5" Gauge Pansy
|Robert Starling||08/06/2011 18:56:29|
|3 forum posts|
Currently machining gunmetal cylinder block for 5" gauge Pansy but I am a bit out of touch with what is used for piston ring material these days. Originally LBSC used graphited yarn which is still available but I suspect some use silicone 'O' rings which are available from Chronos or Blackgates. How well do these wear ? ( I have some minor blemishes in one bore which might be the result of slag in the casting and am concerned that the 'O' ring might tear on this). I have also come across an article in which piston rings were made from 35% graphite filled PTFE but have no idea where to obtain this in the small quantity needed. Other modellers experiences and advice welcomed.
|31 forum posts|
Hi robert. I have used silicon 'O' rings in my Pansy for many years and they seem to last quite a long time certainly 300 or so miles and then they were changed because the pistons were out. If the bores are rough it may be a problem suggest honing out the bore to see if it cleans up, remember that the bore is not critical with an O ring, within reason, as you make the piston and ring groove to match the ring and the bore. Alternately I have heard of filling the blowholes with araldite and then cleaning up the bore. I know this is probably a bit late but all the best with it .
17822 forum posts
Not sure of the dia you need but Noggin End do the filled ptfe
|mick H||10/08/2011 07:39:23|
|718 forum posts|
I have used silicon "O" rings which ran well for a while but their performance petered off quite quickly. On subsequent examination, they did look sad. I spoke to the supplier, Polly Engineering, and was told that I should have used Viton rings, especially if I was using superheated steam. I took this advice and have had no problems with the Viton. Polly do a good range of Viton rings.
Please login to post a reply.
Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!
You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.
Click THIS LINK for full contact details.
For subscription issues please see THIS LINK.