Stuart Models Diagram

[bwal]

Hi,

I've just started a Stuart Models ST Oscillating Engine.

I can read the drawings well enough (most of the time) but I'm not sure what "CRS" stands for.  It's after a given dimension.  I kinda thought it meant "near enough is good enough" but I'm not really sure.

Cheers Ben.

[Jo]

It might mean Cold Rolled Steel i.e. it is identifying the material   

I have just checked another Stuart drawing... CRS is given on centres measurements of holes so it is short for "Distance between centres"

Jo

[bwal]

Thank you.

I too, at first, thought it meant cold rolled steel even when I had a brass extrusion in my hand.

Ben,

[Lew Hartswick]

A common curse of people that use abbreviations without defining them.  At least the first time they are used in text or a drawing. :-(
   ...lew...

[GWRdriver]

The Stuart (British) equivalent of cold rolled steel would be BMS (bright mild steel.)  CRS, as explained, is for "centers."

[steam guy willy]

Hi, Also on an old drawing ..9/64 whit ??????

Willy

[propforward]

Whit means whitworth thread, an old British thread that has largely fallen out of use. Only way to get those taps is to import from the UK (if'n you're not a UK type personage).

Here's what the font of all that is knowable and correct with no errors ever, Wikipedia, has to say about it.

https://en.wikipedia.org/wiki/British_Standard_Whitworth

[bwal]

In regard to the model I'm making, I'm now out approximately 0.4 mm out on the air/steam inlets on the cylinder. The Stuart plans are sometimes funny to read (especially when your converting them to metric).

Ben

[steam guy willy]

Hi This 9/64 whit thread was on a George Gentry drawing about 1912...!! so where you supposed to make a tap and die yourself  ?? I have looked in all my books and cannot find any reference to this thread  so did he make a mistake or realise this did not exist so just changed it to 4BA but forgot to remove the whit one ??

Willy

[propforward]

The whit thread was invented in 1841. Can’t speak to availability of taps and dies in 1912 though

[propforward]

Oh wait, I see what you mean. Maybe 9/64 is the tap drill. Or it's all a huge misunderstanding.

[Jasonb]

The die would not have been a problem as most would have been using the two part dies that covered a small range of diameters depending on how close you adjusted the two halves or using a home made die plate . Tap may well have been available.

[propforward]

That's a nice set.

[steam guy willy]

Hi Jason , ok that is a really nice set of taps and dies  and i suppose you could make a bolt and a tap to cover a wide range of sizes. I do have some die plates that have a range of "fits" that seem to be a bit confusing ??   I will bring them to Forncett  tomorrow.....