how to find spine on fly rod blank mhx on 4 pieces rod

Do the best you can, but it won't make any difference. If it was me, I'd line up the straightest axis on each piece and align them that way, belly down, tip and butt up. This will give you the greatest lifting strength and power.

...............

The below thread from only a few weeks ago explains how to do just what you're asking about .

[www.rodbuilding.org]

If you change how you grip the rod do you have to cut off and re-align all the guides or can you just loosen the reel seat, turn it until it lines up with the guides, and re-glue it?

There is a very big difference in the affect a spine has on a Fly rod versus a Casting or Spinning rod. In a casting or spinning rod, the spine can affect your accuracy, pulling the line to the weaker side of the blank. That is why spining a casting or spionning rod will improve your accuracy. With a fly rod however, the line is pulling the fly instead of the other way around, so if you have your casting stroke going straight ahead, the fly will naturally follow. The spine will have no affect on your accuracy.

There is also the matter of a 4-piece blank - it will have 4 different spines! Lining up the spines may not offer the best orientation of the blank, as the cumulative effect of the spines could give the rod a pronounced curve. It is far better, as noted above, to line up the blank sections to provide the straightest axis. One easy way to do this is to place a piece of graph paper on a box and set it on end on your rod-building counter. Then place the assembled blank in a wrapping stand and with the rod tip about 1/2" from the graph paper, slowly rotate the blank. If the tip travels in a circle wider than 1", adjust the blank pieces at the ferrules and try again. Perfection would be a tip that did not travel in a circle at all, but anything inside 1/2" is very good!

OK, now I understand. If a casting or spinning rod, The accuracy is totally dependind upon the rod and not the person controlling the rod. Still leaves me a bit puzzled when I throw side arm or underhand instead is directly in plane with the spine

Ron Weber

And so the “spine” versus the “straightest axis” saga continues and probably will well past eternity! Build the rod either way = neither is WRONG!!!

Mark Talmo
FISHING IS NOT AN ESCAPE FROM LIFE BUT RATHER A DEEPER IMMERSION INTO IT!!! BUILDING YOUR OWN SIMPLY ENHANCES THE EXPERIENCE.

Spining has no effect on casting accuracy. Rod twist is purely a function of the lever arm effect of the guides and even then, twist around a center axis does not affect casting accuracy.

...........

As long as the reel seat, the ferrules, and the guides are not loose and twisting freely while the rod is cast the rod will cast to the same place. Casting accuracy depends entirely upon the skill of the caster, not at all on guides or rod spine - although it would be nice to be able to buy or build a rod which made any user an accurate caster and an accomplished angler.