I can't rush into this one, but when I get the time and energy, it will be all hands to the pumps, just like the last one.
Gerald, as I said before, this is an interest build, and if it helps you in some way, then great. I am not into making engines for a living, I just use them to support the shop in making models. The income will come from other workshop work. People don't have the facilities I do, so that is why I am building a few.
Now Derek,
About that fiddly little blaster you showed in an earlier post. What a wimpy little thing. Below is mine, given enough pressure it should be able to fire small marbles. But I am lucky, and have a contact who gets me as much glass bead or grit, in whatever grade that I require, and it is just a matter of swapping medium and adjusting pressure to get the effect as needed. Twenty squid from Machine Mart, plus you need a damned big compressor to feed it.
What will do a lot will do a little, but not the other way around. Take no prisoners in this game.
John