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[DBS88]

The Hemmens Caton engine and boiler when compared with the later Hemmens Max 2 engine and boiler uses different thread sizes. The threads on the Caton are finer than on the Max 2, so as a result, for example its not possible to use a Caton Safety valve on the Max 2. The threads on the later Max 2 are ME Threads, 1/4 40 etc.
Do you have a Caton? If so please would you let me know the thread sizes used, in particular the safety valve, thank you in advance for your help it is appreciated.

[pipercub1772]

Hi i don't know if this helps but i have a hemmens water valve never had or could find nuts and cones for it but just by chance
tried some kb10 sent me a couple of years ago for a anton plant i had at the time I think he said if i remember correctly
they are 5mm x 50 hope this helps in some way sorry cant help with the safety valve ,regards Allan

[SteamboatPhil]

The early ones maybe 1/4 32, used a lot, along with nipples and the gland nuts
Hope this helps Dave

[DBS88]

Hi Phil and Alan, thank you for taking the time to respond it is appreciated.


Originally I was told the safety valve  was 1/4 inch, when I saw it the thread was obviously finer than 40tpi, so I started some research and asking questions here and other places.


I later got my hands on the Catons safety valve and on other fittings, I used a micrometer, and realised they the safety valve was way under a 1/4 inch and that the fittings were metric sizes, the safety valve is 6mm and the engines fittings 5mm.
I then used a thread gauge and found the pitch to be 0.5mm which equates to 51tpi. This bears out what Alan is suggesting. A thread of 5 by 0.5mm is not unusual, but 6 by 0.5 is less common, for 6mm 0.7 is more often used.
So I believe the threads on the Caton are 6 by 0.5mm for the safety valve and 5 by 0.5 for the other fittings - I am awaiting delivery of some nuts with these thread forms so that I can confirm whether  or not that is correct.

[Treble]

DBS88 , please note , Tracy Tools supply taps and dies in these sizes.

[DBS88]

Re the Taps and Dies being available from Tracey Tools, thank you. I did have a chat with a helpful rep (apologies can't remember his name) from Tracey Tools at the Midlands Model Engineering show, he was kind enough to show me the M6 and M5 by 0.5 taps and dies that were on the stand and available to buy.

[pipercub1772]

Great news can you let me know who is suppling the   5 x 0.5 nuts ,regards Allan

[DBS88]

Alan have sent you a PM,
kind regards Dave

[SteamboatPhil]

 I hope you have got it solved Dave, please let us know as I am refurbishing an old French steam plant at the moment, and this metric stuff  is alien to me (pitch size etc....grrrr )

[DBS88]

Hi Phil,
Re Caton thread sizes, since the Caton boiler in question is a fellow club members, I do not have immediate access to it. He has decided that the right thing to do is for him to purchase the nuts so the thread forms can be confirmed, rather than me incurring the expense. I will update the forum once he has them.
I am pretty confident, and this is a cheap way to verify our findings. He looked on Ebay and other places to find a supplier of just a few nuts, the sizes we believe are M6 by 0.5mm and M5 by 0.5mm


Re metric fittings, Regner supply them, they have and use on their items, M5 by 0.5mm, also M6 by 0.75


Hope this helps

[rhavrane]

Bonjour Dave,

It is possible to find 6 x 0,50 mm, example  : https://fr.rs-online.com/web/p/filieres-de-filage/0215798

[Mege66]

For UK based buyers I would strongly recommend https://crtoolsuk.com/product-category/taps-dies-tap-holders/taps/

I purchased a complete set of HSS ME taps and dies with 32 and 40 tpi and am very satisfied with them. C R Tools offers reasonable prices for properly ground tools. Not to be compared with cheap tools of dubious origin.

[KBIO]

ello !
Mine is a : 1/4" - 40 TPI .




By the way , I am selling my launch ! If interested = PM. 

[DBS88]

Yves, that is a lovely boat, is the engine and boiler the Max 2? its hard to tell from the photo, if its the Max 2, 1/4 by 40 is correct.


It appears the earlier Caton (the earlier version of the Max 2 generally green in colour) has different threads, and the two Catons I have seen in our club are most definitely not 1/4 by 40, the threads are much finer and their diameter is way below a 1/4 inch, they are the correct diameter for 6mm. In fact a previous owner of one of the Caton plants has wound an incorrect nut onto the engine and tried to seal the thread.


The 5mm by 0.5mm nuts have now arrived, so in the next couple of days hope to be able to confirm whether or not the connections to the engine are metric and 5 by 0.5mm

[KBIO]

Hello David !
Yes , it is the MAX II with 1/4"-40TPI thread.
Concerning the Caton , I remember that the threads on the engine  are finer and looks like a 5x5. mm , but I doubt , that it is !
I have to take it down the shelf , and have a look for you if you wish .
Cheers !

[DBS88]

Yves, thank you for confirming the 1/4 is used on the Max 2 and for your kind offer to check your Caton engine, it is appreciated.
This morning I went to the lake to meet a fellow club member with a Caton Engine, Boiler and fittings. We checked whether the Regner M5 by 0.5 nuts fitted the Caton parts, so male Caton to female Regner thread. We also checked whether Caton fittings would fit with Regner parts, so Caton female thread to Regner male thread, both fit well.
We also checked the thread form of the larger fittings, measured as 6mm, the thread form is the same as the 5mm fittings so we are also confident that the 6mm fittings (safety valve and others) are 6mm by 0.5mm threads.


Hopefully now those with the old and rare Caton steam plants can work on them with confidence knowing the right threads to use, thank you to everyone for your contributions to this journey of discovery.