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Member postings for Martin Field

Here is a list of all the postings Martin Field has made in our forums. Click on a thread name to jump to the thread.

Thread: P.S.Waverley
17/09/2020 19:16:05

They sound great, Neil, but JCB know how to charge! Like 30 quid for one mudguard bolt. Never paid their own bills very quickly though!

M

17/09/2020 16:17:12

Taycols were fine once, they still are. A chap from another forum designed and built me some electric boxes of tricks that enable me to use current brushed ESCs with a Taycol motor, so I'll use one of those for Waverley.

As someone pointed out independent paddle wheels only causes roll, so a BIG rudder may be in order.

Bazyle, chain drive could work if I can get a big enough sprocket for the shaft to get the reduction. And, of course, I have no idea what speed the wheels should turn.

Martin

17/09/2020 12:23:21

Is there one, Ian? What did it hit?

I know very little about it, but it was a birthday p[resent and has to be finished.

Martin

17/09/2020 12:20:08

I'll try paddleducks, thanks. ModelBoatmayhem I was chucked off years ago for criticising somebody's prices. I think he's dead now but they still won't have me!

I would rather use an older motor in keeping with the model. I have several Taycols and clever electrical bits to allow the use of a modern ESC with the field wound Taycol motor.

Martin

17/09/2020 10:38:31

Adrian, I have already been put off by the rules and regs and likely expense, so will go electric.

Cheers,

Martin

17/09/2020 08:35:24

The nearest model boat club is way too far away and there are no other model engineering clubs.

I'd forgotten about the gas tank thing as well.

No, I don't do asking permission very well, so electric it definitely is, but thanks, gents.

Martin

16/09/2020 23:51:02

I do live in the UK, Nigel, but am not a member of a Model Engineering Society. The only one near me was so unfriendly when I visited I came straight home! And it's bad enough having to join the BMFA to insure my model aircraft, without doing it all over again just for a model boat! So, electric it is.

Thanks everyone.

Martin

16/09/2020 21:53:58

I really should have mentioned the size of the boat. It's 5 ft-6in long with paddle wheels about 6" diameter. It's a big devil. I know the Miranda engine, having built one years ago. A launch engine wouldn't be suitable, but it's the boiler I'm most worried about, as a conventional (non pot) boiler needs the inspection for insurance and that's a lot of faff as I've no idea where to get that done.

It looks more and more like electric power is going in.

Cheers,

Martin

16/09/2020 18:07:54

Hi,

I have a very large model of the P.S.Waverley and am torn between a steam plant and an electric mechanism for the paddle wheels.

Is there a good steaming boiler that will provide enough steam without requiring a boiler inspection? I have no idea where to get a test done or what's involved, but I can't see a Mamod type boiler giving enough steam to operate the wheels. I don't want to buy a plant.

Any suggestions gratefully received.

Martin

Thread: 4 stroking a Merco 61...
14/08/2019 21:17:42

Hmmm, I guess you're right. I can't find a decent chrome plater at the best of times!

Is C.I. barstock easily available?

Martin

14/08/2019 20:49:15

Ah, as I thought, Jason. I've never turned cast iron, apart from a smallish flywheel for a stationary engine. But that went surprisingly well actually, so maybe doing a C.I. liner isn't so frightening.

Martin

14/08/2019 20:38:14

Hmm, good points, Jason.

I was wondering whether I could turn the new liner from brass and have it chrome plated like the proprietary engines. I have a piece of 1" diameter brass already which is the right size for the crankcase. OK, I would have to silver solder a flange on top, but that ain't a problem.

Does anyone have any experience of this method?

Martin

14/08/2019 13:31:03

I am still keen on belt drive though, I must say. Decisions, decisions.

Martin

14/08/2019 13:29:26

That does look pretty simple, Jason. Is there a drawing anywhere for that?

I do recall it was the Lynx in the magazine.

Martin

14/08/2019 12:56:07

jason,

I haven't necessarily gone off the belt driven idea, but with Laser Jon's kind offer it would seem to make sense to go with gears, but I will certainly have a look at the Nemett engine. I did once buy a Workshop Special magazine with a Nemett engine in . I must see if I still have it.

Cheers,

Martin

14/08/2019 11:59:03

Jason,

I'm very impressed by your rapid ability to draw on the old pootah!

I can see well what you're suggesting, but wonder what goes on on the gear side of the plate you show nearest to us...or, is that just a generic "face" to actually be part of the gear casing? In which case I understand. Then there would be the double sized gear with the cams on above it?

I have just received an astonishing offer from Jon who makes Laser engines to help by supplying a gear set and cams from one of their "deceased" engines. I'm hoping they will fit the Merco crankcase.

Martin

14/08/2019 10:51:32

That arrangement wouldn't work , Jason as there is nowhere to house the ball race in the Stebro gear casing. I think there's a bronze bearing behind the gear. It shows on the assembled engine outside. I was wondering where an inner bearing could go...unless I'm looking at the gear casing effectively inside out (which I may well be, come to think of it!)

Martin

14/08/2019 10:26:44

I imagine leakage is a problem with rotary valves. But thanks for the reference to Jan Ridders' apparently simple idea.

I was thinking like you that a drive disc with a smaller pinion behind it would have to be the answer on the Stebro. I can't see any dint where the smaller gear (pinion) takes the drive off the extra pin. Also, the backplate of the Merco is quite deep into the engine, whereas the Stebro gear casing is ON the back rather than IN the back so how does that little extra pin even reach the smaller gear?

Strange.

Martin

14/08/2019 10:16:32

Thanks, Jason. Interesting pictures. Pretty much as expected, except for the drive to the smaller gear. I can see a smaller pin pressed into the crankpin, but where does it engage the smaller cam gear? It is, after all, at full stroke, so to go then to a twice size gear with the cams on would suggest a much bigger box at the back. Pity we can't see the cams either.

But all in all I think this is the way to go for simplicity.

Interesting that the Stebro was slightly more powerful than the OS too.

Martin

14/08/2019 09:38:45

Thanks, gents. I do like the neat approach of the Webra rotary valve, but I know nothing about them and would feel a bit lost.

The Stebro has all its valve gear at the back so must have taken the drive off the pin somehow or was perhaps a new crankshaft.

Niels, the Vega was a side valve, like your drawing, but where on your drawing is the drive to a twice as big gear to get 1/2 speed rotation for the cams?

Martin

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