Author Topic: The Teflon Ring Saga  (Read 6185 times)

Online steamer

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Re: The Teflon Ring Saga
« Reply #15 on: August 18, 2015, 04:55:36 AM »
Dave,

After you cut the slots did you put the ring on a mandrill and squeeze it shut then turn the OD to your cylinder size? Or did you not worry about the ring being slightly out of round when compressed?

I'm thinking pretty seriously about a Teflon ring in the Goulds pump and this thread has given me lots to think about and learn.

Thanks,
Dave

Dave, I added to the OD enough to give it about half a lap worth of expansion and then cut the slots.   I didn't worry about it being out of round.   It's Teflon, so not very stiff, so steam pressure just pushed it right out and it sealed just fine.   

I've gotten 3 seasons on them, and they still work pretty well

Dave

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Online steamer

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Re: The Teflon Ring Saga
« Reply #16 on: August 18, 2015, 04:57:41 AM »
I cut mine so that the slots were JUST connected at the corner, then finished the cut with a razor blade.....worked fine

I sized the ring so that when in the cylinder, the gap was half closed up.   That let the Teflon expand under temperature.

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Online steamer

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Re: The Teflon Ring Saga
« Reply #17 on: August 18, 2015, 05:36:55 AM »
Thinking about it some more Dave, my HP piston is 1.5" and my LP is 3" so the rings are pretty flexible.   On a small bore...like under 1"....maybe not so much, so you might want to mandrel turn the ring to final size after on a small engine.....jus make sure you have at least half the lap open when you do so that the ring can expand

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Ian S C

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Re: The Teflon Ring Saga
« Reply #18 on: August 18, 2015, 01:40:01 PM »
The Teflon rings that I know of are made of about 1/4"/6 mm strip of 1 mm Teflon sheet, the ends are cut in a step so that quite a large end ways gap can be left.  These rings are on the piston in a car shock absorber, I don't know how warm that might get on a long trip.
Ian S C

Offline Bearcar1

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Re: The Teflon Ring Saga
« Reply #19 on: August 19, 2015, 05:19:35 PM »
Good day to you Stanů.. I always have enjoyed your work and we have exchanged emails on several occasions. This discussion of PTFE rings is quite educating and eye opening. Have you considered the use of graphites yarn instead? If so, what are your feelings on doing so? It is my feeling that PTFE is a good candidate for running these engines on compressed air, put I prefer (Im of the old school) to use graphites yarn when running in a wet environment such as live steam. It seems to me to be a lot less of a hassle but perhaps I have just been lucky so far.


BC1
Jim

Offline sshire

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Re: The Teflon Ring Saga
« Reply #20 on: August 19, 2015, 05:33:50 PM »
Jim
I have graphite string packing, twisted PTFE pipe tape (which is used on a few of the Rider Ericsson pumping engines), Teflon packing string which is on my Rider.
If the Teflon doesn't work out (though, I suspect it will with better clearance in the groove depth and width) I'm not above trying anything.
Best,
Stan

Offline Tennessee Whiskey

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Re: The Teflon Ring Saga
« Reply #21 on: August 19, 2015, 07:29:09 PM »
Vern, at this point in time, should one possibly entertain the idea of dabbling into the cast iron ring arena? I do say old boy,  one must cross that moat at one point in time,  don't you agree?  Some Sunsetter thinking  8)

Cuz

Offline sshire

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Re: The Teflon Ring Saga
« Reply #22 on: August 19, 2015, 10:14:25 PM »
Cletus
Old school.  :ROFL:
Best,
Stan

Offline paul gough

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Re: The Teflon Ring Saga
« Reply #23 on: August 20, 2015, 12:46:08 PM »
Maybe 'Rulon' might be an alternative to PFTE, I have been told Aster use it in some of their gauge one locos, as a first stop try; www.polymer plastics.com for some info. Paul Gough.

Online steamer

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Re: The Teflon Ring Saga
« Reply #24 on: August 20, 2015, 02:46:36 PM »
Maybe 'Rulon' might be an alternative to PFTE, I have been told Aster use it in some of their gauge one locos, as a first stop try; www.polymer plastics.com for some info. Paul Gough.

Would be a good choice....just expensive.

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!