D420! How about that?

[buddhasummer]

Here's a pic of the D420 without the top decal. The decal is fairly heavy foil, and will come off without bending, if you're judicious. So it could easily be reused. A half-inch hole would expose the hex. A smaller one would allow just the key to fit in, but would serve as a water collection point in the recess for that screw. It's not too ugly without any decal at all.
View attachment 558468

Thanks a bunch Rob, appreciated. Agree, it looks just fine without the decal. Might look for a suitable hole punch.

 

[Angelo Farina]

Thanks a bunch Rob, appreciated. Agree, it looks just fine without the decal. Might look for a suitable hole punch.

A KNOB, not just a hole punch...

 

[lexvil]

A KNOB, not just a hole punch...

It has that with the outer ring I think, adding a knob, I sort of like the idea, would be more like a double knob on an “s” or G260 with the fine tune in the center of the existing knob.

 

[Couv]

What about a mod with a knob permanently fitted in the hex hole, so the diver can adjust the cracking pressure while diving, as in my favourite 109/156 second stages?

@rsingler See, I told you AF was a genius. With the mod @Angelo Farina suggest, that would almost bring this new newfangled plastic toy into realm of serious regulators.

 

[Angelo Farina]

@rsingler See, I told you AF was a genius. With the mod @Angelo Farina suggest, that would almost bring this new newfangled plastic toy into realm of serious regulators.

Well, it could not be the first time I give a good suggestion to SP.
In 1977 I modified my 109, adding a low-friction plastic covering to the metal disc which, at the time, was embedded in the diaphragm and over which the lever was acting. This of course reduced friction.
After testing it successfully in water, I did write to SP Italy, sending them a sample of the modified diaphragm.
6 months later, SP changed their production with a new silicon diaphragm with plastic disc.
Of course I do not know if they did take the idea from me, or someone else had already thought at this mod....

 

[rsingler]

A KNOB, not just a hole punch...

Great suggestion. Just keep in mind, the ENTIRE range of adjustment is 3/4 turn.
How many divers even have a clue?

I'll tell you one thing that is SO COOL about adjusting a center-balanced poppet: it doesn't change lever height!
You know how adjusting the orifice in a G250/S600/A700/"barrel anything" drops the lever? More than one beachfront "freeflow fix" by a helpful diver has reduced flow from that reg to dangerously low levels, because they didn't understand the consequence of advancing the orifice.
Well, the D-series doesn't have that problem. Increasing spring pressure on a center-balanced poppet just increases the spring pressure. And once the hex screw inside the case has been adjusted to set the lever properly for that individual poppet, you never have to touch it again. We'll look at that in the next video.
I am SO HAPPY Scubapro has brought this reg back into service!

 

[rsingler]

that would almost bring this new newfangled plastic toy into realm of serious regulators.

You just went on the naughty list for next year, @couv .

 

[Angelo Farina]

I'll tell you one thing that is SO COOL about adjusting a center-balanced poppet: it doesn't change lever height!
You know how adjusting the orifice in a G250/S600/A700/"barrel anything" drops the lever? More than one beachfront "freeflow fix" by a helpful diver has reduced flow from that reg to dangerously low levels, because they didn't understand the consequence of advancing the orifice.

Well, in my 109/156 what you describe happens if you act on the position of the orifice, by unscrewing the hose and screwing-in the orifice with a flat-blade screwdriver.
Acting on the knob, instead, just changes the compression of the spring, but the lever does not move significantly.
If you screw the knob entirely in, pushing the poppet hard against the orifice, so that the seat is significantly marked by the orifice, than the lever could move very slightly, but in the opposite direction as when you screw-in the orifice.
I suppose the same effect can also happen with the D420. Oh, well, it cannot happen, as the maximum rotation of the spring loading mechanism is just less than one turn...

 

[rsingler]

I suppose the same effect can also happen with the D420. Oh, well, it cannot happen, as the maximum rotation of the spring loading mechanism is just less than one turn...

@Angelo Farina , that's the cool thing about the D-series. If you screw in the poppet spring screw on top as tight as you can, it doesn't affect the lever at all! The lever is controlled by the hex screw in the base of the housing, and is left a little loose deliberately. That prevents the lever from triggering the valve before the diaphragm is activated by inhalation. In the closed position, the poppet sits against the knife edge of the orifice housing (part #18 in schematic above), and there is no lever contact.
That is why the lever is individual-poppet-dependent. In each poppet assembly, part #17 is attached just a tiny bit differently with each poppet. If one is a little long, then the previous hex screw position will be too high, and the poppet won't seal, but will be lifted off the knife edge because it's in contact with the lever already.
But when adjusting this regulator's cracking effort, there's nothing to do but twist the hex screw and read the magnehelic/IP gauges. So easy! Even a dive shop tech can do it!

 

[tridacna]

I want one so bad but not so bad that I want another Mk25...c'mon Scubapro