Jump to content

Recommended Posts

Back to the hull and in particular the openings.  The forward scuttles where marked from a print of the drawing and then opened up gradually using successive drill sizes finally completed with a fine bur.  These will be covered with etched frames later.

 

The rear openings are the engine cooling water outlets and that stick out slighty from the face of the hull and are in turn protected with a prominent timber rubbing strip that curves down below the outlet.  This is clear right at the bottom of this IWM image, which is also the best picture I have of the rear hatch, more of that later. 

 

Anyway, these rubbing pieces curve into the hull and prevent snagging.  One key point is that there are three engines and so three engine outlets, two on the port side and one on the starboard.  However, on the starboard side there is a smaller un-faired outlet for the standby generator engine.  The drawings I have (which seem to have been coped from each other) only show the starboard side, so be careful, the sides are not identical 

 

THE ROYAL NAVY DURING THE SECOND WORLD WAR

 

These fairings are an interesting challenge as they are quite chunky.  In the end I turned down a piece of 10 mm dowel from jelutong and drilled it out  with a 6 mm hole giving me a short length of wood tube, seen here cut free

 

DSCN2318

 

This was then cut longitudinally and the side wings glued in place ready for final sanding.  The outlets are  4 mm brass tuning, pieces shown in this out of focus picture below

 

DSCN2319

 

The fairings are then glued to the hull and final shaping done in-situ, port side below

 

DSCN2322

 

A little more final finish sanding still to go, but you can see the idea, this all worked really well

 

Starboard side has the higher un-faired standby generator engine outlet (3 mm brass tube)

 

DSCN2323

 

Last on tnhis update is the raised forward engine room roof, not totally cream on the drawings, I think this had some scuttles in the sides, more staring at pictures needed to decide, certainly on picture of MTB74 shows small scuttles but this was a variation of the early 70ft boats so not conclusive.

 

DSCN2324

 

So, basically, I'm working my way back with the wood substructure elements, more later

 

Cheers

 

Steve

  • Like 12
Link to comment
Share on other sites

1 hour ago, Dmitriy1967 said:

I don't know how it will be after painting

First, the planks are much wider than scale, I believe they were 6 inch planks, so ~3 mm, these are 5 mm wide for expediency

 

But, my hope is that I'll still be left with the "impression" of diagonal planking, so not totally smooth, but also not massively in your face.  The challenge with the sanding is not to remove all the joints (which is anyway hard) but some of that detail should remain apparent, in particular under certain lighting

 

This is all I'm trying to achieve, an impression of the real vessel and a model that shows more detail as you look closer.. To a point, it should get better the closer you are :wink:

 

Sometimes it works....

  • Like 3
Link to comment
Share on other sites

Broke away from the build today to draw the prop's and send them off to Shapeways for casting in bronze.  These propellers are quite small, only 26 inches in diameter and 10 inches long (13.7 mm and just over 5 mm scale.  The drawings I have are all too vague to be of any use bar the overall size but there is one image of the props of a similar MTB and I've used this as inspiration.

 

Now, a word of caution, I am not clever enough to draw an actual marine propeller, that's way above my paygrade.  But as I showed wit the S-boat and the SGB, I can get something close to work without a huge effort.

 

First, I drew the hub, so far so simple.  Then I sketched a blade shape that fills 100 degrees of the circle, which seemed about right.  I then extruded that to 0.6 mm thick and sliced it into 8 slices.  Then I drew an ellipse in each slice.  Then, starting at the root slice which was rotated 70 degrees, I rotated each ellipse, washing out 10 degrees of rotation each time leaving my final slide (half a step) at 5 degrees.  Then the ellipses where "lofted" to create a 3D blade and that was replicated 3 times round an axis and combined with the hub.  

 

Now, this is not how you draw a propeller, but the result certainly looks like a propeller and as this is a static model, I don't have to worry about it working, just looking about right.  The fact that Shapeways will cast this in bronze actually means more to visualisation realism in my opinion than the exact shape.

 

The picture below shows all the stages in the process (software is 123design, which is free and I'm used to it).  You will see that the outer edge has a flat, that's the result of lofting the ellipses but I can file that easily to a smooth curve, it is tiny..

 

MTB props

 

Obviously, there are right and left hand versions, just rotated the other way.  The hub (or boss) is drilled 1.6 mm for the prop shaft, I'll turn the prop-shaft outer support on the lathe

 

Anyway, $12.50 each plus shipping etc, should be with me before Christmas.  With expedited delivery charge, they are £24 each, would be a lot cheaper in bulk.  The Shapeways software does an auto-check when you load a file to ensure it can be printed, I hope the manual check on Monday works so that they can be manufactured

 

Cheers

 

Steve

  • Like 7
Link to comment
Share on other sites

Continuing the propeller theme, today I pulled the outer prop shaft outer mounts together

 

These start as three 2.8 mm diameter tubes (ID 1.6 mm) 8 mm long and tapered @ 15 deg, forward, here sitting on the porp shafts (1.6 mm brass).  Note, the internal shaft tubes have been cut back to length, they were oversize before.  You will see a theme developing in my modelling, I always cut over size (length etc) and then cut back, file back, sand back etc.  I've long since stopped trying to make stuff the right size before assembly, just too difficult...

 

DSCN2325

 

From the drawing I then filed a section of 0.8 mm thick brass strip to shape, well over length and then cyno'd it to two similar strips and filed the lot to an identical shape.  None of this is really critical or I wouldn't be able to do it...

 

These strips are then silver soldered to the tubes set up as shown below, remember the solder flows to the heat so heat the thickest piece away from it and suck it in

 

DSCN2326

.

The brass rod is a packer to try to get the joint on the centreline of the tube.  At the end I got these three, not identical, but pretty close, who will see?  These have been cleaned up with a wire brush, solver solder loves clean metal so important to clean between stages.  I've also added a little streamlining to the edges

 

DSCN2327

 

Then these were offered against the tiny drawing and sawn to length (or slightly over).  Then they are fed down the prop shafts to see there they end up.  This enables you to file the last stage away in very very small amounts, remembering that they will be mounted to 0.5mm strip so they need to sit back from their final position before soldering

 

This is the set-up to solder them to the plate that is glued to the hull.  You will see I've not bothered to cut the 0.5mm strip, easy to hold it steady away from the joint and cut it later.  These strips are 1/4 inch wide btw

 

DSCN2328

 

I use a vermiculite block that is soft enough to allow drawing pins to be pushed in to hold things in place, these break up after time but last a year of so, about £15 each, anyone wants the links, let me know

 

So, after soldering, they are cut roughly back with snips and then filed to final shape.  For this sort of filing, I use a mircomaster drill and sanding disk, so that it is easy to take off tiny amounts

 

They are attached with epoxy, I don't trust cyno for these, too brittle.  The epoxy overspill will be cleaned up once set

 

DSCN2329

 

Another job ticked off, ready for the propellers  👍

 

Cheers

 

Steve

  • Like 14
Link to comment
Share on other sites

Very interesting, Steve! I have to do the same job soon. Oh, my God, I've never soldered anything in my life! 🙄

 

I was surprised how close the propellers are mounted at the transom. I even started looking for a drawing. Surprisingly, the steering wheel plates are moved back.

 

Edited by Dmitriy1967
  • Thanks 1
Link to comment
Share on other sites

1 hour ago, Dmitriy1967 said:

I was surprised how close the propellers are mounted at the transom.

With these MTB's the rudders are behind the transom so the propellers are right up against it.  The horizontal plates above the rudders create a downward force at speed to keep the bow in the water.  This design requires the props to be right at the stern and the rudders to be external.  interesting design

 

Steve

  • Like 1
Link to comment
Share on other sites

An update containing lots of bits.  Been mixing making stuff with drawing stuff, nothing very conclusive.

 

Here is the forward hull fin that improved directional control.  Brass and soldered to some of the double T section I used on Grey Fox for the bilge keels.  Epoxied to the hull later

 

DSCN2330

 

Then, I decided to make the rear hatch from copper, can't etch everything...  The hatch has a sliding curved cover which make this an interesting item to construct.  As before, these are made around wooden bucks which are removed later.  For copper I use soft solder mostly, it has a tendency to melt with silver solder heat

 

Set-up below ready to solder

 

DSCN2331

 

And finished and cleaned up, wood still in place.  The front side needs filing back later, see completed shots below

 

DSCN2332

 

Next, the actual hatch and hatch cover which is inside this housing

 

DSCN2333

 

And finally with the outer sliding cover made and attached

 

DSCN2334

 

This is all out of 0.3mm copper sheet

 

Lastly on the build side, I installed the depth charge and mine hard rails.  These are clear in the photo above as quite high and with a small step to the deck edge, a little more sanding needed but a start has been made

 

DSCN2337

 

I'm not sure how interested anyone is my 3d drawings, but here is the finished artwork for the 10 cowl vents, ready to print

 

cowls

 

And my first pass through the smoke machine, dimensions fro an elevation on one of John Lambert's drawings and detail from a picture I found on line from a US navy instruction manual.  I'll add some brass wire and tubing to this once its printed

 

smoke

 

So, nothing major, just working my way round stuff I can do while I think through the etching artwork which I plan to start this coming week

 

Cheers

 

Steve

  • Like 12
Link to comment
Share on other sites

I've just read through this whole thread: what I know about MTB's could be written on a postage stamp and there would be enough space left to include my full knowledge of scratchbuilding.  I'm in awe of what you're doing here.

  • Like 1
  • Thanks 1
  • Haha 1
Link to comment
Share on other sites

I've started the etching drawing, but to break things up (too much screen time, boring...), I made the rudder assemblies in brass.

 

First to make the mounts, I silver soldered a length of brass tubing to a strip of 1/4inch brass, below before soldering

 

DSCN2342

 

This is then easily sawn into three different lengths, bottom, top and manual support, seen here below cleaned up, rudder shaft in the foregro9und

 

DSCN2343

 

I then made the rudders out of .8mm brass sheet, cut out roughly and then soldered together with paste for final filing so they end up identical.  The top then has a small notch filed in for the 1.6 mm shaft and then heated to separate them, seen below the first after silver soldering but not yet cleaned up

 

DSCN2344

 

And here both finished and cleaned up, the shafts are overlength of course, cut down later

 

DSCN2345

 

And below the supports epoxied to the hull in a rather odd support arrangement to make sure the stern is horizontal while the epoxy sets

 

DSCN2346

 

The smaller upper support on the starboard side is for the manual rudder, the rudder shafts finish just above the middle support.  There is a cap piece that would have held the actuation lever penetrating the hull to add much later in final assembly.  This will support the rudders so that they can move, they are installed here for alignment only

 

Lastly, the beginning of the etching work, these are the anti-slip canvas edging, printed out and laid on the hull to check fit.  These small strips of brass will edge linen pieces to simulate the canvas decking in those areas

 

DSCN2341

 

I have plenty of drawing work for the etch sheet, will include details as they are developed.

 

Meanwhile, after studying the picture posted above closely, I improved the old 3D drawing or the Depth Charge in its rack that I did for the Fairmile B, added more detail, rivets etc, this one is better

 

dc

 

Progress on many fronts as ever

 

Cheers

 

Steve

  • Like 12
Link to comment
Share on other sites

Lovely work on the rudders and their supports :yes: although I'm quite surprised you didn't manufacture the nuts and bolts to fix the mountings instead of epoxy :wink:.

Always great to watch the working of all those materials. Carry on good man.

 

Stuart

  • Like 2
  • Thanks 1
Link to comment
Share on other sites

10 minutes ago, Courageous said:

you didn't manufacture the nuts and bolts to fix the mountings

Thanks Stuart.  I did in fact consider etching the flats with raised nuts but in the end I wanted to make progress on getting these in place and I've still some way to go on the etching artwork.  You are right to point it out (I know in jest), the lack of surface detail on those supports does worry me but it will remain one of the many compromises I'll have to live with 

 

Steve

  • Like 2
Link to comment
Share on other sites

3 minutes ago, beefy66 said:

very fine work as usual

Thanks Beefy, the pictures flatter the errors...

 

Currently having a lot of fun drawing the etching for the torpedo tube frames,  I have pictures of at least 5 different types of frame, and while the MTB34 pictures don't make it clear, I'm sure 7 squarish holes to the bow end (not round as fitted later) is right with narrow slots beneath the tube support brackets.  The drawings I have disagree on this detail.  I suspect a lot of these drawings simply copy each other (even the Vosper drawing is not necessarily "as fitted" and may have made assumptions regarding the torpedo fitting, who knows?)

 

All part of the joy of scratch-building from your own drawings....

 

Steve

  • Like 3
Link to comment
Share on other sites

More 3D drawing, this time for the torpedo tubes.  For the SGB, I made the tube fittings from brass which I recognise is tough for people without a lathe, so this time I'm going to print the fittings but still use brass for the tube itself and the reinforcing rings (next size up, short lengths, soldered or glued in place)

 

So, the fittings are the assembly flanges, the end cap, the breech mechanism and latch tripper, still thinking about the charging valve assembly which is very tiny, may not print worth having.  These pieces will have a few etched components added from the etch sheet, hence the drawing now as I have to develop all the areas that need etched attachments before I can finalise the etching artwork.  I ALWAYS miss stuff off the etching sheet, normally realising this the second it arrives... Very frustrating as components are basically free to add before, very expensive after...

 

I'm using John Lambert's drawing from Allied Coastal Forces Vol 2 which is the best drawing I have, though without a 3D render, some details are not clear.  It is the 21 inch LC Mk1 tube

 

Here is where the drawing has progressed to, with the brass tube sections added in semi-transparent to show how it will come together, the darker grey items are printed.  This does allow me to show the bolts on the flange joints which I couldn't do with turned connectors.

 

tt perspective

 

Closed up of the breech assembly

 

tt perspective2

 

Ha, I've just noticed the key on the latch tripper is at the wrong end, got to keep checking this stuff.  It's not symmetrical as it sits slightly offset.  The dome handles will be 0.5mm brass wire

 

Cheers

 

Steve

 

 

  • Like 9
Link to comment
Share on other sites

Absolutely marvellous seeing this come alive.

I remain in sheer awe of the variety of building skills, the most recent of which being the CAD/3D printing :clap2:

The wheelhouse really looks the part and not easy with all those odd angles

Rob

  • Thanks 1
Link to comment
Share on other sites

12 hours ago, robgizlu said:

The wheelhouse really looks the part

Thanks Rob, any feedback is always much appreciated.  The wheelhouse still has some way to go as the exterior will be clad with etched brass sheets which will also make up the wind deflector, it works out to be ~10mm higher than it is now.  The actual wheelhouses where externally plated, look closely at the pictures and you can see how thick the walls are at the window openings with no exterior frames, hopefully I will be able to recreate this look.  Later this week i hope to get on to that stage of the etch sheet drawing which is admittedly quite a complex task. I'll post here to show what I mean.  Meanwhile I've had the printer going once again, should have some of those items to show later

 

Cheers

 

Steve

  • Like 2
Link to comment
Share on other sites

Steve - I appreciate you have an element of an engineering and design background.

How long do you estimate that it would take a complete beginner to be able to produce hulls (small ones) in 1/350

I presume you are using Fusion 360 (Autodesk) - I've just sat through a tutorial suggested by @bootneck on You tube by Arnold Rowntree (Future engineering) that Mike references in this thread

 

I understand it but need an "adult" to give me an estimate of how long it's going to take me (No engineering or metrics background) to get to producing CAD designs for hulls to be printed using original paper (non digitised) plans.

I know this is a hard one and is going to be a very rough approximation.  It will help me to decide whether time spent is worth investing

Thanks if possible

Rob

  • Like 1
Link to comment
Share on other sites

45 minutes ago, robgizlu said:

I understand it but need an "adult" to give me an estimate of how long it's going to take me (No engineering or metrics background) to get to producing CAD designs for hulls to be printed using original paper (non digitised) plans.

I know this is a hard one and is going to be a very rough approximation.  It will help me to decide whether time spent is worth investing

Hi Rob,

 

Nice to be called an adult, I'll have to tell my wife... :rofl:

 

Wow, that's such a hard question.  I don't use Fusion, I use 123D, still they are all probably much of a muchness.  I've watched the stuff that @Iceman 29 produces and it simply blows me away, I feel I'm just about up to cleaning his shoes.  He may be a better person to ask

 

First 3D drawing is quite different to 2D drawing of which I've spent a lifetime on.  I trained as a Structural Engineer so was brought up preparing, checking and signing off drawings (old school, pre-computers, rooms full of drawing boards, happy days...).  This means I've very happy interpreting and rescaling drawings but my experience with 3D shapes if far more limited and to be honest after 6 years, I'm still learning and I hope getting better.  The thing to realise is that its not just about drawing something correctly, you also need to draw something that can be printed and that takes more thought regarding thicknesses, unsupported shapes, details that won't print, holes that will disappear when printed etc etc.  I've read all the guidelines, but the more complex the shape becomes, the more challenging this aspect is.  I'm also someone who is generally dissatisfied with everything I produce, which doesn't help...

 

Lastly, hulls are tough as using 123D, you would use a loft function to join the transverse frames, but that doesn't work at the bow as you can't loft to a curving line.  I've tried ships boat's hulls and just given up in disgust, it probably needs mesh work to model the hull entry (connected triangles) but I've not bothered to learn 3D mesh design, jelutong blocks and sandpaper solve this problem in my world...

 

So, I would say that to get a 1/350th scale hull modelled accurately in a form that can be printed and that you will be happy with, is a serious investment in time and frustration.  From a standing start, I would think in terms of months not hours.  Just getting these MTB frames modelled in 2D from a scan so they could be laser cut, with all sheer and transverse lines in a way I was happy with probably took me around 80 hours (it didn't help that the scan wasn't that great to start with...), and I'm very fast on 2D software.  That said, I really quite like 3D drawing, and the more you do, the quicker you get like everything

 

I'll let Iceman add his comments, his hull work is a masterclass in 3D design :worthy: 

 

Hope that helps

 

Cheers

 

Steve

  • Like 3
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...