I have been having quite a time finding the right set of steam and water taps for the build. Although I know that lever style controls are preferred by some over traditional taps, I would really like to preserve the look of the original design. Personally, I find the lever valves are akin to forelegs on a Tyrannosaurus Rex - out of proportion with the rest of the beast.
Alas, the Brugnetti valve is out of production (although there is still a little new-old stock to be found) and I have not come across any of the handles at all. I combed the databases of a number of suppliers to find a likely candidate and found one from Pavoni:
I ordered the valve body and the handle separately and was surprised to find that the handle wasn't the one in the image (it is actually nicer imho). Also, not such a nice surprise, the outlet of the of valve I received is angled back towards the body of the machine. This makes it unusable in the design and I have to find something else. I am guessing that as the Pavoni Bar 2L is still in production that the straight valves can still be found. In an ideal world however, the valve outlet would angle away from the body so that the assembly can be kept close to the backsplash. The Pavoni actually uses an additional spacer to solve this problem. Any suggestions for something closer to the original from another machine in production would be greatly appreciated. Otherwise, I will just have to sort out a right-angle Pavoni valve I suppose.
I had to install the tap that I received temporarily so that I can go on to other things.
Not right at all, but it will have to do for now.
There were a couple of missteps in the last round of plumbing that I had/wanted to fix. The first had to do with the way that the parts were supported when they were brazed. The intense heat from the oxy-acetylene torch combined with the pressure of the vise caused the brass parts to soften and deform. The result was a complete set of oval compression fittings - sniff.
I made a couple of compression dies from some scrap aluminum to try to salvage the work.
Fairly straight forward to use: drop them into the vise and crush the living *&^#&@#$ out of them.
We will find out if these are round enough when I fill the boiler!
I used North American 1/4" tubing for very first run that I made from the boiler to the manometer. The 1/4" is really close to 6mm, but the fittings, well, don't really fit. I was also not particularly happy with the stack of adaptors on the back of the meter, so I swapped it all out for a new 4mm line with a coil to catch the condensation. The nice thing about the 4mm is that it can be bent easily and without much fear of the wall collapsing. I made the coil by winding the tubing around a cylinder by hand.
Here is the line, with the fittings brazed in place (round ones this time) and ready to be installed.
I also wanted to add a tank drain to the plumbing system. I don't really understand why this isn't a more common feature. The HX setup means that the mineral concentration of the water in the boiler is constantly increasing as pure water is drawn off in the form of steam. On the Aurora, a proper boiler flush can only be done by removing the case and disconnecting the lowest convenient fitting, which is the line to the level gauge. What this actually means in practice is that boiler flushes don't get done nearly as often as they should. I built the stainless boiler as a (nearly) drop-in replacement for the copper original. However, I don't intend to build a level gauge as I think that they are vestigial and appendix-like. This means that the ports can be used for something else - e.g. a drain!
That is an ooooold valve. I'll have to find something a little better eventually.
That, I think, is it for now for the plumbing. Here are a few shots of the finished setup.
Pluuuumbing!
First order of today's business is the line from the inlet to the HX - this one is always open but requires an additional connection to the expansion valve at the sump.
I found that the tubing bender has a tendency to drag the section around the mandrel which screws both the tube and the placement of the bend. In order to get them in exactly the right place, I am using a clamp collar as a stopper. The marks on the tubing are either the start, middle or end of the bend and are aligned with the degree marks on the bender where they will end up when the bend is made; by measuring or simply rolling the straight tube around the mandrel (if that is even sort of clear).
Here it is in the bender.
This creates a bend with a radius of about 2.75", but I need this one to be smaller so I tightened it up with the Alien-critter-tool afterwards. Two more bends added and one to go.
This is a skill that needs a fair amount of practice in order to deliver good (and precise) results. I haven't done this for a while, so the first one took quite a bit of time (and plenty of adjustment). I have lots of admiration for the electrical conduit trade (ever looked at a manual for one of those deceptively simple looking tubing benders they use?). There is no correcting bends in that stuff with your bare hands!
The glands are pulled into axial alignment with the fitting when the nut is tightened, so there can't be too much fudging. Next is the auto-fill for the boiler with the solenoid in the line...
...and the connection from the solenoid to the inlet.
This one was done using 8mm line, which was far easier and more pleasant to work with than the 10mm. Next time, I will use only 8mm 'cause life is too short.
Now the really fun part :)
After cleaning the parts, I put little flux on the joint and a ring of the filler metal...
...and use a reducing flame (less oxygen than gas to avoid oxidizing the metals) to heat up the parts. Once the flux melts completely showing that the parts have reached temperature, the silver filler material flows into the joint perfectly. Mustn't forget to thread both nuts on the line because otherwise you are just starting over.
The next step is to throw everything away and start over. :{(
What I didn't notice while I was happily bending the tube is that the inside die, which is made of plywood, had split and allowed the tube to crumple. The outside of the bend looks great, but the inside was a mess. Likely, the tubing is work-hardening as it bends and needs to be re-annealed a couple more times. Also, the setup would be much stiffer if it were in a proper arbor press with metal dies. Given that the flow rate through this part is tiny, it wouldn't have made a difference but as this proved not to be a viable method for making a bunch of these, I went back to the original plan of hard brazing parts together.
Starting with some heavy-wall 3/4" copper tube. First we heat it up to cherry red to anneal the copper.
You can't see it in this picture, but once it cools, it's the color of eggplant, I swear.
Fill up the the pipe with sand to stop the walls from collapsing during the bend.
Install the big bender in the vise and tighten the vise.....
little...
by little....
Next up, a tiny bit of plumbing, which is pretty much where I stopped on the build itself for want of a bunch of parts and time to work with them.
This was essentially a trial run to figure out the best way to bend the tubing and where to put the pressure gauge. I used North American 1/4" tube which is really close to the 6mm it is supposed to be but waaaaaaaaaaay cheaper because of the absence of the novelty factor. I welded a socket head cap screw onto the frame to act as a stud and then machined some a spacer to get the pressure gauge set back at the correct distance from the plane of the back splash. This is just a temporary measure until I sort out exactly which adapters and gauge will be used - then I'll design a bracket with the appropriate forward/aft offset and up/down & port/starboard tolerances.
I sourced a couple of tools for bending the copper tubing but in the end because some of the radii are super tight, I built a some custom tools that can be dropped into the bench vise.
I was pretty sure these tools would work really well for small diameter tube, but I wanted to try to make the main HX tube the same way to avoid having to hard braze the connections (silver solder ain't exactly cheap...).
Concluding the day's posts: I needed to make a couple of 1" BSPP (G-thread) x 3/4" copper sweat adaptors that will form the ends of the heat exchanger tube and make the seal with the boiler plate. These are necessarily custom parts as this they adapt from European to North American standards. However, I think that is it reasonable to consider the HX tube as a non-serviceable i.e. a custom part.
Lead-free hex stock after threading, chamfering and cut-off operations.
View from the other side showing the 90 degree included-angle internal chamfer that will seat and seal with the hemispherical "bi-cone" fitting.
The part is flipped and bored to receive the 3/4 copper pipe.
Test fit of the pipe.
