I didn't say anything about free shipping. Only reasonable shipping. If it's $20 then so be it. BUTTry running a small mail-order business for a while -- then report back on why shipping should always be free.
I would counter that if it takes even a one man shop an hour to fulfill a purchase order - - - - - well - - - - he/she needs to stir their stumps at the minimum or devise better systems. In fact if you're taking more than 20 minutes do the same. (I'm not sure but I think markups have also increased but am not so sure of that!)Possibly to to bring it up to $0, even.
Orders take time to fulfill. Someone has to read them, pack them, make an address label, etc. Unless you're doing it yourself -- and don't value your time -- someone has to be paid to do the work. $20 to send you an empty box, from a one-man business, means that someone is paying themselves around $15 an hour, or possibly less.
To a certain extent, big operations (like Amazon) can refine the shipping process to bring that minimum down, but even then "free" shipping is just a come-on, that results in more expensive orders subsidizing the less expensive orders, to reduce competition and lock in your business.
Try running a small mail-order business for a while -- then report back on why shipping should always be free.
That's mighty thin, but possibly doable. However, keep in mind that when working with models, sometimes the math has to be thrown out in favor of what is practical - most people making the Webster use thicker rings, more like 1.5mm. In my case, I used a Viton o-ring, 1.5mm, and it has worked and continues to work perfectly.I think at 3/8" your rings would be devilishly thin. Rings for my Webster worked out to 0.8mm thick, and while I found making them to be easier than expected (I thought I'd goof up for sure) that's still a little thinner than i feel comfortable making. Plus the engine is far from finished so I can't speak to whether they'll actually work. 3/8" is a little under half the bore diameter of the Webster, so you'd want something like a 0.4mm ring? Crazy.
I think for such small rings I might try making them from bronze. Much easier to get in small sizes, and it works in steam engines so why not IC? Would need a larger gap to compensate for lower stiffness of the bronze.
It's my understanding that the ring seals against the bottom of the ring groove (on the power stroke) so it must either be flat or get forced down into a flat shape by pressure in order to work. Otherwise the gas could go around it via the ring groove.HMMM... Assume I am thick, but why does it stand to reason? The ends (gap) don't have to align perfectly, because there is a gap anyway, and as long as the ring contacts all the way around it should be OK if "close", - with my reasoning? The ring groove does that anyway. With 0.5mm wire it only has a pitch of 0.5mm. as wound. The ring clearance will be only 0.025~0.05mm anyway, - which at max is only 1/10th of the wire diameter, so "I Guess" it will be OK? the slight axial force from the "twist" would probably just form a slight contact on one end on the top, and on the other at the bottom. If this prevented rotation then it would be an issue, but if the ends are suitably fettled they should slide, allowing rotation. I don't remember a "flattening" process on Production rings in H & G's factory. - But my not remembering doesn't mean there wasn't one. I can only suggest "try it and see".
I am fairly new to all this trying to make a first sort of working steam model at some point. ( boiler beeing the problem ) Piston rings beeing an interseting question.Oh hell, not again. This hobby is dying. Why make the barrier to entry more difficult by criticizing how people make their engines? The whole "you're doing it wrong" does nothing but push people away. So what if someone wants to use sealing method over another? Give it up.