MK10 Rebuilding Mods and Best Practices

[Bloody Knuckles]

Timmyjane, If you do a search with the inputs, "MK5" by member "DA Aquamaster" you will see two threads (MK-5 vs. MK10) and (MK5 Questions). Both of these threads are from about 13-14 years ago and contain numerous back and forth comments from DA Aquamaster, Halocline and Awap. Awesome information that will most likely answer any of your questions, and quite a few that you probably didn't have.

I have three MK5's in various configurations, 2 EA with (2 LP & 1 HP port) and one with the (5 LP port swivel & 2 - 7/16" HP ports). One of the 2 LP port regs has the old "circlip" on the swivel (an interesting design that has been relegated to blowing up beach toys...I use it for kite boarding). Regardless of the configuration, I have personally found the MK5 to be much more forgiving in providing a consistent solid lockup with little to no drift and never any creep...Luck of the draw...IDK). As I'm sure you're aware by now, the piston head and spring are much larger and beefier. I'm not sure if the increased mass of the components helps facilitate this or what? I've always wanted to do a comparison between the MK5 and MK10 in regards to the net resulting sealing force at the knife edge / HP seat interface. I need to find someone with a valve spring tester to determine the K-Value or make up some Rube Goldberg contraption...RSingler???

 

[Timmyjane]

To remove the seat, I just take the yoke and use it to hold the seat holder over a tank and crack the valve (have your hand over it or the seat can shoot across the room).

That worked amazingly well! This seat was super stubborn and I used shims to try and get the pressure where it needed to be since I couldn’t get the seat back out. The yoke clamp trick took no time.

I was curious if my Amazon pressure gauge was reading properly so I got an Ashcroft gauge. With the new gauge the pressure was lower.l, down to 120. I decided to go ahead and replace the -II seat to bring it up to a more normal range. Great tip.

 

[halocline]

Why do you like the MK5 best?

I have found that MK5s tend to hold IP more reliably for longer periods of time. I don’t know if I’ve ever had one start to creep. But MK10s work really well too, they have the advantage of being easy to convert to DIN (if you use DIN) and practically all of the ones I’ve ever seen have SS turret bolts.

Actually, my favorites of the SP balanced piston regs are MK15s, and I still have a pair which I used as my primary cave set for years. But….you can’t even find seats for them any more, so when my meager stash runs out, they’ll be paperweights.

 

[mr_v]

What punches do you use for Mk10 and Mk10+ shims?

Here is what I've learned of the last few weeks: After a rebuild, put the reg on a small tank and submerge it in a container you can observe closely. I was losing a few bars over several hours but could not figure out where the leak was happening. My in-water tests were done outside in a large tub and I was looking for visible bubbles. Once I started looking at the reg and the connectors very closely, I realized that my HP hose was leaking - very tiny leaks barely noticeable with a naked eye from 1.5" away. I know a few bars lost here and there over a few hours is not a big deal for some, but I am glad I resolved the matter. That Mk10 is super tight now.

 

[rsingler]

Mk10:
19mm OD
0.5" ID

Yeah, that doesn't make sense, right?
But I've found that hand punches often leave a slightly larger diameter than advertised.
19mm = 0.748, so it fits in a 0.75" land.
Meanwhile, a 3/4" punch that leaves a slightly larger disc won't quite fit.

 

[Timmyjane]

Mk10:
19mm OD
0.5" ID

Yeah, that doesn't make sense, right?
But I've found that hand punches often leave a slightly larger diameter than advertised.
19mm = 0.748, so it fits in a 0.75" land.
Meanwhile, a 3/4" punch that leaves a slightly larger disc won't quite fit.

What material are these being punched from? Do you have some shims that I can buy off of you for my stash?

I found that during 3D printing I was having some pretty nice circular disks that were generated as a by product of some pieces. When measuring the thickness they were just the right size and the thickness could be modified some to be thicker if needed. By default they were 0.2mm thick. I was thinking about printing some shims from ABS plastic. Seems like they would be just fine but I haven't tied them. Anyone have any thoughts on this idea?

 

[James79]

What material are these being punched from? Do you have some shims that I can buy off of you for my stash?

I found that during 3D printing I was having some pretty nice circular disks that were generated as a by product of some pieces. When measuring the thickness they were just the right size and the thickness could be modified some to be thicker if needed. By default they were 0.2mm thick. I was thinking about printing some shims from ABS plastic. Seems like they would be just fine but I haven't tied them. Anyone have any thoughts on this idea?

Couv (RIP) bench tested some I printed for him a few years ago.... They worked, but he had doubts about there longevity (the constant spring pressure might do them in). So we didn't pursue it further, so it's still a question mark.

Respectfully,

James

 

[Timmyjane]

Couv (RIP) bench tested some I printed for him a few years ago.... They worked, but he had doubts about there longevity (the constant spring pressure might do them in). So we didn't pursue it further, so it's still a question mark.

Respectfully,

James

So what would be the proposed test? Seems like PETG or Polycarbonate could be plenty sufficient for any compression loads on the shims. Any idea what material the shims are punched from?

 

[James79]

So what would be the proposed test? Seems like PETG or Polycarbonate could be plenty sufficient for any compression loads on the shims. Any idea what material the shims are punched from?

I believe the shims are nylon. Regarding the printed ones, it would just be endurance/torture testing.... Use them, cycle the reg a lot, open up and inspect them, do it some more. Monitoring for IP shif frequently. Just seemed unnecessary at the time when VDH was still a going concern and the shims were cheap/readily available.

 

[rsingler]

PVDF 0.010" sheet from McMaster is perfect.
Nylon works, too, though it absorbs a hair of water.