Schwert-
Can you comment please:
• Brass vs. wood shaft. Over time, would the brass shaft/piston perform more reliably? Not that wood doesn't perform well, but I'm wondering about susceptibility of the wood-piston versions to humidity/moisture or conversely, shrinkage due to extremely dry climate (read: the deserts of Arizona).
• Rubber O-ring vs. traditional waxed string gasket. I see you have both versions. Does it really matter which? Is the need to periodically rewind/rewax the string so infrequent that it's no big deal?
• The traditional design to capture the small bit of tinder on the end of the shaft is a recessed hole on the end. I've seen some with an open "notch" on the end, which would seem to have the advantage of easier transfer of the ignited tinder to a tinder nest (vs. digging ignited tinder out of recess with a tinder pick or whatever). Or is one as good as the other?
You might discern from my questions ... I'm aiming for reliability over being period correct in the design.
Thanks for the benefit of your experience.
OK...let me try some answers....
Wood vs Brass. I do not have one of the brass lined versions, but did initially have a high friction piston in my first cocobolo piston from Darrel. He reworked it for me and thought that a piece of unseasoned cocobolo was responsible. I live in a relatively wet place and had not had any issues with any of my three wood pistons since. I honestly cannot say what will happen over more time or would happen if I moved to a drier place...however there is a reasonable amount of space between the piston body and shaft that the seal closes...so very small changes should not affect the piston much. The brass lined wood block versions should be stable essentially forever I would think. They use a wood shaft and only if that changed dramatically would they either sieze or be too loose. I really cannot say what will happen, but I have had excellent success with my wood pistons over the past couple of years.
O-ring vs string. I love the string seal. The traditional look and feel really is what I like. I have only had to do one rewrap of a string seal and it is a bit tricky....not too hard but it can require more than one attempt to get just the feel you want. This is really one aspect I do like....if you twist the cotton as you wrap you can "bulk up" the string or flatten it depending on the way you twist....this allows some adjustment to the seal. Slipping on an o-ring is as easy as it gets but there is no fine tuning ability. As you use the piston little flakes of fungus etc can get caught in the string, or gritty pieces could cut the o-ring. So far I have never had my o-ring version fail....and it is a real nice piston. However, if I was only buying one it would be string. You can make a case that the string is field fixable but to me that is a rather esoteric argument to make as I fell a piston is more a fun device than a front line fire making tool that my life would depend upon. Don't take that wrong though as I do find the pistons highly dependable, but I would not purchase a string version for the field fixable aspect alone.
recess vs notch. All mine have the recess. I do think it is important as you make your tinder nest to have a small sliver of wood to pick that ember out. I have been able to poke the coal still on the shaft into my cedar bark nest and blow that ember into flame while it is still on the shaft. However a little notch to pop that coal out seems like a good idea to me. One of my pistons has a bone pick....nice.
The other trick I use is to have a small chunk of fungus in my tinder nest....poke the piston shaft with coal right up to that fungus piece and transfer the glow to that....then set the piston shaft down and blow the nest to flame with the child coal. This works great and is somewhat easier than picking out a tiny coal which can sometimes fall apart.
There are a huge number of operator tricks and preferences to learn with a piston, and I am pretty certain my experiences will be slightly different than others...but I bet everyone enjoys using a piston.
If I lost all my pistons today, I would ask Darrel to make me a cocobolo piston with tinder cavity with string seal as the replacement. I would likely not do add a pick to it. I really like the larger diameter more straight body versions I have rather than the tapered one.
I do think that tinder fungus is the best tinder too. Char is second and everything else is harder for me to light. Dry, soft punky tinder fungus is nearly 80% or greater reliable for me. One or two strikes and I have a coal. The harder outer fungus is much harder to ignite. Char has to be dry and well charred to light with as high a percentage. Sometimes I cannot get it to go especially if it has been high humidity weather.
You can dry damp tinder in the piston....2-4 strikes can drive off water. But if you are up to about 5 good hits and no coal change the tinder.
I hold the piston on my left hip or side and give the shaft a good solid quick whack with the pad of my right hand palm. Quickly withdraw the shaft and a gentle blow to spread the coal. The hit has to be quick...not a press but wham down, then remove the shaft rapidly with a twist (twist to tighten the string...otherwise you can undo the seal).
Make sure you lube that seal plenty. Vaseline or lip balm is excellent.....you cannot overlube I think. Especially as you are learning. Wipe off the string often to keep junk from scoring the piston body too.
That is about all I can think of, except have fun and demo the firemaker with kids....they never get enough of the magic.