Henderson Mark V Pump spares

[yimkin]

I have stripped down an old Henderson Mark V hand pump. I have found the only thing wrong with it is that the "plastic"nut holding the diaphragm discs to the rocker arm has shattered.
I am loathe to shell out for a 'service kit' when I only need one large plastic nut.
I cannot locate anyone who sells individual parts for these pumps and more importantly I am unable to find a drawing /parts list to establish the rocker arm thread type and size.
I would be grateful if anybody on the forum tell me what the details are for the nut in question? Or who sells them.

 

[VicS]

I have stripped down an old Henderson Mark V hand pump. I have found the only thing wrong with it is that the "plastic"nut holding the diaphragm discs to the rocker arm has shattered.
I am loathe to shell out for a 'service kit' when I only need one large plastic nut.
I cannot locate anyone who sells individual parts for these pumps and more importantly I am unable to find a drawing /parts list to establish the rocker arm thread type and size.
I would be grateful if anybody on the forum tell me what the details are for the nut in question? Or who sells them.

If you have the rocker arm you can measure the thread diameter and pitch then look it up in Zeus

 

[emmalina]

Buy a thread gauge set and a vernier. When you know the size buy a tap with the correct size and a piece of nylon to make into a nut ! If its from the last ten years chances are it will be metric.

 

[andsarkit]

Just try it with a nut of known size. Everyone has a selection in the garage. Obviously don't force it if it doesn't go on easily. It will probably be metric but some marine stuff is Whitworth as the coarser thread is better in a corrosive environment.
Have you tried asking Whale if they will send you a nut or tell you the size?
Metric nuts available here Westfield

 

[earlybird]

+1 for contacting Whale. When I 'phoned them, admittedly some time ago, re. an old product they were very helpful.

 

[yimkin]

Many thanks for your responses.
Other than metric I don't have any large nuts of varying threads and it's not a metric.
I have measured the thread. It is about 17mm dia X 12TPI. From a search of thread tables it is possibly 3/4" BSF.
I priced thread gauges but they cost as much as a pump spares kit.
I contacted Whale. The rep said he would look for the info in the archives and ring me back. He hasn't done so.
I will search the web or take the part to our local machine shop to make a couple of nuts in Delrin.

 

[emmalina]

12tpi is about a 2mm pitch (12.7 exactly) M18 is about 16.5mm but with a pitch of 2 is not that common BSF has not been used for a long time but its a distinct possibility. I would use something like a nylon cutting board myself as when the nylon gets wet it expands and will lock itself. Suppose I better check my manual pumps now you have me thinking about it LOL Good luck.

 

[andsarkit]

If you decide to make your own nut I can recommend Tracy tools. They have every imaginable tap and might be able to identify the thread if you can accurately measure it. They used to be based in Dartmouth but have moved to a big warehouse in Torquay. I was there last week to pick up a non standard tap to fit my towbar.

 

[bristoljim]

Many thanks for your responses.
Other than metric I don't have any large nuts of varying threads and it's not a metric.
I have measured the thread. It is about 17mm dia X 12TPI. From a search of thread tables it is possibly 3/4" BSF.
I priced thread gauges but they cost as much as a pump spares kit.
I contacted Whale. The rep said he would look for the info in the archives and ring me back. He hasn't done so.
I will search the web or take the part to our local machine shop to make a couple of nuts in Delrin.

Have you any pipe fittings to try ?? - what you have measured is close to 3/8 B SP & if you do not have thread gauges the 12 tpi is an estimate . Where are you based ?
Jim

 

[northwind]

Buy the service kit, at some point you will need the rest of it, the rubber does deteriate over time, might as well have it ready to fit. Or better still service it now while you have it in bits. Do the job once and then you can forget about it.

 

[lumphammer]

Check the service kit contents though, none of the ones I've bought over the last 10 years or so has included the nut that clamps the diaphragm to the actuating arm

 

[Spirit (of Glenans)]

Buy a thread gauge set and a vernier. When you know the size buy a tap with the correct size and a piece of nylon to make into a nut ! If its from the last ten years chances are it will be metric.

Post deleted.

 

[PeterV]

I’ve just bought a new operating arm for mine and it did include the nut. It was very expensive though and, what’s worse, I used the new nut and threw the old one away!

 

[awolfe]

I've also got a broken rocker arm nut. I'm thinking of tapping the center of the threaded "bolt" and stacking some washers around it to hold everything in place.

 

[Poignard]

I’ve just bought a new operating arm for mine and it did include the nut. It was very expensive though and, what’s worse, I used the new nut and threw the old one away!

You threw something away!

What sort of a 'practical boat owner' are you? ?

 

[yimkin]

Problem was solved: I handed the Rocker arm to Ron Smith at Neyland. He handed me back 2 purpose built Delrin nuts and charged under a tenner. Ron has a one-man machine shop close to the marina. He is a skilled machinist. Whatever dimensions or threads asked for will be exact.

 

[Slocumotion]

O

If you have the rocker arm you can measure the thread diameter and pitch then look it up in Zeus

Okay Vic, if no-one else will, I'll play straight man :-
Zeus who?

 

[Spirit (of Glenans)]

O

Okay Vic, if no-one else will, I'll play straight man :-
Zeus who?

Zeus book, instantly googled: www.haguefasteners.co.uk

 

[awolfe]

@yimkin Any chance that Ron Smith at Neyland would make me a couple and ship to New York? Thanks.