Where are we all, what's been going on. Spent part of today making nylon bearings for my trailer jockey wheel, took the trailer out the other day and after a couple of miles thought a wheel bearing had gone on the van. Stopped to check and found the jockey wheel on the ground with the nylon bushes missing/melted. Sorted out a load of Stainless which went to the scrap man this morning and had a bit of a tidy up. Anybody have any idea where I might obtain graphite to make pistons with.
Graphite for pistons? Pray tell more. Google for graphite suppliers and you get some hits but possibly big =A3 =A3. What size do you need? Motor or generator brushes are available sometimes. Peter may have a few but how they would react when aproached by a lathe tool I don't know. I've seen some decorative ornaments made from graphite. I've a nice looking candle stick holder but again, I doubt it would machine well. I assume it's a graphite resin mix which is cast then polished. I've also got a coal model that takes a nice shine. There's always the occasional rod in a neuclear power staion of course. It may glow a little and if you get one, I'm keeping away. Are carbon rods for welders still around? Now if you still had the Bedford, a quick decoke would provide all you could want :-)
Nothing that size, I also wanted some for electrolysis but found that even low grade stuff was pretty expensive, but there are suppliers around.
Morganite were the best-known, but we found a couple on the net that would supply, at a price.
Couldn't find any used sources or places that had bits and pieces available.
The film lighting industry used rods for the arc lamps, but I think they have been replaced by modern discharge lights. I still have a contact and can ask. Typically they were 9/16" diameter and copper coated for contact (they went through an inconel sliding contact)
One carbon was fixed, one rotated and there was a feed mechanism that fed the carbon in as it burnt away. The trick was to get it so that it was self-adjusting.
Look for 'Mole-Richardson' and 'Brute' they were the maker and knickname respectively of the 110V 25kW arc lights that we used to use.
-- Peter & Rita Forbes Email: firstname.lastname@example.org Web:
Peter answered your question, low delta T hot air engines use graphite for pistons as they self lubricate especially in a glass tube. As to machining, high speed sharp tools. By the way kept Bedford in top trim and always worked her, so no need for decoke.
I'm told that pistons are first made from pitch and then autoclaved to some extreme temperature. Graphite pistons have some interesting heat conduction characteristics, being almost as good as diamond in one plane and a near insulator in another. Is this effect made use of in a stirling?