Proportional dividers and how I use them.

[Erik Nyren]

Hello

 

A few words on how I use a set of proportional dividers during planking, I hope some of you can find it useful

 

I´m planking HMS Victory and in doing so I´m putting my set of proportional dividers to good use. This tool is not by any meens absolutely nessecary to have if your starting out on your first few kits, but as one gets further in to the hobby one finds that this Little engenious tool has many uses around the ship, one beeing aiding in those precarious tapering jobs during planking.

 

When I first started to look for a set of dividers I noticed that they where not that easy to come by in Sweden and that turned out to be a story in it self. I cant remember how, but I got in contact with a violin builder in germany by the age of 80-something. He apparently also made proportional dividers of different sizes. Now I had little knowledge about theese thingies and what size I needed for my models. This man simply sent me a few samples of his dividers in different sizes stating. - Pay for the one you want and send the rest back !!! So I did just that. You don´t find that kind of confidence and trust in people often theese days, in the years to come I recieved a christmastcard from him every year as probably most of his violincostumers.

 

So what does the dividers do, originaly designed to divide circles in equal parts this tool serves by dividing a sertain distance into equal parts depending on how you set them. I have set the  dividers in the Picture to 3 meaning that the smaller pointers will show exactly 1/3 of the distance between the larger ones.

 

Lets get ito it

Edited June 28, 2014 by Erik Nyren

[Erik Nyren]

Stage one is to decide how may strakes I want to use in one go, in this case I chose 5 strakes, holding the m up midship and drawing a line along the lowest one I get a battenline where 5 strakes will fit midships....... So far so good.......

 

I then place a strake along this line and letting it run naturally along the hull fore and aft, drawing a line above I  get a natural flow of the strake which is what I´m looking for, I want to put a minimum of stress to the plank when glued to the ship as this helps to keep the keel straight and aids to the overall strength of the hull.

 

More to come ( I´ll be going on for a while

[Erik Nyren]

This is what I came up with, the stern looks fine but I can see that the line at the bow does not allow room for the five strakes (pic 5) given that I do not break the rule of never taper more that half of the strake width.

Oh well I decided on the easy way out and apply a little stress to the strakes by deciding on a 2,5mm taper at the ends by the bow rabbet line. I´m using 5mm strakes so thats about all I can get. The new line is shown in Picture 6. We cant win them all.

 

 

[Erik Nyren]

Finally we get to use the dividers.

 

Pic 7 shows that I have set them to five corresponding to the number of strakes I decided to use for this run.

Pic shows how I messure the distance midships and then pic 8 shows how the dividers Point out 1/5 of that distance at the messurement Point. this meens that the plank used should have that exact width at that point.

 

But as I originally drew the line there using five strakes as a base, to no surprice no tapering is needed there.

 

Bare with me......

[Erik Nyren]

Folowing my battenline aft I noticed that the dividers are showing a distance exceeding 5mm (the strakes used are 5mm)

You guessed it, I´m going to need a stealer. brrrr.

 

Lets leave the stealer for a while and go on

Edited June 28, 2014 by Erik Nyren

[Erik Nyren]

Working on the bow

Pic 12 shows how I after soaking the plank let it run along the previous planking marking a few referencepoints on both the plank to be and the plank already fitted.

Pic 13 shows how I took messurements at each referencepoint using the dividers and transfering them to the plank creating a line along which the plank needs to be tapered. Ingenious is it not 

 

Pic 14: The final cut   (Yes I am a Pink Floyd fan)

[Erik Nyren]

Pic 15-17 shows the plank fit to the ship and pinned. I prefere to use pins if I can as they enable me to start on the next plank immediately without any clamps getting in the way. Note that this ship will be filled and paited so the pinholes will disappear. If I´m working on a model displaying the natural wood I would use a different way to secure the planks

 

 

[Erik Nyren]

Now, Before we go on to the stealer lets dive a little deeper into the magic of the dividers. It would seem that the dividers weakness is also their strength.

As pic 20 shows the problem is that the two pointers of the dividers messures a straigt line between them...duh !!

The hull of a ship is pretty much never a straight line (well those stealthy things are to a sertain degree but thats another story)

this meens that there will be a inbuilt fault in my messurements represented by the curve of the hull. The more planks I use between the battenlines the more apparent this fault will be.

 

Pic 21 shows in an exaggerated way how the dividers, divide a straight line however I´m implementing the messurement to a curved surface.....Problem?

 

THE MAGIC HAPPENS

 

Pic 23: The work around, after I have glued the first plank represented by the grey area on the upper left in the picture. I reset the dividers to 4 representing the four planks left to do. Now the instrument will devide the area left between the first plank layed and the battenline into four equal parts showing the need of tapering at each Point messured.  

 

Pic 24: The greyed areas show the planks, The straight line by the number 5-2 represent the line between the pointers of the dividers and you can clearly see how theres a problem by nr5, however the problem is compensated when the dividers are reset in correspondance to the plank I´m working on 5-1 and as I´m closing in on nr 2 the problem is all but gone.

 

And thats the magic of the dividers. Only remember to set them correctly.

 

Now on to that stealer. 

[Erik Nyren]

1. I let a plank run naturally laong the hull aft and marked the spot where it strated to deviate from the plank above.

2. At this Point I drew a line 2,5mm down and 2.. to the left representing the start of the stealer.

3. I continued to draw a line along the natural run of the plank mentioned above

4. I used my dividers to mark where the stealer would reach 5mm width (width of the planks used)

5. And then finally I drew the stealer to be on the hull. Note that the distance between the start of the stealer and the point where it needs to be 5mm as mentioned in Point 4 marks the tapering of the actual stealer. 

[Erik Nyren]

The stealer was tapered from the start where it needs to be 2,5mm (half of its original width) to the Point where the natural flow of the plank below has a distance of 5mm to the plank layed above not counting the stealer to be of cource.

 

After tapering the stealer was glued to the ship.

 

The dividers are then set to 4, representing the four planks still to go in this run.

 

Messurements and tapering are done in the same manner although the dividers are set to 4 and some tapering has to be done to accomodate the stealer. At the same point (or there about) as the stealer reaches 5mm the plank below should reach 5mm. To much tapering kind of eats away on the effect of the stealer although that can be adjusted later if it happens.

[Erik Nyren]

Still some sanding, filling and final touches needs to be done

[Erik Nyren]

A Word on cutting. My kit is old meaning dry wood that splinters ieasily and much care has to be taken not to have a bladerunner ( yep fan of the Movie too) with the grain of the planks.

 

I use a steel ruler as a supportbast for the plank, a small one above to mark the cutting line and last a wood block to hold the plank in place so that it does not move with the blade.

Many lite strokes with the blade is the trick. Never ever try to cut through the plank in one go, it will be a mess, I assure you.

 

And the last one...well that would be me wearing all the binocular aid I need to make a decent job on planking.

 

I hope this will be of use to some of you, comments, questions, ideas and opinions are of cource wellcome.

 

Best regards

Erik