Mike Y

Impressive! You managed to preserve that smooth "corner" in the transition between the flat bottom and angled sides, creating a very beautiful line It would have been too easy to loose it during the fairing process!

I use a very thick black fishing monofilament for the bolts (designed to catch alligators and giant squids, I guess). No problems with any chemicals bleeding into the wood, etc. It is held inside the wood with CA glue and sands nicely to be flush.
 

Nowadays, I use almost exclusively the larger Proxxon PD 360 lathe for all my needs, so my Unimat 3 is practically unused, but some time ago I decided to modify the hopeless original power transmission to toothed belts. Simply put, the frequent replacement of broken V-belts (actually round in cross-section), and also their tendency to slipping, became too annoying over time.
 
The attached video shows a prototype drive system made to verify in practice the assembly and operation of the replacement kit, and the attached photo shows most of the components from a few sets that I made with a view to selling them to other Unimat 3 users. All components are already fully machined and with tolerances within 0.03 mm for important dimensions. The replacement set maintains the same rotational speeds as the original.
 
I also thought about replacing the motor with a more powerful one, but this could be too much of a strain on the rather delicate Unimat 3 and could lead to rapid damage of the lathe that would be difficult to repair or costly.
 
 

Unimat 3 modified.mp4    
 

 

I've never found any citation to academic authority answering that question. I do have a theory, though.
 
There are different types of "curves." Specifically, there are ship's curves, of which the two most common sets are "Copenhagen curves" and "Dixon Kemp's curves." There are "irregular curves," also called "engineering curves" or "Burmester's curves." And there are "French curves."  (I  don't know why they were called "French curves."  The British always seemed to add a place-of-origin adjective to anything from elsewhere. Perhaps it was intended as an insult, much as they called condoms "French letters" and syphilis "the French disease."
 
Burmester designed the now-classic set of 28 "irregular curves" bearing his name in 1904, at least 150 years after the differently-shaped "ships' curves" came into common use. "French curves" were also in existence long before Burmester designed his curves.  Of Burmester's set of 28 "irregular curves," three are the most commonly encountered today and are still in production and sold in art and stationary stores, often incorrectly labeled as "French curves." Burmester's curves are mathematically defined curves designed to solve mechanism solutions for full link rotatibility, compactness criteria, and feasible transmission angles in multiple position linkage mechanisms. (Or so says one research paper.)  Each curve is defined by algebraic equations. Beyond that, it's way above my pay grade!   In summary, Burmester curves can be used to draw fair curves in the same way as French curves or ships' curves, but they were specifically designed for use in mechanical engineering to design linkage systems.
 
As far back as we know, patterns and templates were used in shipbuilding by the Romans, who built fleets of sister ships from standardized full-size lofting patterns. The use of drafting curves in naval architectural drafting appeared in the Eighteenth Century contemporaneously with the practice of drawn ships plans demanded by the development of  scientific approaches and the use of theoretical models in naval architecture, which previously had been an exercise in trial and error and "monkey see, monkey do."  In Western Europe, at least, the "Father of Scientific Naval Architecture" was Fredrik Henrik af Chapman of Architectura Navalis Mercatoria (1768) fame. Chapman devised the "parabola method" of ship construction and design, which identified the relationships between certain fair curves and their effects on speed, stability, and the displacement of ships. (Increased stability was a huge advance.  More displacement and stability meant more guns could be mounted and higher above the waterline, which meant they could open the gun ports in heavier weather.) It may be presumed that as Chapman's scientific curves were adopted as part of the naval architect's lexicon, curve templates for drawing them were created. Chapman's curves were, like Burmester's, defined by algebraic equations, but for different purposes.
 
I suspect we have Chapman to thank for the English term "Copenhagen" curves. Chapman's theories certainly occasioned their invention even if that was by someone else. Chapman was an interesting fellow in many ways. He was a self-made shipwright who virtually invented scientific naval architecture, going back to school to learn the cutting edge mathematics of his time. In the mid-1700's, as most know, Western Europe was in political flux and wars were commonplace. Chapman was British, but born in Stockholm, Sweden, to a British father. He traveled around, studying the shipbuilding practices of the various nations' navies. At one point, that landed him under house arrest in Britain, which considered him a bit too cozy with the French, and, right after that, tried to hire him to design ships for the Admiralty. He almost did, but then took a similar job with the Swedish. In those days, his ability as a warship designer made him the Werner von Braun of his day, with nations so eager to secure his technical expertise that his prior political affiliations were ignored. But Copenhagen is in Denmark, not Sweden, and Chapman worked in Stockholm. That is so, but from 1397 to 1523, all of Scandinavia had been united under the flag of the "Kalmar Union" and Norway continued to be united with Denmark between 1524 and 1824. Copenhagen was the capitol of the Kalmar Union and the Norwegian-Danish Union. It's reasonable to conclude that Chapman's technology was common to all the Scandinavian nations and, from the perspective of  England, anything coming from Scandinavia might be called "from Copenhagen" in much the same way the world refers to "Washington," "London," or "Moscow" to reference the U.S., Britain, or Russia. And so, they became "Copenhagen curves" because that's where the English thought they came from. They already had "Stockholm tar," so maybe they thought they'd spread the credit around and call them "Copenhagen curves."
 
At least that's my best guess. Can anybody shed any more light on the subject?

Beat me to it! That's a copy of the Keuffel and Esser catalog page showing the Copenhagen curve set. There are 56 curves in the standard "Copenhagen curve" set. Check out the old K&E catalogs on line and find the details. Here's one:  http://archive.org/stream/pricelistcatalog00keuf#page/231/mode/1up   They were sold as sets, but I believe they could also be ordered individually. Each curve has a K&E part number on it. The famous British naval architect, Dixon Kemp, designed a set of ships' curves, as well in the late 1800's. Kemp's curves were sort of "egg" or "kidney-shaped" and nested inside of each other with three or four "rings" to a set. The sets, of identical shapes, came in two sizes. I've seen pictures of these in books, but have never seen them in the flesh. They were a British item and apparently never caught on in the rest of the world.
 
 

Beautiful build, subscribed with interest 😊 Looks like it is by far not your first POF build based on the quality!

Beautiful build, subscribed with interest 😊 Looks like it is by far not your first POF build based on the quality!

I started with both of my daughters around the age of 6 (see the Polotsk build in my signature, the youngest does not have a build log yet). It may sound young, but at that age they usually have basic precision required.
 
Of course the motivation is different, they saw me modelling and wanted to try that too, to a large extent as a together-time, as opposed to going into the hobby purely for the sake of hobby.
They were never interested in getting the final result, but wanted to try the process. Sanding wood, shaping wood - all of that was a learning curve and a joy. It is very different with plastic and not sure fiddling with plastic glue and tiny parts is enjoyable.
Do not expect that the model would be completed, it's too much of a stretch. And by the age of 10-12 they have got a lot of other hobbies, so might be too late   Expect that they would never finish the model, and by that age - would stop caring about finishing, but would hopefully cherish the memories you had together.
Modelling for them is just an excuse to try all these new skills and spend time with their dad, while feeling a joy of building something more complex than a Lego.
Surprisingly the type of a ship does not really matter, as long as it is a fairly straightforward kit where you just cut pieces, glue them together, etc. But it is really beneficial to have a kit with pre-splined planks that would fit together nicely.
 
Skill-wise expect to teach them the very basics, that we, adults, do not even think about. Keeping the knife straight (yes, they can already use it carefuly), moving file straight, how to hold a piece of sandpaper between your fingers, how to draw a pencil line on wood, etc etc. And prepare some scrap to practice, of course. 
Some tools are off-limits though - no table saw, very careful with disc sander. Dremel is fine, but watch out for hair and sleeves. Band saw can be introduced a bit later. 
Introduce dust and eye protection for certain operations from day one, for them it is very natural and not weird if they see you do it as well.
Prepare for practicing every new skill on scrap pieces, for kids to sidetrack to "side projects" like building random stuff out of cutoffs and similar foolery. It might be frustrating, but again - the journey is the goal, not the destination.  
 
Of course it is all very anecdotal and your experiences may vary, just sharing mine. Do not wait until they are pre-teens, do not start with plastic, just dive right into the wood if that is what they want. There is nothing extremely difficult in cutting and gluing wood pieces for elementary school kids. Just need supervision and patience.
 
Some teaser pics, she has just turned 6. 

I started with both of my daughters around the age of 6 (see the Polotsk build in my signature, the youngest does not have a build log yet). It may sound young, but at that age they usually have basic precision required.
 
Of course the motivation is different, they saw me modelling and wanted to try that too, to a large extent as a together-time, as opposed to going into the hobby purely for the sake of hobby.
They were never interested in getting the final result, but wanted to try the process. Sanding wood, shaping wood - all of that was a learning curve and a joy. It is very different with plastic and not sure fiddling with plastic glue and tiny parts is enjoyable.
Do not expect that the model would be completed, it's too much of a stretch. And by the age of 10-12 they have got a lot of other hobbies, so might be too late   Expect that they would never finish the model, and by that age - would stop caring about finishing, but would hopefully cherish the memories you had together.
Modelling for them is just an excuse to try all these new skills and spend time with their dad, while feeling a joy of building something more complex than a Lego.
Surprisingly the type of a ship does not really matter, as long as it is a fairly straightforward kit where you just cut pieces, glue them together, etc. But it is really beneficial to have a kit with pre-splined planks that would fit together nicely.
 
Skill-wise expect to teach them the very basics, that we, adults, do not even think about. Keeping the knife straight (yes, they can already use it carefuly), moving file straight, how to hold a piece of sandpaper between your fingers, how to draw a pencil line on wood, etc etc. And prepare some scrap to practice, of course. 
Some tools are off-limits though - no table saw, very careful with disc sander. Dremel is fine, but watch out for hair and sleeves. Band saw can be introduced a bit later. 
Introduce dust and eye protection for certain operations from day one, for them it is very natural and not weird if they see you do it as well.
Prepare for practicing every new skill on scrap pieces, for kids to sidetrack to "side projects" like building random stuff out of cutoffs and similar foolery. It might be frustrating, but again - the journey is the goal, not the destination.  
 
Of course it is all very anecdotal and your experiences may vary, just sharing mine. Do not wait until they are pre-teens, do not start with plastic, just dive right into the wood if that is what they want. There is nothing extremely difficult in cutting and gluing wood pieces for elementary school kids. Just need supervision and patience.
 
Some teaser pics, she has just turned 6. 

The Bellona balcony and corresponding quarter galleries are undoubtedly the most difficult things I have ever attempted to make! Progress is slow but moving along.
 
To make accurate card patterns for the panels in the balcony, I first needed to construct the balcony moldings both at the level of the deck and the level of the railing. I had decided to capture the panels in rabbets, so I constructed the moldings in two parts (see below). The molding at the railing level will have a seam between the fore and after parts, and it will prominently show, so I needed to fair these two together as accurately as I could. To make it more interesting, the aft part runs all the way across the stern, while the fore part is trapped between the two sides of the hull. I pinned the aft one in place and then used graphite paper squeezed between the two to locate high spots. Trim and check, trim and check.....
 

The fore piece also needed the rabbet in its lower outer edge, and a molding on the fore face. Here it is:

With these pinned in place, I could then make up card patterns for the panels and the stanchions between. I made up small pieces of card that could fit firmly on the lower rabbet, and glue to the next card fitting firmly in the lower rabbet. With the lower curve firmly established, I could then trace the lines of the upper and lower moldings on the face of the card assemblage. You can see this in the second row first column below. I then scanned this and put it into my CAD program to trace and then draw in the detail.
 
This proved to be surprisingly difficult. It seemed every time I drew one, glued it to card and installed it, the curves were wrong. Here is a selection of failures:
 

I finally got one to work.
 

The moldings top and bottom are still oversized and unmolded to keep them rigid until I can install the panels.
 

Meanwhile, I finally painted the blue on the quarter galleries. Here we can see for the first time what the original Bellona ornament might have looked like on the quarter galleries. these are just resting in place, not yet glued down. So they are not entirely in place and not tightly pulled down to the underlying surfaces. But it shows what we are headed for.
 
I give full credit to Chuck Passaro for this. He offered his laser cutting skills when I was bemoaning how I would ever make these, then he cut them beautifully, and then he pointed out in an earlier version that everything needed thinning down. What it looks like now is a great deal due to his skill and practiced eye. Thanks, Chuck!
 

 
 
I now need to do some experiments with super gluing these together. I think the wide panels need to be glued at their edges into the red stanchions. And then the filigrees over the red stanchions need to be glued down onto the mating surfaces of the panels. I have to avoid at all costs any glue on the blue or red surfaces. But these parts are only .026 inches wide. I am going to experiment with 1) taping everything in place, then applying super thin glue for a capillary action into the joints; and then 2) thicker glue at a few spots along each edge, then eased into place. There is no room for failure at this point!
 
Anyone has good advice on how to glue these, I am open!
 
 
 
 
 

Hi dear friends photo Anson.

Thanks, I am doing well now, on the road to recovery and back to doing what I like to do with some limitations.
 
Apologize for being preachy, you know how it is, you go through a tough experience, and hope others will not.
 
Happy modeling!
 
-Rich

First batch of birthdays and holidays (Wife's on 10/22, Brothers on 12/6) behind me so now on to the Cheerful. Worked on the trees before the mast as I think it will be easier to make the mast fit the trees rather than trees fitting the mast. I copied the plans and glued to wood for part.

Using the scroll saw cutting the image leaving enough too finish with the disk sander. (I'll put a new sandpaper)

next using the oscillating spindle sander to finish the parts inner curve. Like other logs where the used a mill to cut the slots into the cross pieces, why with others success why reinvent the wheel, I did the same process. Using four pieces of material glued together so the protecting the inner pieces from chipping as the cutter existed.
T
The parts where assemblied on to of the plans image. I left the center cross piece long on purpose to file it close to the adjoining part.

When the glue dries I sand the center flush to the sides. With to trees done I'll move on to the mast. Gulp
 
 
 
 
 
 

Beam arms
Beautiful piece of the deck structure, was waiting for this moment for a while!
Tried to use my fancy Vallorbe files, but the easiest way to shape these was a coarse sanding stick followed by a quick pass with finer grit. Then scraping to flatten the edge - and you get a fine finish with very little effort. Just need to be mindful of grain direction to not scrape against the grain  

Joints are milled, of course. That kind of precision work is where a mill really shines!

Speaking of milling - I added a crudely made light into my Proxxon MF70. It is based on strange 3d model that I found online, trimmed off all the strange bits and glued in a cheap USB-powered LED strip, cut into short pieces and soldered with dodgy cuts of solid wire. It works, excellent value for money!
Can definitely recommend to spend time on making your own, one of these "I should have done that sooner" moments. There is nothing off the shelf that you can buy for MF70, only some dim LED ring on ebay for way too much money.

In other LED updates - got a lamp similar to the one recommended by Chuck (amazon/aliexpress, 50 USD, likely same manufacturer, but smaller size). It is awesome! Angled "ears" allow you to illuminate the piece from multiple angles, which is very handy when carving notches. The light quality (colours, flickering) is very good in my unscientific tests, and makes for a good photo light. The adjustable arm is solid (joints not too tight, not too loose, very elegant), and it is not an eyesore. A lot of adjustability and tilting angles. More than enough brightness, and the adjustable colour temperature is handy. The only downside is that the touch controls are facing forward, so I touch them by accident way too often  

The arms are slightly curved to follow the deck shape. I over-curved them at first, but luckily had enough margin to smoothen them with some battens. The resulting curve is very gentle:

And here they finally glued in. Actually the first part of the deck that is now permanently glued in place! I am avoiding the final glueup as much as possible, feels much better when everything is dry fit  

Now I have a pile of carlings ready for installation

And here they are all in place!
Notches on the exposed side are left empty to avoid obstructing the view. I might put some carlings into them later.
They needed more care than the non-empty notches, since you want all notch surfaces to look smooth and pretty, no chance to cover them with a carling later on. So I was cutting a smaller notch and then make a few final cuts once it is done, cutting off any tear-out.

That concludes the carling phase, next in line are the lodging/hanging knees and ledges!

I started with both of my daughters around the age of 6 (see the Polotsk build in my signature, the youngest does not have a build log yet). It may sound young, but at that age they usually have basic precision required.
 
Of course the motivation is different, they saw me modelling and wanted to try that too, to a large extent as a together-time, as opposed to going into the hobby purely for the sake of hobby.
They were never interested in getting the final result, but wanted to try the process. Sanding wood, shaping wood - all of that was a learning curve and a joy. It is very different with plastic and not sure fiddling with plastic glue and tiny parts is enjoyable.
Do not expect that the model would be completed, it's too much of a stretch. And by the age of 10-12 they have got a lot of other hobbies, so might be too late   Expect that they would never finish the model, and by that age - would stop caring about finishing, but would hopefully cherish the memories you had together.
Modelling for them is just an excuse to try all these new skills and spend time with their dad, while feeling a joy of building something more complex than a Lego.
Surprisingly the type of a ship does not really matter, as long as it is a fairly straightforward kit where you just cut pieces, glue them together, etc. But it is really beneficial to have a kit with pre-splined planks that would fit together nicely.
 
Skill-wise expect to teach them the very basics, that we, adults, do not even think about. Keeping the knife straight (yes, they can already use it carefuly), moving file straight, how to hold a piece of sandpaper between your fingers, how to draw a pencil line on wood, etc etc. And prepare some scrap to practice, of course. 
Some tools are off-limits though - no table saw, very careful with disc sander. Dremel is fine, but watch out for hair and sleeves. Band saw can be introduced a bit later. 
Introduce dust and eye protection for certain operations from day one, for them it is very natural and not weird if they see you do it as well.
Prepare for practicing every new skill on scrap pieces, for kids to sidetrack to "side projects" like building random stuff out of cutoffs and similar foolery. It might be frustrating, but again - the journey is the goal, not the destination.  
 
Of course it is all very anecdotal and your experiences may vary, just sharing mine. Do not wait until they are pre-teens, do not start with plastic, just dive right into the wood if that is what they want. There is nothing extremely difficult in cutting and gluing wood pieces for elementary school kids. Just need supervision and patience.
 
Some teaser pics, she has just turned 6. 

If you put it close to the object (close enough to not be in a way of your tools and files) - with the right light angle you can visibly see how fairly large dust particles are immediately sucked by the stable airflow into the filter, away from you. I assume that the much more dangerous fine particles (the ones not visible with the naked eye) are following the flow even better  
It's not like the vaccuum hose sucking from one spot, but it creates a continuous movement of air towards the filter from a much wider area.

So yes, it is not very powerful at all, but by putting it next to the sanded object you end up with fairly good efficiency. When experimenting you will see that the distance is crucial. Move it away - and you no longer capture particles at the source, but start filtering the "air in the room", needing large fans with much larger surface area and airflow.
And it is also very quiet, so you will run it for hours, and not turn off immediately (any tool is better than the tool turned off ). You would not sneak away to sand things quietly, avoiding a loud dust collector to not wake someone up.
 
It would be quite useless for general woodworking or sanding large surfaces - since you would no longer be able to place it close enough. But perfect for our needs I think (sanding a small part by hand or in a vise, with a part located close to the filter).
Remember that it is just a replacement for a vaccuum hose, not a magic tool that solves all dust issues.
This is what it replaced for me - a fiddly hose that I always need to somehow place as close to the vise as possible, it falls off, bumps around, and is less efficient on such distance, since it creates a very local suction zone, rather than a steady airflow away from me.

Ofc the vaccuum is still used with power tools (table saw, disc sander, mill, etc) - anything where the dust source is fixed in place with a way to get the hose very close to the source. 
 
I still wear a respirator mask when sanding - when working close to a part with an optivisor on you can inhale dust straight from  the source.
 
None of the dust protective measures are 100% effective on their own, it is all about multi-step reduction and reducing percentages. The mask would also not be working well if you are sitting for hours in a cloud of fine dust, the vast majority of the dust must be removed away from you before it can spread around. This compact purifier is taking that role, while the mask is preventing you from breathing it in too easily.
Masks are also sensitive to the proper fit, not really compatible with beards, etc. 
 

Beam arms
Beautiful piece of the deck structure, was waiting for this moment for a while!
Tried to use my fancy Vallorbe files, but the easiest way to shape these was a coarse sanding stick followed by a quick pass with finer grit. Then scraping to flatten the edge - and you get a fine finish with very little effort. Just need to be mindful of grain direction to not scrape against the grain  

Joints are milled, of course. That kind of precision work is where a mill really shines!

Speaking of milling - I added a crudely made light into my Proxxon MF70. It is based on strange 3d model that I found online, trimmed off all the strange bits and glued in a cheap USB-powered LED strip, cut into short pieces and soldered with dodgy cuts of solid wire. It works, excellent value for money!
Can definitely recommend to spend time on making your own, one of these "I should have done that sooner" moments. There is nothing off the shelf that you can buy for MF70, only some dim LED ring on ebay for way too much money.

In other LED updates - got a lamp similar to the one recommended by Chuck (amazon/aliexpress, 50 USD, likely same manufacturer, but smaller size). It is awesome! Angled "ears" allow you to illuminate the piece from multiple angles, which is very handy when carving notches. The light quality (colours, flickering) is very good in my unscientific tests, and makes for a good photo light. The adjustable arm is solid (joints not too tight, not too loose, very elegant), and it is not an eyesore. A lot of adjustability and tilting angles. More than enough brightness, and the adjustable colour temperature is handy. The only downside is that the touch controls are facing forward, so I touch them by accident way too often  

The arms are slightly curved to follow the deck shape. I over-curved them at first, but luckily had enough margin to smoothen them with some battens. The resulting curve is very gentle:

And here they finally glued in. Actually the first part of the deck that is now permanently glued in place! I am avoiding the final glueup as much as possible, feels much better when everything is dry fit  

Now I have a pile of carlings ready for installation

And here they are all in place!
Notches on the exposed side are left empty to avoid obstructing the view. I might put some carlings into them later.
They needed more care than the non-empty notches, since you want all notch surfaces to look smooth and pretty, no chance to cover them with a carling later on. So I was cutting a smaller notch and then make a few final cuts once it is done, cutting off any tear-out.

That concludes the carling phase, next in line are the lodging/hanging knees and ledges!

I started with both of my daughters around the age of 6 (see the Polotsk build in my signature, the youngest does not have a build log yet). It may sound young, but at that age they usually have basic precision required.
 
Of course the motivation is different, they saw me modelling and wanted to try that too, to a large extent as a together-time, as opposed to going into the hobby purely for the sake of hobby.
They were never interested in getting the final result, but wanted to try the process. Sanding wood, shaping wood - all of that was a learning curve and a joy. It is very different with plastic and not sure fiddling with plastic glue and tiny parts is enjoyable.
Do not expect that the model would be completed, it's too much of a stretch. And by the age of 10-12 they have got a lot of other hobbies, so might be too late   Expect that they would never finish the model, and by that age - would stop caring about finishing, but would hopefully cherish the memories you had together.
Modelling for them is just an excuse to try all these new skills and spend time with their dad, while feeling a joy of building something more complex than a Lego.
Surprisingly the type of a ship does not really matter, as long as it is a fairly straightforward kit where you just cut pieces, glue them together, etc. But it is really beneficial to have a kit with pre-splined planks that would fit together nicely.
 
Skill-wise expect to teach them the very basics, that we, adults, do not even think about. Keeping the knife straight (yes, they can already use it carefuly), moving file straight, how to hold a piece of sandpaper between your fingers, how to draw a pencil line on wood, etc etc. And prepare some scrap to practice, of course. 
Some tools are off-limits though - no table saw, very careful with disc sander. Dremel is fine, but watch out for hair and sleeves. Band saw can be introduced a bit later. 
Introduce dust and eye protection for certain operations from day one, for them it is very natural and not weird if they see you do it as well.
Prepare for practicing every new skill on scrap pieces, for kids to sidetrack to "side projects" like building random stuff out of cutoffs and similar foolery. It might be frustrating, but again - the journey is the goal, not the destination.  
 
Of course it is all very anecdotal and your experiences may vary, just sharing mine. Do not wait until they are pre-teens, do not start with plastic, just dive right into the wood if that is what they want. There is nothing extremely difficult in cutting and gluing wood pieces for elementary school kids. Just need supervision and patience.
 
Some teaser pics, she has just turned 6. 

I started with both of my daughters around the age of 6 (see the Polotsk build in my signature, the youngest does not have a build log yet). It may sound young, but at that age they usually have basic precision required.
 
Of course the motivation is different, they saw me modelling and wanted to try that too, to a large extent as a together-time, as opposed to going into the hobby purely for the sake of hobby.
They were never interested in getting the final result, but wanted to try the process. Sanding wood, shaping wood - all of that was a learning curve and a joy. It is very different with plastic and not sure fiddling with plastic glue and tiny parts is enjoyable.
Do not expect that the model would be completed, it's too much of a stretch. And by the age of 10-12 they have got a lot of other hobbies, so might be too late   Expect that they would never finish the model, and by that age - would stop caring about finishing, but would hopefully cherish the memories you had together.
Modelling for them is just an excuse to try all these new skills and spend time with their dad, while feeling a joy of building something more complex than a Lego.
Surprisingly the type of a ship does not really matter, as long as it is a fairly straightforward kit where you just cut pieces, glue them together, etc. But it is really beneficial to have a kit with pre-splined planks that would fit together nicely.
 
Skill-wise expect to teach them the very basics, that we, adults, do not even think about. Keeping the knife straight (yes, they can already use it carefuly), moving file straight, how to hold a piece of sandpaper between your fingers, how to draw a pencil line on wood, etc etc. And prepare some scrap to practice, of course. 
Some tools are off-limits though - no table saw, very careful with disc sander. Dremel is fine, but watch out for hair and sleeves. Band saw can be introduced a bit later. 
Introduce dust and eye protection for certain operations from day one, for them it is very natural and not weird if they see you do it as well.
Prepare for practicing every new skill on scrap pieces, for kids to sidetrack to "side projects" like building random stuff out of cutoffs and similar foolery. It might be frustrating, but again - the journey is the goal, not the destination.  
 
Of course it is all very anecdotal and your experiences may vary, just sharing mine. Do not wait until they are pre-teens, do not start with plastic, just dive right into the wood if that is what they want. There is nothing extremely difficult in cutting and gluing wood pieces for elementary school kids. Just need supervision and patience.
 
Some teaser pics, she has just turned 6. 

I started with both of my daughters around the age of 6 (see the Polotsk build in my signature, the youngest does not have a build log yet). It may sound young, but at that age they usually have basic precision required.
 
Of course the motivation is different, they saw me modelling and wanted to try that too, to a large extent as a together-time, as opposed to going into the hobby purely for the sake of hobby.
They were never interested in getting the final result, but wanted to try the process. Sanding wood, shaping wood - all of that was a learning curve and a joy. It is very different with plastic and not sure fiddling with plastic glue and tiny parts is enjoyable.
Do not expect that the model would be completed, it's too much of a stretch. And by the age of 10-12 they have got a lot of other hobbies, so might be too late   Expect that they would never finish the model, and by that age - would stop caring about finishing, but would hopefully cherish the memories you had together.
Modelling for them is just an excuse to try all these new skills and spend time with their dad, while feeling a joy of building something more complex than a Lego.
Surprisingly the type of a ship does not really matter, as long as it is a fairly straightforward kit where you just cut pieces, glue them together, etc. But it is really beneficial to have a kit with pre-splined planks that would fit together nicely.
 
Skill-wise expect to teach them the very basics, that we, adults, do not even think about. Keeping the knife straight (yes, they can already use it carefuly), moving file straight, how to hold a piece of sandpaper between your fingers, how to draw a pencil line on wood, etc etc. And prepare some scrap to practice, of course. 
Some tools are off-limits though - no table saw, very careful with disc sander. Dremel is fine, but watch out for hair and sleeves. Band saw can be introduced a bit later. 
Introduce dust and eye protection for certain operations from day one, for them it is very natural and not weird if they see you do it as well.
Prepare for practicing every new skill on scrap pieces, for kids to sidetrack to "side projects" like building random stuff out of cutoffs and similar foolery. It might be frustrating, but again - the journey is the goal, not the destination.  
 
Of course it is all very anecdotal and your experiences may vary, just sharing mine. Do not wait until they are pre-teens, do not start with plastic, just dive right into the wood if that is what they want. There is nothing extremely difficult in cutting and gluing wood pieces for elementary school kids. Just need supervision and patience.
 
Some teaser pics, she has just turned 6. 

I started with both of my daughters around the age of 6 (see the Polotsk build in my signature, the youngest does not have a build log yet). It may sound young, but at that age they usually have basic precision required.
 
Of course the motivation is different, they saw me modelling and wanted to try that too, to a large extent as a together-time, as opposed to going into the hobby purely for the sake of hobby.
They were never interested in getting the final result, but wanted to try the process. Sanding wood, shaping wood - all of that was a learning curve and a joy. It is very different with plastic and not sure fiddling with plastic glue and tiny parts is enjoyable.
Do not expect that the model would be completed, it's too much of a stretch. And by the age of 10-12 they have got a lot of other hobbies, so might be too late   Expect that they would never finish the model, and by that age - would stop caring about finishing, but would hopefully cherish the memories you had together.
Modelling for them is just an excuse to try all these new skills and spend time with their dad, while feeling a joy of building something more complex than a Lego.
Surprisingly the type of a ship does not really matter, as long as it is a fairly straightforward kit where you just cut pieces, glue them together, etc. But it is really beneficial to have a kit with pre-splined planks that would fit together nicely.
 
Skill-wise expect to teach them the very basics, that we, adults, do not even think about. Keeping the knife straight (yes, they can already use it carefuly), moving file straight, how to hold a piece of sandpaper between your fingers, how to draw a pencil line on wood, etc etc. And prepare some scrap to practice, of course. 
Some tools are off-limits though - no table saw, very careful with disc sander. Dremel is fine, but watch out for hair and sleeves. Band saw can be introduced a bit later. 
Introduce dust and eye protection for certain operations from day one, for them it is very natural and not weird if they see you do it as well.
Prepare for practicing every new skill on scrap pieces, for kids to sidetrack to "side projects" like building random stuff out of cutoffs and similar foolery. It might be frustrating, but again - the journey is the goal, not the destination.  
 
Of course it is all very anecdotal and your experiences may vary, just sharing mine. Do not wait until they are pre-teens, do not start with plastic, just dive right into the wood if that is what they want. There is nothing extremely difficult in cutting and gluing wood pieces for elementary school kids. Just need supervision and patience.
 
Some teaser pics, she has just turned 6. 

I started with both of my daughters around the age of 6 (see the Polotsk build in my signature, the youngest does not have a build log yet). It may sound young, but at that age they usually have basic precision required.
 
Of course the motivation is different, they saw me modelling and wanted to try that too, to a large extent as a together-time, as opposed to going into the hobby purely for the sake of hobby.
They were never interested in getting the final result, but wanted to try the process. Sanding wood, shaping wood - all of that was a learning curve and a joy. It is very different with plastic and not sure fiddling with plastic glue and tiny parts is enjoyable.
Do not expect that the model would be completed, it's too much of a stretch. And by the age of 10-12 they have got a lot of other hobbies, so might be too late   Expect that they would never finish the model, and by that age - would stop caring about finishing, but would hopefully cherish the memories you had together.
Modelling for them is just an excuse to try all these new skills and spend time with their dad, while feeling a joy of building something more complex than a Lego.
Surprisingly the type of a ship does not really matter, as long as it is a fairly straightforward kit where you just cut pieces, glue them together, etc. But it is really beneficial to have a kit with pre-splined planks that would fit together nicely.
 
Skill-wise expect to teach them the very basics, that we, adults, do not even think about. Keeping the knife straight (yes, they can already use it carefuly), moving file straight, how to hold a piece of sandpaper between your fingers, how to draw a pencil line on wood, etc etc. And prepare some scrap to practice, of course. 
Some tools are off-limits though - no table saw, very careful with disc sander. Dremel is fine, but watch out for hair and sleeves. Band saw can be introduced a bit later. 
Introduce dust and eye protection for certain operations from day one, for them it is very natural and not weird if they see you do it as well.
Prepare for practicing every new skill on scrap pieces, for kids to sidetrack to "side projects" like building random stuff out of cutoffs and similar foolery. It might be frustrating, but again - the journey is the goal, not the destination.  
 
Of course it is all very anecdotal and your experiences may vary, just sharing mine. Do not wait until they are pre-teens, do not start with plastic, just dive right into the wood if that is what they want. There is nothing extremely difficult in cutting and gluing wood pieces for elementary school kids. Just need supervision and patience.
 
Some teaser pics, she has just turned 6. 

If you put it close to the object (close enough to not be in a way of your tools and files) - with the right light angle you can visibly see how fairly large dust particles are immediately sucked by the stable airflow into the filter, away from you. I assume that the much more dangerous fine particles (the ones not visible with the naked eye) are following the flow even better  
It's not like the vaccuum hose sucking from one spot, but it creates a continuous movement of air towards the filter from a much wider area.

So yes, it is not very powerful at all, but by putting it next to the sanded object you end up with fairly good efficiency. When experimenting you will see that the distance is crucial. Move it away - and you no longer capture particles at the source, but start filtering the "air in the room", needing large fans with much larger surface area and airflow.
And it is also very quiet, so you will run it for hours, and not turn off immediately (any tool is better than the tool turned off ). You would not sneak away to sand things quietly, avoiding a loud dust collector to not wake someone up.
 
It would be quite useless for general woodworking or sanding large surfaces - since you would no longer be able to place it close enough. But perfect for our needs I think (sanding a small part by hand or in a vise, with a part located close to the filter).
Remember that it is just a replacement for a vaccuum hose, not a magic tool that solves all dust issues.
This is what it replaced for me - a fiddly hose that I always need to somehow place as close to the vise as possible, it falls off, bumps around, and is less efficient on such distance, since it creates a very local suction zone, rather than a steady airflow away from me.

Ofc the vaccuum is still used with power tools (table saw, disc sander, mill, etc) - anything where the dust source is fixed in place with a way to get the hose very close to the source. 
 
I still wear a respirator mask when sanding - when working close to a part with an optivisor on you can inhale dust straight from  the source.
 
None of the dust protective measures are 100% effective on their own, it is all about multi-step reduction and reducing percentages. The mask would also not be working well if you are sitting for hours in a cloud of fine dust, the vast majority of the dust must be removed away from you before it can spread around. This compact purifier is taking that role, while the mask is preventing you from breathing it in too easily.
Masks are also sensitive to the proper fit, not really compatible with beards, etc. 
 

Mike, thank you so much for your exhaustive reply. MDF is my biggest concern, over the years I’ve always sanded resin using water etc but ship building is another genre. The major sanding I’ll do in the garage where all my large wood and metal working machines are. Thanks for the advise it’s food for thought
 
Phil.
 

If you put it close to the object (close enough to not be in a way of your tools and files) - with the right light angle you can visibly see how fairly large dust particles are immediately sucked by the stable airflow into the filter, away from you. I assume that the much more dangerous fine particles (the ones not visible with the naked eye) are following the flow even better  
It's not like the vaccuum hose sucking from one spot, but it creates a continuous movement of air towards the filter from a much wider area.

So yes, it is not very powerful at all, but by putting it next to the sanded object you end up with fairly good efficiency. When experimenting you will see that the distance is crucial. Move it away - and you no longer capture particles at the source, but start filtering the "air in the room", needing large fans with much larger surface area and airflow.
And it is also very quiet, so you will run it for hours, and not turn off immediately (any tool is better than the tool turned off ). You would not sneak away to sand things quietly, avoiding a loud dust collector to not wake someone up.
 
It would be quite useless for general woodworking or sanding large surfaces - since you would no longer be able to place it close enough. But perfect for our needs I think (sanding a small part by hand or in a vise, with a part located close to the filter).
Remember that it is just a replacement for a vaccuum hose, not a magic tool that solves all dust issues.
This is what it replaced for me - a fiddly hose that I always need to somehow place as close to the vise as possible, it falls off, bumps around, and is less efficient on such distance, since it creates a very local suction zone, rather than a steady airflow away from me.

Ofc the vaccuum is still used with power tools (table saw, disc sander, mill, etc) - anything where the dust source is fixed in place with a way to get the hose very close to the source. 
 
I still wear a respirator mask when sanding - when working close to a part with an optivisor on you can inhale dust straight from  the source.
 
None of the dust protective measures are 100% effective on their own, it is all about multi-step reduction and reducing percentages. The mask would also not be working well if you are sitting for hours in a cloud of fine dust, the vast majority of the dust must be removed away from you before it can spread around. This compact purifier is taking that role, while the mask is preventing you from breathing it in too easily.
Masks are also sensitive to the proper fit, not really compatible with beards, etc.