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Offline steamfriend  
#1 Posted : 07 December 2023 00:33:55(UTC)
steamfriend


Joined: 19/11/2002(UTC)
Posts: 378
Location: Leuven, Belgiium
Hi all,
I was wondering if there are any life steam addicts in here that are enhousiastic about the Märklin production of stationary steam engines. Particularly, I am looking for more technical information, e.g. as to the threads M used in the 30’s - 50’s. They uses, apparently, 40 turns per inch threads, but do not math BSW nor UNF 6 diameters...

OK, maybe I’m becoming too detailed technically, but my question is: is there anybody passionate about these marvellous machines?

Thanks,

Bob

foto3.jpg
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Offline kimballthurlow  
#2 Posted : 07 December 2023 05:29:31(UTC)
kimballthurlow

Australia   
Joined: 18/03/2007(UTC)
Posts: 6,675
Location: Brisbane, Australia
Hi Bob,
40 tpi is a typical model engineering thread used world-wide.
Example - in live steam engines for any gauge up to 12 or 15 inches, it is used for olive/nut/flange pipe fittings and can be applied to any spanner size that suits.
Take a look at Reeves of near Birmingham https://www.ajreeves.com/6525.html
Descriptions like this abound - BLOWER VALVE 1/4" x 40 where 1/4" is the stud or bolt diameter and 40 is the thread pitch.

Also I wonder if it might be one of those weird hybrid fastenings that proliferated at that time.
Example - you could get British Association (BA) fasteners with metric threads and standard BSW hex bolt heads.
Example - BA 4 and BA 5 are marginally either side of 40 threads per inch.

I purchased a British 1948 model MG sports car, and it was completely BSF (British Standard Fine) bolt heads with metric threads.
I cant remember the pitch, the bolts were probably manufactured in Germany.

Kimball

Edited by user 08 December 2023 02:22:12(UTC)  | Reason: Corrected dimensional description

HO Scale - Märklin (ep II-III and VI, C Track, digital) - 2 rail HO (Queensland Australia, UK, USA) - 3 rail OO (English Hornby Dublo) - old clockwork O gauge - Live Steam 90mm (3.1/2 inch) gauge.
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Offline EMD_GP7  
#3 Posted : 07 December 2023 14:45:41(UTC)
EMD_GP7


Joined: 23/11/2010(UTC)
Posts: 192
Location: U.K. Midlands
The 1/4 inch dimension is the outside diameter of the thread NOT the spanner flat size which depends on the application, Bolt head, Nut , Pipe nut Etc.
I have a valve similar to the Reeves valve on my 5" gauge loco where the Lock nut and the pipe nuts are different sizes although both are 1/4" x 40 TPI ( bought from Reeves who are now 35 miles from Birmingham in Leicestershire _ I cycle past there regularly )
Colin
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Offline steamfriend  
#4 Posted : 07 December 2023 18:29:21(UTC)
steamfriend


Joined: 19/11/2002(UTC)
Posts: 378
Location: Leuven, Belgiium
Thanks a lot for your comments and thoughts, guys. What I really wanted to know is where one can find those Märklin nuts, with internal thread of 40 TPI. I tried both BSW1/8 and UNF Nr6, both with 40TPI internal gauge, but none of the fit the diameter of the bolt (is true for the valve shown below, but also for the fixing screws in the machine).

IMG_4203AbsperrhahnMarklin4098_txt.jpg

Another question is how to dismantle the water level inspection glass safely. It is tightly fixed apparently... cannot move it out.

Bob
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Offline cookee_nz  
#5 Posted : 07 December 2023 22:29:28(UTC)
cookee_nz

New Zealand   
Joined: 31/12/2010(UTC)
Posts: 3,956
Location: Paremata, Wellington
I have a couple of Engines, but I would not say I was passionate about them. Possibly more of a passing fancy than anything.

I've got the 16051 reproduction and an original smaller one 4097 from c. 1930.

Whether they will endure long-term in my collection is yet to be decided.

I can't answer your specific question but in the back of an old catalogue (1939) some parts for the Dampfmaschine were listed that might be of interest for reference


1939-DD16-p78.jpg

1939-DD16-p79.jpg
Cookee
Wellington
NZ image
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Offline kimballthurlow  
#6 Posted : 08 December 2023 02:25:13(UTC)
kimballthurlow

Australia   
Joined: 18/03/2007(UTC)
Posts: 6,675
Location: Brisbane, Australia
Originally Posted by: EMD_GP7 Go to Quoted Post
The 1/4 inch dimension is the outside diameter of the thread NOT the spanner flat size which depends on the application, Bolt head, Nut , Pipe nut Etc.
I have a valve similar to the Reeves valve on my 5" gauge loco where the Lock nut and the pipe nuts are different sizes although both are 1/4" x 40 TPI ( bought from Reeves who are now 35 miles from Birmingham in Leicestershire _ I cycle past there regularly )
Colin

Hi Colin
Thank you so much for your correction.
I have edited the text in my post.

Regards
Kimball
HO Scale - Märklin (ep II-III and VI, C Track, digital) - 2 rail HO (Queensland Australia, UK, USA) - 3 rail OO (English Hornby Dublo) - old clockwork O gauge - Live Steam 90mm (3.1/2 inch) gauge.
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