Freelance 3/4” traction engine

[Team ricky]

Hi all,

Here’s an interesting project part built and re-built !!

I do want to make a traction engine but at a cost I can do !
Brought partbuilt here’s the good :

Rear wheel rims ready for spokes
Main cab all built minus a water tank
Boiler parts individually ok
Parts made so far are scale
Several valves were made to a good standard

Bad bits :

The boiler was lashed up with soft solder and the front of the throat plate was slot milled to clear the horn plates and was very dangerous indeed….

No plans or drawings

No engine castings No n this scale available

So the way I’m tackling this is to come up with a sensible spec, stick to it , discard any bad bits and do over!

Silver solder the boiler

My spec as I see it going in is:

3/4” scale parts only
Engine casting set is from a Revees Trojan
Silver soldered boiler
Gas or meths (I thought about coal )
Engine reverse gear
Simple 1 speed gears with a neutral setting
Traditional crank and rods
Water pump (either axle or manual


I think so far I’m on the right track…

I have fully stripped the boiler and removed all traces of soft solder (big job)
And silver soldered the bushes back in and fire hole , Hopefully more pics soon

[propforward]

Heck of a project - look forward to seeing it take shape. Sounds like a readonable recovery plan - would be wise to cross reference the boiler to an established design, or else go through the design against a model boiler design reference and check to make sure it’s up to the task. Not knowing your background I don’t know how comfortable you are with either approach. Assuming you are in the UK it would be wise to engage the help of a model engineering club before you go far, as I think you’ll need to have it inspected in some manner if you wish to show it.

[Jasonb]

Rather than a freelance the tender/hornplates you show suggest it is built to or very closely base on the design "Modular" that was published in Model Engineer Magazine in the early 80s

With the cylinder, valve gear and crank on it's own platform it could be removed from the traction engine and used as a stand alone steam engine hence the name "Modular"

[Team ricky]

Small world !!

Yes I think you are onto something there…. The give away is the two entrance cut outs and the steam turret design… both features I have matching the one picture on the net !


I wonder what overall design/type I should go for ? Manufacturer’s?

I’m pretty sure I’m just going off piste with this one and probably will enjoy that alot more than hunting/following drawings- Famous last words !

I did forget to picture the smoke box end and chimney as they are complete

[Team ricky]

As for the boiler …..

A drawing for that would go a long way , However I’m pretty confident it’s to a general design up to this point and research and books I’ve brought pretty much show the overall design is sound just the soldering was terrible!!

The boiler design is a wet back front sides like a larger scale would be, Therfore stays will added which are not drilled for yet as you would expect, the doubler I’ve added allows for the fire box sides to be extended as normal- this will get fixture rivets for soldering.. I also extended the doubler to fix the mill slot a rank amateur did , Very dangerous as it was ….

I’m going for 80psi test and 30 psi on the relief valve , If it fails I’ll do what’s needed to fix or make a new one which isn’t too tricky looking at the build so far..

[propforward]

Good deal. Hope to see pics of it at some point. 👍👍

[Jasonb]

General arrangement and boiler.

There is mention of testing to 150psi so that would suggest a working pressure of 75psi.

[Team ricky]

Brilliant find thanks !!

Looks like the same design as my parts would suggest

16g copper throughout

Same fire box design

Only big question I have is it shows no stays….
Would not be detrimental to add and at those pressures mad not to …!

I’m definitely not going over 100 psi test 40 psi WP , that’s a good amount of power especially with the low gearing traction engines run !

[Team ricky]

A little soldier done ✅

I made up the crown sheet and soldered the tubes to the fire box and the front half of the crown sheet,

All went well but borderline on heat so I’ve ordered a 30 jet torch to finish the boiler ,

Offering up the parts inside the shell it all looks good and on drawing, To finish the fire box I will solder inside joints too just before soldering the fire box in the shell!

One other feature missing is the crown sheet gussets….. I don’t think it’s necessary but maybe at the higher pressures mentioned…

[Jasonb]

I think as the crown is arched rather than flat you should be OK without staying that.

Text does mention that it is about on the borderline for needing stays to the firebox but designer felt that provided you stuck with 16swg it was OK.

[Team ricky]

Interesting…..

I guess heat cycle the fresh made boiler before pressing test to harden the copper to nominal (half annealed) is a must

And I guess two stays per flat side would not hurt ?? Or just reduce the pressure to be on the safe side …. Many options all I think are ok

[Team ricky]

Here’s a bit more done ✅

Cylinder bored
Ported
Valve face lapped in

I’ve gone for 1/2” bore 3/4” stroke and the piston will be 8mm deep/thick

That’s pretty much the same as the Basset and lowke 3/4”

[propforward]

Interesting…..

I guess heat cycle the fresh made boiler before pressing test to harden the copper to nominal (half annealed) is a must

And I guess two stays per flat side would not hurt ?? Or just reduce the pressure to be on the safe side …. Many options all I think are ok

What heat cycling will you do that will harden copper? I know there are some exotic copper alloys around but I wouldn’t think you have one of those here. Copper can be work hardened but when heated enough it anneals. Heating it to anywhere below its annealing temperature is not going to harden it.

I know that some of the actual alloys like Cr-Cu, some bronzes, probably Be-Cu and I expect brasses (some of them maybe - haven't checked) among others can be precipitation hardened, and that there are heat and quench cycles for hardening (some of) them. Do you have one of those? (Unlikely - readily available copper sheet is just high purity copper around 99.9% or so depending on which one you have). If it’s just one of the high purity coppers then I am pretty sure it won’t be hardened by heating, quenched or otherwise. I did read something once about bulk oxidation of copper for hardness - but it also embrittles the material. Not good for boilers.

Reducing pressure / adding stays makes sense if the design is “close to the edge” which is never a good place to be with a boiler or pressure vessel.

[crueby]

Heat cycling will not harden copper or brass, it will only be hardened by working it.

[propforward]

As usual I dive in too deep and start thinking about all the exotic materials, none of which apply. They are all very fun to work with, though, by the way. Thanks, Chris, for the succinct answer.

[Team ricky]

Ah ok …. An incorrect wife’s tale I’ve remembered!

So onto the most sensible approach of dropping the pressure I think….

I would at a guess think that during the pressure test you would get signs of issues as the pressure rises, I.e visible distortion of the flat surfaces and or cracking sounds both of which are a fail even if the boilers in tact it would show it’s been pushed too high !

I can’t think of any real need to go over 40psi WP unless I’m missing something here !?

[Jasonb]

.

[Team ricky]

That’s a interesting read

Thanks for sharing that !

I guess the 80’s were just built different ! Accepting bulging seems a bit wild !

[propforward]

I would at a guess think that during the pressure test you would get signs of issues as the pressure rises, I.e visible distortion of the flat surfaces and or cracking sounds both of which are a fail even if the boilers in tact it would show it’s been pushed too high !

Also, if you're pumping away and the pressure won't go up - that's a problem. Or if the pressure drops during the hold periods. There should not be any pressure drop. Not all failures are accompanied by a sudden sound on pressure vessels. Keep an eye on all your joints for little bubbles coming out. It doesn't always take much of a leak before the pressure suddenly won't hold, even on a great big vessel. I'm more familiar with those than small model ones.

As for bulging it's a question of how much - I think the article mentions "slightly" which is a bit ambiguous. Everything will deflect some amount - it's just how much is allowable. If the material yields that is a problem. But the material can still permanently deform and be sound. I can't tell if the author means for the material to bulge permanently or temporarily (elastically - i.e. goes back where it started when the pressure is relieved). I think I'd prefer that myself, but I am the cautious sort.

So, there I go complicating it again. Interesting though, isn't it?

[Michael S.]

I can still remember testing my self-made Kupfee boiler with a pressure of 4.8 bar. The normal operating pressure is 3.0 bar. Operating pressure x 1.6 = 4.8.
The copper, which is still soft after soldering, will deform slightly during the pressure test. It should not be visible to the eye.
It could be that the test pressure is calculated differently in each country. For us it is a factor of 1.6.
(If it hasn't changed again)
My copper boiler was an 89mm diameter tube.


Greetings Michael

[Jasonb]

Usually twice working pressure here.

Best to look for water not bubbles as you should really be hydraulically testing the boiler as should something let go the water inside won't go bang like it would if the boiler was being tested with 150psi of air. Usual trick is to put a small boiler on a paper towel and see if it darkens where it gets wet. Even if using compressed air to provide the pressure for testing the boiler should be filled with water and air only in the eairline and  a bit of pipe work.

You should also be able to isolate the pump so that any drop is not due to leak back through the pump

[crueby]

What Jason said!  With water filled boiler, any minor seep is visible as drops forming on the outside if tiny, anything larger will throw a visible stream like a squirtgun. Even full size boilers are tested with water.

[propforward]

Even full size boilers are tested with water.

Yes - it tends not to go "bang" as badly if something hasn't worked out. 

[propforward]

Just for the sake of interest - not wanting to go too far off topic - in the states the Boiler and Pressure Vessel code is used to govern just about everything. The hydro test in Section VIII Division I is based on the ratio of material stress at test temperature divided by the material stress at design temperature - all multiplied by 1.3. So not a fixed factor so to speak. That said every model pressure vessel I have seen simply goes to 2.0 X the working pressure, because the actual code requirement lands between 1.5 and 2.0 typically, so 2.0 is easier to remember and adds a bit of safety factor.

The piping codes have a different value. The BPV code also makes allowance for pneumatic testing, and in that case it's the stress ratios multiplied by 1.1.

But again, this is all for interest value only. Everyone needs to go with their local laws and codes and be guided by their local clubs / inspectors.

[Team ricky]

Thanks for all the tips chaps

I now know what to look out for !

I have a garden spray pump which I’ll use for the test ….. should get 100psi at its upper limits….

A bit more done today, I drilled the steam ports into the cylinder and machined up the slide valve which turned out very good 😊

[Team ricky]

It’s been a while

Moved house and just picked up some project work now !

Here’s the boiler close to finished, I did luckily find a better boiler shell and fire box on eBay which im much happier soldering and finishing

I’ve just finished soldering the main areas and leak checked briefly at 60 psi and alls good so far !

Just the blow down bush to solder in and it’s ready to test at full pressure

[Team ricky]

Couple more

[Team ricky]

A little more done / underway

Mainly a mock up as I’m not following the plans for the engine/cylinder side of things

I’m going for a simple achievable engine that runs forward only and I will use the steam regulator to set it going!

The cylinder and trunk , bottom cover are made up, The flywheel is good , the crankshaft material is here now so I will probably make that tomorrow

The mamod wheels are ok not brilliant but will get things going, They will look alot better with decent solid rubber added…

[Team ricky]

A small part made today

A slightly reduced cross head taken from the Borderer twin engine plans

Looks great so far and will take a good looking connection rod

The trunk guide I made in cast iron and honed the inside just for practice 😉

[Team ricky]

Here’s the crank shaft done ✔️

Simple built up crank with taper pins

[crueby]

Nice!

[Roger B]

Coming along well  nice family pictures 

[Team ricky]

Hi Chaps,

Like most folk I tend to have too many things on the go!

I’ve come back to finish the boiler and cylinder mounting and setup 😁

A bit of advice just on pressure testing needed !

I have a sealed boiler up to 100 psi on a slightly scuffed set up but it works…I have brought a reasonable quality hydro tester which I haven’t hooked up yet but can make an adapter for it to work, Question is should I take it further and go for say 150psi and run the boiler at 75psi? Would a higher pressure yield any real world benefit?

Cheers R !

[Team ricky]

Some pictures 😁

The bronze ring fits the od of the boiler and will be trimmed to a minimum for the cylinder mount to solder to, The mount goes between the cylinder and valve chest,I will reduce the width of the cylinder and valve chest as much as possible!

[steam guy willy]

hi just a thought,  are you using bronze for all the boiler flanges to reduce the risk of dezincification if using brass ? looking good ..I built a boiler about 50 years ago and used brass throughout  which means i can never get a boiler certificate for it ?!  This was built along time ago when there was no club or internet or phones available to advise !! the model was the 440 County Carlow.. so it remains unfinished...sadly

Willy

[Team ricky]

Hi Willy,

The boiler itself is all copper and rivets too, The bushes are bronze so all good 😊
It’s a shame your one had brass in the build as you say not ideal although for personal use it would e ok for quite a while especially if drained after use……. Mamod ect are brass…. But low pressure 20psi I’m not sure on a pressure limit for brass shell boilers !

Cheers R

[Team ricky]

Here’s a short video of the boiler under steam testing….

All went well with the hydraulic test up to 150 psi, I decided to go with the design spec here , Yes it did distort once as the design said, I measured across the boiler and chest did not change which so far it hasn’t.

Known faults :

I set light to one of the plastic valve discs lol 😂
Slight leak to the steam output turret , probably so small lime scale will fix that
I ran very low on gauge glass and it currently only just bridges the gap


When I tested the boiler up to 150psi I had left my fixture bolt through the turret as to eliminate all the top fittings, This was later drilled out and then I could concentrate on separate testing of the fittings at 3/4 working pressure to fix any leaks which I had a few small ones prior to nipping things down fully

Onto how to fire this ? I used a blow torch to get 60 psi then lit the little meths burner , No blower installed so it struggles a bit , But it did hit 75 psi (no engine yet) So coal is an option as I found a grate

Other option I’m open to is making a meths burner and trying again with a blower and fire hole door fitted !

Cheers R

[Team ricky]

Here’s the obligatory loose assembly!!

Cheers R

[crueby]

Looking great!

[Kim]

Excellent progress! 

Kim

[Team ricky]

Cheers chaps !

Here the gear set complete 🙂

A good mile stone out of the way , It took a bit of set up to get each meshing nice and quiet, The crank gear will be finally set when I make the bronze crank bearings

Cheers R

[Kim]

All the gears look great!  Lovely work there 

Kim

[crueby]

What kind of rubber is the tire on the wheels? Any issues with heat from the boiler?

[Team ricky]

The tyre rubber is nitrile…

It may well not be great but a bit of an experiment! I have got wheel rims but not spokes and I knew I’d get bogged down making a set …. Maybe one day !

The rubber isn’t fully finished and trimmed yet too 😁


Cheers R

[Team ricky]

Here’s the crank set up on two almost fully split GM bearings…

I just slit sawed almost all the way with the correct thickness blade to allow the blocks to slide onto the frames , Drilled and reamed for the crank , All turns over well

There was a little void in the flywheel casting so I filled it with JB
Next I’ll make the cylinder mount and then eccentrics


Cheers R

[Roger B]

Looking good     

[Team ricky]

Thanks gents

I’ve ticked off a number of small jobs to get closer to assembly

The speciall boiler ring now fits the frames, I’ve replaced one of the boiler valve disc handles, Fitted fully the fire hole door, Drilled oil ways and securing bolts fit the main crank bearings….

I’m at the stage now where I have to decide on how to fire the model !

I have built the boiler to take a grate as pictured
The plans do offer a method of meths burner with tank
And I have got a gas burner but need a tank

I’m open to suggestions!!

[Roger B]

I've always wanted to run my engines on prototypical fuel, my diesel has to run on standard pump diesel, but I know there are scaling problems  Coal in the grate would be good but there are potential problems 

[MJM460]

Hi Ricky, I’m enjoying following along your attractive little model.  Always good to see them running on steam, so looking forward to that, but all in good time.

Regarding fuel, I am a strong supporter of meths.  It’s safe, not likely to explode and easily extinguished with water, it’s clean and readily available.  You have the plans for a burner and fuel tank, so why not try it out? 

I have not tried coal, but understand from others that it might be a challenge to operate in a smaller model.  But, already having the grate, again worth trying out.  Make sure you have a suitable brush to clean out the tubes regularly.


MJM460

[nj111]

Lovely model, well done!

[Team ricky]

Thanks gents

I will make up the meths parts It looks straight forward!

Here’s the slide valve set up with the valve rod, I will add a little gland to the top of the valve chest later on , I did opt for a silicone o ring in an internal groove within the valve gland nut …. Nice and smooth

[Sanjay F]

That's all looking very tidy - nice work 

[Team ricky]

Here’s a fair bit more done ✅

I had a bit of a push and mounted the cylinder, put the frames back together, mounted the manual water pump , made up the eccentric rod and eccentric….

Also I had a gas tank around and wondered if it would fit ! And it did perfectly without a hair to spare ! So the first test runs will be on gas ..

The crank turns nice and free

I went with valve travel of 2x the ports just as a starting point, If needs be another eccentric can be made with more travel 😁

[Team ricky]

Another good day

I managed to modify and fit a commercial cam style lubricator and set it up off the eccentric to give a small drop which looks perfect!

I soldered a brass pad to the boiler over a dent I put in the boiler earlier so that’s great 😀 The water tank mounts to the pad, I got the tank fully fitted and the inlet pipe connected, Also fitted the eccentric gear complete which went well….

I’ll machine up the valve chest cover in the morning and test run everything on compressor, See how good the timing is and run in a fair bit

With the lubricant pump I’m guessing just make a fitting to go into the valve chest cover!?

The exhaust fitting and pipe needs making up along with the water pump outlet pipe to clack

Close now and surprised at the number of little things that need completing

[Roger B]

Very nice     

What is the water tank, part of the engine or from another source?

[Team ricky]

Hi Roger,


It’s a commercial aluminium conduit box 😁 I think I found it on AliExpress…

It’s pretty much the size as per the drawings ! Lucky …. It will certainly be needed as the boilers very good at steaming

[Team ricky]

All up and running 🙂


There is some running in to do ! The big ends intentionally not fully tight but is very close about an hour of running and I’ll fully tighten everything

I’ve not made any effort to seal the cylinder to mount and mount to valve chest or made and fitted the small end valve rod gland , Still with that it will run at 10 psi so I’m not expecting any problems going forward!

Next jobs are the valve rod gland and more pipe work 😀

https://youtube.com/shorts/nDaB-_F8e2Q?si=Bzn8LVsZc-ep0RzX

[Kim]

Very cool!  It runs! 

Beautiful!
Kim

[Admiral_dk]

Congratulations - always great to see them take off     

Per     

[Team ricky]

Cheers Chaps

I’m definitely at a point where the bulk of the work is completed !

Today I fully fitted the gas system, Pipe work to the blower and exhaust complete, Water pump pipe work completed, final fitting of the right side frame completed, Running in complete

The gas burner I had in the back of a draw ! Luckily it fits well and has a number 8 gas jet , As long as the boiler warms the gas tank a bit it will provide a lot of heat and will be able to be throttled

Here’s a video at low speed on air at 10 psi

https://youtube.com/shorts/y39600M5dDA?si=oBhTxsYpWwzagLJO

https://youtube.com/shorts/5ZPQMm5SAO0?si=iasip_J2ZfV7iS0N

[Team ricky]

Just tried a quick stream up on gas

I found out combustion is combustion!! On gas it will need a blower assist to get up to temperature as at the moment the gas flame struggles for air when there is no chimney draw, as soon as the blower can be opened the gas works great 👍🏼 But wasting steam and heat to get going is a big of a struggle..

If anyone knows of a fan (small) that would be handy I think it will be fine with that

Water top up was relentless due to having the blower open so much, The water gauge isn’t the best so I kept topping up until a little priming happened so that’s ok

Tomorrow I’ll hook up the steam supply to the cylinder and connect the lubricator and run the engine on steam !!

[samc88]

Would something like this work? Seems cheap enough to experiment with
 https://www.amazon.co.uk/Bireet-4000mAh-Handheld-Rechargeable-Portable/dp/B0F8QKZPVB?asc_campaign=2b5a785186b501c352c95398a3440b1b&asc_source=01HGDYH4RNM2XCDDM3YKD5BH6D&tag=snxgb279-21

[Team ricky]

Hi Sam,

Yes I think it might 🙂, If a y piece was used vertically then the hot air would not go through the fan …..

I have since made the meths burner assembly to the drawing, All went well except I’m not too happy with the cotton wicks , They burn a little then clog up and the flame goes low ! It might be just right when steam has been raised but my gut feeling is it would take too long to raise good pressure especially 60-70 psi…

I have ordered some glass fibre wick material which should do the job a lot better ..

It currently burns for 22 mins on a tank of fuel


Also I have set up the steering column, Worm bracket and chain worm , I used Wilesco gear for this to save a bit of time

All fits well and smooth , The wheel is plastic so temporary solution!

Next jobs are the water tank filler cap and a new water pump outlet pipe is needed to clear the new meths tank , On the bench about cylinder lagging , draw bar attachment .

I think that’s about it !!

[MJM460]

Hi Ricky, before you go to too much trouble with fans, it is worth trying using a piece of suitable pipe to extend the chimney.  Not too hard to hold in place and easily increases the draft considerably without power supplies or worries about overheating components.  I find a significant effect with two or three times the original chimney length, same diameter.

Nice job on that burner.  If it does not burn as strongly as you would like, I wonder if the cotton is packed too tightly.  Does the tank cap have a vent?  It will be interesting to see how the fibreglass wick works. 

Good progress on the other parts of the project, it is coming together very nicely.

MJM460

[Team ricky]

Good idea

I did make the chimney a slip fit on a thin wall sleeve for maintenance etc of the blower pipe or exhaust if needed , So it’s absolutely possible to slip a long pipe on in leu of the chimney and heat it with a torch to get things going ….Yes the cotton is a tight fit currently and I did wonder if that could cause issues!

I think I’ll try the glass fibre quickly and see what’s best and or open up the holder diameter

The steering chains arrived so I’ll get that done today

[Team ricky]

Just in conclusion …

I did re make the chimney with a bigger scale tapered bore which in combination with the glass fibre wicks gave a good steaming model luckily!

It’s now possible to light the wicks and just leave the model to raise 20 psi, Then open the steam blower to get to 40 psi then it’s fine to run the engine and it holds around 30 psi from thre exhaust draft

Cheers R