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Haggerleases17/05/2019 20:07:32
77 forum posts

Odd sort of question, but just how simple/small/basic a lathe can be used to build say a 2 1/2 inch gauge locomotive? What features are vital, and what sort of accuracy is required?

David George 119/05/2019 07:32:45
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797 forum posts
282 photos

Hi i see that you havn't had a reply but i can't help as i don't know about locomotives but I would have thought that you could find out what diamiter the larger parts are and find a lathe which is capable to turn it. But don't restrict yourself as the next job will probably need a larger lathe etc you can turn small parts on a larger lathe but not always the reverse. I would buy what you can afford and as good as you can get.

David

Boiler Bri19/05/2019 07:56:21
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776 forum posts
275 photos

Hi. I know people who make garden gauge engines on cowells and similar. Its all about the tooling that you make to help you. Some peoples ingenuity allows them to make oversize engines on very small machines.

Have a look at the MAP series of books they give great advice and practical demonstrations  

 

 

Bri

 

 

 

 

Edited By Boiler Bri on 19/05/2019 07:57:38

Nick Clarke 319/05/2019 08:48:50
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253 forum posts
3 photos

If we are talking about a new lathe then almost any one will be physically big enough to do the job.

The largest jobs in building a locomotive are wheels, cylinders and trimming the boiler tube (if you intend to build your own boiler)

Taking the modern 'mini' lathe with a swing of 180mm and the largest wheels you will ever encounter on a 2 1/2" loco at say 115mm over the flange there is no problem fitting them on the machine. Outside cylinders will fit easily as well, but where there is a double inside cylinder block it could be more tricky, however if you use a boring bar between centres and fix the block to the crossslide it can be managed. The boiler tube of an express engine may be more of an issue, because of its length, but if you can't fit it careful filing or a visit to someone with a ;larger lathe would be a possibility. choosing a smaller prototype would obviously help.

I fact all of the components of even a 7 1/4" LBSC Tich loco would physically fit on a long bed version of the mini lathe, although the boiler barrel would be a serious squeeze I suspect!

But your problem isn't just fitting the components on the lathe it would be is machine be powerful enough, at slow speeds especially and rigid enough to do the job? Taking care here I suspect anything is possible, but I have to confess it is outside my direct experience.

If you are considering buying a lathe then a bit bigger is definitely better and means less fiddling, and there is more likely to be enough power for the job.

Interestingly in the past there have been smaller lathes of 100mm swing or even less and while these would be too small physically to make an express engine, even in 2 1/2" gauge, if fitted with a back gear would have more than enough power to make a loco with smaller wheels successfully!

michael m19/05/2019 09:24:45
60 forum posts
3 photos

If you can get acess to the ME of 21/11/69 a Mr. Drakeley gives an account of building a successful 2-1/2" gauge engine with a Super Adept lathe. The work done on the kitchen table.

Haggerleases19/05/2019 10:54:56
77 forum posts

Duly ordered! Many thanks. I do love the old machines and stories of more being done with less. If anyone has any anecdotes I'd be pleased to hear them.

Thanks again.

John Haine19/05/2019 11:15:03
2512 forum posts
132 photos

Most of the classic loco designs around 3.5" gauge and smaller were for people with Myford or similar lathes which have 3.5 inch centre height and can swing quite a bit larger than 7 inches in their gap bed. Lots of Myford old iron about though at silly prices. Boxfords also about and generally cheaper (and probably better), or a Chinese new lathe round about the same size probably costs the same or less. If you are starting I wouldn't suggest getting an old lathe, such as an Adept, you don't want to be fighting the tools as well as what you're trying to make.

SillyOldDuffer19/05/2019 11:16:39
4318 forum posts
944 photos
Posted by Haggerleases on 17/05/2019 20:07:32:

... and what sort of accuracy is required?

I agree a mini-lathe would be big enough, and it has most of the features needed. The most obvious omission on the mini-lathe is a slotted cross-slide, not fatal, but certainly a nice to have. Next size up would make the job easier, and bigger lathes tend to add features like gearboxes, powered cross-slides, a clutch, and bigger dials. I'd say a mini-lathe is about the minimum needed, and a bigger machine would make the job much easier.

Accuracy is an interesting requirement, and perhaps - within reason - it's one you don't need at all.

The reason I suggest that is because most model makers and home workshops use 'fitting' rather than precision engineering techniques. Because people are expensive, industry has long since moved away from craftsmanship to making tightly specified interchangeable parts. This method eliminates expensive fitters by working accurately within well specified tolerances . Wheels can be made in one factory, axles in a second, assembled together in a third, and spares can be swapped without fuss.

This is not what goes on in my workshop. I would drill a hole in the wheel of about the right size to take the axle. Then I'd carefully turn the axle down to just fit into the wheel. With a little experience it's possible to make anything between a tight press-fit and a loose running fit. Nothing is measured accurately and the lathe doesn't need to be accurate because the wheel is used as the gauge. The method depends on comparison rather than accurate machinery, and it can produce high quality results. The disadvantage is fits made this way can't be swapped.

Although the old timers did everything this way with simple tools, much time and effort is saved by owning a digital caliper, micrometer and an unworn machine fitted with trustworthy dials or a DRO.

Simply put, an imperfect lathe, whether Far Eastern made down to a price, or a worn industrial machine, can still produce good results. It's more to do with technique and operator skill than the machines. An expensive tool-room lathe might be a pleasure to use but it's trustworthy accuracy is unlikely to be essential in a hobby workshop. On the other hand, a badly worn, damaged, too basic, or too-cheap machine is likely to frustrate the operator. But it's more about slop, inconsistency, poor finish, continually having to fiddle with gibs and other irritations than lack of 'accuracy'.

Be interested to see what experienced machinists think of this view.

Dave

Haggerleases19/05/2019 11:24:44
77 forum posts

Thank you ever so much for your comprehensive replies. To a beginner it's all good stuff.

I may go for a Chinese mini lathe, as they are relatively affordable, available new, and a popular choice, but I'm fascinated by stories of people doing good work with very little.

Hopper19/05/2019 12:41:57
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3618 forum posts
72 photos

Chinese mini lathe is a good choice for a beginner. Trying to coax a worn-out vintage machine to produce precision work is very romantic but not a good thing to combine with learning basic machine use. If the job is not going well, you have no way to know if it is your technique or the worn-out machine that is at fault. Frustration then sets in and jobs get abandoned.

Nicholas Wheeler 119/05/2019 13:26:16
240 forum posts
13 photos
Posted by Hopper on 19/05/2019 12:41:57:

Chinese mini lathe is a good choice for a beginner. Trying to coax a worn-out vintage machine to produce precision work is very romantic but not a good thing to combine with learning basic machine use. If the job is not going well, you have no way to know if it is your technique or the worn-out machine that is at fault. Frustration then sets in and jobs get abandoned.

I agree with all of that. When I bought my first lathe 16 years ago, I had never used one. I looked at several knackered Myfords - as a mechanic that was obvious - that were at least twice the price of the mini-lathe I bought from Machine Mart. About 45 minutes after getting it home, I had my first two parts - a pair of axle locating pins for a Capri. Over the time I had it, I bought a number of accessories(4 jaw and collet chucks for example) to make it more useful although I've still never used a travelling steady. When I eventually upgraded to a bigger machine(WM250) I sold it for about 2/3 of what I had spent on it. As that was 10 years use, any number of parts for my hobbies and projects and learning how to use the thing, I consider it a pretty good use of the money

ray r19/05/2019 23:41:55
5 forum posts

Lathes are like garden ponds,you build the first one but it soon becomes too small,the second pond is a bit bigger but the third one is bigger still which is the one you should have built in the first place,It`s the same with lathe,you buy a small version but you find that it doesn`t have the capacity to do what you want so you buy a slightly bigger one & then find you need something like a Warco WM240 which is the lathe you should have bought in the first place.People say you can`t buy experience but they are wrongsmiley.

Ray.

Howard Lewis20/05/2019 15:53:44
1947 forum posts
2 photos

Am certain that, eventually, your horizons will expand, and you will find the need for a larger machine. Whether you learn on gradually larger machines, or you buy a large and complicated machine at first, will depend on availability of space, cash, and time. You don't need to use all the "bells and whistles" from the start. Their usefulness will become apparent as you become used to the machine. (Just like me and this computer!)

The first lathe that I owned was a well used Myford ML7; replaced by a new larger Far Eastern machine with features that the ML7 lacked. And No, I still don't use all the facilities of this one, even after 15 years!

It has been said many times that "You can do small work on a large machine, but not the other way round".

If possible, buy a larger machine at the start, and learn how to make full use of it as you gain experience, would be my advice. (Never having touched a lathe before, I had to start learning. on Ward 2B, Herbert No7 PreOptive, Edgwicks, and a 21" swing Dean Smith and Grace. Within 6 months, the latter became my favourite)

H T H

Howard

Richard brown 120/05/2019 18:17:31
85 forum posts
27 photos

Hi

If you want to know what sort of features are useful or what a lathe can do a good book is The Amateurs Lathe by Lawrence Sparey. Its a very good text on what you can do with a lathe. It was this book that made me realise that lathes don't just turn round stuff.

Good luck with the build.

Rich

Nigel Graham 219/06/2019 22:05:49
242 forum posts

Following that, and more generally, it's worth building a reasonable library of model-engineering reference-books.

Some will give you the appearance of trapping you into making machine-tool accessories for ever more, but collected in a reasonably discerning way, they accumulate a wealth of valuable information on techniques, materials etc directly relevant to us in our own workshops.

The Workshop Practice series is very good, and I have about 10 selected by relevance to my workshop and projects. They are clear, concise and each details a single field of skill. Those by Harold Hall on machining techniques do use specific projects but to help you both master the methods and equip your workshop in a reasonably no-frills way.

Another single title is Geo. Thomas' The Model Engineers' Workshop Manual - though at first sight this looks like the tools-to-make-tools sort aimed at very experienced model-engineers, it contains a lot of valuable information, thread-tables, etc. (To be fair this book does address that reputation!)

Much older books can be useful too, because they were written to show how to make things with quite limited equipment, as was common in their day.

Also look for books on model locomotive building and operating - not ones specific to individual projects though they can be helpful, but more general ones.

Have a peruse of TEE Publishing's web-site. They usually have a stand at the major exhibitions, too.

Howard Lewis19/06/2019 22:25:12
1947 forum posts
2 photos

+ 1 for Tubal Cain's the Model Engineer's handbook. Contains LOTS of info that will be useful at some time.

Ian Bradley's "The Amateur's Workshop", and L H Sparey's "The Amateur's Lathe" ( old enough to feature the Myford ML7 quite heavily, but very good nevertheless in terms of basic information )

Brian Wood's "Gearing of Lathes for Screwcutting" is useful reference to have on the shelf.

All the Workshop Practice Series will help you, with a particular problem, at some time; probably many times!

A small library of books filled with useful information, such as those already mentioned, will be a good investment, over the years.

Howard

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