Why is a Conshelf so reliable long term?

[halocline]

I was wondering if the Conshelf is so good then why no one is making(copying) them? Surely the manufacturers in Republic of China should have known about it.

In a sense, most balanced diaphragm 1sts and downstream 2nds are 'copies' of the conshelf design, just in the way that most balanced piston 1sts and barrel poppet 2nds are 'copies' of the MK5/109. These designs have been enormously influential in today's regulators, including atomic and apeks.

There are plenty of excellent, high performing modern regulators. There's nothing magic about old regulators, it's just that a few of the old classics have lasted for decades and are still proven workhorses. IMO the main way regs have actually gotten worse is the use of more plastic and 2nd stage designs that are more about test machine numbers than comfort while diving. Another thing is that it's much easier to self-service the old regs. Parts are available everywhere and there aren't that many to replace. And the regs are inexpensive to buy. A fully metal 2nd stage made today would be very expensive and considered too heavy to sell in the dive shop. Of course, since you're underwater and it's filled with air when you're using it, the weight doesn't really matter, but that's way too much for a dive shop salesman to have to explain.

I am not the conshelf nut that some others on this thread are. I own one but will likely never use the first stage for back gas due to the hose routing and the fact that I have a drawer full of MK5s and MK10s. I paid anywhere between $30-$50 for those 1st stages, and I have several nice old SP 2nd stages that I paid between $20-75 for. I can rebuild them for a very low cost. I enjoy diving with them and I know they're extremely reliable.

 

[rhwestfall]

perfect example is the 109/156 -> G250 series that then had to be "better" still, and the abysmal G250HP was produced. Not a bad regulator per say, but it only added complexity with very minimal improvement.... If you notice, they then re-introduced the G250 as the G250v....

Then decided to scrap it all in the name of sales and introduced the G260 (different internals so the longevity won't bite them....)

I get that it is much cheaper to produce resin bodied molded stages and can live with that (though I have stashed away many pristine 109/156 seconds for prosperity) and dive modern and vintage stages that at least use the same guts. Simple to keep going...

 

[H20doctor]

i was certified for scuba in 2000 here in puget sound , and I bought my scuba gear at a garage sale for $100.00 and in that Purchase was a full set of us diver Regs.. Conshelfs .. the 1st stage is the SE2 .. I still today Dive these same regs , they have been to many Dive places, and adventures.. i have put 2500 + dives on them , and they still perform like the day I got them.. I service them , take care of them , and they have never Failed me ... No free flows , No Issues , Nothing ... They work , they breath , and they are truly the best regs I have ever used and I will only use till the day I die ..
I found this thread today and just wanted to share My love of US diver Regs

 

[iain/hsm]

I was wondering if the Conshelf is so good then why no one is making(copying) them? Surely the manufacturers in Republic of China should have known about it.

Thank you for the offer but I love my Apeks.
The seats in both Apeks 1st and 2nd stages are the weakest link in the whole set up. There must be some reasons for choosing inferior material!! The dealers have to earn some money every now and then!

The Conshelf is good for one reason only, the engineering that designed it.
And the reason no one is making a copy in China is that engineers involved back then were a more principled group and would never dream of disclosing US Divers intellectual paid for property to the Chinese.

Attempts at copy were made but more the style and shape than the mechanical mechanism.
Back then it was Japan not China,

By example the Kawasaki X2 second stage was styled after the Conshelf with the 1st stage internals after the US Divers Deepstar.

This nearest “copy” if thats the correct term was manufactured in Japan by Nihon Aqualung who were part of the Aqualung group of companies of which US Divers were part.

Most copy regulators today are from Taiwan, one company in particular how they get to show there face at DEMA is a mystery. Made for profit at the lowest common denominator, Frankly if the polymers shore hardness and mechanical drawings were ever emailed to Taiwan I doubt they would copy it as they would always find a reason to use cheaper materials and sloppier machine clearances.

Apeks is another story a company that benefited from what is called “gifted” designs again you can see the point at which from a military manufacture contract they were “gifted” with the mechanical component drawings to manufacture, resulting in to date the same product with little change with the internals with only the superfluous shape style and fashion requirements to jack the pricing being the only real development.
That, and a range of neoprene hot pants, watches baseball caps and tee shirts I guess for the Guru’s.

As for your observation as to the inferior Apeks seat material It will be interesting to note if Apeks are once again "gifted" with a solution, or if there hapless attempt to jack up dealers profits by not suppling spare parts to divers will continue.

 

[iain/hsm]

cost to manufacture an all metal 2nd stage is my guess

Interestingly at the time the cost to manufacture the plastic second stage was more than the metal.

The tooling cost for the plastic I can’t remember but it was huge when compared to the metal box top tool for the XIV then from memory was $10,000 The purge button wasn’t much and spring, cents.
But pre plating polishing of the box top was long and labour intensive

The box bottom was even more, in three individual brass stampings. Parts had to be soldered together with the mouthpiece tube, exhaust housing, flow deflector and inlet port each having to be silver soldered together before treating and plating the assembly.

Back then if you were making a regulator a metal 2nd stage was cheaper in production tooling but heavy in manpower assembly and process. More so making one today.

By comparison today plastic injection tooling although more expensive are manufactured direct for assembly, so work better for the higher >1000 production run rate components.
The old metal production runs were in in hundreds, or less and when compared to plastic parts made in 1000,s much more expensive in material cost, manufacture cost in man-hours, production cost and in the various process procedure,

For a metal stamping the IPP was something like this:
Stamp - clip - inspect - polish - inspect - solder - inspect - final polish - inspect - copper plate - inspect - chrome plate - inspect - assemble - test. With rework added into the IPP process

For plastic it’s simply: Mould - inspect - assemble - test. With no re work.

 

[Centrals]

Republic of China = Taiwan

Apeks spare parts, not just the service kits, were readily available before the company was taken over by Aqualung. If its HPseat is made from tougher material, I believe its 1st stage will last many yrs without requiring any service. What a pity(from a consumer point of view)!

 

[iain/hsm]

How about the 1st stage?
I don't believe the plastic casing of the 2nd stage would have any effect on the performance.

And yet it did, and for many reasons.

The early plastic material was hygroscopic and deflected, the glue used to locate the 2nd stage LP tube carrier off gassed toxic fumes. the metal insert discussed earlier was needed for strength, The 2nd stage exhaust deflector support being plastic was wider than the metal and impeded the exhalation WOB. The plastic purge button would twist and catch against the box top being plastic on plastic than plastic on metal. Heat exchange on the plastic was inferior then on the metal units, WOB increased by reducing the exhaust portage.

The open front box top was a hazard for working divers in black water, compared to the side ports on the metal box top. Although the bigger holes in the plastic top aded diaphragm response and reaction time, the early diaphragm was so stiff and thick hysteresis and overshoot was a measured problem.
The Delrin “tip” dome on the end of the tilt lever improved performance from the older metal on metal side slide by reducing contact area and friction.

I trust thats enough for now to convince you otherwise

 

[iain/hsm]

Republic of China = Taiwan

Apeks spare parts, not just the service kits, were readily available before the company was taken over by Aqualung. If its HPseat is made from tougher material, I believe its 1st stage will last many yrs without requiring any service. What a pity(from a consumer point of view)!

Sales and marketing aside there are problems to manufacturers allowing the great unwashed to muck about inside products.

Health and safety, life support equipment is the standard “claim” quoted against pubic supply but the real reason is to enable profit to your small dealers at no or little expense to the manufacturer.
The “value added” is that most small dive retailers make more profit servicing a regulator than selling.
Due to at present the top 8 warehouse discount online retailers sell more product than all of the small independent local dive shops combined.

Now as to the HP seat if you make the seat harder/tougher you need to make the contact area where the HP metal seats meets the polymer seal sharper to effect a seal.
If you indeed do make it sharper it improves performance granted but indents into the polymer and reduces seal life. If you then reduce the spring load tension to lessen the polymer indenting you then loose performance and the valve is sluggish and overshoots.

Conversely if you increase spring tension you need to compensate by increasing the contact area of the poppet to reduce indenting permanent set”
If you reduce spring tension for a better performance you need a sharper contact area to effect a good seal and you back to the beginning.

I guess the reason why engineers should design regulators for diving and not divers.
Just a pity when they do and finish a design diving companies find no reason to retain there hire.

 

[oldschoolto]

Fit and finishing of any production part will have a profound impact on the useful life.. Using the highest grade material available will also impact its life...

We make stuff today as cheap as we can get away with.. Think of going into a junk pile and finding a chrome bumper on a 1950's car that still intact... And then see a new car with chromed plastic flaking off after a few months...

I have a friend that is working on rebuilding the F-1 rocket ... He said.. They got it so right the first time... With pencils and slide rules... And now here we are trying to screw it up.. Just can't beat old school engineering...

Jim...

 

[Nemrod]

Apparently you have not seen the videos where they crash new cars into old cars. N