I'm going to build a couple UL spinners and wanted to know if there is a reason, "other than that's the way it has always been done", not to put the reel seat off center, fit the reel seat so that the blank sits at the top of the reel seat???
See the link for a little better idea of what I'm talking about.

[www.rodbuilding.org]

No reason at all. In fact, you may remember that Steve Gardner makes his TN handles that way.

It also allows you to rest your thumb easily on the rod blank just ahead of the seat, if you want to use a "no-foregrip" set up.

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Would it be a good idea to position the reel seat so the effective height of the spinning reel is reduced when using the NGC or 27x method for guide placement?

If you do that, you're apt to find that the reel bail/line roller smacks your hand/fingers as it comes around each time. There is a certain distance you need to maintain there.

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All my reel seats end up just left of center just by fate, being right handed I think when you lay down thread and use your dominate eye (right in my case) it just happens. I have yet to have any complaints. The offset is small enough that you cant tell its not centered unless your really looking for it.

I would seriously wonder about offsetting it a large amount for the same reason as Tom but also think it would be rather cumbersome to cast.

JMHO

Tom,

It shouldn't matter where the blank goes through the reel seat. The distance between the bail and your knuckles is set by the length of the stem on the spinning reel. I could see offsetting the blank to the bottom of the seat increasing the chance of line slap a bit, but not contact from the bail assembly. Is there something I'm missing here?

Joe