Engine scale

Hi folks.

I've just hit the jackpot and scored a Logan 10x24 late.

My long term goal is model traction engines.

What scale plans should I be looking toward for this size machine?

Thanks.

J

A 2" scale engine will have a flywheel and final drive gear of around 9" so that would be about the biggest you could handle. Wheels often don't need to be turned so look at those two items what working out what will fit

Thanks Jason 👍

For a 10" swing lathe, without a gap-bed, you are probably looking at a 1 1/2" to the foot scale for most traction British or European engines engines. That's to be able to turn the hind wheels. If they aren't a problem then 2" to the foot should be well within the capability of the lathe,

Note:- I haven't made a model traction engine, even though I've got a set of 1" Minnie castings.

Note 2:- I type too slowly.

Edited By Mark Rand on 12/06/2022 20:30:49

Thanks Mark, that's a good shout.

I'm going to work my way up, but interested to see where my ceiling will be.

Just want to be able to drive around the steam rally LOL.

Jay,

You are asking the right questions with the right sort of approach and the answers so far are valid but just to throw a few more thoughts into the mix;

You want to drive round at steam rallies? That being the case you may want to broaden your horizon to 3 or 4”, much easier to keep going and much more forgiving of some rally fields that are less than smooth! You can drive round with a 2” but it’s a strain. If you want to ride behind it balancing and reaching from some kind of cart can be tiring!

Scale; scale is important but a 2” fowler ploughing engine is about 4’ long, rather slow and lumbering (like it’s big brother) while a 4” Ruston steam tractor is the same length, much more useful speed, more ground clearance so a bigger grate that will let you eat lunch without it going out and a fair bit quicker, with not so much bending down!

Lathe; You can always farm out the large diameter bits to someone else or maybe borrow a bigger lathe. What may limit you more is the size of milling machine you get - and if you want to build a TE you will need one! That is likely the thing that will limit you more in the size of the bits you can make, especially cutting gears than the size of your lathe!

Lastly, remember this is going to be a long term project over a number of years. Always worth thinking about your ambitions for it when done when you compare the hundreds of hours of your time you will put into it!

Good luck, I would recommend that before you buy drawings and castings for your chosen engine you look at a completed one in action, if nothing else it will spur you on to achieve having seen what you are building is capable of when finished!

Paul,

If you want to drive around on the steam rally field,then a 3 inch traction engine is the smallest size that is practical,rally fields are not very smooth and although 11/2 and 2 inch models are seen on the rallyfield the rough ground cannot do them any good. I started on an allchin over 50 years ago ,at that time the allchin was one of the few models with dwgs and castings available,but after visiting rallies and chatting to other owners it was obvious to me that the allchin would be more suitable for running on a very smooth lawn.So I gave up , and built a bungalow and started collecting and restoring i/c stationary engines and still do it,I have had experience with a miniature traction engines as I bought a 6 inch Burrell and ran that for some time until age got the better of me,though I did eventually get a live steamer which I had wanted since I was about nine years old when I went to the ME exhibition after the war anbd saw a model TE. If i had my time again I would go for a 41/2 model though a 3 inch is still practical. My advice would be select a model then set about building the 4 wheels,apart from the hub castingsthough these can be fabricated the financial outlay is not excessive,if you can build the wheels and make a good job of them then the remainder is a lot easier.

Thanks Paul, that's great advice.

I had the same thought re larger engines and items.

I've bought some books and plans for scrap wobblers and stationary engines etc to get me started.

The TE is definitely a long term goal. Besides it's going to be long term before a decent mill is on the cards for me. I'm currently very limited on space, so vertical milling is my only option for the time being, but that's why I went for the Logan, it's the only thing in my price bracket with power cross feed.

I've had a difficult few years, so I'm just excited to get started.

I did things the other way round; I decided which engine to build and then bought a lathe to suit. I am building two 4" scale Burrell SCC engines. I bought a Harrison M300 lathe as it had the between centres length to turn the axles (~30" ) and turn the final drive gears and flywheel (~16" diameter) in the gap, like this:

However, those are the only parts for which I needed the gap. I would agree with Paul, the choice of mill is far more important. I have three; a Bridgeport, a large universal horizontal and CNC. While most of the work "could" be done on the Bridgeport the horizontal is excellent for cutting gears and acting as a poor mans horizontal borer. Even then some ingenuity is needed:

The CNC mill allows me to make parts i can't make on the other mills, like true bevel gears, worms and special cutters:

To summarise, by farming out a few parts the Logan lathe should be capable of being used for a 3", or possibly 4", scale model. The key to the build is selection of a mill, or mills if space is available.

Andrew

Addendum: Logan lathes are quite rare in the UK, but are good lathes. I had one as a kid in the early 1970s, bought for £10 via the local model engineering club. It was in a building in the centre of Bedford that was being knocked down, so either I bought it or it went for scrap. I bought new half nuts from Powermatic Houdaille in the US while still at school. Fortunately i worked at Texas Instruments, up the road from my parents, as a summer job and their accounts department helped me sort out payment in US dollars.

Edited By Andrew Johnston on 12/06/2022 23:39:48

As already mentioned, the size of your model depends on the size of the original engine. I have a 6" scale Ruston Proctor SD which is about the size of a 4" Fowler 4NHP engine and took 7 years to build.

The capacity of the lathe in workshop should not be the limiting factor for your build. You can get the larger parts made elsewhere. I only have a 9" x 20" Southbend lathe (4 1/2" swing) and the flywheel is 15" diameter, which I did on a bigger lathe owned by a fellow club member.

I found that the majority of the machining was a milling operation and not turning.

Build of my engine found here: **LINK**

Don't forget to think how you will transport a larger engine. 2" will go into the back of an estate or SUV . Much larger and you will need a trailer or van. Not sure what the pulling power of an electric car will be by the time you get round to finishing the engine.

Further to the above you are not permitted to fit a towbar (which can't be homemade) unless the vehicle is rated as such by the maker. This does not apply to vehicles from the last century, which means you can do what you like with classic's

Yes, you can dangle a trailer off the back of your Austin 7 but not your brand new BMW or Skoda etc. That makes perfect sense. Thank goodness for the bureaucrats.

It's not so much what a car can pull but how big a load it can stop. Many modern cars (in Australia) can tow a trailer and the maximum unbraked load is specified by the manufacturer. Heavier loads can be towed if the trailer is fitted with brakes.

The combined weight of my engine and loaded trailer weighs about 900kg and is easily pulled by my Mazda 6. The car is only rated for an unbraked towing capacity of 750kg and I have fitted electric brakes to the trailer to make it legal. Now the trailer will stop the car.

The biggest problem I can foresee with an electric vehicle is having enough battery power to tow a load over a big distance on one charge.

Edited By Paul Lousick on 15/06/2022 13:15:27

I am nearing the end of a 7" scale steam lorry build. Machine tools used:

Kerry 11 x 23 lathe

Tom Senior M1 mill.

Try looking at lorries, the big bits are smaller in a given scale. Alternatively contract out the really big bits, most suppliers also do a machining service for flywheels, final gears, crankshafts etc.

Dont forget you will also need to manhandle, tansport and house a sizeable lump.

Martin

Good point Jason I believe at this moment you cannot tow with electric car

H

I'm not sure what EV can tow but we might see an increase in showman's engines. Just the thing to have generating and charging the car battery for the trip home from a rally assuming we can still burn coal and wood to fire them!

Doing a Michael G link but nor as professional

https://www.carwow.co.uk/blog/electric-cars-and-towing-what-you-need-to-know?utm_source=google&utm_medium=cpc&utm_campaign=71700000092373949&utm_group=58700007754306652&utm_keyword=&utm_term=DYNAMIC+SEARCH+ADS&network=g&utm_account=700000001745867&gclid=Cj0KCQjwhqaVBhCxARIsAHK1tiPKS7RVElXVK-44Ov_IriLzVxvWtaDLE4kgm20X4mtiz-AL6UCtZhQaAuX6EALw_wcB&gclsrc=aw.ds

H

Not true. In autumn 2019 a mate and I took our gliders down to Talgarth (in the Brecon Beacons) for a few days of ridge running. My mate has a Tesla and he towed his 18m glider from Bideford to Talgarth, about 75 miles, on around half full charge.

Andrew

Getting off topic here but my TD5 will do just shy of 600 miles on a tank. The furthest rally from home I have done so far is around 200 miles away, I can leave home on Friday morning, be parked in a muddy field with no power Friday night, stay there through Saturday and Sunday, leaving Sunday tea time and be home before midnight without needing to refuel (stop for charge). I can tow up to 3.5t (braked) and strangely the fuel consumption does not seem to vary much with or without the trailer. When my latest engine is complete it will weigh between 900 and 1000kg so with the weight of the trailer and other kit I will be dragging around 2t.

There are other EV’s I understand that can pull this weight but loaded they won’t do it on a single charge. More importantly for me the Disco cost me £6k second hand, if I could find a second hand of the aforementioned EV’s I imagine I would be looking North of £40k to own one - the engine in materials and castings will have only cost me around £10k. So yes there may be a clean solution to my problem but not in my price range and not with the same flexibility so from my perspective it’s not really an option.

Paul.