Lathes

[scouse]

Hello Everyone,
I'm new to model engineering and whilst I've decide on the lathe I'm going to buy namely the Warco WM-180 i'm still not sure whether to go for Imperial or Metric?
As a newcomer,I intend to build a Stuart 10V Vertical Steam Engine to familiarise myself with the lathe and then move on to 3.5" or 5" Steam locomotive construction.
I'd be grateful for your advice as to which to purchase.
Thanks,
scouse

[ron]

Hi Scouse
If you are comfortable using imperial, it's probably a better bet for model engineering, Stuarts' drawings are all imperial as are most well known model locomotive drawings.
A bit of a problem you will come across is, although they give imperial sizes on drawings you have to use the equivalent metric stock nowadays and make allowances for it, ie 1/8" steel is actually 3mm etc.
Ron

[paul]

Scouse I'm a newcomer too (I just bought the Clarke CL300). As I needed to buy tools from scratch and my first simple kit was in metric I decided to 'go metric'. To be honest it's been a bit of a pain as although some (few) materials are available in metric as Ron says, most drawings, fittings, references etc are imperial.

I suppose more stock will appear in metric as time goes by but at the moment I usually end up using material that's fractionally too big (imperial) and turning it down before I even start work proper.

As far as your lathe goes I don't think it will matter except you may need a kit for it (££) if you want to cut threads in metric.

Although I'm old enough to remember decimalisation I find it easier these days to work in metric... 5/32" means nothing to me!

[ron]

Scouse
Could I also add a bit of heresy, I think the bigger Stuart engines are much better than the 10V for a beginner, they are no harder to make, in some cases they are actually easier as the parts aren't so fiddly and when run on steam they behave much more like a full size steam engine, only downside is they tend to be considerably dearer.
Paul
Even though I'm of the 'imperial' age group I find fractional sizes quite antiquated, I was in machine shops and drawing offices in the late 60s and 70s and 5/32" would have been given as 0.156" usually followed by a machining tolerance, ie + or - 0.002" for example, fortunately when metrication came along I'd moved on to other things.
I liked the system where a tolerance is given, it lets you know whether the part needs to be approx 1/2", nearly 1/2" or spot on 1/2" ;D
Ron

[paul]

Good one Ron - me, I always make everything to approx sizes (involuntarily!)

[Chris Kelland]

Hi All,

Not quite on topic, but, a fair time ago (groan) I had to learn the imperial system and both metric systems as the powers that be had not decided whether we were going MKS or CGS anything to do with maths like exams involved working in all three systems.

I ended up buying metric machines, lathe and milling machine and on the wall of the workshop is a large chart giving imperial equivalents x 1/64 to decimal and metric. I now get by quite well regardless, working in any units. Back of envelope designs end up dimensioned in what ever is flavour of the day!


Regards,


Chris.

[chameleonrob]

buy either, then invest in a calculator and remember that there is 25.4 mm in an inch. I'm happier with metric so I'm designing my loco using that system, but some parts have to be imperial and only half (including my lathe) my machine tools are in imperial so I'm having to convert all the time.

rob

[baggo]

I tend to work in a similay way to Chris i.e. I use whatever dimension system suits me at the time! I'm quite happy using metric or imperial. My lathe and mill are imperial so tend to use that system for model engineering. I still dimension my drawings in fractions but convert those to decimal when turning etc. as I use a vernier caliper all the time. Like Chris, I've got a chart I printed out with 64ths and the equivalent decimal and millimetre. I use AutoCad for my drawings and the beauty of that is the ability to draw out a design and dimension it in either metric or imperial or both at once!

John

[ron]

Just before I moved on from working as a draftsman, metrication arrived and there was an interim period of both, we had to do the drawings with the imperial sizes above the line and the metric sizes under the line, no wonder nothing fitted, I wish they had CAD back in these days!
I also had the luck to be working part time in a bar when decimalisation arrived, that exercised the grey matter, especially if you'd been sampling the product.
Ron

[Shawki Shlemon]

Hi
I worked all my live in aircraft industry and every part had some kind of tolerance . Started in model industry and surprise all parts have one size even a moving shaft in a bush. In my book this is not wright,so I set my own tolerances . One must use commonsense when making parts .Merry Christmas to all .

[Peter W.]

Yes, it's surprising that tolerances hardly ever appear on
ME drawings, even in a simplified form. They'd be a real boon
for the lone beginner.

Mind you, for my first loco, which I'm still building, I felt I had to
have the 'words and music' to tell me what I'm aiming at.

Didn't LBSC make a good job of this, by having the
drawing and description on the same page.

[chameleonrob]

when making a one off (which most of us are) tolerances are of less importance than knowing hte required fit (and definition of it), saying an axle is (say) 1" dia +0 -0.002 with a bearing for it being 1" +0.001 +0.003 would be less use that saying a running fit with a clearance of between 0.002" and 0.004". this means that if you make the axle a little undersized you can compensate by making the bearing udersized by the same amount. In industry, when making several examples or where you are buying a part in then a tolerance is essencial but for most of us it isn't used much, plus there are likly to be less parts scrapped. (don't jump on those figures above, they are picked out of the air)

rob

[havoc]

While I do agree on the "one-off" principle above, if you don't have the tolerances, you don't know what to make.

On the other hand believe me, setting the tolerances -and make them consistent throughout the job- on any plan is a large part of the work! (been there, done that etc.)

As for the imperial/metric question, apart from Burma, Liberia and the US no-one is using that anymore And then the issues about building one-off's start counting. If the plan asks for 1/8" and you use 3mm (or the other way round), you can compensate. But it will require vigilance throughout the building proces.

[Shawki Shlemon]

Hi
"But it will require vigilance throughout the building process". I spent a week or so going through the plans penciling tolerances, slight dimension changes to suit my supply of BA/UNF/ME/METRIC whatever,matching changes on applicable drawings before cutting material .I also completely agree with selective fittings, after all we can't afford to scrap too many items.This is the reality of our hobby .

[alanstepney]

The one fact that we should recognise is that if all drawings were to industrial standards, they would cost a lot more.
Many of the "designers" could not do them themselves, so that would need someone else to actully convert the "sketch" to a "proper" drawing, presumably using CAD.
Then they would need checking, and preferably, prototypes built to verify the crawings and find the inevitable errors.
Having seen what this costs industry, I would hate to see "our" drawings come out at the prices they would need to be to cover these costs.

Then again, suppose that we couldnt get the specified material (as in the 1/8" versus 3 mm we now expereince). That would mean a complete re-draw, again involving more cost.

As things are now we have to study the drawings and make judgements.
BUT, in the process we learn what parts are, what their function is, and all about fits and tolerences.
At least, at the end, we have a clear undertanding of the "innards" of our models.

[chameleonrob]

alanstepney said:

Many of the "designers" could not do them themselves, so that would need someone else to actully convert the "sketch" to a "proper" drawing, presumably using CAD.
Then they would need checking, and preferably, prototypes built to verify the crawings and find the inevitable errors.
Having seen what this costs industry, I would hate to see "our" drawings come out at the prices they would need to be to cover these costs.

I Imagine thats a high percentage of the cost of modelworks kits