Making a piston valve engine from mainly junk materials

[bogstandard]

Eddy,
There is no such thing as a stupid question.
Glad you now understand it, in fact it is a lot easier this way than with a little end in the piston. I know because I also build I.C. engines and they are a pig to machine the piston area, but not as bad as making the camshafts.
As I said before, I am trying to design this to be fairly simple to construct, with hopefully nothing that is not achievable by someone like yourself, that is why there will be no ballraces in this design and the crankshaft will be made out of about nine pieces all held together with bolts.

John

[crash93]

bogstandard

 I think you may find they are for OIL they have oil cups at the top of the columns. these are hollow and the bars are tubes just touching or not so oil is transferred to the rod. its the same as Martin howes and baylis used on some of there engines.

Peter

[bogstandard]

Hi Crash,
I stand corrected, thanks for the info. Thats what happens when you look at a picture and assume. If you learn one new thing a day, by the end your mind will be full of information you can never use.
It now surprises me even more that they have no side thrust support, but maybe because it is such a short stroke engine they deemed it not neccessary.

John

[bogstandard]

Away we go again.
I had to prove that this system would work before I could post, that is the reason for delay.
The crosshead is the link between the linear motion of the piston shaft and the rotary motion of the crankshaft/conrod. There are a lot of side loads imparted onto the piston and rod by the conrod so the crosshead transfers this side load to a more substantial bearing area than the bottom of the packing gland. I hope I explained that right, I am sure someone will let me know if I didn't.
The crosshead blocks that I am showing now are going to be the hardest part on the engine to make, if you can make these you will have no further problems making this engine.
First pic shows blocks prepared for machining, fully deburred and cleaned. All holes to be put thru this block should be done before any other work, this will make sure that they should be square and parallel.
Second pic shows two blocks fully machined, the raw one on the left and the partially dressed one on the right, you can use the raw version with no problems but I always think that the components should look the best they can.
Third pic is showing how the crossheads will fit onto the engine. The support plate and crosshead rods are not finished yet, these will be in the next post, plus a little bit of machining of the block to a stage where we can start to think about the crankshaft.
The sketch should be self explanatory.

John

[sandy_ACS]

   

Hi PD's,

John.....I am so pleased to see that you have fitted a proper crosshead arrangement...looks great and should work just fine.
When I looked at your initial sketch (1st post) and saw the arrangement this showed I was going to comment on it, however, since you were still in the design stage at that time I had a feeling you would re-consider the original method (which would not have given any support at all, at least not after the first few minutes of running)...well done.
 :no1

Keep up the good work.

Best regards to all.

Sandy.    :computer  

[Eddy Matthews]

Well, although very few members are asking any questions or making any comments, they must be interested judging by the number of times your photos and drawings have been downloaded John!

I can only assume the lack of comments mean that you are explaining things very clearly

Keep it up John, I'm certainly following things with great interest....

[steamboatmodel]

Well, although very few members are asking any questions or making any comments, they must be interested judging by the number of times your photos and drawings have been downloaded John!

I can only assume the lack of comments mean that you are explaining things very clearly

Keep it up John, I'm certainly following things with great interest....

I think John is doing an excelent job of explaining    
I check this form every morning to see if he has posted more ( also to see it Sandy has posted anything), sometimes I even check in the evening when the computer is free.
Keep up the good work :wink:
Regards,
Gerald

[bogstandard]

Thanks for the encouragements lads, shame I can't get better photos.
You were right Sandy, after a couple of hours pondering I knew exactly what was required for the crossheads, the problem is keeping it easy enough for people to have a go, there are so many designs that could have been used but this was one of the simpler ones, and keeping within the format of no complicated decimal places is another restriction. Also for the few who cannot be as accurate there has to be an inbuilt element to allow for 'tweaking' to get the parts to run correctly.
Hopefully another thrilling installment tonight.
I nearly didn't make it yesterday, when milling I have to sit down, and when I swivelled round to pick up my mic the chair broke dropping me rather heavily onto the floor, but after an hours pampering and sympathy from the better half I was up and running again, managed to get 32 x 2mm holes drilled and tapped before the aches and pains took over.

John

[bogstandard]

The first thing to do is to get a few more holes into the main block.
If you check the first sketch it shows the positions of the four ports that are going to be feeding steam to the top and bottom of the pistons. It is fairly deep drilling but if you take it steady there should be no problems.
Do NOT deburr the ends of the holes on these, we need them nice and flush.
Top caps and gland seals. I have taken a picture of how to use a square to get your holes looking neat. Once you have them in the right position dab a couple of drops of superglue around the edges and let it go off for a bit. Cunning don't you think, and the glue just scrapes off easily afterwards.
Anyway, get the drill that you used for drilling the holes in the caps and just spot thru to give you a dimple for your centre drill to pick up on. Tap the caps off and just centre drill all the holes, followed by either a 1.5 or 1.6mm drill to a depth of about 8mm. for the top caps it is not too important, but for the glands I mark the gland and the block to keep them as matched sets.
You should now have all the holes in fairly good register. Now 'just' tap them all out with a 2mm tap (or if you are using BA or similar use whatever drill and tap that is required). Forgot to mention, do one end of the bore first then clean off and proceed to the other end, otherwise you will find it wobbling all over the place as you try to drill. For tapping small sizes I always use a hand tapping fixture that I made using an old surface plate (this is what I take most of my pictures on), but Arc Eurotrade sell them for about £35+, I have very rarely broken a small tap when using one of these as you have a lot more 'feel'.
Another tip here, you will notice in the pic a weird set of pliers, go to the pound shop or market and buy a couple of cheap pairs of electricians pliers, hold the jaws slightly apart with a bit of metal shim (pepsi max) and drill thru holes, any size you want to hold, I have two pairs one metric up to 6mm and one imperial up to 1/4", you will find these are indispensable when you hold shafts when tightening (no marks like mole grips leave), and great when grinding bolts to length.
Fit the glands to the block, and make the support plate (don't worry if your plate isn't exactly the right thickness, but don't go too thin, as we can fix that when we come to fit the main block to the crankshaft area). Yet another of my grotty sketches, and spoiling you lot as well, I've used a ruler this time, again it is self explanatory except that on the photo it shows more cutouts, this is me again, tidying things up and reducing weight, not neccessarily needed, you can do it if you want to. You will also notice I have done a bit of rough engine turning on the plate, this is a very easy way to cover up all the marks and scratches from the plate being kicked around the scrapmans floor, if you want to polish it go ahead, it will be your engine.
The large holes in the plate are to go around the glands, if you are not up to doing these, no problem. As long as the six holdown bolts for the plate are there you can make these square, triangle, oval or any other shape that takes your fancy. The reason I did it this way was to accurately locate the mounting plate around the glands while the holes were spotted thru, the plate has to be VERY square to the block for the crosshead to function properly. But again things can be 'made' to work if not quite there, how to do this comes later, don't need to worry about that yet.
Drill and tap the block for the six mounting screws (B on the sketch) 2.5mm by 10 deep, and bolt the plate on.
Now you have got the holes drilled and tapped we can give you a bit of 'tweaking' power.
On the glands only, reduce the 18mm O.D. by 0.1mm and the same amount on the spigot that fits into the bore. You might find now that the piston is a lot freer in the bore and if not totally concentric with the shaft will allow you to spin it a full 360deg. rather than binding up. Tighten up when all is running free. If you still can't get a full rotation on the piston, just stick the piston assembly back in the lathe and dress it again with emery cloth on a stick (as previously described) until you get the desired result.
We will get back to the block later, after we have finished the crankshaft, as I have to design the cams for the piston valve and the valve area itself towards the end of the build (God, I hope this engine works, I will have people chasing me round with axes if it doesn't), think positive, how hard can it be, all will come right in the end.
Hopefully next we will be getting the crossheads and pistons into unison, something that moves that you can play with and really impresses the neighbours (I'm talking about the engine bits), plus a start on the crankshaft area.
Having a couple of days at the sewerside, sorry seaside, with the grandson, so no post for the next few days, but hopefully back with a vengance after that.

John

[Eddy Matthews]

Just to clarify things John, is it the top caps and gland seals that you are temporarily holding in place with superglue?

You briefly mention doing engine turning.... How do you go about that exactly?

[sandy_ACS]

 

Hi All,

Coming on a treat John......only one issue....

....I've used a ruler this time, again it is self explanatory

You may/will need to spell this out in 1 sylible terms for our Derek..... especially if it's got numbers on it......      :music


Keep Happy.

Best regards.

Sandy. :computer  

[bogstandard]

You've caught me just in time, getting ready for a bit of relaxation.
Hi Eddy, yes it is the top caps and glands that you stick down while you spot thru with a drill.
What I call engine turning, I use to cover up badly scratched bits that would need a lot of cleaning and polishing otherwise. But it can also be used for decorative effect.
All I use is a piece of dowel or soft metal with the end faced up in the lathe. Then it is mounted into the chuck of your pedestal drill, with the faced end downwards towards the job, put a bit of grinding paste on the faced end and go thru the motions of drilling the plate but in fact all it is doing is scratching a pretty circle. Move the plate along a bit and repeat, move the plate along a bit and repeat, move the plate along a bit and repeat, move the plate along a bit and repeat, move the plate along a bit and repeat, move the plate along a bit and repeat, move the plate along a bit and repeat, move the plate along a bit and repeat and so on until you have a pattern that takes your fancy, if you don't like the pattern, start at the beginning and go over the old pattern. You don't have to use grinding paste, metal polish, a bit of emery stuck on the end, toothpaste, in fact any abrasive material will do, and they all give variation to the depth of pattern. If you mount the job into a cross vice and take your time very regular patterns can be produced using this method.
My ex friends (now no longer with us) son works for Bentley motors and suggested this for their dashboard, it was taken up and is now standard fitting, but they black anodize afterwards. So if it's good enough for them........
Have a go and play about, soon everything in your boat will be engine turned. I made an oscillator for a model shop owner in Frankfurt, Germany for his collection to put on display in his shop, I did 4mm engine turning on every flat surface of the engine, using metal polish, the result looked spectacular.
I forgot to mention in the last article that the plate holdown holes could in fact be drilled straight into the block using the dimensions on the drawing rather than being spotted thru.

Back soon

John

[derekwarner_decoy]

Hi PD's... & what some call "What I call engine turning"....others of proud Convict  :gather nature were taught   this process as "Radial Burnishing of Metals" during our elementary mechanical training [which also included the 'BOLT cutters in the coat trick']  

I must agree, a limited surface of radial burnished metal does add an asthetic dimension  :kewl which is better than scratches & dents...

A note from my relo on the first fleet to OZ suggested that in 200 years or so some WIZARD from OZ may invent a clear epoxy spray for such work so the process of polishing did not ruin the beautiful radial burnished metal surface    :music

Oh BTW John....in OZ we use a mixture of 1/4 tea spoon of IRON ore + 25 ml of VB   + 100 gms of goats milk butter to make our own lapping paste :nah

[bogstandard]

Hi all,
Fairly refreshed and glad to be back.
For those who would like a bit more info on engine turning, the first link is to a chap who makes a living at it, the second link is another type using what is called a Rose Engine, mainly used by watchmakers and jewellers.
http://www.cs.ucr.edu/~eamonn/et/et.htm
http://www.rgmwatches.com/engine.html

Derek, my formula is a secret, but we use cow dung instead of aussie goats milk butter, it smells better.

Back to the build, very little tonight, just a sketch showing the crosshead support rods and the now finished to size piston rod, plus how the top of the piston and steam inlet hole should look when setting up.
The pic shows my two engines with the area totally assembled.

Building up - As you assemble put a spot of oil on all parts. Screw out the gland compression screw by about 1mm, then insert the piston and rod through. Now slacken off the holding screws on the gland and position the gland on the bottom of the block until you can get a free full up/down movement and a full 360 deg. rotation of the piston and rod without it binding, once you have this tighten up the screws and recheck.
Screw on a 3mm nut onto the end of the piston rod and follow it up with a crosshead, screw all the way on. Move the crosshead to a clear area of plate and push it down all the way, the piston should be near the top of the bore. Lift the crosshead 1mm away from the plate and adjust the screwed in piston rod until the inlet hole at the top of the bore is only just totally uncovered by the top of the piston (see sketch), tighten up the locknut (not too tight, they have a tendency to to deform things if too tight).
Put one of the crosshead support rods thru the crosshead and screw it to the plate, if the crosshead has locked up slacken off and adjust until it frees off, then put the other rod thru and do the same. All mine locked up totally solid, so I gave myself a bit of movement by opening out the support rod screw holes to 2.7mm. Do NOT on any account touch the piston rod/gland/crosshead assembly, all adjustment is done on the two rods. It took me about an hour to do the first one and about 10mins each for the others.
All adjustments on the rods should be with the crosshead against the plate, it is just a matter of slacken off, turn rod slightly and retighten, try again. It also helps if after tightening to tap the blocks with a plastic screwdriver handle, nothing heavier unless you get really piddled off then a 7lb lump hammer comes into its own.
What you want to end up with is the piston being able to go thru its full travel without jamming up, slight finger pressure is great but if you have to push a bit it should be ok, we will use the engine itself when completed to sort itself out. I check by putting the piston at the top of its stroke, block the end of the cylinder with my finger and put a bit of air into the steam port on the side, keep your fingers away from the crosshead, it comes out with a bit of force.
After all this by the way, it has to be stripped down at the end to finally seal, but you will have a lot more experience by then and you will be able to do it in minutes.
By the way, an engine doesn't come to life until you have some of your own blood on it, try not to make it too much.
The next time I will be starting on the bottom half of the engine. Some of the bits are common to my last engine so it should progress a little quicker. Going now to my scrapman box to see what I have to work with.

John

[bogstandard]

This is just on one subject tonight, It has taken me all day almost non stop to get these made.
There is as usual one of my quickie sketches.
Next pic are the raw blocks and the piece of metal they were hacked out of is in the background.
You will notice that the blocks have colours on them, the green is on the datum face and red on the opposite end to aid identification. This datum face is critical as will be explained later.
The next pic shows a row of blocks all in perfect register with regard to height. Pressure can be put across all the blocks and the shaft still rotates.
The picture of the lathe setup is showing the last operation on the blocks.
The last pic is showing all ops carried out on the blocks.
Now the long winded explanations.
The blocks should be made to the sizes stated, in fact the 10mm size could be made maybe 0.2mm undersize, it will allow a bit more freedom when we get to the big end area.
It will require four for this engine, I usually make an extra one or two just in case of mistakes, but this time I ended up with all perfect.
The reason for the coloured marking is now explained. Mark a datum face on every block on a 20mm x 10mm face, this is the face that is always against the fixed jaw of your vice when boring the 5mm thru hole. Everything else on the bottom end of the engine can be tweaked but not the fixed height of the hole unless you have a long 5mm reamer to line ream.
After every block is bored the whole vice area has to be cleaned, a small amount of swarf can throw the height of the hole out completely. I use back stops to aid positioning, thus I just have to position a new block and tighten the vice, no slide movements at all during the hole boring procedure.
If You are lucky you should be able to put a 5mm rod thru all blocks, put them down on a flat surface and apply pressure to the tops of all blocks, the rod should still be able to turn, if not one or more hole heights are incorrect and will have to be sorted before going any further, maybe by putting shims under the low hole blocks, do NOT remove metal from the others to get them lower.
Assuming all is ok we can carry on. Instead of external oil cups we are going to build them into the blocks, just drill thru where shown with a 1.5mm drill then follow it down with a 4mm drill for a depth of 3mm including the drill tip, spin the drill or reamer in your fingers you used to bore the hole in the crankshaft hole to deburr the oil hole, job done.
Turn block over and drill and tap 2.5mm the two holes on the datum face. Don't forget to put a small chamfer on these holes otherwise it will throw the height of your crankshaft hole out.
The last job on each block is to machine a small boss on each side. The reason for this boss is to reduce friction, because we are not fitting bearings into this engine, if the crankweb comes into full face contact with the block there would be a lot of friction produced, by using this little boss friction is reduced to a minimum.
Turning the boss. Get one 5mm bolt and cut the head off. Put cut off bolt into chuck with threads sticking out and tighten up really well. Now just put a block onto the threads and put a nut on and trap the block between the chuck jaws and the nut (look at lathe setup pic). Bring the lathe tool into contact with the rotating block face until it just touches. Stop the machine and lock the saddle if you can. Wind tool off block and using the topslide put on a cut of 0.15mm (0.006"), now start machine and cut across the face until it nearly gets to the nut (not critical), now wind out on cross slide and stop machine, turn block around so face just machined is against the chuck. Repeat the process on the other end. Do each block the same, the bosses might not be concentric with the bored hole but it does not matter.
Blocks made, deburr and smile, the critical bit is over.
Next will be baseplate and hopefully crankshaft.

John