Back when I was deciding on whether to buy a lathe or not, I made a list of things I would be able to make on it. When it had grown long enough, I bought it. Well, in all honesty, I probably bought it because the tinkerer in me wanted it...
But high up on that list was a pressure gauge. Now, you don't actually make the gauge but only the adapter so it is not really that advanced;-)
I had two main goals with this; it had to be smaller and lighter than the one I have from Omer and there had to be minimal air loss when taking readings.
I could have just made a quick sketch on paper but I also wanted to get a bit more time in on Fusion360, a free CAD software, and in swank renderings the adapter came out like this:
The machining itself was pretty simple, definitely aided by the fact that I went with aluminum. Brass wasn't really an option as I wanted it to be light and I am waiting for a sturdier tool post before I take on titanium again. I didn't take any pics during the machining but the only real obstacle was to hold the part in the chuck without messing up the thread or the knurl. (I had to thread and bore both ends so the part had to be swapped around in the chuck). I solved it by making a split bushing. Delrin is actually too smooth for this but I didn't want to scratch the part and it worked out:
Here's the gauge on my Mirage 93:
And by itself:
The gauge itself is a 40mm dial size, it's liquid-filled and quite sturdy. I paid 3 euros for it and it's the same as I used on my scuba filling adapter where it has held up nicely.
To reach the goal of having no substantial air loss I needed an adjustable pin. I made one from an M5 titanium bolt though the machining on that one could be better and I might make a few more. The through-hole is Ø1.5mm:
The gauge has a male straight G1/8 thread with a little 4mm stub on it. I measured it and figured I could just about use it to hold an o-ring (I bored out a corresponding o-ring seat in the adapter). I do think it is designed for a sealing type of washer, though:
Now, as for the results.
Well, first of all, it holds air when it takes a reading;-). And the o-ring on the gauge itself even works, so no need for plumbers tape nor silicone caulking.
The adjustable pin works well, too and I can tune it so I loose no air when taking readings. Well, of course, I loose the air that is in the adapter and gauge but that is not much. So little in fact, I can't tell that I lost any on subsequent readings. An added bonus with the small bore of the pin, and I guess the fact that the bore sits right on top of the ball in the valve, is that the air comes into the gauge very gently. It doesn't have a practical say, but it just feels really nice. No sudden swooshes or pops.
The adapter itself weighs 11g:
The assembled pressure gauge is 100g on the dot:
This is less than half of Omer's version (208g) is and I even turned down the brass adapter on that one a while back:
For size, the comparison looks like this:
So, I guess I managed to hit both of my goals (no real air loss and making it lighter and smaller). The pressure gauge itself is actually heavy and surprisingly sturdy for such a small one, so I could probably trim it by another 1/3 by going with one without glycerin and one that has thinner walls.
Here's the drawing I went by:
I do think I will make a titanium version in the future - just so I won't have any corrosion issues. Or as an alternative, try to get my hands on some marine grade aluminum.
But high up on that list was a pressure gauge. Now, you don't actually make the gauge but only the adapter so it is not really that advanced;-)
I had two main goals with this; it had to be smaller and lighter than the one I have from Omer and there had to be minimal air loss when taking readings.
I could have just made a quick sketch on paper but I also wanted to get a bit more time in on Fusion360, a free CAD software, and in swank renderings the adapter came out like this:
The machining itself was pretty simple, definitely aided by the fact that I went with aluminum. Brass wasn't really an option as I wanted it to be light and I am waiting for a sturdier tool post before I take on titanium again. I didn't take any pics during the machining but the only real obstacle was to hold the part in the chuck without messing up the thread or the knurl. (I had to thread and bore both ends so the part had to be swapped around in the chuck). I solved it by making a split bushing. Delrin is actually too smooth for this but I didn't want to scratch the part and it worked out:
Here's the gauge on my Mirage 93:
And by itself:
The gauge itself is a 40mm dial size, it's liquid-filled and quite sturdy. I paid 3 euros for it and it's the same as I used on my scuba filling adapter where it has held up nicely.
To reach the goal of having no substantial air loss I needed an adjustable pin. I made one from an M5 titanium bolt though the machining on that one could be better and I might make a few more. The through-hole is Ø1.5mm:
The gauge has a male straight G1/8 thread with a little 4mm stub on it. I measured it and figured I could just about use it to hold an o-ring (I bored out a corresponding o-ring seat in the adapter). I do think it is designed for a sealing type of washer, though:
Now, as for the results.
Well, first of all, it holds air when it takes a reading;-). And the o-ring on the gauge itself even works, so no need for plumbers tape nor silicone caulking.
The adjustable pin works well, too and I can tune it so I loose no air when taking readings. Well, of course, I loose the air that is in the adapter and gauge but that is not much. So little in fact, I can't tell that I lost any on subsequent readings. An added bonus with the small bore of the pin, and I guess the fact that the bore sits right on top of the ball in the valve, is that the air comes into the gauge very gently. It doesn't have a practical say, but it just feels really nice. No sudden swooshes or pops.
The adapter itself weighs 11g:
The assembled pressure gauge is 100g on the dot:
This is less than half of Omer's version (208g) is and I even turned down the brass adapter on that one a while back:
For size, the comparison looks like this:
So, I guess I managed to hit both of my goals (no real air loss and making it lighter and smaller). The pressure gauge itself is actually heavy and surprisingly sturdy for such a small one, so I could probably trim it by another 1/3 by going with one without glycerin and one that has thinner walls.
Here's the drawing I went by:
I do think I will make a titanium version in the future - just so I won't have any corrosion issues. Or as an alternative, try to get my hands on some marine grade aluminum.
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