Guess I've used 100 weight silk so much of late that size B and larger nylon looks like rope. The question for those who regularly build 12 weight and heavier fly rods is what size thread do you use? The guides will be size 4 snakes forward of the last stripping to the tip top. My guess is size B nylon would be OK as the stress is distributed over 2 feet per guide. However, the stresses tend to be concentrated on the last 2 or 3 turns of thread and the guide foot heel, which argues for size C or D.

So, what size nylon thread do you use for similar situations?

I do not think thread strength is an issue in building 12 weight or even heavier fly rods. Twenty turns of four pound test thread (without epoxy) will lift 80 pounds, much more than any fly rod can stand.

Donald,
Why don't you do a test.

Take a broom stick and wrap on some old guides with different sized thread - starting with 100 size silk. Also, put on a conventional coating of thread finish as you would finish a rod.

Then, put a 1/8th inch rope through the guide and add weight to the rope until the thread breaks, if it ever does.

I doubt that you will be able to break the guide loose from the broom stick - no matter the amount of weight that you add.

The adage about breaking a single stick, compared to a bundle of sticks applies here to the wraps on your guides. i.e. many wraps of even thin thread gives a very impressive bond to the attachment of the guide to the blank.

My guess (and it is a guess) that even size A would be sufficient, but if you want to go to a size B, C, or D, you could certainly do that as well.

The other thing to consider is how much actual force could really be exerted on a guide using a given weight of fishing line and pull from a fish.

If you do some testing - let us all know what you find out.

Good luck

I've used A thread on rods that exceed your needs for many years with no problems, I bet your silk thread would work fine also, it's the strongest per thread size there is.

I also use "A" thread on 12 wts. I've had no issues.

Basically wrap with any size thread you want. They are are more than strong enough.
Norm

"A" works for me, and I only build fly rods, including 12 wts.

Hi Donald

As others have stated, "A" will work just fine. I have tied dozens of tarpon rods using "A' thread without issue. You'll pull the guides off before you'll see failure in the thread! The biggest issue I have with tarpon rods is the thread damage that occurs from repeatedly sliding them in and out of the rod storage systems on flats boats. Especially with 4-piece rods where the top ferrule wrap is pretty exposed. I'm wondering if PermaGloss would solve this problem. Might need to give it some "field testing" this May!!

Brian