Renovating an old steam engine and boiler

Hi !
I live in France (so please pardon my English).
I've had through some family members an old steam machine. Though some pieces are missing or broken, I did manage to run it a few years ago.
But I want to give its orignial beauty and completion, so then I can start trying to make my own live steam engine

My problem : most of my measuring tools are in metric, but bolts etc seem to be in inches.
Here are my measures :
1/ Tubes thread : 3.4mm diameter, 40 - 0.635 for the thread (I got a thread reader in inches !)
2/ Bolts for cylinder fixation : 2.78mm, 48 - 0.529
3/ Support for water level : 5.96mm, 30 - 0.846
4/ Water Tube thread : 7.84mm, 30 - 0.846
So from this table ( http://www.allcap.co.uk/Conversi.htm ) I guess 4/ is something between 4BA and 2BA - 30, 3/ is 5BA - 30, 1/ is around 10BA - 40 and 2/ around 12BA - 48 ?
Or are those unusual and could be in metric/other system ? (doesn't makes much sense considering the values)
I'll try uploading pictures of the machine when I'll get the PC-phone connection working ^^'

Thanks !
Best regards,
Thomas.

/5 diameter of 7.84mm is .310 inches. So just under 5/16". Most threads are made a few thousandths of an inch smaller than the nominal size. Try looking at other thread systems for something that is 5/16" by whatever the threads per inch is. (30?).

Depending on where the engine was made, threads could be other than BA, such as British BSP (pipe thread), BSF (fine), ME (Model Engineers), BSB (brass) and so on. Or American NPT (pipe), UNF, UNC etc.

PS, this chart might be easier to use than the one you posted link to.

Thanks for yout quick and complete answer !

Though, I'm wondering :
The measures I gathered are for the "male" parts (for wich I need a die). Female parts are a fraction different in diameter (for the tap). Does this chart work for both ? As inside and outside diameter aren't the same +/-3% of the diameter around the thread.

Edited By Thomas DION on 07/04/2018 10:06:17

Taps are usually made to the nominal diameter or a few thousandths of an inch less. So a 5/16" tap will usually measure 5/16" diameter, or within a couple of thousandths. Yes, the chart works for both. The hole in the middle of the die will be approximately the same as the listed tapping drill used to drill a hole before tapping the thread in it.

Thanks ! I'll dig into that !
BTW here are the badly taken pictures of the thing (and another old machine) :
https://imgur.com/a/HhMwS

As you can see it had been badly damaged and repaired. I'll work into that too one day or another

Link to pics - **LINK**

Thomas, if you follow instructions in the albums section on the green line at the top of the page you can bring your photos direct from your computer to an album, then directly onto the page. I find this much better than other sites where you have to go through Photo Bucket or something similar.

Ian S C

I tried, but for unknown reasons it was extremely slow :/
So I prefered uploading on imgur, and having only to post the link ^^' (wich I didn't link properly, sorry !)

Thanks for your advice though !

Hi Thomas , I was given last year a present from my daughter ,who lives in America,a model steam engine,made by an American company called" WEEDEN toys". The one I have was made about 1904 .If you look on this company you will find many kinds of engines and the one I have looks very much like your vertical one.

Welcome to the gang,Maurice.

Thanks ! I've checked on their website, even if some are a bit similar, the logo doesn't match :/
But I think after some research, that the logo is for "Gebr. Märklin". So the engine is german

> **LINK**

I'll try keeping updates around here, but from other sources, I've found most threads aren't conventional, and I'll try making my own taps and dies