Beginner making first steam engine

Hi all,

As a complete beginner to this hobby and someone who has only owned a lathe a few weeks I feel I'm now getting past the 'swarf making stage' and have decided to try and built my first steam engine.

I've decided to have a go at this :-

**LINK**

If it proves to be beyond my skill level I'll put it to one side for a few weeks till I have the necessary skills and/or tools to do the job.

The plans are in imperial but I've decided to work in metric (my lathe and measuring equipment are all metric) so whilst I am working to the basic design the measurements are flexible and I'll modify / embellish it as I go along.

As I say I am a complete beginner so if people want to offer me advice or tell me better ways of doing things I'm more than happy to listen.

Here goes :-

Firstly I decided to machine the cylinder block / steam chest, I didn't have a piece of brass big enough to hand so I settled for aluminium (It's unlikely the engine will ever see live steam so I figured aluminium will do for compressed air).

Block turned and faced to size then power piston bore done.

Steam chest bore done, I decided to make this slightly larger diameter than the plans as I think that may prove more forgiving at my skill level.

Ready to begin drilling inlet port.

Drilled through as far as power cylinder, I was a bit relieved at this point. With my limited tools and experience I wasn't certain how parallel the bores were etc. However once the inlet was drilled through my scriber seems to suggest they are reasonably true.

I decided to omit mounting holes for the cylinder at this point as I'm not yet certain how I'll go about it but will probably deviate from the plan.

So - I decided on the piston next. This time I had a suitable piece of brass

I did damage the first piston when I turned it around in the chuck but had better luck second time

I decided to cut in a couple of very small oil rings that aren't on the plan but I thought they may help me get a better airtight seal.

Edited By Peter Nichols on 26/06/2015 12:22:38

I found a couple of pages about rescaling recently which you may find useful

Hi Peter

Nice to see you starting your first engine, I'll be following all the way..!

Enjoy, and the very best of luck with it.

Regards

Garry.

Thanks guys.

Ady that thing about rescaling brings back memories, I was taught that at school 40 yrs ago and completely forgot about till you mentioned it. The article also mentions slide rules ! I even remember them from school too

I been having another look at the plans and have decided to try and make the con rods a bit more attractive than the plans and possibly machine the cylinder top off then make a separate bolt on cylinder head, that would make it a bit more attractive and allow me to see what's happening in the cylinders when it comes to adjusting the valve timing.

Peter.

You might find brass and aluminium is a poor combination corrosion wise.

Looks nice, keep up the good work.

Edited By V8Eng on 26/06/2015 22:17:34

I put aluminium fins in the copper cooling tank of one of my hot air engines. The motor was driving a little generator, and I was checking the voltage, for some reason I put the metre across the fins, and copper tank, result .5 of a volt.

Aluminium is a poor choice for a sliding contact in it's ordinary state, it improves with anodizing, or as in some small IC engines chrome plating. It will work, but wear quickly, but a good practice session for your new lathe.

Ian S C

For a low power compressed air operated engine, I think you will be fine with the metal combination you have chosen. It is not as if you will be running it for hour upon hour, so it will take Years before you get any significant wear.

Across the Pond, particularly, ali/brass combination is used more frequently than any other in small air models. Have a look at the HMEM site. http://www.homemodelenginemachinist.com/

Dave
The Emerald Isle

Hi all,

Thanks for the advice, I didn't have a piece of brass the right size so I just used aluminium without thinking too much about it. I've now made the valve/exhaust piston also, with both pistons done they seem to fit nicely and slide smoothly, whether it will run is another matter !

Thinking ahead a little, I'm intending to try it on compressed air, can anyone advise me what is the usual diameter airline for such models so I can machine an appropriate sized inlet fitting ?

The plans go on about soldering a tube etc, I'd rather just insert a threaded fitting to accept a small airline.

Thanks

Peter.

Ordinary aquarium plastic airline will do just fine. A barbed type fitting or one with a knob on the end will hold the airline in place. You don't want sharp ridges because the tubing might tear.

Have you considered what air system you will use? If it will be a one off air powered engine, consider getting an airbrush compressor. They put out a sufficient volume and pressure to run one or two little engines at a time. They are also very quiet compared to the usual Aldi/Lidl 2 HP or bigger versions they sell from time to time.

Dave
The Emerald Isle

Hi Steve,

I did think about air supply and initially considered an aquarium pump but having since looked around I've seen paint spraying kits with a compressor for just over £60.

Something like this was what I'd thought about :-

**LINK**

I think I'd rather pay the extra and get a spraying kit, it's bound to come in handy for hobby work.

Peter.

That's the type of copressor I was meaning.

Dave
The Emerald Isle

If you are getting an airbrush compressor and all teh bit sthen make a threaded union to take the airbrush hose.

As Dave says you should be fine with ali/brass, I have quite a few ali pistons running in bronze cylinders so similar situation and no problems with them.

Hi all,

Today I thought I'd have a go at making the valve/exhaust piston, It's basically just a brass cylinder bored through to a blind end just a few mm before passing right through with an slotted exhaust port bored in at 90* to meet the central bore.

Firstly I faced, turned, and bored out to fit the cylinder bore.

To drill the exhaust port I decided that without a bench drill I'd probably be just as well using a rechargeable power drill. I realise that isn't a precise method but I'm only wanting to drill 2mm holes only 2-3 mm deep and minute accuracy isn't crucial. As can be seen the hole and adjoining recess aren't perfectly aligned but I think they will meet the requirements

I struggled to file the slot alongside the exhaust inlet and although it's not attractive it does appear to be the right size and in the right place.

This photo shows the piston valve at it's furthest travel so TDC will be just slightly short of this position, so for now at least I'm satisfied the valve will align with the port correctly when turned 180* to face the power cylinder port.

The next photo shows the top of the valve piston with the inlet port for the power cylinder just about visible at the back. So I'm hoping that once the valve piston has been rotated to face the power cylinder port the exhaust will line up near TDC. Well that's the theory anyway !

The valve piston now with a shoulder turned at the con rod end (that I should have done earlier but forgot !) All the remains is to cut a slot to accept the con rod.

Both pistons and the cylinders almost complete.

Peter.

Hi,

Although the plans have this as a vertical engine I'd prefer to have it as a horizontal so have been doing a lot of thinking how I might best go about it. Part reason I didn't try a 'wobbler' as a first project was that without access to a milling machine I didn't feel I could reliably file the necessary flat face by hand with sufficient accuracy.

After some helpful advice from other members here they suggested I could face off a piece placed a cross the lathe chuck if I was careful about it.

I decided I wanted to bottom mount the cylinder block and reasoned the only way was to face off in the way others had suggested, with the intention of bolting it to a plate. The cylinder walls are fairly thin and bottom mounting seemed the best option.

I decided to have a test run with a piece of similar sized aluminium and sure enough it worked with ease. At least now I know that till I get a mill it is possible to do very basic 'milling' in the lathe. As this was only a test piece I didn't go to the trouble of lining it up properly but you get the idea.

I figured that lining up would be a problem but with the use of parallels and a few faint scribe markings that were still left from earlier drilling operations I could just about manage. I used the tool point to align with the scribe markings and rotate the work by hand in the chuck 180* whilst not moving the tool.

In order to get access to the scribe markings along the centre line I needed the work out of the chuck slightly beyond its diameter so it's actually only being held firmly by the 2 flat ends with the other 2 chuck jaws gently touching the curved sides. I realise that's far from ideal but the intention is to take light cuts on a soft material and I have got a very firm grip of the flat ends of the work.

Success ! - A bit of filing and tidying up to remove a few minor scrapes and chuck marks and also seems to be ok.

Edited By Peter Nichols on 28/06/2015 15:34:48

Found it, I thought I recognized the plan, not too sure about the boiler that is suggested, others may know, it's from Popular Mechanics, and the boiler is made from a 6" X 2" water pipe nipple, with a pipe cap on each end. I would not trust water pipe, the bit of 1 3/4" pipe I used to make a cylinder for my second hot air engine split along the seam when I bored the weld bump off(welded it along the outside and it's still going).

At least you picked an easier one than I did from the same source, I built the Elbow Engine, it takes up room on my model shelf.

Ian S C

Hi Ian,

I found the plans online, this is the link :-

**LINK**

Is it the same as you were thinking off ? I'm broadly working to it but adjusting a few dimensions to suit and intend it to be a horizontal rather than the vertical in the plan.

I'd have liked to start on the con rods and possibly the main axle/crank next but decided I'd be better getting the cylinder mounted on a brass plate and on a piece of scrap wood for now, then I can look at where the crank needs to go etc and finally make the con rods to suit. I indend to make the rods out of round brass bar rather than the flat strips in the plan.

I'm looking at buying a small compressor/airbrushing kit (about £65) as an air supply as the airbrushing is bound to come in handy as well but I did notice aquarium airline on Amazon - £2 with free delivery ! so I ordered some.

Till I've decided how best to clean up the brass base plate I thought for today I'll just do the airline fitting, I didn't think ahead at the time but I decided to risk drilling it out to cut an M8 thread into the cylinder block as I think anything smaller wouldn't pass sufficient air.

The result meant I have an M8 to 4mm airline fitting bored through to 2.5 mm, I wanted to try and bore it out a bit more but though I'd be pushing my luck

I can't say I'm overly happy with the result but the likelihood is it will only be a temporary measure and it does look like it will do the job till I come up with a better idea.

Peter.

Edited By Peter Nichols on 29/06/2015 13:33:44

I'v got a set of Popular mechanics DIY books that Dad had, it's a collection of articles from the magazine. The suggested cylinder is bronze, and the piston cold rolled steel, same for the valve piston.

Ian S C

I started making it using the materials I had, so I'm hoping it will work using the materials I'm using.

It's only ever going to have a few test runs on compressed air till I can get it running then it will be a glorified desk ornament so I'm not overly bothered about wear or efficiency issues so long as I can satisfy myself it is a 'working' model.

Peter, it sounds as though you work in a similar way to me, most of my time on a new construction is hunting around the workshop for the materials, spent half of today looking for some suitable steel to make a flywheel. I use mainly scrap steel that needs machining all over, over the years I'v built a few ornaments.

Ian S C

Hi Ian,

As I'm only starting out at this game I'm gradually building up a stock of materials (and tools) but for the moment working with what I've got till I have a better stock.