Speedy bore and rings

[nigel jones 5Participant @nigeljones5]

Just lookes at the cylinder dia and its 1 9/16. It looks like packing instead of rings but I would like to use rings. 1 1/2" dia rings are very easy to buy but not 1 9/16. Is there any harm in having the bore slightly smaller so I can buy rings instead of having to make them? In addition, have people built it to the original drawings and run it ok?

[nigel jones 5Participant @nigeljones5]

[Paul LousickParticipant @paullousick59116]

Hi Fizzy, The OD of the rings should be the same diameter as the bore otherwise they will not seal properly.

See the link at:- http://users.tpg.com.au/agnet/make%20piston%20rings.html

[nigel jones 5Participant @nigeljones5]

Thanks – I appreciate that, im asking if going to 1 1/2" bore will make much difference so that I can buy rings??

[Paul LousickParticipant @paullousick59116]

Can't see that a slightly smaller bore will effect much. The smaller bore will reduce the output power of the engine slightly but should not be a problem with its operation. In the future if the bore is worn and you have to re-machine you can always take it back to the original size.

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi Fizzy ,

(1) Look for piston rings from engineering suppliers rather than the model trade and look for metric sizes . 40 mm should be easy to find .

(2) Alternatively use O rings – most people think they are nearly as good as piston rings anyway . Large range of metric and Imperial sizes available .

(3) Full size engine had 17 – 1/2 inch cylinders which scales to about 1.550 inches .

1 – 9/16 inches is 1.562 so cylinders as specified by LBSC are just a little overscale anyway .

LBSC never ' designed ' his engines – they were usually just thrown together anyhow so I woudn't worry too much about altering dimensions to suit available materials and tools .

Regards ,

Michael Williams .

[Sub MandrelParticipant @submandrel]

As someone who freely admits to having no practical experience of this, I have read criticism that many of LBSC's designs were 'over cylindered' so they had plenty of power to pull passengers, but could run out of puff. especially if run without linking up the motion to make better use of steam.

The differnce is more than you may guess – 1 9/16" cylinders are nearly 9% bigger than 1 1/2", but yusing proper piston rings and gettinga better seal may make up some of the difference?

Only you can decide, but isn't being C.M.E. the best bit?

Neil

[Boiler BriParticipant @boilerbri]

Try – EAP International in Google. They have all sizes of o rings.

Bri

[nigel jones 5Participant @nigeljones5]

Thanks for the pointer Michael – thee are lots of 37mm rings on ebay very cheap! Looks like the way to go to me!

[Ian Headland 1Participant @ianheadland1]

Hi Fizzy You can go to the best design and get hold pf Clupet Rings I think they still exist somewhere in the UK

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