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Scubapro MK20 upgrade to MK25

Discussion in 'Regulators' started by dave22387, Apr 11, 2019.

  1. abnfrog

    abnfrog Tech Instructor

    # of Dives: 2,500 - 4,999
    Location: great white north
    upgrade downgrade its all BS plastic was cheaper to make .....that's why they switched for gods sake !!!!
  2. Pavao

    Pavao Manta Ray

    To make it more expensive to make the regs, since they have been using metal for some years now?
    See my point about the ones using titanium barrel, or have I misunderstood your point?
  3. lexvil

    lexvil Loggerhead Turtle

    # of Dives: 1,000 - 2,499
    Location: jamestown, ca.
    I would like to point out that there is an ignore feature on this website, it’s wonderful.
  4. couv

    couv Instructor, Scuba

    # of Dives: 1,000 - 2,499
    Location: 13th floor of the Ivory Tower

    OK back to civility now. Please elaborate on this point. I've heard the same from an engineer friend; but rather than miss-quote him or worse, get it wrong, I'd like to hear a little more detail.

    Thank you,

  5. rsingler

    rsingler Scuba Instructor, Tinkerer in Brass Staff Member ScubaBoard Sponsor

    # of Dives: 500 - 999
    Location: Napa, California
    Interestingly, I decided to look back into this issue, since the statement above was contested.
    The short answer is yes and no. @jchance is right, and @Pavao is right.
    While the Mk25 schematics show a .219 shim between the spring and the reg body, when the composite piston was first introduced for the Mk20 at the time of the Mk25 release, Service Bulletin #272 for converting a Mk20 to a Mk25 states on page 2, "Note that when installing these kits, no shims (01.060.219 or 01.060.220) should be used."

    Most techs would say that putting a shim on top of the piston decreases rust deposition from the spring deep in the body, but it's not wrong to leave it out, per Scubapro above. If you're having trouble getting a low enough IP, that's the first place I'd start. I've even put a spring on a low speed belt sander (to avoid changing metal temper) and taken 0.2mm off one end with good results. All on the DIY side, of course. SP would never endorse that move.

    Attached Files:

    jchance, couv and rhwestfall like this.
  6. jchance

    jchance Nassau Grouper

    # of Dives: 5,000 - ∞
    Location: Tennessee
    Thanks rsingler. Opinions are like (left unsaid) but everyone has one. That said, I usually put just the thin one in to serve somewhat like a washer (as shown in some of the newer schematics) unless I have a problem getting the pressures I want but that is just a personal preference not endorsed by Scubapro.

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