Stuart 10V questions.

[fla Jim]

This is my first engine from castings.
I just received the building a "Vertical steam engine from castings" book.
I hope to get the engine kit next week.
Here's some questions right off to bat for you'all that have experience with this engine.
I'm putting an order for BA taps and a die. So far, I 'm going to order;
5 BA die
Three tap sets for;
5 BA
7 BA
8 BA
What are the threads on the valve and cylinder glands?
The book shows 1/4"X32 for the valve, and 5/16X26 for the piston. Is this correct?
In my home shop I have a 12X36 lathe, 9X42 Bridgeport, and a 6X18 surface grinder.
As an aside my best friend calls my shop the "Magic Garage" because of all the stuff crammed into a 10'X20" shop :
Again the book shows machining the bed, and sole plate, etc, with the lathe. Has anyone done this with a mill, or even a grinder?
A lot more questions to follow, when I get the kit.
Thanks in advance for the help.

Jim

 

[Jasonb]

Those are refered to as ME (Model Engineer) threads in the UK, you can get the taps & dies from MorrisonMiniatures in the US. These fine 40,32 & 26tpi threads are used on a lot of english models for steam fittings etc. You could also substitute a suitable american thread. Don't forget to order a suitable sized tapping drill for each of the threads if you don't have one, and a clearance as well but that can be a bit oversize if you have something close.

http://secure.enginemodels.com/cgi-...hispage&thispage=tools1.shtml&order_id=287461

At the time the book was writen most hobby workshops would not have had a milling machine so all the work was done on the lathe with the aid of a vertical slide, if you have a mill available it will be a lot easier, a ground surface is not required, so just stick with your mill.

Jason

 

[mklotz]

1/4-40 and 5/16-24 are common American sizes.

Here's the chart I use when making substitutions for BA threads.

	British Association			Closest American
   	   Threads				  Threads

	BA 	 OD	TPI	PITCH		THREAD	 OD
	Size	(in)		 (mm)			(in)

	16	0.031	134.0	0.19
	15	0.035	121.0	0.21
	14	0.039	110.0	0.23
	13	0.047	102.0	0.25
	12	0.051	90.9	0.28		0-80	0.060
	11	0.059	82.0	0.31
	10	0.066	72.6	0.35		1-72	0.073
	9	0.075	65.1	0.39
	8	0.087	59.1	0.43		2-56	0.086
	7	0.098	52.9	0.48		3-48	0.099
	6	0.110	47.9	0.53		4-48	0.112
	5	0.126	43.0	0.59		5-44	0.125
	4	0.142	38.5	0.66		6-40	0.138
	3	0.161	34.8	0.73		8-32	0.164
	2	0.185	31.4	0.81		10-32	0.190
	1	0.209	28.2	0.90		12-28	0.216
	0	0.236	25.4	1.00		1/4-28	0.250

 

[kellswaterri]

Hi Jim, the drawing calls for ...
Valve---1/4 by 32
Piston---5/16 by 26
the problem I encountered when building Stuart stuff was if I strayed from their thread sizes on the drawings I then ran into problems with Steam fitting adaptability thread wise and had to make my own fittings...try making a Steam valve for instance ;D
In saying this, I would suggest you decide on a supplier of steam fittings, find out their thread sizes and obtain tooling to suit...much easier on the nerves. ;D
I have the 10v up and running also the Score currently working to finish the Coombes and build a Corliss.
All the best for now,
John.

 

[tel]

What are the threads on the valve and cylinder glands?
The book shows 1/4"X32 for the valve, and 5/16X26 for the piston. Is this correct?

You'd be better to so what I did, and substitute 1/4"x40 and 5/16"x32 respectively.

Making fittings is not a problem - in fact it (for me) is one of the most satisfying aspects of the hobby.