rings of S/S as you have done over the 1.5 diameter wire trialed
5) use the smaller blue hand held small gas burner for final S/S melting

Will trial the revision this weekend if I can get the 0.5 wire locally & so I say to myself... :luck

Oh BTW...please offer my hearty congratulations to the DOG....he looks so pleased  

[bogstandard]

Hi Derek,
By the picture you have a few problems here.
You do really need real firebrick (the type used to line firebacks), it doesn't take the heat away but keeps it very local, in fact when you are doing something larger the bricks glow bright red around where the heating is taking place. The size of pipe you are doing there can easily be done with the little blue torch you have there.
By the look of the deposits of black on the brick, suggests you are using a carburising flame. The black you see on my bricks is caused by twenty years of use. This is caused by not enough air in your gas mixture, check the air supply holes around your nozzle to see if they are blocked, sometimes the nozzle itself can be knocked into a bad position, if the nozzle has a securing screw on the outside, slacken it off and try sliding the nozzle back and forth until you get a nice bunsen blue area in the centre of the flame. The tip of this centre cone is the area of maximum heat, and this is the part of the flame that is used.
From the look of the workpiece the flux just isn't doing its job. There should be nice clean areas around the joint, as I showed in my post.
It might be you are taking too long in heating up, and killing the action of the flux, that is why I use an aggressive type flux. For small jobs like this, if it isn't all over and done with in ten to fifteen seconds you are most probably cooking the flux.
What you can do with your silver solder rod is give it a real good going over with a hammer until it is very thin and cut off a very small piece and place on the job, it just might be the big rod being put onto the joint is soaking away what heat you have there.
Hope this helps for your search of the perfect joint (for medical reasons of course).
Bandit the dog says thanks, cat says nothing, even to me.

John

[bogstandard]

Hi All,
I forgot to mention in the post about the stand off flanges about drilling them out. As the tubes were silver soldered into the flanges, the end of the tube protrudes inside the steamway. You need to run a 2.8mm drill down to cut off the end of the tube inside to allow full steam flow, be careful you don't drill all the way thru, you only need to take off the first bit of tube you come to. Put a drop of milk down to act as lubricant otherwise you might break off your drill inside trying to cut the very soft copper.
I have included this time a couple of pics to show how far I have got with the steam control valve, doesn't look much, but trying to get all the holes missing each other inside and also making it fairly easy to make took a lot of working out, hence the delay.
I have decided to use the main block and the two piston valve blocks to act as jigs while it is all soldered together, so really all this needs to be done before engine assembly, I am lucky, I have a second set of parts I can use.
The reason I have done this post is to show how close we are to finishing and because of medical problems I am having to take a few days out of the workshop. I can still answer posts if you have any questions or comments, but I won't be doing any machining.

John