Venturing into DIY with an MK-5

[parzdiver]

Well, I am venturing into DIY. In the short term it is costing me a bit, but I'm thinking long term it will be a good thing.

I picked up a Scubapro MK-5 extremely cheap, essentially off a junk table. Based on the ScubaPro regulator museum site, it is the MK 5 SPEC (1981-1985). The reg has a stamp on the yoke, so I think it might have been a rental at some point. Most of the ports were open when I got it. It does look like the regulator was well used and there are tool marks on the yoke retainer. Looks like someone took an inappropriate tool to it.

I ordered and received today Regulator Savvy, the ScubaPro Multitool from Scuba Tools. I also got the exploded schematic for the reg from a friend (Thanks H). I am still looking for a small torque wrench (Lowes only had big ones in Ft-lbs). Not putting anything tightly together until I have that. I was about to use the ScubaPro tool to open the regulator. There is a little corrosion inside, but nothing significant.

The only part I am concerned about is that it seems to have the original brass Swivel Retainer. From other threads it seems difficult to find a stainless steel replacement. Otherwise, I think a cleaning and some new o-rings and I have a great regulator on my hands!

 

[parzdiver]

Here are some pictures:

 

[herman]

the one other tool that is a good idea with that reg is a "bullet" tool. Basically, it's a dowel with one end turned down to just fit inside the piston with the body the same diameter as the piston stem and the other end tapered some. You use it to guide the piston stem through the stem O-ring to keep from knicking it. You can get away most of the time without it but it helps. You can make one out of plastic, wood or pretty much anything else you can machine to the correct diameters.

 

[parzdiver]

the one other tool that is a good idea with that reg is a "bullet" tool. Basically, it's a dowel with one end turned down to just fit inside the piston with the body the same diameter as the piston stem and the other end tapered some. You use it to guide the piston stem through the stem O-ring to keep from knicking it. You can get away most of the time without it but it helps. You can make one out of plastic, wood or pretty much anything else you can machine to the correct diameters.

Thanks - I figure that is one of the things I need. I was told a plastic straw would do in a pinch. I already had my Scuba Tools order placed and then realized there were 2 or 3 or 100 other things I *should* have gotten.

 

[herman]

Got a new lathe coming and I need an excuse to play with it, maybe I will turn out a few next week.

 

[redacted]

I have at least a half dozen Mk5s, with 3 currently in service. I also have a few spare swivel retainers and all appear to be chrome plated brass. While SS swivel retainers would be nice, close inspection and light torquing seems to be working fine for me.

 

[halocline]

My favorite first stage. One tool that is extremely useful for these is the scubatools double hook o-ring pick. It's shaped just right for removing the old HP o-ring without scratching the seating groove. A piston bullet is necessary, I don't think a plastic straw will do the job. If I needed one today, I'd go get a set of round wooden chopsticks and try to do something with one of those. If it's the right diameter, you could cut it, then try to carve a little cut out on one end to fit inside the piston. The other end should have a taper; the round chopsticks usually do.

Another very useful tool IMO is a jeweler's loupe or powerful magnifying glass. You can inspect the piston edge for tiny imperfections, and it is possible to clean those up. It's a delicate job due to the knife edge, but I have done it and ended up with zero creep. Another good use for the loupe is to very closely inspect the threads on the turret retainer. Unless it's been severely over torqued, it should be okay.

There's a reason the MK5 is among the most copied 1st stage designs in history. Find yourself a 109, convert it to balanced/adjustable, and you'll have a true classic combination.

 

[Zung]

You can make a dozen o-ring picks yourself for a couple of bucks.

But if you decide to place another order, I'd second halocline and suggest you get the bullet tool, maybe even the o-ring tool: me, even after 3-4 (successful) attempts, I'm still not comfy with that o-ring.

You can find cheap torque wrenches almost everywhere; you can calibrate them yourself.

 

[parzdiver]

Thanks to everyone. I was told I would be able to find great support on the board. I'll be hunting for the R109's to complete the set.

 

[redacted]

You can make a dozen o-ring picks yourself for a couple of bucks.

But if you decide to place another order, I'd second halocline and suggest you get the bullet tool, maybe even the o-ring tool: me, even after 3-4 (successful) attempts, I'm still not comfy with that o-ring.

You can find cheap torque wrenches almost everywhere; you can calibrate them yourself.

Good looking picks but not the right shape for that HP o-ring. This "double hook" model that Matt referred to is the only one I use on the HP o-ring and works on most other o-ring also. O'ring Pick, Double Hook, Plastic Handle. I keep one in my service tool box and one in my save-a-dive kit. I dull the sharp point and add a little more bend to it to make it easier to hook that HP o-ring.

Some folks use a straight pointed pick to stab and lift that o-ring to dislodge it. I guess that might work OK as long as you work from the ambient pressure side where you should not be able to damage any sealing surfaces, but I would just as soon leave no unnecessary scratches.