|
Post by Fibonacci on Jul 14, 2023 18:57:45 GMT -8
Been given a Heinke Merlin MKV from a recently retired former marine biologist who was hanging up his fins but wanted it to go to a good home! He used it daily back in the day and said it was very reliable, particularly good for UW photography.
Externally the reg looked a bit tatty with torn hoses and patches of verdigris on the chrome showing through the crackle finish black paint but came up surprisingly well after paint stripper, treatment in a hot Citric Acid bath and a session in the US cleaner. I was able to download the original user and service manuals from the VDH library which was very helpful and at least helped shed light on the mystery threads on the case screws and reserve valve screws... they are BA! Of course...
If anyone needs to replace galled or seized machine screws on a Merlin, the specs are:
Case cover (8): 4BA x 3/8" round head, slotted, nickel plated brass Reserve valve body (6): 4BA x 1/2" cheese head, slotted, 316 stainless Hose clamp screws (4): 6BA x 1/2" round head, nickel plated brass
The diaphragm is still in excellent condition, very supple with no cracks... as is the mouthpiece. Wagon wheels are quite distorted due to over-enthusiastic tightening. but seem to be the same size as USD.
The HP seat is also sound. The MKV appeared to have the exhaust valve mounted near the end of the exhaust hose before it joins the can... later changed to the more usual duckbill valve within the can on the MKVI. Can a duckbill be retrofitted to a MKV?
I've measured all the o-rings but due to age and developing a set over time, the results are inconclusive. I assume they would be BS1806 or AS568, but given the Siebe Gorman links maybe they are Metric or even French R series!
So just wondering if anyone can supply the correct o-ring specs for these iconic British regs please? I'm keen to get it back in the water! Thanks in advance!
|
|
|
Post by vance on Jul 15, 2023 7:21:15 GMT -8
Nice find!
I don't have the o'ring specs, but would love to see photos of the restoration, and read a dive report. We don't see many of these in the US.
Are you repainting?
You might be able to re-round the wws with a heatgun. Heat and fit them into a bit of tubing (or the mouthpiece if it's metal) to push them back into shape.
Concerning a duckbill, just be sure that the diaphragm doesn't squeeze the db closed when exhaling. Do the MKV and MKVI have the same cans? And does your reg utilize an intake non-return?
The BA threads are interesting. They are obsolete, and were mainly used for modeling and instruments. Are you able to source them?
|
|
|
Post by vance on Jul 15, 2023 7:46:31 GMT -8
CG-45 has some good photos and diagrams of the Merlin regs. I read that the MKVI had a couple of changes made to the cover, one being in aid of installing a conventional style duckbill. CG-45 is translated from Portugese, so some terms are confusing.
This statement in reference to the cover change is directly from the CG-45 page: "A new project for a new placement of the "duck-bill" was made." This leads me to suspect that a duckbill could not be simply installed.
Does your regulator have a reserve valve, or just a reserve cover?
|
|
|
Post by Fibonacci on Jul 15, 2023 21:40:10 GMT -8
Thanks vance I must admit it was not on my radar this side of the Pacific either! Apparently the MK V and VI were used by the Royal Navy for decades and were well regarded… mine has the reserve with red lanyard. Been working on it again today, the internals are in excellent condition, will keep on looking for o-ring specs, the MKV only has three plus a flat seal similar specs to a -013 and a fibre washer on the surface supply port. Looks like this will readily convert to a LP port for BC and octo and it already has a HP port built in. By all accounts these upstream tilt valve regs breathe very well. Heinke designed the OPV to sit inside the dry side of the can, one issue with the Nemrod Snark is the OPV is often corroded shut.. like Poseidon XStream for that matter! There are moulded in standoffs inside the cover, so maybe with a modified brass inner reinforcement tube it will accept a duck bill.. Don’t think I will repaint it, once the flaking black paint was cleaned off the chrome underneath polished up very well… Found a model steam train supplier that has a wide range of obscure British fasteners and taps/dies to match… BA, British Standard Brass, British Standard Cycle etc Happy to upload pics of progress once I work out how! Any tips on free photo sharing platforms now that Photobucket is gone?
|
|
|
Post by james1979 on Jul 16, 2023 5:26:13 GMT -8
Any tips on free photo sharing platforms now that Photobucket is gone? I use imgur with good success. I just make the imgur posts as private posts (not visible to everyone on imgur) but bb code share links here work fine. Respectfully, James
|
|
|
Post by vance on Jul 16, 2023 7:08:23 GMT -8
|
|
|
Post by SeaRat on Jul 16, 2023 12:00:25 GMT -8
Photobucket is now gone! WOW, did they ever make a mistake by taking us to the cleaners; a lot of us simply went away.
Now, about that black paint, Fibovacci, that may have been done by the Navy, and not the factory. So the underlying chrome really probably represents the new condition of the regulator.
John
|
|
|
Post by Fibonacci on Jul 16, 2023 15:27:19 GMT -8
Righto, Flikr account updated!
Here's what the Heinke Merlin MKV looked like when I received it... a bit tatty but basically sound, these things are built like a tank!
Paint stripper, Citric Acid pickle, ultrasonic cleaning in Simple Green Crystal 1:20 The plunger type HP gauge originally connected to the G1/8 HP port actually cleaned up very well, just needed a new -006 90 o-ring!
This is what was under the black electrical tape... must have breathed a little wet as the in-hose exhaust valve was also missing
The firm rubber can horn was quite oval shaped, but soaking in some hot water enabled the distorted inner brass support tube to be pushed out, and using a 3/8" drive 9/16" long reach socket as a mandrel it was able to be made circular again. It appears to be 13/16" OD thin wall brass tube, crimped at one end and nickel plated.
I'm going to see if a revised brass support tube will handle a duckbill upgrade, but those inner support ribs may be too close?
Note the differences between the MKV and MKVI... the later model is definitely the one to get, and seems highly prized on the UK market at least.
O-rings So far the two main Reserve Housing o-rings appear to be AS568 -112 90 The Reserve Plunger is close to a AS568 -007 90 but unsure if its just been distorted over time... its as hard as a rock! Erik's O-ring Calculator however gives a -007 o-ring a pass based on the bore diameter, piston diameter and o-ring groove details.
Next project is new hose clamps, I will try the excellent tutorial by vance
|
|
|
Post by Fibonacci on Jul 16, 2023 15:57:15 GMT -8
Photobucket is now gone! WOW, did they ever make a mistake by taking us to the cleaners; a lot of us simply went away. Now, about that black paint, Fibovacci, that may have been done by the Navy, and not the factory. So the underlying chrome really probably represents the new condition of the regulator. John Not sure they've actually fully gone, but their actions were a huge 'own goal' with massive negativity!
You are quite right, the Royal Navy used Merlin DHs for many years and may well have painted some black for a more stealthy appearance.
However I know the provenance of my reg, the original owner bought it new, and it originally had the black crackle finish paint. Seems the later MKVI's came as unpainted chrome, most I've seen also have the reserve blanked off, though it was still an option mainly for use in zero viz waters. The original owner said he liked both the reserve lanyard and the plunger style pressure gauge as it could be felt with a thumb without having shift his UW camera around to check. Start feeling a restriction in breathing, pull the lanyard for the last 300psi and head for the surface... though he always dived in the fairly shallow warm tropical reefs of Far North Queensland back in the day.
|
|
|
Post by SeaRat on Jul 16, 2023 18:03:16 GMT -8
Wow, that is going to be a great regulator! I have a Heinke mouthpiece, which is currently on my Nemrod Snark III regulator. It's a great mouthpiece.
John
|
|
|
Post by Fibonacci on Jul 16, 2023 18:54:53 GMT -8
The more I delve into these Merlins the better I like them!
The MK6 had a lot of modern refinements and was designed to be modular to accept a reserve assembly, surface supply hose on a banjo bolt (so it could be oriented as required), HP gauge, externally adjustable IP vs shims on the MK5 and it seems they were made into the 1970's.
A spare plated brass surface supply port blank off plug (which is BSPP Port G3/8-19) it could be drilled and tapped for a SAE-3 ORB port to accept standard 3/8-24 UNF hoses for my MKV...
The tilt valve has a tiny contact point with the stainless diaphragm plate, so friction would be very low and the mechanism simple.
Note the MKVI cover seems to have identical inner reinforcement ribs to the MKV just with an inner anti-collapse spring for the duckbill vs the crimped brass tube.
|
|
|
Post by Fibonacci on Jul 17, 2023 19:57:55 GMT -8
Quick check with a new silicone rubber duckbill reveals it fits the can pretty well, but I can see why they added an internal expander spring. Clears the diaphragm standoffs too... Heinke Merlin MKV duckbill check by fibonacci101, on Flickr
|
|
|
Post by vance on Jul 18, 2023 17:18:24 GMT -8
Cool! It looks like it fits well. Just be sure that the diaphragm doesn't impinge the duckbill function on the exhale. You need a very solid intake non-return to be sure that the diaphragm doesn't expand on the exhale cycle.
|
|
|
Post by SeaRat on Jul 18, 2023 17:29:31 GMT -8
Cool! It looks like it fits well. Just be sure that the diaphragm doesn't impinge the duckbill function on the exhale. You need a very solid intake non-return to be sure that the diaphragm doesn't expand on the exhale cycle. I see that there are six bars, "diaphragm standoffs," and two buttons, which seem to be designed to protect the duckbill from being impinged by the diaphragm. They seem to make a hole for the duckbill. John
|
|
|
Post by Fibonacci on Jul 21, 2023 18:55:57 GMT -8
Cleaning out the reserve housing and can screw 4BA threads... lots of white crusty deposits gone! Heinke 4BA hole cleaning by fibonacci101, on Flickr I think I have sourced some of the unique OPV rubber seals, working on the HP diaphragm which is of course just slightly larger than the usual US Divers diameter and 3/32" thick double layer fabric insert. It has a central hole for the HP valve and washer to pass through which seems a poor design choice but reduces the overall length required for the HP spring and housing. Anyone with any leads on suitable diaphragm material would be a great help. While I can find some suppliers with what appears to be correct neoprene rubber with insert, so far its only available in vast commercial quantities like 1.2m x 10m rolls!
|
|