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!