Guide spacing is an interesting exercise. It is very important because guides transfer the load to the rod. You can negate the qualities of a good blank with poor guide spacing. Imagine the extreme of only having one guide and how the rod would look under load. The ideal is for the rod to have an even bend under load. That transfers the power of the stiff butt section up through the slender and flexible tip. The tradeoff is that the more guides there are the more line friction there is, thus reducing casting effectiveness and also making the rod stiffer with all those wraps.
A rule of thumb is that you put on a guide for every foot of rod, plus one. (ie 9 for 8 footer, 7 for 6 footer) Round down for less than a half foot, round up for more. For a 6 ½ foot rod the option is mine to go for 7 or 8. I decided on 7, since that is how many came with my kit.
There are various sizes of guides of course, with various rules and guidelines on what to put where. Once again, here I am just going to go with what came with the kit. I suppose someone else has already optimized this. I will go with the rule of thumb that the smallest go towards the tip, and the biggest toward the butt.
Now to figure out the spacing. I use a mathematical formula to find a starting place. I suppose this is because I am an engineer and I just naturally gravitate towards a formula that gives me an answer. I got this from Art Scheck’s Fly Rod Building Made Easy. (This is my primary reference for this project and a darn good book for a beginner.) He contends that this formula gets as close as anything.
The formula depends on knowing three measurements: the length of the rod, the distance from the butt to the stripping guide, and the distance from the tip to the first guide. I know the length of the rod is 78”. I place the stripping guide 32’ from the butt. This is a personal preference found by pretending to grab an imaginary line and finding out where my hand ends up on the blank. This will be from 28” to 32” for most people, and since my arms are rather long I end up at the top end of the range. I also checked the other rods that I liked and found out that was about where the stripping guide was. The first guide goes 4” below the tip top, pretty much because everybody says it goes there.
78” total minus 32” to stripping guide gives me 46 inches along the blank to put the seven guides. The distance to the first guide is 4” and the distance to each other one needs to increase by a consistent rate – x. This gives us the equation:
46 = 4 + (4+ x) + (4 + 2x) + (4 + 3x) + (4 + 4x) + (4 + 5x) + (4 + 6x)
or
x = .86
I can transform this into a table that will help me determine where to mark the blank.
Guide from top from previous
1 4 n/a
2 8.86 4.86
3 14.58 5.72
4 21.16 6.58
5 28.60 7.44
6 36.90 8.30
7 46.06 9.16
Although hundredths of inches are huge in some application, say fitting bearings to a shaft, in this case they are just too hard to measure. So to put this on the blank I will round to the nearest 1/8th inch, and feel lucky if I can get it that close.
Guide from top
1 4
2 8 7/8
3 14 5/8
4 21 1/8
5 28 5/8
6 36 7/8
7 46
What do you know, this works out so by measuring from the top the stripping guide ends up in the same place as measuring from the bottom with the original assumption of 32 inches.
One word of caution. Round each measurement individually and don’t carry the rounding forward. This can lead to a lot of frustration when the stripping guide location doesn’t check. Don’t ask how I know this.
Now mark the location of each guide on the blank with a small piece of masking tape. I use some ¼ “ wide tape that I had left over from a model painting project. Less is better here since it is just for marking.
During this process I recommend that you ask the assistance of your lovely and charming spouse to help with the measuring and marking. She will agree because of the great person that she is, and it will make for a lot quicker and more accurate job. And you will probably only have to agree to complete some minor task in return.
You may find that one of the guides ends up right on the ferrule. In this case you have to move it up the rod so that you can get at least one inch or thread wrap on the ferrule plus the wrap for the guide. Then you have to divide the space that you took out equally between the guides above that one, and divide the extra space created between the guides below that one. This can be a tedious pain in the kiester. It didn’t happen for this rod but it did for the last one.
Now I know where the guides go. I’ll be back to continue this as soon as I am done cleaning out the garage.