Beginner making first steam engine

[Steven GreenhoughParticipant @stevengreenhough56335]

Sir,

If these are indeed your first steps at machining then I am very jealous, you seem to have a knack to me. I've just made a crank for my little steam locomotive, quite similar to yours, but I would'nt have even thought to make it 1 piece from solid.

Very, very impressed.

[Gas_mantle.Participant @gas_mantle]

Thanks Steven,

I hope to have it finished in a few days but struggling a tad with the eccentric at the moment.

Peter

[Gas_mantle.Participant @gas_mantle]

Hi,

Today I wanted to make the valve eccentric and possibly the eccentric strap (which would virtually complete the model) but was a bit unclear about the measurements for the eccentric.

I decided to tidy up the flywheel first and ask the help of others on the forum regarding the eccentric then try it after a bit of further thought and a second opinion.

The wheel I made a couple of weeks ago wasn't made for this engine and did have a lot of score marks but I thought it was repairable and the right size for this engine so I opted to try and make use of it.

I struggled to find a way of getting into the recess to take out the score marks so thought of trying with a parting tool, I know it's probably not a good way of working but there's a few thou cut will take out all the marks and I'm only moving radially about 15mm.

Fortunately it worked well, and it gave me a chance to give it a few light cuts elsewhere to true it up.

By now I'd had a bit of advice regarding the eccentric so set to work on it.

I didn't want to mess around soldering etc like the plans suggest so decided I'd sandwich the eccentric between 2 disc to keep the eccentric strap in place. This method would hopefully allow me enough width to insert a retaining grub screw that I could the use to adjust the timing.

First I turned a piece of steel to 16mm dia and drilled the hole for the main axle.

The central hole is 5.4mm in dia and the offset needed to cut the eccentric is 2.5 mm, so the new turning centre lies within the central bore.

A bit of a makeshift idea, but using a dial indicator and only loosening 2 opposing jaws on the 4 jaw chuck I was just able to move the workpiece 2.5mm in one direction only.

The resulting eccentric has the right throw (I think) but in order to turn it down to be flush with the attached disc I got a bit closer to the cental hole than I had expected.

Parting off the combined disc / eccentric.

I'm reasonably pleased with the result, on one side the 2 diameters lie flush to accept a grubscrew.

Just need to make another similar disc to go on the other side of the eccentric and trap the strap between the 2.

Peter.

 

Edited By Peter Nichols on 08/07/2015 15:26:15

[Gas_mantle.Participant @gas_mantle]

Hi,

The engine is nearing completion now and there isn't a lot more I can do at the moment.

I've ordered a knurling tool to make a decorative bolt for the bearing oil hole and a few assorted grub screws to secure a few components to the main axle. Until they arrive the only thing left is the eccentric rod and pin plus a few axle spacers.

I decided to tackle the eccentric rod get it filed down to size at the eccentric end then when I can secure it with a grub screw I'll work out where the hole to connect the valve piston needs drilling and file the other end accordingly.

The plan suggests making it using a rod soldered to a ring of copper pipe as the eccentric strap, I don't have any soldering equipment and thought I could make a better job by hand filing it as one piece from a piece of brass plate.

Much filing later it's starting to take shape.

One end just about done and a nice fit on the eccentric.

As it's a gift for someone I bought a decorative plinth and overall I'm pleased with how it's starting to look.

Peter.

Edited By Peter Nichols on 09/07/2015 11:10:39

[john carruthersParticipant @johncarruthers46255]

Looking good. I had similar problems chucking parts until I made a back stop for the spindle.

[Gas_mantle.Participant @gas_mantle]

Thanks John, I think that's something I need to do, when I started this project I didn't even have any parallels, it got a damn sight easier once I got myself a set.

That plinth looks tidy but its made of MDF so I don't think I'll be able to drill it and screw the brass base plate down, I've already drilled the plate so I think I'll just make some ornamental dummy fixings to sit in the holes but glue the plate down.

Anyone got any ideas what sort of glue would be best to stick brass to MDF and something to glue some of the screw threads so prevent them working loose if the base is glued down and they become inaccessible.

Thanks

Peter.

[john carruthersParticipant @johncarruthers46255]

I still don't own any 'proper' parallels, I use old bearing races (quite accurate) and bits of drill rod, must get some.

I found some little coasters made from squares of black granite on Tesco's 'reduced' shelf, 50p, make excellent plinths.

[Neil WyattModerator @neilwyatt]

Well done Peter,

Making great progress and learning a lot as you go.

> I'm sure there must be an easier way,

.. of turning an offset crank pin.

Yes, there are a other few ways, both potentially risk marking the shaft unless you take car to ensure it is gripped carefully:

1 – a short length of steel bar with an offset hole the shaft fits into. Perhaps the best grip comes from slotting the bar along its length through the hole so when tightened into a 3-jaw chuck it becomes a sort of 'offset collet'. You can also superglue the shaft in and use heat to get it out.

2- holding the shaft offset in the 4-jaw chuck – can be very fiddly to get the offset right, and you need to use some suitable packing (bits of aluminium can) to protect the shaft.

3 – holding the shaft in a 3-jaw chuck but with extra packing under one jaw to get th eccentricity. I forget how to calculate it but its an approximation anyway so use trial and error.

 

Your way works, but it would be better to put a short piece of packing between the chuck's face and the disk to ensure it stays lined up.

I've used 1 and 2 for crankshafts, and only used 3 to drill eccentrics.

Neil

Edited By Neil Wyatt on 09/07/2015 18:19:07

[Gas_mantle.Participant @gas_mantle]

Thanks Neil,

I gotta say it's been great fun building this little engine, I've never done anything like this before and have really got bitten by the bug. I'm glad it turned out ok, if it had been a disaster I'd have risked getting disheartened only a month after buying a lathe.

I'm starting now to think what to have a go at next, I'd love to tackle something bigger and a bit more sophisticated but something that's not too complex. I've considered a Stuart S50 but think it's a bit beyond my skill at the moment and I don't have a mill, though at this rate I can see me buying one before too long !

A simple beam engine also appeals to me if I can fine one that's reasonably straight forward.

[Roderick JenkinsParticipant @roderickjenkins93242]

Peter,

I think you're making a very fine job of the little engine. I can see no reason why you shouldn't be able to make an equally good job of an S50. Here's a **LINK** to Tubal Cain's S50 build instructions: He called his Sally and it is made without a mill. Just change sally-1 to sally-2 etc to get the following installments.

Cheers,

Rod

[Ian S CParticipant @iansc]

Peter, when I attach things to a wood/MDF base, I use little bolts, and recess nuts underneath. That's what I did with this Stuart Turner S9, the base is a black marble patterned MDF, with a ply wood surround.

Ian S C

[Gas_mantle.Participant @gas_mantle]

Hi Ian,

The problem is I drilled the holes in the plate before ordering the plinth thinking it would be wood and I'd have no trouble using 4 small brass screws. I think now the holes are too close to the edge and will risk splintering the plinth. I'm actually pleased with the plinth so don't want to damage it.

I think what I'll end up doing is to glue it down and make some dummy fittings to cover the holes – I guess it's an excuse to make a decorative brass 'handrail' round it.

There's not much I can do now till the postman brings my knurling tool and grub screws so I got thinking about how to test it once it's finished.

As it's really going to end up as a glorified ornament I'm happy just to make do with a temporary boiler just so I can say it's been tested and is a working model. Alternatively I'm looking at buying a small airbrush set up with a compressor.

For now I thought I'd have a go at rigging up a temporary boiler.

I dug out my old Kelly Kettle and camping stove and made bung to take the aquarium airline. The bung is simply a crude push in taper and the air line is only a push fit so I'm happy it's still relatively safe without a safety valve or pressure gauge.

First attempt was disappointing. Struggling to inflate a balloon and a lot of water travelling down the tubing.

I cut the tube much shorter for another go.

Looking better this time.

Anyone able to have an educated guess as to how many PSI that might be ?

Do you think it will power the engine just for a one off test ?

Peter.

[Jeff DaymanParticipant @jeffdayman43397]

It takes less than 5 psi to inflate toy balloons, many inflate with 1 psi. Unless your engine is exceptionally well fitted and perfectly timed it will not run well at first on much less than 10 psi. Later after break-in it may run on 5 psi.

Kelly kettles are not intended to be used as pressure vessels (or to generate a lot of steam, for that matter). They are intended for heating liquids to just below boiling point. They are not safe for any other purpose.

I suggest you make a simple copper or brass boiler to one of the published designs such as those in the books "making simple steam engines 1" and "making simple steam engines 2" by Tubal Cain.

For testing your engine an air compressor with a regulator to increase the pressure slowly from 0 psi, under control, would be better. If you don't have one, and no one you know does, take a spare car tire down to your local garage and fill it to the recommended 28 to 32 psi for that particular tire and use that as a short term source of compressed air. A valve inline with the tire to engine hose will serve as a makeshift control valve. (don't use a plain valve if you use a compressor, use a proper regulator for that, due to the compressor's higher pressure)

Be safe. JD

Edited By Jeff Dayman on 10/07/2015 22:44:46

[HopperParticipant @hopper]

Solution to too much water in the steam line might be to run the water level in the "boiler" lower and use a smaller flame once water reaches boiling point.

[Steven VineParticipant @stevenvine79904]

Hi Peter

If the Kelly Kettles does not get it moving then you could try a car foot pump. It should provide enough pressure to get it turning over for a test.

Nice build, I've enjoyed following this.

Steve

[Ady1Participant @ady1]

As with most things in life genuine talent makes itself obvious from the start

A very nice first build

[john carruthersParticipant @johncarruthers46255]

I hooked mine up to the esspresso machine steam pipe with a bit of tube

[Ian S CParticipant @iansc]

I'v got a (?) 2 L garden spray pump which is ok for any of my small wobblers, and a Stuart Turner Progress VS, this has a bore of 1/2" and stroke of 3/4", and has a slide valve. we,v just got a ST 10H, must try that one.

Ian S C

[Gas_mantle.Participant @gas_mantle]

Hi all,

Many thanks for the positive comments received.

My postman arrived with my knurling tool and grub screws today so I'm now in a position to hopefully complete the engine.

I've never used a knurling tool before but after a quick look decided to put it to work on a few trial runs before making the bearing oil bolt.

After a few tries using different speeds and depth I ended up with this.

It looked to me worth keeping as the finished product so set about turning it to size and cutting a thread. Since I wasn't able to cut a thread right up to the head using a die I decided to turn a plain shaft slightly undersize just beneath the head. I hope this will allow it to seat flush on the housing once tightened down.

The remaining stock in the chuck came in handy to make a threaded arbour to hold the work whilst I turned it round to face off the head.

5 minutes later and a bit of filing to shorten it and this is the result.

So far so good, I reasonably happy with it.

Now I have grub screws to secure the eccentric and the flywheel I'm able to have a go completing the eccentric rod and attaching it to the valve piston.

I wasn't really sure of the best way of going about this but as a start point pushed the valve to it's furthest travel then use calipers to see how far the wrist pin will be from the main axles centre.

When the piston valve is bottoming out at it's furthest travel the wrist pin hole is nicely aligned with the end of the cylinder block as shown in the photo.

So by lining up the wrist pin hole out side the cylinder I can see where the valve ports lie in relation to the inlet when the valve is at maximum travel. The little indent I've cut next to the hole allows the main power piston to exhaust when the valve hole has slightly gone past the port linking the 2 cylinder bores. So when the valve is in this position exhaust can still occur even though the main holes are past alignment. (I think !)

One last check with the calipers tells be this is maximum travel so the 2 centres on the eccentric rod need to be just a tiny bit less than this distance to prevent the valve striking the far end of the cylinder.

Well it's drilled and filed now, I can tidy it up later once I'm happy it works.

I really hope I've done this last step correctly.

I did put a bit of wire staple in as a temporary wrist pin to give it a bit of a try blowing down the airline. Unfortunately is far too much of a loose fit for the valve to operate properly and I need to make a few spacers for the main axle to keep things in correct alignment and prevent the eccentric strap coming off the eccentric as it does now without a retaining feature on one side.

On the plus side the engine turns smoothly and the power piston does respond nicely to a puff of air.

With a bit of luck it will be finished tomorrow.

Peter.

[Brian JohnParticipant @brianjohn93961]

I hope my first efforts on the lathe are as good as this. I am waiting to see how it runs so any chance of a youtube video link when it is complete ?

Edited By Brian John on 12/07/2015 05:10:12

[Gas_mantle.Participant @gas_mantle]

Hi,

Thanks Brian, I had thought about trying to do a short video. At the moment I don't have a Youtube account but I'll get round the problem somehow and if necessary I open an account on youtube.

Hopefully I'll get the axle spacers and wrist pin made today and set about getting it to work.

Peter.

[Gas_mantle.Participant @gas_mantle]

Hi all,

I set about trying to finish the engine yesterday and hopefully give it a test run.

Firstly I needed a better wrist pin than the temporary staple I was using. It involve turning a piece of brass rod down to about 1.5mm but with care that shouldn't be a problem.

At about 2mm the rod is starting to flex and the tapered cut I'm getting becomes apparent, thankfully the Poundshop sell these blue travelling steadies at 6 for a quid in the biro section

The taper seems to have gone

Eventually I arrive at this,

1.55mm and just right.

Cut to length and the end lightly peined over all seems ok.

The wrist pin needed to be just short of the end of the cylinder at maximum travel and have a 3/16 stroke, so I'm hoping I've achieved that with sufficient accuracy.

With the wrist pin done all that's needed now is a few spacers for the axle and then a test run.

I'm satisfied this is the alignment needed, so I need a spacer with a disc to keep the eccentric in place then possibly another one between the eccentric and crank and finally a small one behind the fly wheel may help.

A steel bar turned at one end to 16mm (the eccentric retaining disc), reduced down to a smaller diameter for the spacers and drilled to accept the axle.

A bit of a makeshift idea but I reckon the eccentric disc/spacer need to be 6.5mm

So using this crude method I cut small reference grooves in the work piece marking the parting cut position. I did the same method for the other spacer hoping I'll get 3 components in one procedure.

Parting tool at the ready and here we go, buy 1 get 2 free.

I took the next photo at the wrong time, it should show the tool further left to part off a disc for the eccentric, but you get the idea.

I end up with these 3 and just a bit of filing and tidying up to do.

Looking like a 'proper' crank assembly.

Well does it work ?

I rigged it up to a Kelly kettle and aquarium tubing and although it coughs splutters and hisses it does kind of work.

The eccentric rod has a bit too much lateral movement and the valve piston is a shade too small in diameter. the result is steam escapes past the valve as it wavers in the cylinder.

I'm going to file down the eccentric today and make a better fitting valve piston in the hope of rectifying what I think is the main issue.

I'm confident it will work though, the valve although a bit sloppy in side to side travel does seem to operate properly.

Peter.

<

[Brian JohnParticipant @brianjohn93961]

One thing I discovered when building a wobbler engine with no piston rings is that you might find you have a nice piston to cylinder fit when running on air but once heat and steam is applied then things expand…and not always equally. My nicely fitting piston became jammed in the cylinder once everything got hot ! But if you make the piston and valve too small then you lose a lot of steam. I found that it was a delicate balancing act to get it just right. None of this advice may be applicable in your case ; I think it depends on the engine.

Edited By Brian John on 13/07/2015 11:18:54

[Gas_mantle.Participant @gas_mantle]

Thanks Brian,

I'm wondering if it may run better on air anyway.

For reasons I don't understand it works better pointing skyward with the flywheel uppermost !

It's very sensitive to adjustment, I put an allen grub screw in the eccentric to allow for valve timing adjustment but under live steam it soon gets scalding hot and a pain to adjust.

I'm still pleased with it though, it needs a few minor glitches sorting but it does cough an splutter along now if I catch it right so I don't think there's a great deal wrong with it in principle.

Peter.

[Gas_mantle.Participant @gas_mantle]

Many thanks to everyone who followed this thread and offered their encouragement.

I can now say I've got the little engine running on live steam, (I made a new valve piston) it's still very sensitive and struggles when horizontal but rattles along in an upright postion.

Hopefully the fact it runs ok upright suggests there isn't much wrong and it should be simple enough now to sort it out.

I've only had a lathe a few weeks and this was the first thing I made, I've never done anything like this before so although it was a simple project compared to many on this site I'm very pleased with it and enjoyed every minute of making it.

I don't have a youtube account but if anyone wanted to see the engine running I'll resister and upload a video (can I upload one direct to this forum ?).

Peter.

[Author]

Posts