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KeithAug

Schooner Germania (Nova) by KeithAug - Scale 1:36 - 1908 / 2011

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23 hours ago, Jim Lad said:

Looks like you're nearly ready to make sawdust

John - yes I am keen to move on - I may however have a go at the prop first - as a reward for getting through the drawing and colouring in marathon.

 

6 hours ago, wefalck said:

It may be worthwhile asking on what drawings his model was built. Keith, if you want, I can contact him and ask.

Wefalck - Thank you for the link - I have done a lot of internet trawling but I hadn't come across this particular build. The photos will be very helpful and any plan information would be most welcome if you could enquire on my behalf. Thank you for your help.

 

19 hours ago, Mark Pearse said:

 

Do you know how they manoeuvred the top staysail & topsail when going about?

Mark - I spent a long time wondering about this when I was building Altair. Here is by best shot at the answer:

 

The worst case is the obstruction caused by the (fixed) stays that brace the fore and main masts.

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Clearly the topsails have to be rigged on one tack and they are unobstructed by the rigging on the tack they are hoisted on.

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When going about, one option is to take them down and re rig them.

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I think only the most dedicated of crews would do this - and then not often.

Most crews seem to ignore the problem and just accept the loss of efficiency by letting  the sails lie on the rigging lines.

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I have only ever sailed sloops so I'm not an expert and would welcome any other views.

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So it's about time I made something to relieve the draughting blues. I am developing a habit of having go at the prop early in the build so here we go again.

 

I don't have any photos of Germania's prop but I can get enough detail from the plans (shown earlier) to get an idea of the size and shape. 

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From these drawings I think it is a 4 bladed variable pitch prop. I did a web search of variable pitch props and picked up a couple of images that were similar in shape (albeit they had 3 and not 4 blades).

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With the available information I drew and dimensioned the prop.

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I started the construction with a piece of brass machined to .385" width by .375 deep. This was to be the basis of the 4 blades. I machined one end to give a .040" web that would form the basis of a location / mounting pin. This web was off centre as per my design sketch.

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On to this I stuck the blade shape.

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I then shaped the blades with jewellers saw and files, leaving a small attachment web.

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Then it was on to the mill to slit off 5 blades - one spare in case of mishaps or workshop disappearances.

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I then cut off the web with the jewellers saw and feathered the blade edges with a needle file and emery cloth and then gave the blades a quick polish.

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At the base of each blade is a conical sectioned hub. I turned up a brass rod to .200" diameter with a .040" axial bore. I then cut a 45 degree chamfer on one end. This was then moved to the mill and the chamfered end was slotted with a .040" slot through the centre.

I could have used a slitting saw to form the slot but thin slitting saws tend to wander off the desired line, so I made a single point slotting tool. This consists of a round bar which fits in the mill chuck and holds a tool made from high speed tool steel.

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The mounting pin on the blade was then inserted into central hole in the hub and the blade was soldered in place.

 

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Then it was off back to the lathe where the blade hub was parted off .100" long. More to come later.

 

 

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On 1/23/2019 at 3:09 PM, wefalck said:

There has been a 1:100 scale (sorry metric ...) model of the GERMANIA by a German modeller:

 

https://www.arbeitskreis-historischer-schiffbau.de/mitglieder/modelle/germania3/

 

 

Hi Wefalck,

many thanks for sharing your link.

Next to the pics of the "Germania" I had a look at the member`s models of that Arbeitskreis-forum and can reccomend to look into the list of models........,  and was blown by the 1:100 model build log pics of the Atlantic liner "Augusta Victoria",      Wow !

Nils

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Keith,

That looks like a lot of filing and cutting to shape the blade; how are your fingers holding up?

RE: staysail tacking: back in the old days (1950's) I spent summers on an Alden schooner that came with a fisherman's staysail (Quadrilateral between main and fore above the foresail) and we had to lower it and rerig when coming about, if that's any help.

Tom

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Tom

36 minutes ago, TBlack said:

how are your fingers holding up?

Hi Tom. They are fine with the exception that my fingerprint recognition on my phone does not recognise me. I think I am now safe to commence my bank robbery career.

 

Re rigging must have been an awful pain on short tacks.

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So to finish the prop.

 

The next step was to make the hub. I started with a .500" diameter aluminium rod. I drilled the bore on the lathe (.125") to take the prop shaft. I then mounted the rod in a square collet block and drilled cross holes (.200") to take the blade bosses. 

 

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The rod was then moved back to the lathe and the end was turned down (.400" diameter) prior to turning the spherical hub.

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My ball turning tool then got one of its rare outings to turn the ball of the hub. The ball is actually symmetrical about the 4 radial holes - the camera seems to have introduced an optical illusion to move them off centre.

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The ball was then parted off to the correct length (as per drawing). I next made the exit cone from brass rod - .375" machined down to .282". The rod was then mounted vertically in the mill and the 4 mounting holes were drilled axially to form the bolt holes. Then back to the lathe to machine the 45 degree cone angle before parting off. I did leave a .125" protrusion on the parted off face to locate in the axial hole in the hub. The exit cone was then pressed into the hub. The blue pencil gives some idea of scale.

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The prop shaft was then superglued into the hub and then the blades were glued into the hub using 5 minute setting epoxy to give me time to set the angles. The gluing of the blades was done with the hub held in the lathe chuck and I used a piece of ply (cut at 30 degrees) to set the angles.

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I then made the prop tube / boss and did a bit of s clean up and polish.

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So now (unfortunately) its back to those annoying frame templates.

 

 

 

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Keith,  your propeller turned out to be very good, but in order to have absolutely everything correctly, it is necessary to twist each blade a little around its axis.

I hope that I do not interfere too much with your process.  :) 

s3.jpg

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Thank you John.

5 hours ago, Valeriy V said:

but in order to have absolutely everything correctly, it is necessary to twist each blade a little around its axis.

Valeriy.

 

You caught me out taking a short cut. For a 30 degree tip angle the calculated mid chord angle is 40 deg and the hub angle is about 60 degrees, (I used to design compressor blades which were equally affected by changes in velocity with diameter). I could have made a former and done a bit of tin bashing but I decided not to. Perhaps next time.

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7 hours ago, KeithAug said:

I could have made a former and done a bit of tin bashing but I decided not to. Perhaps next time.

Even so, but what you have done is exquisite Keith. I can see that this project is going to be a delight to follow. I really enjoy seeing how you approach these sub projects.

 

Michael

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8 minutes ago, michael mott said:

Even so, but what you have done is exquisite Keith

Thank you Michael. I thought you might say I should have put bolts in the 4 holes in the cone. I actually tried as I had a few 1mm thread  x 1.5mm head spectacle screws. Having spent some time cutting one down to size only to loose it, then doing it again and inserting it, I decided I couldn't see it at the bottom of the hole anyway. 

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And so back to the frames:-

 

I did, however, start with a diversion.

 

I decided to print out the side elevation. I tried printing at 1:36 scale but this proved a step too far as the loss of definition was marked. At 1:72 scale the definition was reasonable and multiplying dimensions by 2 to get the final scale seemed a reasonable compromise. At 1:72 the image printed out on 6 A4 sheets. I made a jigsaw of these and mounted them on a piece of MDF.

 

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I then spent a long time accurately cutting out templates for all 46 frames. You may recall that I had coloured the edges orange as a cutting guide. I offered the cut out templates up to the plywood that the frames were going to be cut from and decided that the orange wasn't a good contrast for sawing. To provide contrast I went over the edges again with a blue felt tip marker. 

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A this stage I also marked on;

1) the deck - red line on the above picture and

2) the cabin floor blue line on the above picture.

 

The curvature of the deck isn't very great so I printed out a set of large radius curves from the web and used one of these to make a marking out template from a piece of scrap 1/64" ply.

 

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I used the 20" curve as this seems to give the desired curvature.

 

I had purchased 4 sheets of 48" x 12"x 3/16" ply from which to cut out the frames. I have used the supplier before and they duly arrived a couple of days later - unfortunately they sent 1/8". I sent an email which was responded to within an hour saying they had already dispatched replacements and that I could keep the 1/8" sheets. The replacements duly arrived the next day. Good service is not dead!

 

I took some trouble in mounting the templates on the ply. Pencil lines were drawn at right angles to the edges and the templates were aligned accurately on both the mounting board edge of the template and on the centre line. Hopefully this will help with frame alignment during the build. I used a glue stick (Pritt Stick) for mounting as I wanted later removal to be reasonably clean and easy.

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I tried to minimise waste.

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Some time later I had all 46 templates mounted (and moved on to the snooker table as I had been "encouraged" to vacate the dining room).

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The next step will be some serious scroll sawing - a new learning experience as my previous use has been very limited.

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On 1/24/2019 at 6:13 PM, wefalck said:

Nils, are you a member ? You are welcome to join 😏

No Wefalck, not member of the German Forum, it would be too time consuming for me with two memberships, but thanks for the kind words....

 

Nils

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Hi Keith

 

Your prop - now, that’s an absolutely magnificent piece of metal workmanship.  It definitely sets the standard for the rest of the build.

 

I’m glad That you’re able to start making sawdust now, too.

 

Cheers

 

Patrick

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Keith, the layout of the frames on the sheets brought a smile to my face. It really is satisfying to be able to use the symmetry of the hull form to advantage when organizing the layout for cutting.

 

Michael 

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Thank you to all who have visited and thank you for the comments and encouragement. From your comments there seems to be a great desire for sawdust production and not wishing to disappoint I started the process.

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I had a few practice runs on some scrap and I played around with different blades. In the end I chose a 20TPI x .031" wide by .013 kerf standard tooth blade. I'm not sure what the best choice would have been as the permutations seem endless.

 

The primary skill to learn seems to be concentration. After a few minutes of focusing on the blur of the dancing blade I found my mind and the cut wandering somewhat. I decided to proceed with caution and cut the initial frames with about 1/32" waste. Just visible in the blown up image below.

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I will remove the excess with the disc and spindle sander later. Hopefully by the end of the week I will be proficient enough to eliminate the need for sanding.

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Keith

 

I am so happy to have gone wandering today and found this build.  Notwithstanding the incredible quality, it is your process I love watching to develop the frames from limited drawings.  I bought a scroll saw last year so I could advance my schooners to include frames.  I find the continual lift of the blade an issue even with the one way blades. I tend to break the frames on the inside cut if the wood is too thin. I since bought a spindle sander. I find it too strong and great for shaping but difficult for very delicate pieces as many frame shall be.  Somewhere between the two I will make some frames.  

 

anyway I look forward to following and  learning 

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41 minutes ago, Jond said:

I find the continual lift of the blade an issue even with the one way blades. I tend to break the frames on the inside cut if the wood is too thin. I since bought a spindle sander. I find it too strong and great for shaping but difficult for very delicate pieces as many frame shall be.  Somewhere between the two I will make some frames.  

I finally gave up on the scroll saw machines, I am thinking about a straight up fretsaw with the deep throat. I have also been thinking about a modification to an old idea, so that instead of a treadle type tool with the parallel arms. Of having only one arm on top that is flexible but long enough to eliminate the odd motion that the scroll saws seem to have, with a vertical shaft below that works only on the pull stroke and the arm pulls it back up. Ill keep you posted.

Nice to see the frames taking shape, Keith.

 

Michael 

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46 minutes ago, Jond said:

I find the continual lift of the blade an issue even with the one way blades. I tend to break the frames on the inside cut if the wood is too thin. I since bought a spindle sander. I find it too strong and great for shaping but difficult for very delicate pieces as many frame shall be

Hello Jon - It is good to be in touch again. I am not having too much trouble with lift but I am using a blade where I struggle to detect which side has the teeth on. This may be the reason why lift isn't a problem. The saw does have a device for preventing lift but I find it gets in the way so I have removed it.

 

My spindle sander is a drum mounted on my mill spindle and it does not oscillate. I use 240 grit and run the spindle quite slow and this seems to make it quite controllable. For fine work I stick Dremel sanding drums in the mill.

 

 

 

 

 

 

 

 

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My PROXXON fret-saw does have a down-holder/saw-guide that one sets just above the material that is being sawn:

 

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The sawing-/filing-machines of old had a kind of articulated arm, that could be arranged so that the tip was near the saw-blade. That's ok for working on small pieces, but gets in your way, when working on large pieces of wood:

 

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This kind of thing could be retro-fitted to many fret-saws. In the above example, the holders just clamp to the table.

 

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13 minutes ago, michael mott said:

I finally gave up on the scroll saw machines

Hi Michael.

 

Having spent a day on the scroll saw I think I could get to like it. My machine is parallel link rather than parallel arm. This  reduces the inertial loads and reduces vibration. The machine also has continuously variable speed and I have been running it at half speed and resisting the urge to put pressure on the blade. I may master the art, time will tell.

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