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Author Topic: Bob's H.M.S. Polyphemus  (Read 208407 times)

Bob K

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #100 on: August 26, 2012, 07:47:04 pm »

I like a bit of lateral thinking. Well done that man  :-))

Ta.  It does look a bit Cornflakes-boxish at the moment, but hopefully as I reinforce and 2-part epoxy each bulkhead into place and remove another section of scaffolding the method in my madness will become apparent.  I aim to use 5 x 5 mm hardwood strips as joint reinforcing, but shops don't open until Tuesday.
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HMS Skirmisher (1905), HMS Amazon (1906), HMS K9 (1915), Type 212A (2002), HMS Polyphemus (1881), Descartes (1897), Iggle Piggle boat (CBBC), HMS Royal Marine (1943), HMS Marshall Soult, HMS Agincourt (1912)

Bob K

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Re: H.M.S. Polyphemus (1881), internal structure
« Reply #101 on: September 12, 2012, 05:01:10 pm »

Internal structure

A few delays due to non modelling activities, but we are underway again.  Key thing here is that after working out a practical methodology it needed to be carefully planned in stages. 
Masking tape proved insufficient to hold it in place so I used elephant tape instead.  Modified clothes pegs were required to clamp in narrow spaces.

With the balsa boxes in place, start at each end to epoxy bulkhead and 5 x 5 mm hardwood joint supports.


Working inwards from the ends, remove a balsa box and epoxy bulkheads and supports as each becomes accessible.


Gradually working further inwards add reverse side supports, then remove another of the temporary boxes.


This takes some time as each epoxy operation needs to set off before the next stage can be started.  It’s coming along though.  The complete frame will be removable until all internal structures are finished off, then it will be permanently set into the hull.

PS:   To see some nice photos of a completed HMS Polyphemus model featured on Mayhem Sales this week.
http://www.modelboatmayhem.co.uk/forum/index.php?topic=39421.0

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HMS Skirmisher (1905), HMS Amazon (1906), HMS K9 (1915), Type 212A (2002), HMS Polyphemus (1881), Descartes (1897), Iggle Piggle boat (CBBC), HMS Royal Marine (1943), HMS Marshall Soult, HMS Agincourt (1912)

Bob K

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #102 on: September 13, 2012, 03:38:02 pm »

Frame Assembly

I have now completed the basic frame, with everything square in all planes, and components that sit snugly into the hull.  Good start point  :-))



Next will be the watertight under-deck in 2 mm clear Lexan.  This will extend to the hull sides to form the top of the ballast chambers.  Openings for the watertight hatches will be cut into this deck.  The deck will then be epoxied to the top face of the frame.  An interesting measuring and cutting exercise as it all has to be very accurate for fit, against a good flat frame surface for bonding.
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HMS Skirmisher (1905), HMS Amazon (1906), HMS K9 (1915), Type 212A (2002), HMS Polyphemus (1881), Descartes (1897), Iggle Piggle boat (CBBC), HMS Royal Marine (1943), HMS Marshall Soult, HMS Agincourt (1912)

Bob K

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #103 on: September 23, 2012, 03:24:10 pm »

Frame Fitting

Quite a bit of time has been taken to ensure the frame assembly fits snugly inside the hull, with a constant 5 mm from top surface of the frame to top edge of hull.  Using paper ‘feeler gauges’ under each edge to check point-fits, filing back where necessary.  5 mm hardwood strips and micro spirit level were used to check distance from frame top to hull edge.  The 2 mm clear Lexan under-deck must be flat across the frame, plus space for the actual deck which will slot onto it.



The under-deck will be in two parts, main deck and fore deck.
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #104 on: September 24, 2012, 10:50:16 pm »

Hi Bob,
Looks good, but I sawyour comment on multiple steam cylinder noise unit, be honest you are wasting your money, have worked on steam recip engine boats and apart from leaky valves to the whistle, there is no engine noise what so ever, used to go down to the engine room and stand between to engines flat out of similiar IHP to the model and speak normaly to the engineer. But what colour scheme do you intend to use, that is what interests me, I have a model of the same size to refurbish and that is what is going through my mind what paint scheme to use.
All the best on your build,
David.
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Bob K

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #105 on: September 25, 2012, 12:11:33 am »

Hi David.  I have been in several ships engine rooms and found them to be quite noisy, but there are two additional factors here.  This is a fairly early (1881) steam engine, and I aim for a more realistic scale audio distance than most audio powered model boats I see.  If the model is a ships length distant you should just hear it on a quiet day.  Copious amounts of smoke from the mister though, in keeping with the less than efficient combustion of those early coal fed engine systems.

Several models of Polyphemus have been painted with black hulls and white superstructure, which looks very attractive for a Victorian warship.  However I intend to render her in the grey paint which she was one of the first to pioneer as a 'stealth' role ship.

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HMS Skirmisher (1905), HMS Amazon (1906), HMS K9 (1915), Type 212A (2002), HMS Polyphemus (1881), Descartes (1897), Iggle Piggle boat (CBBC), HMS Royal Marine (1943), HMS Marshall Soult, HMS Agincourt (1912)

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #106 on: September 26, 2012, 07:45:49 pm »

Underdeck

Going step by step on this one as I have to plan several build stages in advance.

Thinking about the waterproof hatches I made up a dummy hatch assembly to do some measurements.  I thus figured the underdeck was going to be 1.5 mm too high.
Quite a bit of time was spent grinding down the bottom edges of the frame assembly to lower it a bit, making sure fit stayed intact.



Cutting clear Lexan is not as easy as plywood.  Card template, jig saw, and finish with files.  Reasonable fit. 



Before removing the protective films I will need to mark out the access cut-outs and nutsert holes, then do some careful drilling and cutting. 
The foredeck will be separate and enclose the various waterproof connectors and switches.
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HMS Skirmisher (1905), HMS Amazon (1906), HMS K9 (1915), Type 212A (2002), HMS Polyphemus (1881), Descartes (1897), Iggle Piggle boat (CBBC), HMS Royal Marine (1943), HMS Marshall Soult, HMS Agincourt (1912)

Bob K

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #107 on: October 01, 2012, 11:23:49 am »

The new dockyard workers are very keen to get into every aspect of this build.  Unfortunately their inexperience limits their help to playing with the printed strips and investigating the gluing operations.



Marking out for Hatches

Using lining tape I marked out the positions of the bulkhead edges.  Using this as a guide I printed out 10 mm strips of paper with 5 mm nutsert holes at 30 mm pitch.  Temporarily fixed with glue stick.  The full length hatch plate is in 2 mm Lexan, to be clamped to the underdeck so that 3 mm pilot holes can be drilled through both thickness.  5 dia holes to be cut at hatch cutout corners, then threading through a fret saw blade to cut appatures.



Once drilled the hatch holes will be opened up to 3.5 dia and c/sk.  Underdeck holes opened up to 5.0 dia for M3 nutserts. 
Drilled hatches then  to be cut into separate pieces so each can be independently removable.
I will be using "U" section greenhouse glazing rubber gasket strip for the hatch edges.  4.0 x 3.8 section.

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #108 on: October 01, 2012, 11:44:00 am »

Underdeck

Going step by step on this one as I have to plan several build stages in advance.

Thinking about the waterproof hatches I made up a dummy hatch assembly to do some measurements.  I thus figured the underdeck was going to be 1.5 mm too high.
Quite a bit of time was spent grinding down the bottom edges of the frame assembly to lower it a bit, making sure fit stayed intact.



Cutting clear Lexan is not as easy as plywood.  Card template, jig saw, and finish with files.  Reasonable fit. 



Before removing the protective films I will need to mark out the access cut-outs and nutsert holes, then do some careful drilling and cutting. 
The foredeck will be separate and enclose the various waterproof connectors and switches.

Would using an "o" ring style seal be less obtrusive.... something like this (forgive the poor paint drawing)
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Bob K

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #109 on: October 01, 2012, 12:08:34 pm »

Interesting idea.  Good sketch too.  This would make the overall thickness more compact, but unforunately I do not have the tools to create half-round groves. 
That would probably need a pillar drill and a ball section cutter.
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #110 on: October 01, 2012, 12:54:09 pm »

You don't need to put grooves in. You just need a piece of flat plastic either side of the o-ring cord- allow a bit of clearance for the cord to squish out.

Also note that it's best to put the bolts on the outside of the seal. If you use a sponge rubber type cord, I would think half a dozen screws per hatch would be quite sufficient- these hatches are not required to deal with water pressure, so you only need a small amount to keep the seal compressed.

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #111 on: October 01, 2012, 01:03:51 pm »

Interesting idea.  Good sketch too.  This would make the overall thickness more compact, but unforunately I do not have the tools to create half-round groves. 
That would probably need a pillar drill and a ball section cutter.

I have used a dremel with a ball ended grinding bit to do mine. made a template of the shape i wanted with a slight recess at the bottom to allow for the ball, then holding the shaft against the template I made the groove.

The shop bought water tight radio box I have in my huntsman actually has flat bottomed channels for the O ring Seal
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #112 on: October 01, 2012, 01:57:27 pm »

A square channel is the correct way to do it, and easier to make too.

If you want figures, I would use 4mm diameter rubber cord, either silicone or nitrile (Polymax sell this). Silicone tends to be a bit softer, and is also more reistant to ozone. Nitrile has a tendency to wetaher and age. I would use 3mm thick plastic sheet to form a groove either side 5mm wide. This will allow the seal to squish out as the bolts are snugged down.

http://www.polymax.co.uk/rubber-cords/silicone-cord/

Bob K

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #113 on: October 01, 2012, 07:36:16 pm »

Some interesting suggestions and discussion.

As you said, hatches need to be waterproof, not pressure tight.  My thoughts were that 2 mm Lexan has some flex, hence the number of holes.  Maybe too many?

The intended rubber beading is a “U” section greenhouse glazing bead that can be bonded to the edge of the hatch.   The underside of the removable main deck needs to sit flush with the hatch tops, so not sure if I can fit round section without cutting grooves.  4 dia with 25% compression would mean a 3 mm ‘gap’.  3 dia with grooves might work, if I can secure it to one face effectively.  To do so in one piece the grooves would need to be curved at the corners.  Tricky !

I was going to curve the hatch corners to have a single bead joint where the hatches abut.
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HMS Skirmisher (1905), HMS Amazon (1906), HMS K9 (1915), Type 212A (2002), HMS Polyphemus (1881), Descartes (1897), Iggle Piggle boat (CBBC), HMS Royal Marine (1943), HMS Marshall Soult, HMS Agincourt (1912)

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #114 on: October 01, 2012, 09:43:06 pm »

Giving this some more thought, it is logical that the seal would be better fitted inside the screws line now you mention it. 
Moving it to the underdeck reduces the access cutouts a bit but saves 1 mm by not having it on the hatch and may save possible handling damage when underneath.
M3 stainless csk socket head screws.


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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #115 on: October 04, 2012, 08:07:38 pm »

Every time I seem to be making progress I get stuck for something I have to end up ordering.  This time it’s as simple as a fine line marker pen that will write on shiny plastic for marking up the next set of clear Lexan parts, by marking through from the underdeck.

Also I’ve been having further thoughts on the gasketing after doing compression tests on the glazing rubber strip.  Back in my Drawing Office days we used a lot of MIL standard expanded neoprene for sealing cast aluminium electronics cabinets on submarines.  I have found some online and ordered it.  This will alter the design a little, but still keep access cutouts full size.  It will also avoid corner radii.  
Outer brass angles afix to the underdeck, inner to the undersides of the hatches.  OK, the angles are overkill but protects the gasket and aids hatch location.


With hatches secured the main deck will lock onto the underdeck.

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #116 on: October 04, 2012, 08:51:05 pm »

Pound shop, look for pens used for writing on DVD's or CD's.

Bob K

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #117 on: October 04, 2012, 09:08:15 pm »

Thanks Andy:  I had tried CD/DVD pens but they were too thick-nosed for accurate marking out.  Fine liners don't take to plastic. 
No worries, Faber-Castell Multimark 1513 pens have been dispatched so hopefully should arrive Friday or Saturday. 
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #118 on: October 04, 2012, 10:32:55 pm »

you can get some fineline markers in drawing pen sizes, I always had a .5mm one for fine work. I cant find one at the moment but Pentel rings a bell. but I guess faber castell will do the job.
Grendel
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Bob K

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #119 on: October 04, 2012, 11:40:55 pm »

If only I still had my old Rotring draughting pens Grendel.   {:-{
They were really precision tools, but it would take a long time for draughting ink to dry enough for handling though.
I mainly used 0.35 0.50 and 0.70 in the D/O.  That was before it all went CAD.
What I am marking onto is not the clear Lexan surface itself, but the translucent protective covering film. 
I am using a sheet of glass with a lamp under to simulate a Lightbox (which I also used to have for PCB work, but not now).
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HMS Skirmisher (1905), HMS Amazon (1906), HMS K9 (1915), Type 212A (2002), HMS Polyphemus (1881), Descartes (1897), Iggle Piggle boat (CBBC), HMS Royal Marine (1943), HMS Marshall Soult, HMS Agincourt (1912)

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #120 on: October 05, 2012, 12:03:12 am »

Hi Bob,

If you can draw in Cad you could probably have the lexan laser cut for the price of buying suitable pens...

An alternative to pens might be..
What about using masking tape (the thin paper type say 50mm width) then use fine line retractable pencils ? the thin masking tape should still allow for light to come through?

Regards,
Kim
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Bob K

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #121 on: October 05, 2012, 12:15:22 am »

Hi Kim.  You are on the right lines there, although I no longer have access to CAD either. 
I drew up strips in my DTP and temporally attached the printed strips to the underdeck with Prit Stick  (see image on earlier post).  I now need to accurately trace the hole and line positions onto the hatch panel.  With translucent protective films, hence the light source required underneath.
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HMS Skirmisher (1905), HMS Amazon (1906), HMS K9 (1915), Type 212A (2002), HMS Polyphemus (1881), Descartes (1897), Iggle Piggle boat (CBBC), HMS Royal Marine (1943), HMS Marshall Soult, HMS Agincourt (1912)

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #122 on: October 05, 2012, 12:30:03 am »

Hi Kim.  You are on the right lines there, although I no longer have access to CAD either. 
I drew up strips in my DTP and temporally attached the printed strips to the underdeck with Prit Stick  (see image on earlier post).  I now need to accurately trace the hole and line positions onto the hatch panel.  With translucent protective films, hence the light source required underneath.

Hi Bob,

I know you will probably want to do your own thing but if you were to trace the outline i could convert to cad and we could laser the lexan. Probably still cheaper than your fancy new pens :)

I know this sounds like an advert and yes it is but may help others ..

I could also laser the neoprene given we have a neoprene manufacturer just 'up the road '
If i can help I'd be delighted or if you want to do your own thing I'm also happy & forgive my intrusion on your build.
|Regards,
Kim
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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #123 on: October 05, 2012, 12:57:37 am »

I still have a full set of rotring pens (but alas no ink) but more importantly have CAD software as I have an educational copy (courtesy of an educational email address from the open university) you can get any version of the Autocad software as a fully functional version just by having an email address associated with an educational establishment. the drawback is when you print out it places a stamp on the border of the drawing, plus if you open the drawing in a non educational version and copy anything out it infects the new drawing with the educational stamp, and then autocad charge the earth to remove it - once the second time they will prosecute for licence violation.
I learned before CAD then moved on up to keep up with the times.
I use both autocad and its rival microstation (and like the good points of both, hate the bad points of both)
just getting into creating plans for model ships as a new challenge after my former employer decided to axe the whole department I worked in, then got a job part time with one of the subcontractors doing exactly the same work I had been doing, the olympics put most of our jobs on hold as no maintenace was planned during the event so we are now just getting back up to speed.
Grendel
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Bob K

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Re: H.M.S. Polyphemus (1881), not quite a submarine
« Reply #124 on: October 05, 2012, 01:06:24 am »

Kim

Thank you.  I have been reading the threads on laser cutting with great interest.  If I still had access to Pro/Engineer this whole build would have been much easier as I could have replicated the hull and produced accurate sections for all the frames and bulkheads decks etc.   If I could have done that I would have been more than pleased to send the DXF’s off to you to quote for laser cutting.  Could have saved me weeks. 

However, by ‘traditional’ methods described on previous pages I have had to be manually creative.  If I can trace this I can cut the holes through both thicknesses and the same time etc. 

Grendel

I can't access a student licence, I've looked into that, and would need a much higher spec PC.  I was in Engineering design most of my working life, then got made redundent as the firm wound down.  Sadly Britain is now mostly retail and banking, almost no manufaturing or design left.
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HMS Skirmisher (1905), HMS Amazon (1906), HMS K9 (1915), Type 212A (2002), HMS Polyphemus (1881), Descartes (1897), Iggle Piggle boat (CBBC), HMS Royal Marine (1943), HMS Marshall Soult, HMS Agincourt (1912)
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