Hi Dave,
 Just a thought, could you bore under size for the cylinders and vacuum chips out there?

Well   3 steps forward and 2 back....

I got the block set up on the lathe and started to bore it.    But I ran into a problem......ME!

I left .040" material when I roughed out the block....but captain dumb dumb didn't think that would be 0.080 on diameter!    I was OK on the main bore...the boring bar JUST fit, but I can't get the 1/2" diameter boring bars in the roughed out 15mm bores at all!.....hmmmm

OK   so I'll start by opening the crankshaft bore, 32mm finished diameter out to about 30mm...    I found the next problem!
I can't get chips out of the block very well  Like NOT at ALL!    I end up recutting chips and it's a problem.   So my boring bar is basically too big in diameter.
So I made a 0.020 pass on the bore, and split the case  and clean out the case, reassemble the case and make another cut

OK   so the intent with all of this was to bore all the bores in one set up so that they're parallel and consistent.
Breaking the case open is not serving that very well, as I can't evacuate the chips.   I have 0.040 worth of material to come out of the 32m  crankshaft bore, so I'll leave that for now

but what's worse is I can't get into the bores of the 15mm bores at all until I open them up past 1/2" diameter.   They need to be opened up.   
OK  So I put a 1/2" long shank end mill into the lathe and bored these holes as deep as I could.  I then put a long shank 1/2 inch drill in the lathe and bored through.

I know this does not do well for locational accuracy, but the material has to come out.

So now Im at this state... I"m sitting Wondering what I should do.    So much for game plans right?

OK   

Plan 1
I think I need to make up a boring bar that is slightly smaller in diameter and 9" long.    with this I'll "worry" out the 15mm bores to say 14mm and then put my between centers bar in and take out the remainder.

Plan 2
pick up a 14mm diameter long shank end mill and long shank drill and open the bores to 14 mm  and finish with the between centers boring bar to 15mm.     I like this solution the best, as it's simple, and apparently effective.   I don't like long drills as then tend to wonder around though.

either way, I don't feel confident that I cant hold super tight tolerances with the bar alone as I can't get the chips out.   That said, I think I'll need to make up some laps to finish the bores to the tolerance I want. 

I'm going to buy some tooling and then mentally chew on this overnight, and see how it looks in the morning.

I have the mains at about 30mm and the 15mm at about 13mm currently. 

Going in the right direction, just trying not to screw it up.

Dave 

For Bent - a jpeg markup is attached of the crowd engine steam supply swivel joint on an Erie B steam shovel just FYI. These shovels were much smaller than the Marion one Chris gave details on, just FYI, but the fittings are similar in function. The swivel fitting is formed from two elbow fittings with a packing joint to seal the steam flow, and a mechanical groove and static pin to keep the halves together. The Erie fitting also has a through-bolt to keep the halves together under pressure. Hope this info is of interest.

Ah - yes! I forgot that the revolving shovels still needed a swivel so the boom could be tilted.      Usually on the railroad shovels with a turntable, the boom was at a fixed angle where the revolving shovels usually had them adjustable for angle.

Yup, that's right Jason. I should include photos just to show what I'm talking about -- here's the headstock end of my lathe with the leadscrew extension and stepper location under the headstock.

And the second photo is my fake "gearbox: housing with the switches, wiring and the tiny computer that does it all -- an arduino nano type. You can see a pencil in the photo for size comparison. The computer is dwarfed by the wiring to it, and the "gearbox is cavernous.

I'll neaten this stuff up and secure it before installing. It's easier to connect a USB cable to it while it's loose -- you can just see the mini USB connector at the bottom of the board for sending it programs. This board cost I think $4 -- I think I got 3 for $12 ? -- can't remember.

If you did have a spare moment Jo it would be nice if you could wave your majic wand on the following. Although Pat says he has no intenion of using 3DMP these may be of use to others.

The post where it was asked if Brass and bronze cold be printed

My reply that generally not but wax then investmet is how they do it

My later post about costs where I attached the two images of the pump.

And possibly the couple about pipe fittings being printed.

Thanks.