Pomeranian Rahschlup 1846 by wefalck – 1/160 scale – single-masted Baltic trading vessel

[wefalck]

Thanks again to all for their encouragement !

 

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Some small progress in the true and literary sense of the word:

Bilge-pump

 

Although not drawn in the original drawings, the ship must have had at least one bilge-pump. Such pumps would be logically located at the lowest part of the hull, usually somewhere close to the mast. As its location is not marked on the drawings, this is a bit of guess-work.

While Downton-pumps or similar existed already, when the Rahschlup was designed, they were comparatively expensive items. As the ship was built in a rather economically marginal context, it is more likely that a traditional wooden pump was installed, that could also be built and maintained with local materials and by local craftsmen, such as a blacksmith. Nicely rendered drawings for such pumps can be found, for instance, in the Danish naval yard archive.

Example for a bilge-pump from the former Danish naval yard (extract from G-2357-09)

 

The trunk would have been fashioned from a single tree, typically elm, that was bored out with the aid of spoon- or canon-drills in a sort of primitive boring-lathe. Iron bands kept it together and served as attachment points for the lever. 

 

https://youtu.be/pj-XKqW29XE?si=9Q8RTsXOMxMuPPVN 

Example for drilling of wooden pipes.

 

I made a rough sketch to fix the dimensions and settled on a height of 4 mm and a diameter of 1 mm, which would be 64 cm and 16 cm on the original respectively. The body was turned from a short length of acrylic rod, leaving the future bands as proud rings.

The mechanism is composed of four lengths of 0.2 mm tinned copper wire. The wire was first bent to shape and flattened at the appropriate places with a special kind of flattening pliers. Initially, I intended to solder the parts together, but they were just too small and flimsy, so I settled on cementing them together with lacquer. The procedure is a bit difficult to document photographically while doing it, so there are only pictures of the finished product.

The completed bilge-pump

 

I am afraid the translucent pump does not show very well in the photograph, but I generally only paint everything at the very end to avoid damage during repeated handling.

 

To be continued …

[JacquesCousteau]

Very impressive work!

[Keith Black]

 Very nice micro work, Eberhard. 

[BANYAN]

That pump looks great Eberhard, although translucent there is enough detail visible to show the craftsmanship that went into making it.

 

cheers

 

Pat

[wefalck]

Thanks again for your moral support, verbal and via the buttons !

 

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A Mystery Resolved

 

When constructing the hull of the Rahschlup, it bugged me that there was no obvious way to free the deck quickly from larger amounts of water taken over in bad weather. The Jacht/Jagt-type vessels often have a gap between the covering board and lowest bulwark plank, but on all illustrations of Rahschlup-type vessels no such gap was visible. Freeing ports, as on modern ships came into use only later and the lead-lined gutters would not be sufficient.

 

Then I scanned through the images of the restoration project (https://www.jensine.dk, but the link does not seem to work at the moment) for the Danish Jagt JENSINE (1852) for a different reason and two images caught my eye:

 They show that sections of the lowest bulwark plank are actually hinged and can swing out. In calm weather they are secured with latches. Subsequently, I noticed similar features on other restored vessels.

I am not sure that this is an ideal solution for securing, as the wedges would need to be removed individually and kept for re-use. Also, the latch is attached to the plank section and could get caught between the plank and the covering board. I think a solution with a hook fastened to the stanchion that engages a staple in the plank would be a better solution.

 

How to represent such parts now in 1/160? Producing the hinges will be relatively simple, although they will be tiny, but the hooks is another matter.

 

For the hinges I took 2 mm long lengths of 0.1 mm tinned copper wire that was squeezed flat on my repurposed watchmaker jewelling tool to a predetermined thickness. These jewelling tools have a micro-meter stop that allows to very precisely set the distance between the anvil and the stamp. By squeezing, the ends of the flattened wire become rounded, which suited well the purpose. There was also a slight dimple in the anvil from the turning, which resulted in a slight boss in the middle of the strip to simulate the actual hinging mechanism. The ‘hinges’ were glued on with varnish.

 

The latches are another matter and had to be much simplified. A double L-shape was bent into a short length of 0.1 mm tinned copper wire to simulate the hook and then one end was squeezed flat to represent the part that would have been screwed to the bulwark. These tiny pieces were then glued with varnish to the lowest bulwark planks and to the bulwark stanchion.

 

I decided to make only every second space between the bulwarks ‘swinging out’ and scored the lowest plank on the outside lightly to mark these sections.

Unfortunately, these parts are so tiny, that they are almost impossible to photograph, unless I use my macro-photography set-up and then they would probably look discouragingly crude …

 

To be continued …

[Bedford]

Yes my friend, some details are better left unphotographed as that could make them look quite crude compared to your normal standard of work but rest assured the bigger picture will suffice as we know they will be very well built.

[BANYAN]

Nice find/observation Eberhard, any other puzzles to resolve?

 

cheers

 

Pat

[wefalck]

Hopefully not too many, Pat !

 

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Another small toolmaking digression

 

One of the great advantages of watchmaker’s lathes is the multitude of work-holding options/spindle tooling. There are collets and chucks of many different sizes and types. One type, however, never seems to have been made and this is collets with square holes. In a way it is understandable, as making exactly centric square holes with the technology available 50+ years ago, would have been quite a challenge and expensive. Today with EDM that would not be a problem anymore. It seems that watchmakers actually had little need for them and when they needed to chuck up a winding stem at the square end, they would have used a so-called 8-screw chuck, which however, is worse to set up than a four-jaw independent chuck.

 

I expect to have to work at the ends of some square section materials soon. While I have also a centric four-jaw chuck for the lathe, it does not fit onto micro-mill and for parts of less than 2 mm edge length it is not very precise. Working on such small parts in a chuck does not feel very safe either. Therefore, I decided to finally implement and idea that I have been tossing about for years: square insert collets. A standard fitting for watchmaker’s lathes is a set of brass insert collets that are used to hold delicate objects, such as small screws by their threads. They fit into a 5.0 mm collet and have three slots to ensure concentricity. The idea was to make collets with two cross-wise slots (like the cheapo brass collets you can buy for handheld drills) and a bore in the centre. By combining an appropriate slot width with an appropriate bore, you can make square stock fit diagonally into the collet and centre it exactly.

 

I worked out the geometry needed for 1 mm, 1.5 mm and 2 mm square stock/parts respectively. The other dimensions were taken from the existing insert collets, i.e. the diameter of 5 mm and the length of 20 mm. Blanks were turned up from some quality old brass rod, bored from the back with 2.5 mm and threaded M3 for depth stops to made at some later stage, if needed. The blanks then were turned around and drilled 1.1, 1.7 and 2.4 mm respectively for the three collet sizes. A shallow groove turned in facilitates the extraction from the main collet. The parts then were transferred to the mill and set up in a vice with a square collet block for slotting exactly across the centre. They were all slotted 0.5 mm.

 

A test turn with a 1 mm square polystyrene rod shows that this works very well.

Size 1 mm, 1.5 mm and 2 mm square insert collets for 5 mm watchmaker’s lathe collet.

 

Back to the Rahschlup now.

[druxey]

I have seen square-hole WW type collets offered on sBay in the past, but they are rare and consequently expensive.

[wefalck]

Really ? I have only seen such 5C collets and other larger types. Schaublin at some stage offered them on demand I think, but don't ask about prices ...

Edited 4 hours ago by wefalck