For D-series lovers!

[rsingler]

Well, the stuff arrived today!

You know all the trouble we have getting (even brand new) Scubapro D-400 seats to tune smoothly? You think you have it, then you rotate the spring just a little, and it's leaking? Or you've got it, and then the next day, there's just a slight freeflow?

Under the microscope, the Scubapro seats have been made from a variety of materials. But they all share one thing in common: they're just the least bit uneven on the surface. We've had advice to ultrasound it for ten minutes before installing, etc., etc.

I'm going to try and one-up Scubapro. I've just ordered/received Silicone and EPDM sheet in Shore 40, 50, 60 and 70.

Here is my first hand punched seat:

20180104_174619

• rsingler
• Jan 4, 2018

,
with the stock seat just to the right.
It's smooth, it's flat, it's soft...and I'll let you know.

I'm looking for a consistent light seal at 0.5" cracking effort, with stability over time. Yeah, I'm no manufacturer, but the darned seats are the one inconsistency in this reg (after you learn how to get the cover off, and replace the dive switch o-ring, lol!). I'll try to make some videos on those two issues. Meanwhile...

The D-400: the almost-best damned second stage in the world!

 

[Umuntu]

Here is my first hand punched seat:

20180104_174619

• rsingler
• Jan 4, 2018

,
with the stock seat just to the right.
It's smooth, it's flat, it's soft...and I'll let you know.

A Perfect donut ! What are you using to punch it out ?

 

[johnnywulff]

I will like to try it looks great!
Cheers

 

[Couv]

I'm looking forward to your updates.

 

[rsingler]

A Perfect donut ! What are you using to punch it out ?

Two McMaster-Carr round punches were used. McM has washer punch sets that do both, perfectly centered, but the diameter of the seat was an odd 11/32", which didn't come in any set. So with a modest failure rate from not eyeballing it correctly, I punched the outer first, and then the inner hole.

All that said, the soft seat at 11/32" comes out a tad fat when punched, as the material undergoes some instantaneous compression.

So I'm going to experiment with using a smaller OD (5/16"), which may be compatible with one of the washer sets.

More to follow.

First issue is that air tracks down the center post of the poppet, hence the need for the tiny o-ring under the cap. But that o-ring doesn't seal consistently against 40 Shore material. We'll see how it works with harder seat material. The Scubapro seat has a bonded metal insert which ensures a seal against that o-ring. I've glued a flat washer backing to mimic the bonded insert, but I can tell that this is going to be a long process.

It's turning out to not just be a matter of finding a better seat material.

I'll post photos in the next week or so.

 

[buddhasummer]

I've got my pom poms out....

 

[buddhasummer]

My arms are tired and I've lost my voice, hows it going Rob?

 

[rsingler]

Making slow progress, but I think I'm on the right track. Pics soon.
Too soft, and the seat pops out of the white cap from air flow around the edges.
At 70 duro, I'm getting a consistent 0.4-0.5" cracking effort. Hooray!

But I can't get the cracking effort above 1"!
I suppose that's a good thing with the D's, but theoretically it's bothering me.

I have to try Shore 90 before I come to any conclusions. I never would have thought the seat should even be as hard as Shore 70 with that light spring. So I may be missing something.

With a little more data, I'll post what I've found and let the SB collective brain work.

 

[buddhasummer]

Don't let it bother you, not being able to achieve a high cracking effort bothers me not. Ok, I'm rested, back out with the Pom poms, "Go Rob, Go Rob..." Good luck.

 

[northernone]

Second line also cheering from the peanut gallery!