What Am I Missing

[acaron41120]

         Trying the planking method in Donald Dressel’s book “Planking Techniques for Model Ship Building” with setting up the bands rather than my normal way of planking. I have installed the wale and the garboard plank. Measuring the distance from the bottom of the wale to the top of the garboard plank this measurement is 156mm. Next I take that measurement and divide by 3 (for the number of bands I want) and that comes out to three 52mm bands. BUT…when I measure the space of the bands along the middle frame I get 52 for the top, 52 for the bottom and 66 for the middle. Add those numbers up and it does not come out to 156mm, it comes out to 170mm.

          Should I add 7 to the top and bottom band making them all 59mm? If I do that the numbers don’t come out correct (59+59+59=177) but the total space is only 156mm. I might just say the heck with it and go with my normal way? I have read Donald Dressel’s book several times and thought I understood it but evidently not. What am I missing here? Any help appreciated.

[JacquesCousteau]

I'm not familiar with Dressel's book, but have marked out planking bands before in some of my own builds. How are you measuring the distances and how are you marking out the band locations? Before doing anything else, I'd triple-check that your measurements are being taken from consistent points on the same bulkhead/frame (something that I've certainly gotten mixed up on before), and using a material that won't stretch. For instance, string might stretch when you pull it tight around the bulkhead shape or to measure it, but a strip of paper or cardstock won't stretch. 

[Desertanimal]

With that much difference it almost sounds like you are measuring with calipers off some sort first. Giving you a shorter distance. Obviously only guessing though. 
Chris

[Dziadeczek]

I don't know D. Dressel's book, but I first learnt the planking technique from the brochure by Jim Roberts "Planking the Built-Up Ship Model".
Basically, after you VERY PRECISELY! installed the wale and the garboard strake (make sure they are perfectly symmetrical on both sides of your hull), you proceed to determine the runs of your battens (very thin temporary glued wood strips). If you chose three spaces (two battens), that's OK.

Very important is that they run symmetrically on both sides, along the entire length of the hull, and equidistantly to each other.

In other words, the spaces between the battens should be the same, and not like you say, one is 52 for the top space, 66 for the middle and 52 again for the bottom space! All spaces should be 52 (or something else, in your case). Reposition the battens.

I assume, these measurements are for the edge of a middle frame/bulkhead, the one that is the bulkiest. Do the same for the remaining bulkheads, taking precise measurements in between the lower edge of the wale and the upper edge of the garboard strake, taken with either a strip of paper or dividers, and then divide the distance into three to obtain the width for each ellipsoid space - for the corresponding bulkhead/frame. Do this for ALL frames, make a pencil mark on each frame and finally connect them all into a curve delineating the run of your batten.

It is easier to do it, than to explain it...   😬

This method is foolproof, if you do it precisely.

Hope this helps,

 

Thomas

Edited 18 hours ago by Dziadeczek

[acaron41120]

Thanks for all the help. I erased all the pencil marks again and used a piece of white cardboard. Set on the top of the garboard strake and ran it all the way up to the bottom of the wale and marked it. Then I measured from the edge of the cardboard to the mark with a cloth tape measure and came up with 156mm. Then I remeasured with a metric ruler and came up with 148mm. So I took the cloth tape measure and laid it along the metric ruler and what a difference. At 100mm on the ruler the tape was 108mm. So the tape went back to the sewing box. I divided the 148 by 3 and came up with three bands each 49mm. I used the card and made my marks and the bands now are really close. Off by 0.3mm by the calipers. So I was relying on a fault marked tape. Thanks for all your much appreciated help

  Thomas I believe I have that same book you show here but have not read it yet. But I’ll definitely fish it out of my library and give it a good read.

Edited 16 hours ago by acaron41120

[Dr PR]

Allen,

 

I have a collection of rulers gathered over the ages, and it is surprising that some of them differ greatly from the rest - even the triangular "engineering" and "architecture" scales. Some are off as much a 1/8 of an inch in 12 inches (1 part in 96 or 1.042%). Good enough for grade school or making dresses, but not OK for precise measurements.

 

I have a steel ruler marked in 100ths of an inch and it agrees exactly with a CAD created scale printed at 1:1 (viewed with a magnifying loupe). This is my "standard" ruler.

 

When I need to measure around a curve (like the edge of a bulkhead) I cut paper strips, ark them carefully, and measure with the ruler.