1st stage recommendations (Aqualung Calypso Series ???)

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kassj0peja

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# of dives
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Me and friend (who has Scubapro tools) tried to fix my Scubapro MK25 (it was broken when it came back from the annually service) and I think I broke it even more.

So now I am looking for a 1st stage that I can open with usual tools (not like the one you need for the MK25 for example) and fix by myself. It also should be easy to repair/service. I don't need anything special. It should be robust and not too heavy. Just for diving in warm water.

Are there some that you can recommend?

Thanks.
 
A couple of questions,... What is "broken" on the MK25? What is it doing? Why did you not send it back to the shop to set it right, or find another that could service it properly? There are only 2 specialized tools I can think of that are a "must" for the MK25. 1 is a stem O-ring insertion tool that holds the stem O-ring & plastic rings in place for insertion & reverses to help hold the stem O-ring & plastic rings in the regualtor body, as the piston is inserted & the other is a brass "bullet" that slides down into the piston to prevent tearing the stem O-ring when the piston is pushed through. Most everything else can be dones with ordinary tools. The ScubaPro multitool can be used on most parts of the regulator, but other tools will also work. Tools I can think of atthis time are: 12" Cresent wrench, a regulator holder that can be screwed into both high & low pressure ports, a spanner wrench to seperate the top & bottom of the regulator, proper sized allen wrenches for the IP adjustment & remove the high & low pressure port plugs & another allen wrench to take apart the rotating bottom part. A small wooden dowell rod is nice for getting the stem O-ring & plastic rings out of the regulator, a pick to help remove O-rings, a small, thin flat bladed screw driver can help sometimes also, the stem O-ring instertion tool, the "bullet" & 9/16" & 5/8" wrenches for hose removal. Now this does not go into testing equipment, just the general tools for servicing. It might help to also find someone who is familiar with servicing that regulator to help guide you. It's not the toughest regulator to service, but it is not the easiest either.

As for the Calypso 1st stage, it is an ordinary unbalanced first stage. Pretty simple to work on (as long as you can get the HP seat out). Most unbalanced regulators are work horses, but generally don't have the Work of breathing ease that the balanced regulators have.
 
Any flow-by piston.....Scubapro MK2, Mares R2, Oceanic SP4, AquaLung Calypso.......is a simple reg to service but they do require a pin spanner to remove the end cap.
The US Divers Conshelf, SEA, Cousteau and Mares MR12, 16 and 22 don't require the pin spanner, are balanced diaphragm designs and are simple to service with normal shop tools.

Pretty much all regs are simple to service.
Maybe getting some education would be the best route.....the two books that everyone is going to recommend would be a good start.
 
..................................................As for the Calypso 1st stage, it is an ordinary unbalanced first stage. Pretty simple to work on (as long as you can get the HP seat out). Most unbalanced regulators are work horses, but generally don't have the Work of breathing ease that the balanced regulators have.

All are solid regs but as long as the first stage is connected to a balalanced or for that matter a user controlled second stage (ie SP-109) they will do as good a job as the best first stage sold. 99% of the preformance of a reg is in the second stage, the first stage has little to no effect on WOB when paired with a good second stage. These regs are usually paired with low end seconds which is the reason they do not have as good a WOB as their more expensive counterparts, pair it with a good second and you can't tell the difference.

Any flow-by piston.....Scubapro MK2, Mares R2, Oceanic SP4, AquaLung Calypso.......is a simple reg to service but they do require a pin spanner to remove the end cap.
The US Divers Conshelf, SEA, Cousteau and Mares MR12, 16 and 22 don't require the pin spanner, are balanced diaphragm designs and are simple to service with normal shop tools.

Pretty much all regs are simple to service.
Maybe getting some education would be the best route.....the two books that everyone is going to recommend would be a good start.

I agree. The one special tool that you would want to consider for the Conshelf, (old style) Titan and MR-12 would be an assembly tool for the first stage. It can be done without one but it's a huge pain to do so. Apeks or any of it's clones would also be a good choice.
 
These regs are usually paired with low end seconds which is the reason they do not have as good a WOB as their more expensive counterparts, pair it with a good second and you can't tell the difference.

I most certainly can tell the difference. When under a heavy work load, the unbalanced regulators can not keep up. Even under minimal workload, at depth, breathing normally, I have overbreathed the unbalanced regulators easily. The balanced ones I have yet to be able to overbreathe. I have had both unbalanced & balanced,.... the unbalanced regulators can not hold a candle to a balanced one.
 
I most certainly can tell the difference. When under a heavy work load, the unbalanced regulators can not keep up. Even under minimal workload, at depth, breathing normally, I have overbreathed the unbalanced regulators easily. The balanced ones I have yet to be able to overbreathe. I have had both unbalanced & balanced,.... the unbalanced regulators can not hold a candle to a balanced one.

What happens is that lower performing 1st stages experience a greater IP drop during hard inhalation, especially at depth, than higher performing 1st stages. This isn't directly related to whether or not the stage is balanced, although there is some connection as unbalanced pistons are limited in the size of the orifice.

The big thing though, is if the lower performing unbalanced 1st is paired with a lower performing unbalanced 2nd, you really feel the IP drop. For example, if you took a R190 (or similar) 2nd stage, and tested a MK2 (surprisingly good performing, but unbalanced) vs a MK25 (mega-flow rate) and breathed really hard at some depth, you'd tell a big difference. But if you did the same test with a very high performing 2nd, say a D400 or G250, you'd notice far less difference between the MK2 and MK25. I've tried this, it really is surprising.


Anyhow, getting back to the OP, I have to agree that you should have returned to the shop where the problem occurred. And actually, I find the MK25 a pretty easy 1st stage to work on, and you don't really need the bushing install tool or the bullet. (But they do make the job quicker and easier.) A MK2 would certainly fit your bill, but so would a MK5 or 10 and the tools are very similar. You do need the bullet tool for those; they have a sharp edge piston. Rebuild parts for the MK5/10 are easily available, at vintage double hose for one place.

Whatever you get, I think your best and first purchase should be the Vance Harlow book on regulator repair. That's an excellent source of information.
 

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