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Author Topic: TUG CERVIA HULL BUILD by Bluebird  (Read 29691 times)

John W E

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Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #50 on: January 08, 2008, 07:55:39 PM »


I moved on to tackle the next job which was planking of the fore and aft decks; there were one or two problems which I had to overcome.  A new method I wished to try.  The problem being that I already fitted the bulwarks around the outer edge of the decks and this made fitting the planking rather tricky and awkward, but, not impossible to do.  However, I wanted an easier method.  My solution is first of all trace the area of the deck planking onto a piece of 1/64 plywood – very thin and very flexible.   You could use 0.5mm plasticard for this instead of the 1/64 ply if you wish.  When I had transferred the area covered by the planking onto the plywood; I then cut it out; which gave me a template.   I stuck this template onto a thicker piece of ply wood (half inch in my case) with some double sided carpet tape.  This double sided tape, I found releases pretty easily. 

I then marked out and cut to length - the edge planking.  This is the planking which runs around the outside of the rest of the planks on the model.   If you note, in one photograph, I have glued on one piece of edge planking of the bow planking section - next to it you will see I have pre-bent and clamped the next piece of edge planking to the thick piece of plywood, to hold it in shape, whilst it cools down and dries out.

Once you have finished the edge planking; the next stage is to commence laying the planks.   Start with the centre plank; this is sometimes called the ‘King plank’.  Glue this one in place first; and, then commence laying one plank each side of this alternatively. 

This is where I had a debate, and, it’s entirely up to oneself when doing planking.  I wanted to try the method of using black electricians tape to assimilate caulking on the edge of the plank.   This required me to assemble six planks on their edges and apply a length of electricians tape over the edges along their length.   

When the electricians tape had stuck to the edges of the planking, I then proceeded to cut one plank off at a time, leaving the plank with one edge with a piece of electricians tape down one edge.   To be quite honest, for the amount of planks I had to put on, and, the work required getting the electricians tape to stick on the edge of the planks; it was for me more trouble than it was worth.   I ended up using a permanent black marker – marking the edge of the plank with that.

Once I had finished all of the planking; I used a piece of medium sand-paper glued to a flat piece of plywood – 4 x 6 x ½ inch thick and sanded the planking level.  After this, I sanded again with finer sand paper; and, when I was happy with the finish I removed the planking and the 1/16 ply base which the planks were glued to from the double sided tape that was securing it to the thick plywood.

I then positioned this on the fore deck; glued it in place.   I found that it bent quite easily with the camber of the deck, without the planks opening up which was my fear.   I proceeded to do the stern planking with exactly the same method and when both decks were in position and glued down, I applied one coat of matt varnish.  These decks will later be covered with a satin varnish.
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John W E

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Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #51 on: January 08, 2008, 07:58:04 PM »

and more pictures ......
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Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #52 on: January 08, 2008, 07:59:39 PM »

and the final picture shows the planking at the bow fitted
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John W E

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Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #53 on: January 12, 2008, 09:37:31 PM »

I have included a couple of scribbles because the camera I use isn’t very good for ‘close-up’ shots – I know I know a bad craftsman always blames his tools.

If we look at scribble number 1, this is how I made up the valve cover hatches.  These sit, front and back of the funnel.   Basically, I started off with a piece of 2mm thickness lite ply; 1mm smaller than the dimensions on the plan.   I clad the edges with 1mm plasticard glued on with superglue, and, then the lid of valve hatch is made up of 1.5 mm thickness plasticard.

I assimilate the hinges with 2mm wide x 1mm thick plasticard strip.  At the end of the hinge, on the opening side, I glue 2 short lengths 4mm long of thin copper wire.

I made 2 of these hatches as above.

Next move on to the ship’s binnacle, which is on the flying bridge; It is made up from pieces cut from an old ‘biro’ pen, various size dowel, a bit of cocktail stick and 2 beads and some plasticard strip.  I think the drawing is pretty much self-explanatory; where I cut the pieces of biro pen apart and where I used these pieces and I feel it makes for quite an effective pinnacle.   The most difficult part to be honest was to stop playing with it and knocking pieces off whilst the glue was setting. 

I moved on to make the engine room telegraph and this again was made from 2 pieces of doweling, a steel washer and a length of bell copper wire which had the insulation removed.    The hardest part here was actually making the handle – follow the steps I have drawn – this shows the shape of the copper wire and the sequence in which I bent it in.  This again was painted and set aside.   

I then went on and made 7 bulkhead doors for around the superstructure.  I commenced using 0.5 mm thick plasticard, this assimilates the flange which runs around the outside of the door and holds the door seal – it is roughly 1mm larger in height and in width than the actual door.   The door was cut from 1mm plasticard and glued onto the 0.5 mm plasticard in a central position – so, you had a 1mm overlap all the way round.

The hinges I manufactured in the same manner as I did for the hatches, from plasticard strip and also copper wire.    I also made the handles from the same copper wire which were then glued onto the doors (they don’t open, they are all glued shut).
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Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #54 on: January 12, 2008, 09:40:36 PM »


The ship’s wheel was my next job.    The ship’s wheels I make from 1/64 ply and 1/32 ply, and, a piece of small diameter dowel for the hub of the wheel and copper wire yet again, for the spokes and handles.   The sequence I construct a wheel is as follows – I cut the outside diameter section of the wheel first, which is a circle from 1/32 plywood of the diameter you require. 

On one face I mark the position of the spokes around the circumference of this circle.   I then remove the centre of this circle and move on to cut two further circles from the 1/64 ply – (these two 1/64 circles are 0.5mm smaller diameter than the 1/32 circle).   The inside hole of the 1/64 circle is exactly the same size as that of the 1/32 circle.
 
I then glue one piece of 1/64 circle onto one side of the 1/32 circle – centrally.    I then glue the other piece of 1/64 circle to the other side – thus sandwiching the 1/32 ply circle in between them.   

I move on to construct the hub.   I cut the length of the dowel slightly longer than the thickness of the ship’s wheel. My first operation is to drill two holes – one dead centre through the middle of the dowel; and one through the side of the dowel from 9 to 3 (on a clock’s face) i.e. straight across.  :)

Now, on the ship’s wheel itself; I drill a corresponding hole – this goes through the edge from 9 – 3 or straight across again  :) as above.

Next operation is to place the hub in the centre of your ship’s wheel, in order that all the holes on the sides of the hub and the wheel line up.  Then, you pass copper wire through all of the holes – holding the hub in the centre.  With superglue you glue the hub in place on the copper wire and also glue the copper wire in place on the outer wheel – ensuring that the hub is central to the ship’s wheel and the hub is flat.

Once the glue has dried; you drill at 12 o’clock through the side of the ship’s wheel in the centre; into the hub but not all the way through.  Be careful not to bend or push the hub whilst drilling into it.   Once you have done this you place another length of copper wire through the hole into the hole that you have drilled into the hub, glue in place and allow it to dry.

Then drill the opposite side – so if you have drilled your hole at 12 o’clock the next hole will be drilled at 6 o’clock.  Once you have done this, you should have four spokes in your wheel.   I normally have eight spokes in the steering wheel; and once they are glued into place – allow them to dry for a good few hours – then trim away the copper wire so that they are all even.  If you wish and I have done this in the past – is put a drop of superglue on the end of the wire and hang it until the superglue dries – this forms like a ‘pear shape’ on the end of the copper wire and it does look like the real handles on the ship’s wheel – but take heed here it does take a long time for the glue to harden.  :)

I have attached a couple of photographs of the ‘flying bridge’ and before our Dicky says anything about me painting – that white band is masking tape – whilst I paint the red band around funnel.
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John W E

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Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #55 on: January 12, 2008, 09:44:15 PM »

Just going to include a couple of pictures of how the tug and flying bridge are at this moment.

I'm in the process of painting.

The one thing I forgot to mention and add a drawing too - is, I made a 'voice pipe' up for the bridge as well.  This is an easy, simple way, its a piece of 15 amp copper wire straightened and a blob of solder on the end.   The solder is filed to the correct 'pear shape' and a flat face added to it.  It is then bent to the correct angle - you can see it next to the engine room telegraph on the picture.

Aye
john e
bluebird
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Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #56 on: January 15, 2008, 08:55:33 PM »

     
The Electrical side of things  :D
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Before we go too far down the road, building fittings and attaching them to the model, we have to pause for thought for a minute.   

Although we have the motor and gearbox installed and we have a rough idea of what size battery we are going to put into our model; we need now, to look in depth at the type of speed controller we are going to fit, where we are going to fit the TX receiver for the radio and are we going to fit any working functions in the model such as lights, water pumps etc.

The main thing on our list at the moment is:

What size speed controller to do we need?  When we say what size? What we mean is – how many amps do we need and how many volts?

Now the motor I have installed into this model is a 550 motor.  When we tested it ‘free running’ coupled to nothing, the motor was sitting on the bench and we ran it at 6 volt.  According to the book we have and the information sheet, for this particular motor, at 6 volt; she should draw between 0.4 and 0.5 of an amp and she should rotate in the region of between 15000 and 16000 rpm.

This motor is going to drive through a 2-1 ratio belt drive gear box.  So, we will say, she is turning at 15000 rpm connected to the gearbox at the output end of the gearbox, she should be turning or will be turning in the region of 7500 rpm.   At the end of the output shaft, we are going to connect to the propeller shaft, via a Dyco coupling unit; and then onto the propeller shaft and on the end of the propeller shaft; we have the propeller  :) in my case it’s a 50 mm three blade brass prop.  Now, with all of this connected up; sitting on the bench in the tug; the first stage is to connect the electric motor up directly to a 6 volt battery and let it run for at least an hour (aye you have to sweet-talk/make the Mrs a cuppa  O0 ) as it can be on the aggravating side for those who don’t know what is going on  :)   What is actually happening is – we are RUNNING THE MOTOR IN and the PROPELLER SHAFT and we are constantly checking for ‘hot-spots’ – is the end of prop shaft running hot WATCH YOUR FINGERS!!!! IT DOES HURT!!!!   :'( When we have ran the motor for about an hour with no load on; disconnect one lead off the battery – preferably the positive lead.  In between the wire from your motor and the battery; connect an amp meter up.   Make sure the amp meter can handle at least 10-20 amps.

Now once we have connected the amp meter between the motor and the battery; check the reading on the amp meter.

When the motor was free running on the bench, we knew that it was drawing no more than 0.5 of an amp.  So, in theory, with the coupling and propeller shaft and propeller all connected up to the motor through the gearbox; it should be no more than ¾ of an amp to 1 amp.  If this reading is higher; we have some friction somewhere and something must be preventing the propeller shaft from turning freely.

If we have a hotspot or we are pulling in the region of more than 1 amp – or maybe more we have to start to looking for problems in misalignment in between the gearbox and the propeller shaft.   Problems with the gearbox and we must have these problems sorted out before we advance any further.

As soon as we are happy  {-) and we have the motor running between ½ - ¾ of an amp we can go and get the model’s ‘bum’ wet – aye, the big test tank – stick the model in the test tank – apart from checking for leaks, first job is to place the battery in the position in the hull; and, then ballast it down to its waterline with your chosen set of weights.   I am lucky; I have a bit lead left over from the Church roof down the street  8) so, we ballast the hull down to waterline level.   Sometimes it is adviseable here to have two pieces of cable to make up an extension.  This is because multi-meters or amp meters do not like being dropped in water  :-\ yes I have done that myself,  balanced the amp meter on the model and its fallen straight off into the water.

Anyway, we need to take the reading now – of how many amps the motor is actually drawing whilst under full load.

So, just with the amp meter connected; in circuit with the battery and the motor; this will give us the total amps at full power - the motor is consuming, driving this propeller and in my case it was 5.8 amps.  For those who like it spot on, we will just say – what we have to take into consideration (although the motor is using 5.8 amps) when she is actually running free and moving and not being held, the amperage will drop slightly; only slightly though.  So, we have a reading now of 5.8 amps.

We are going to round the 5.8 amps off to say 6 amps.  Its back to the worktable once again, we need something now between the battery and the motor to control the speed.

In olden days and still today sometimes we used to use:-

•   Bob’s boards –
•   the fixed resistance type boards (where you had a series of resistors of different values giving you different speeds);
•   Resistant wire controllers, which looked like the old fashioned bar-type electric fire (those ones with the elements showing);

These types are semi-mechanical – where you require a servo to adjust them; through a mechanical linkage. 

Today though the norm is to use a purely electrical speed controller, and, for those who wish to have an easy description of how these work – they work on switching the electrical power supply ON and OFF lots of times per second.   So, if the switch is switched on all of the time; the motor is running at full belt – flat out – with full power from battery.  But, as you commence decreasing the speed, what happens is the speed controller begins switching ON and OFF – the more times it’s being switched OFF in a given set time, the slower the motor is going to go.

So that is an ‘easy’ description of how an electronic speed controller works.

What we need to do is to determine what size (as in how many amps) speed controller we require.   Now, maximum amps free running the tug is going to use 6 amps.  So, that was with me holding the tug stationary in the test tank, allowing the motor to thrash round at full belt.  So, if I am towing something that stops the tug dead in the water; I know it is not going to pull more than 6 amps.  In theory then what we require is a speed controller to handle double 6 amps i.e. 12 amps.   The reason I have doubled the amps that I require for my speed controller (and also a lot of other people do that too) is for a safety margin.  The unforeseen – a plastic bag floating in the water which gets wrapped around the propeller; the occasional lump of weed; and that dreaded swan feather; all get mangled around the prop.  Insufficient enough to stop the propeller dead, but sufficient enough to take the motor into what is called the ‘Stall amperage’.  The stall amperage is where the motor has been stopped physically whilst still under load.  In the case of the 550 it’s in the terrifying region of between 45 and 50 amps – these are the amps the motor stops at.

If we are to physically hold the motor stationary whilst the power was still being supplied, we would start to see smoke either from the wiring, or the motor, or worse case you would see your batteries EXPLODE and the WIRING BURSTING INTO FLAMES so, to prevent this, we could, if we required, fit a speed controller which is capable of handling 50 amps.   To be honest though, a bit of unnecessary expense and a bit overkill, for this particular model anyway.   What we do the safeguard this is add a fuse in line between the battery and the speed controller.  Now, our speed controller I am going to use a 10 amp one – protected by a 10 amp fuse,  So if the situation does arise where the propeller is stalled and stopped, before it does any damage the fuse WILL POP.  A 20 pence fuse is a good deal cheaper than a £30 speed controller or in the worse scenario watching your model BURST INTO FLAMES.

Electric Speed controllers then – there are literally dozens on the market today; and, as they say THE CHOICE IS YOURS.  But, before you go away handing out money – a couple of pointers which have taken me a long way:-

Although today’s trend is to ‘Purchase the cheapest we can because if it goes wrong, we can throw it away’ because that is the way a lot of cheap imported speed controllers are built nowadays;  it is a bit of a heartache when you know – you have fried the speed controller yourself by a silly mistake – by getting the wires mixed up and when you read the small print – you are not covered under the warranty for that and, I do not think there is not a modeller on this earth who can put his hand on his heart and say – “I have never made an error by mistakenly picking the wrong wire and connecting it up”.  :angel:  This is one of the reasons I try to purchase from our ‘home-grown’ industry.  Because, as some will tell you on this forum, there have been one or two occasions where I have picked up the telephone and spoken to the manufacturer and said “Hands up – I have dropped a clanger – can you help me?” .   Once or twice I have had the reply “BLOOBS – A FULL TEAM OF DOCTORS AND NURSES COULDN’T HELP YOU MY SON!!!!”  ::) But, it will cost you the postage and the replacement is always there for the next morning.  O0  You try and find that response from one or two Companies from abroad. 

So, I do like to build ‘kit’ speed controllers and, the particular one for this model I chose P79/79S CONDOR 10/2 SPEED CONTROLLER.   Kit build, I am going to include a couple of photographs because there are on this Forum kit building speed controllers and switches – so you could follow those threads if you wish.

Now, last but not least; the wiring side of things:

•   The motor has been what is known as ‘suppressed’ and for anyone requiring further information on suppression the subject is well-covered on other threads.

•   The supply wires from the speed controller to the motor are led and fed down one side of the hull; well away from any signal carrying wires.   This is what is commonly known as ‘The dirty side of the hull’.

•   On the opposite side of the hull there are the ‘clean wires’ and these are the wires that carry the power supply and signals to your servo and your speed controller and also extra units which you may wish to add in – such as switchers for lights and radar working.   These lead to your RX radio receiver which is on the clean side of the hull.

Following this practice helps to eliminate SOME OF THE electrical interference which can be troublesome at times. 

One picture will show the layout of the speed controller along with the RX mounted at the front (bow) of the hull.  The other pictures show you what you will find when you purchase a kit speed controller – from YOU-KNOW-WHO   ;) and you can see these are the basic tools I used to assemble the kit and lastly the assembled kit, but, without the casing – JUST SO YOU CAN SEE WHAT THE INTERNALS are like.  O0

Aye
John e
Bluebird



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John W E

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Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #57 on: January 15, 2008, 08:57:25 PM »

couple more pictures - parts from the speed controller

 O0
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John W E

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Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #58 on: January 15, 2008, 08:58:42 PM »

Leather jacket required  {-) {-) {-) {-)

aye
john e
bluebird
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John W E

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Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #59 on: January 30, 2008, 07:28:57 PM »

hi all

Time for a new plan and then a new build.

aye
john e
bluebird
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Re: TUG CERVIA HULL BUILD by Bluebird
« Reply #60 on: March 23, 2008, 09:44:43 PM »


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