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Author Topic: Nobby - Morecambe Bay Prawner  (Read 111625 times)

rmaddock

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Grumpy scrap man
« Reply #75 on: January 12, 2012, 11:39:43 AM »

I've just been to the scrap metal yard behind the house.  :D

I've acquired 10kg of lead. It cost me 14.40 including VAT. I don't think I'll get mad at that. Not as mad as the metal man himself seemed to be. He obviously did not want my business this morning and was taking it out on his (obviously) long suffering wife in the office.

I've also now got my 1kg of bentonite clay.

I can feel the purchase of some silica sand and a solid but cheap pan coming on.  The large gas burner that I used the last time has died the death. I'm wondering if a BBQ will be hot enough to melt the lead. Hmmm.
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rmaddock

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A very manly afternoon!
« Reply #76 on: January 14, 2012, 04:10:38 PM »

I've just spent a very manly afternoon casting ballast.....well, half of it anyway.

First, I mixed up my DIY green sand:

Not very green, is it? With the builder's sand fresh from the bag it seemed to have about the correct consistency so I didn't add water. Oh, I did 10kg of sand to 1kg of bentonite clay. It's a bit more than the 8% I've seen talk about but not by much.
Next, the plaster plug went into the bottom of a make-shift wooden box:

Note that the bottom of the box is not attached as you need to remove it later.
Then, using a stick to tamp things down, I filled the box with green sand making sure to work it well round the plug until it was full to the brim.
Then another board is put on top and the whole thing slipped over whilst holding the breath.  O0

I removed the plug by the simple expedient of sticking something pointy into the plaster and lifting it out.
I was not unimpressed by this first effort  :-)) and so ploughed onwards.
I used my trusty old Coleman Peak One camping stove to melt the lead in a normal domestic pan. I went for steel as I was a bit worried aluminium might not be up to it.

I've no pictures of it being poured as I was busy  >>:-( However, it was not too hard. The pan was, of course, heavier than you expect. I simply poured gently directly into the mold and a few minutes later........

It doesn't take long to solidify so I didn't have to wait long either to see if it had worked:

YEAH!
And, finally, here are the ballast and plug together. I think it might fit.
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rmaddock

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Dodgy videos
« Reply #77 on: January 15, 2012, 12:09:11 PM »

The Things and I have made the other half of the ballast.  I thought it was the sort of thing that would expand their horizons. They're quite impressed that you can do real metal work in the back garden. Anyway, this time we shot a couple of videos. They were done on the mobile phone so they're not the best quality but still an interesting record I think.

First, the pouring of the lead:
http://youtu.be/Bq9BylD_6g8

Then the removal of the finished item from the mould:
http://youtu.be/_JiQLF7KWBQ

[as an aside, is it possible to put YouTube videos in these posts as something more than just a link?]   
Not at the moment ... Sorry.           Ken

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rmaddock

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Re: Nobby - Morecambe Bay Prawner
« Reply #78 on: January 15, 2012, 01:57:04 PM »

Thanks Ken. Never mind.

I've done the bath test! YEAH! It's funny, it shouldn't feel so important but the first time a model floats is brilliant. It ceases to be a thing and becomes a living boat......and no, I've not been drinking.

Two more videos....the first is the newly ballasted hull in the Morecambe Bay tide simulator.  She lifts herself from the sand beautifully.
http://youtu.be/ImxwlcflpMQ

The second is when she really floats.....I got quite excited.  :embarrassed:
http://youtu.be/k_oNg_urx88
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rmaddock

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Prop, shaft and motor!
« Reply #79 on: January 17, 2012, 12:04:32 PM »

Less than a month into the year and it feels like Christmas again!  :embarrassed:

That lovely postman brought me a package from Cornwall Model Boats this morning; contents, one Raboesch propshaft and matching prop.  :-))



The shaft I chose, Raboesch Waterproof Propshaft 290mm M4 HERE is waterproof and also adjustable in the length department. I thought I'd go fancy as the shaft and couplings are all below the waterline. Belt 'n' braces  O0

The prop, 40mm M4 Threaded 4 Blade L/H Brass A-Type HERE, is larger (by 5mm) and has more blades than scale. Again, I wanted some usable power but I could always change it later.

The positioning of the prop is about to scale......I'm not going to get hung up on it......and would allow for a few more mm of prop if I wanted them.



This picture shows the other end of things.  The motor is positioned approximately where it needs to be to fit under the scale motor housing; the horizontal beam aft of the motor will form the edge of said housing. As you can see, a fair amount needs to be lost from the prop shaft....hence getting the adjustable one  8)

Note also the tailor made ballast.  :D
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rmaddock

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Re: Nobby - Morecambe Bay Prawner
« Reply #80 on: January 17, 2012, 04:00:12 PM »

Not the most elegant of installations, but the propshaft's shortened and installed:



I've also faired it into the hull outside and am not displeased with the result:  8)

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rmaddock

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Re: Nobby - Morecambe Bay Prawner
« Reply #81 on: January 19, 2012, 01:47:00 PM »

I've soldered Action Man's supressor kit to the motor:


I've also taken receipt of two pulleys and a matching belt courtesy of MotionCo.

Many thanks to those who posted the link on here  :-))
Strangely, the aluminium pulleys are cheaper than the plastic ones. The site also has an excellent calculator which, given the pulleys and belt chosen, give you the distance between the centres; great for choosing the correct belt.
What it didn't do was warn me that the motor shaft is 6mm, not 4mm. Duh!  :embarrassed: That's the sort of mistke that my wife likes to keep reminding me of  <*<
I'm wondering if I can drill out the centre or if I should just order a bigger one.
Hmm.
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rmaddock

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Re: Nobby - Morecambe Bay Prawner
« Reply #82 on: January 19, 2012, 02:10:26 PM »

What the hell! Ive ordered another one. I choose not to keep track of how much these boats actually cost to build. It'd be frightening.  %%
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boatmadman

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Re: Nobby - Morecambe Bay Prawner
« Reply #83 on: January 19, 2012, 03:25:07 PM »

Shame you didnt ask if anyone could've drilled out for you, I could do it, save a few pennies to spend on other boaty bits.

Ian
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if at first you dont succeed.....have a beer.....

rmaddock

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Re: Nobby - Morecambe Bay Prawner
« Reply #84 on: January 19, 2012, 04:36:23 PM »

Thanks for the thought Ian. Sometimes I think I live in a little too introverted a universe for my own good.

I was a bit concerned that drilling it out wouldn't leave much material, especially where the locking screw is, but I suppose it could have been worth a try.

Next time I'll ask  :embarrassed:

Since the last post, I've been liberally, if inellegantly, fitting motor bearers.  Lathering all this pink stuff everywhere always seems to result in something straight out of an Alien movie  :o
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rmaddock

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Re: Nobby - Morecambe Bay Prawner
« Reply #85 on: January 20, 2012, 01:34:55 PM »

I do like a bit of jury-rigged impatience satisfying  :D
The new pulley arrived this morning. 10/10 for Motionco's service  :-))
So I've jammed it all into the hull and stuck wires between all the components. Obviously all black wires as that's what was to hand. The final installation should look a bit more organised but I couldn't wait to watch the prop go round.

I started with a 12v 1.2Ah battery but got only noise and little movement from the motor. So, I dug out the 7Ah battery I used to use to start model aircraft. That did the job! I assume the other just needs a bit of a charge.
So, now it all goes round but is rather noisy...as you can hear in the video. Does it sound right to people? I suppose there's nothing but resonant surface around it right now.
http://youtu.be/mfbb8GF8eBM
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HS93 (RIP)

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Re: Nobby - Morecambe Bay Prawner
« Reply #86 on: January 20, 2012, 03:05:31 PM »

is everything free turning and have you put n amp meter in line as it sounds tight on start up,(well it does to me), can you not get rid of the geared motor and just use the belt drive , I have used them on a few models and they are very quiet, your boat will probably  sound better  when you get it all decked etc keep up the good work and posts

Peter
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thelegos

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Re: Nobby - Morecambe Bay Prawner
« Reply #87 on: January 20, 2012, 03:32:13 PM »

As peter says it does sound tight. I assume the long shaft is unsupported at the end we can't quite see, Is the belt too tight and pulling the prop shaft across against one side of the bearing?
Roger
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rmaddock

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Re: Nobby - Morecambe Bay Prawner
« Reply #88 on: January 20, 2012, 03:53:18 PM »

The long shaft is unsupported and due to get "removed".  The belt isn't very tight but I've no idea how tight they should be.
The ammeter says 1.1A (approx) at full forward and reverse.....with no load on the prop'.
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thelegos

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Re: Nobby - Morecambe Bay Prawner
« Reply #89 on: January 20, 2012, 04:50:02 PM »

I have one of those motors and recall they do have quite a bit of gear noise, I've just been and tried it again and I think some of what you can hear may well be from the gear reduction on the motor.
I would probably remove the belt, run the motor to see how it sounds, check the shaft is nicely lubed up and running free, attach the belt and experiment with the motor position to find the optimum. If you screw it down with round head screws there will probably be just about enough play to shift it a little either way.
Roger
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rmaddock

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Re: Nobby - Morecambe Bay Prawner
« Reply #90 on: January 20, 2012, 05:06:10 PM »

Roger, Roger!
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rmaddock

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Re: Nobby - Morecambe Bay Prawner
« Reply #91 on: January 20, 2012, 06:31:20 PM »

It would seem that most of the noise is the motor itself...and the gears of course.  With the belt removed it's still noisy.  I might try putting some rubber under the motor mount but I suppose that once it's all boxed in it'll be better.
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thelegos

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Re: Nobby - Morecambe Bay Prawner
« Reply #92 on: January 20, 2012, 07:34:47 PM »

The hull will be more rigid when you're finished, it's acting like a soundbox at the moment. I guess you could always change the motor to direct drive and modify the gear ratio through the toothed belt system, from what I can see in the pics they are the same size at the moment. If it's just to use in an emergency then hopefully you'll never fire it up!
Roger
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rmaddock

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Re: Nobby - Morecambe Bay Prawner
« Reply #93 on: January 21, 2012, 04:53:47 PM »

I'm steamnig along now!  :}
Now that the motor's in, I've been fettling the cockpit interior...or starting to anyway.

Using my usual rule or thumb/make it up as you go along planning system, I've put deck beams into the hull. The red card then served as a starter template for the sides.

Half a deck has been roughed out and the new cockpit side inserted.  Now you can see how my rudder servo is nicely hidden. Towards the bows, where Jemima is standing, there are horizontal benches that reach under the deck to the hull sides. There will then be a bulkhead (with door) forward of that into the cabin.

A second side was rustled up, mirror image style, from the first. Jim seems quite happy with the work so far.  :-))
And so am I. These spells of sudden rushing progress make up for the slow drag that model making can sometimes be. Right now, it feels like the whole boat will be finished this time next week!  {-)
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rmaddock

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Re: Nobby - Morecambe Bay Prawner
« Reply #94 on: January 23, 2012, 01:25:19 PM »


He never smiles! There's no pleasing some people.  <*<
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Norseman

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Re: Nobby - Morecambe Bay Prawner
« Reply #95 on: January 23, 2012, 04:07:42 PM »

Well you might as well know that you have scuppered my good intentions
to work this afternoon - I started reading your build and look at the time.
Nice work and a nice thread all round  :-))

Dave
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rmaddock

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Re: Nobby - Morecambe Bay Prawner
« Reply #96 on: January 23, 2012, 05:16:03 PM »

Well you might as well know that you have scuppered my good intentions
to work this afternoon

Well thank you for the kind words Dave but I shall never, NEVER appologise!  :P
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rmaddock

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Re: Nobby - Morecambe Bay Prawner
« Reply #97 on: January 24, 2012, 12:26:51 PM »

In my current life role as a newly qualified unemployed primary school teacher  <*< I'm finding lots of oportunity to get on with this model.



In this picture you can see how I've planked the bulkhead. The planks are lime and that's as smooth as they're going to get.  I'm after the work-a-day fishing boat look that the original manages; so no lovely smooth finish for me.

Also visible is one of the magnets that are going to hold all the insides together. The plan (what there is of it (and I'm making it up all the time)) is to have all of the cockpit interior held in with magnets so that it can be easily removed - unlike the bonnet of my Volvo at the moment....but that's another story.  >:-o  That way, I should be able to get at, and maintain, all of the rigging lines that are going to have to be squeezed in there somewhere.

Lunch time!  O0
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rmaddock

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Re: Nobby - Morecambe Bay Prawner
« Reply #98 on: January 24, 2012, 07:52:41 PM »

Gosh I have been busy! So much so, that poor Jim's quite exhausted!  {-)



This whole boxy assembly is held in, as promised, magnetically. So, now you see the motor.....now you don't!



That perked him up again.  %)

There follows a wide(ish) shot of the real boat's cockpit....so you can see what I'm aiming at. As mentioned earlier, the motor enclosure is bigger than scale to get the motor in...shame but, hey, beggars can't .....'n' all that.

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nhp651

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Re: Nobby - Morecambe Bay Prawner
« Reply #99 on: January 24, 2012, 09:10:40 PM »

looking very very nice indeed, looking forward to seeing her sailing.

neil.
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