A Proper engine.

adrian

Flying Squad
Earlier in the year I stumbled across a neat little live steam engine on YouTube. I posted the relevant video earlier in the year but will repeat it again here to start this thread. As my 3F build is nearing completion I thought I'd have a go at making one of these as a little Christmas/New Year project.


I emailed Les Proper for a set of plans earlier in the year and have been slowly accumulating some of the material for the build. The dimensioning on the plans is a little unusual to what I would normally expect from an engineering drawing. You can work out the required dimensions but the formating is not what I would call conventional. Also everything is dimensioned in decimal imperial, so you have dimensions like 0.68", 0.22", 0.3" etc. I ended up using the dimensions as a guide.

So today I made a start deciding to tackle the crank axle first. For reasons that will become apparent later on the axle is made from 2mm dia. silver steel. I then got a short length of 3/8" steel bar and using a centre drill spotted the centre. Before drilling the centre hole I marked out the 1/8" radius circle for the "big end". The centre 2mm hole was drilled in the lathe. The bar was then transferred to the pillar drill for drilling the offset hole for the crank. The bar was then returned to the lathe for parting off the two disks.

crank - 1.jpg
This was then assembled for silver soldering, using some soft iron binding wire to hold it together.

crank - 2.jpg
Having seen others use silver solder paste I was keen to try it on this job. I tried it on a test piece with some pieces of nickel-silver sheet and it worked fine so I gave it a go.

crank - 3.jpg
Unfortunately it didn't work out that well, I'm not sure what went wrong but the solder didn't really flash across the joint as I expected it too but rather just ended up as blobs around the work piece. So everything was taken apart as none of the joints worked and cleaned up. For the second attempt I went back to my silversmithing technique of easyflow flux and small pallions of silver solder. This worked better as the solder flowed into the joints as expected but somewhere along the route the discs twisted such that the crank pin wasn't aligned along the main axle.

So attempt number 3 involved making the crankpin much longer so when I wired it together I could check everything was parallel.

crank - 4.jpg

Once I'd silver soldered together the extended crankpin was cut to length and the discs were tidied up in the lathe before finally cutting out the centre part of the axle.

crank - 5.jpg

So the next stage is making up the base plate and support pillars.
 

Osgood

Western Thunderer
Well how frustrating - all through the video I was trying to work out the big end arrangement, to the extent of missing bits of the commentary and having to rewind, and then Les slips in that teaser right at the end! :rolleyes:

The only thing I can think of is a split tube somehow silver soldered together on the crank pin without sticking to the pin?
Guess I'll have to keep watching this thread now!!
 

adrian

Flying Squad
When I emailed Les for the drawing he sent a short set of build notes which has a few more details. The big end arrangement is a rather basic split tube arrangement.

This is from his notes

Screen Shot 2017-12-29 at 10.54.21.png

Simple and effective so I don't intend to do anything different on this part. As it's a single acting cylinder I don't think it needs anything more substantial. Although he seems to use the same arrangement on the double acting engines!
 

ceejaydee

Western Thunderer
I love this kind of thing.

I picked up this book by Tubal Cain a few years back following reading a couple of articles in some old and now gone Model Engineer magazines.

811gP6DN25L.jpg

Maybe I can have a go at one this year.

Look forward to your adventure Adrian :thumbs:
 

adrian

Flying Squad
As usual I don't always follow the script! The plans use 4 vertical posts and then solder a brass bush between them for the main crank bearings. I had some 1/8" thick brass bar which I thought could make the end supports. It was like back to college days filing and fitting square and to length. The U slot at the top is required to clear the valve spindle linkage. The bottom of the plates then filed to match to give it "feet". The posts were then drilled and tapped 10BA. I scalloped the sides so that I wasn't drilling and tapping blind holes.

The base plate and top plate were fashioned from a length of 1/32 brass strip.

proper_engine - 1.jpg

The top plate was reduced in width and drilled and cut out for the cylinder and valve tubes. I had some miniature ball races spare from another project, these are 2mm bore and 5mm o/d, hence using the 2mm rod for the crank axle.

The flywheel and valve eccentric were turned from brass bar. The valve eccentric is grooved for a 1/32" rod. I didn't have a suitable round nosed lathe tool for this so it was a bit of a fudge using a V nosed tool to make the groove and then rounded out using a rat-tail needle file.

proper_engine - 2.jpg

So the bottom half was assembled to make sure everything fitted .

proper_engine - 3.jpg

proper_engine - 4.jpg

With the bearings fitted it spins quite nicely! cue action shot.

proper_engine - 5.jpg

So onto the cylinder and valve guide next.
 

adrian

Flying Squad
The cylinder and valve guide is made up from standard K&S tubing. The end cap requires turning from a bit of brass bar.

A small hole is drilled in both the cylinder and valve guide to admit the "steam". Again the drawing is a bit convoluted in it's dimensioning. It wasn't clearly marked the dimension. I had to add and subtract half a dozen dimensions to work out a marked position.

cylinder - 1.jpg

The cylinder, valve guide and cap is then soft soldered to the base plate, I used a little spring steel in the "steam hole" so it didn't get blocked.

The inlet pipe is then soldered onto the side of the valve guide, which is then drilled through into the valve guide. Just a word of warning be very careful in drilling this out, it's very easy to drill all the way through into the cylinder! No need to guess yes I made that mistake, this is the second attempt.:rant:

cylinder - 3.jpg

In the mean time somebody on the Guild Forum posted a link to "Clickspring". Some wonderful engineering with very informative videos.
So whilst on the lathe I had a quick go making the "Delicate Scriber/Pick"
Delicate Scriber/Pick

cylinder - 2.jpg

There's a few other projects on that site I'm tempted to have a go at. In the meantime this is the cylinder loosely placed in position.

cylinder - 4.jpg

The piston is next although this will have to be turned down from larger rod. Although notionally 1/4" bore in the cylinder a length of 1/4" brass bar stock was quite loose fit. So I'll have to turn it down from something larger.
 

garethashenden

Western Thunderer
Going back to the first post for a minute, decimal inches are the standard American way of manufacturing things. Fractions get messy quickly, so everything gets measured in thousandths, 0.001". If things need to be really precise you can measure them in "tenths" (or more accurately ten-thousandths) 0.0001".
A dimension of 0.3" would be expressed as 300 thou or 0.300" but not as 3 tenths (even though is it 3/10") because most machinists would think 3 tenths is 0.0003".
 

adrian

Flying Squad
Have you made any more progress with this, Adrian?
Unfortunately much to my chagrin - no. :(:(:(

It's still on my workbench to remind me to keep going with it as there is a specific long term aim with this experiment. Unfortunately real world priorities, life and work have preventing any time at the workbench over the last couple of months. I've not been completely idle as I have managed some time on the computer drawing out an idea for a steam generator, starting with the gas tank. I just need to turn this into a real world physical item! :confused:

Screen Shot 2018-08-09 at 22.17.32.png
 

Richard

Active Member
From my experience with small scale live steam, you need to take the gas outlet as high up the tank as possible otherwise you will be carrying over liquid into the burner unit.
 

adrian

Flying Squad
I'll post a fuller explanation later - probably on another thread. Suffice to say Christmas lockdown has been spent trying to finish off a number of unfinished projects to have a clean start in the New Year so I'll be resurrecting a few dormant threads over the next couple of days.

This is the first one - the cylinder, con-rod etc were all made as per the drawing. The valve was made as per the drawing except on the original video I saw he'd fitted a small screw to the end. So I threaded the end of the valve 12BA and on the top of the valve rod put a small slot in for a screw driver. It allows for fine adjustment but also easy dismantling of the valve.

Anyway the final engine - I think I will replace the countersunk screws with a hex head screw just for appearance.
PC291954.jpeg

I then had to hook it up to my air compressor to give it a test - I just need to build a little boiler to power it now!

 

Osgood

Western Thunderer
Two points arise:

1. I’ve often wondered if there is a formula for determining the size of the flywheel for an engine.
2. How much of a challenge would it be to balance this engine up?
 

adrian

Flying Squad
Two points arise:
1. I’ve often wondered if there is a formula for determining the size of the flywheel for an engine.
2. How much of a challenge would it be to balance this engine up?
Not too sure although some of the multi cylinder engines do appear to be better balanced.

The 3 cylinder version looks interesting as that is self-starting.
 

simond

Western Thunderer
I’ve often wondered if there is a formula for determining the size of the flywheel for an engine.

Tony,

rather like the question about neutral axes a couple of days ago, this takes me back to University days, and it’s a subject I have not touched since 1982, so please forgive a vague reply.

I don’t recall a formula as such, but the calculations for balancing (we used the Audi 5 cylinder as our model) were somewhat tedious, probably rather quicker with today’s availability of computing power. Establishing some kind of static balance allowed us to calculate the effective rotating inertia of the crank, rods & pistons, and that, when compared with the torque required to complete the next compression, allowed a calculation of the necessary extra inertia - hence minimum flywheel size.

the actual flywheel is likely to be rather larger, as smoothness is a key criterion in most vehicles - and it will also tend to reduce loads in the transmission. Dampers are often fitted to the other end of the crankshaft to reduce torsional vibrations within the crankshaft itself, and they too form part of the rotating inertia.

A static balance of this engine would certainly be possible, if fiddly. You’d need at least one balance shaft to get close to dynamic balance.

Atb
Simon
 

Max M

Western Thunderer
Two points arise:

1. I’ve often wondered if there is a formula for determining the size of the flywheel for an engine.
2. How much of a challenge would it be to balance this engine up?

1. Of course there is. Have a read of this, please pay attention as you will be set a test at the end. :eek:

2. This is possible but how easy it would be on something so small is more debatable.

For those interested in all matters of engine tuning you could do a lot worse that invest in a copy of 'Tuning for Speed' by Phil Irving (he amongst other things designed the Vincent V Twin motor) which contains all sorts of information that you didn't know you needed to know.
Available as a PDF here.
 
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