Modifying the solenoid valve - Part 2
Alright, its been mostly talk thus far. Good talk, but talk. Its now time to get down to business and do some of this work we've been talking about. So, lets get to modding the solenoid valve!
Here we have the valve body. The hole in the center is 2.5mm in diameter, and we need to make it .9mm in diameter.
To do this, we are going to use this handy 3/32" rod. 3/32" is 2.38mm, so it fits very nicely into the 2.5mm hole with not much slop at all.
I stuck the rod in the valve body, and made a mark so I could cut it off to the correct length.
Test fit, it sticks up just a little bit. This is perfect as I'll sand it to bring it down to the correct height.
Next up, time to drill the .9mm hole in it. For this and the jets (I'll get to those later), you will need a micro drill bit set. Below is the one I used. It was $13 on amazon.
First step, center punch the brass rod to help center the drill.
Next, I started drilling by hand. This went really slow, so I set it up in my drill press. You need to be VERY careful dealing with these small drill bits. They break extremely easily.
Now, the drill bits aren't that long. So, I notched out the brass rod with a dremel to intersect the drilled hole.
With the opening made in the rod, I sanded the rod down to the correct length. I made it close to flush with the old sealing surface.
Next, I sanded a chamfer on the brass rod. This will reduce the sealing area, and increase the pressure rating of the valve a bit more. Really, I should have calculated things with the sealing area, not the orifice diameter. I don't think it'll be a problem, but that is the more correct way to go.
Now, we don't want the valve's sealing surface to get the the way. So, time to grind it off. I actually went a bit farther and put a tiny bit of divot into the valve. The next step is soldering things, the divot will help hold the solder and keep solder out of the .9mm hole.
Alright, we're to the last step of the solenoid modification, soldering up the brass tube into the valve body. To do this, I used normal electrical solder, and also plumbing flux like you use for sweating copper pipes. This may seem like a weak material choice, but it will work fine. The brass rod is taking the load that is pushing down on it because it sits all the way down into the valve body. The solder is just holding it in place sideways and sealing the tiny bit of space around the rod between it and the valve body. Here is the stuff I used.
I used the flux from this kit.
I was going to use the plumbing solder until I looked at the diameter of the solder... The plumbing solder was just too large to use on the tiny solenoid valve. I was concerned with getting solder inside the .9mm hole.
I also used map gas. I would recommend propane, but I didn't have any. Map burns a decent amount hotter, and honestly too warm for this. So, I just had to be a little careful getting things too hot.
To prepare the parts for soldering, I did sand down the rod, and also took a tiny dremel bit to the inside of the valve body hole. This should make the joint a bit stronger. Then I coated the rod in flux, and stuck it in the valve body.
The actual soldering process is really easy. Just warm up the part for a while, take the flame away, and touch the solder to the joint. If it melts and sucks into the gap, its warm enough. If it doesn't, it needs more heat. I did have to be careful not to get too much solder in the joint. I didn't want to plug up the hole.
This is the end result right after soldering. Looks pretty messy. I think I got the parts too warm with the map gas torch. If you get things too warm, the flux doesn't work as well and can burn and not do its job well. Flux's job is to keep the solder joint clean as the solder flows and bonds the metals together. In any case, I will have to pressure test the joint to be sure it seals up well.
And, here is one picture after I took a brass wire brush to it to clean things up a bit.
This wasn't a ton of work to do. But, with things being SO small, it is tedious. However, this is also the most difficult part of the build. So, if that is the worst of it, its really not that bad.
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