I am replacing a reel seat that cracked. I will be replacing the rear grip from the bottom of the rod blank. Is there an easy way to ream the rear grip evenly throughout the whole grip? Also I plan on using masking tape for the arbors. Is there something besides masking tape that would work better?

Using a variable speed drill at slow speeds, gradually increasing the bit size to just remove enough material to fit the blank butt end, and letting the grip periodically slip in your hand to keep the hole concentric should work if the grip isn't more than twice the length of the bit itself. Drilling from both ends of the grip and letting the bit find its own path helps keep the hole centered. Masking tape arbors are the easiest to use and should be fine for freshwater applications.

Bands of thread would be my choice over masking tape. As you approach the seat you can double and then triple the layer as necessary to obtain a straight non-tapered section from butt to seat.

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

If you have a lathe, it is easy to use a lathe to spin the grip to and center drill the grip to a constant diameter.

If not using the lathe, I use the variable speed drill with drill bits, and I also wear a cloth glove on the hand that is holding the grip. The cloth glove lets you slip the grip from time to time to let it rotate slowly as you drill. By letting the periodically slip as Ross points out, the hole remains centered much better than if you don't let the grip rotate from time to time and you are free hand drilling the hole.

I do as you suggest. i.e. I just use masking tape to make an arbor, so that the od of the arbor is the same diameter as the butt section of the rod blank. Then, just slip everything on from the butt end of the rod.
When I do use masking tape, I use various widths to make arbors, but I leave about 1/16th-1/8th inch space between the rows of masking tape arbors. Then, when I glue up the grip and reel seat, I use epoxy, and fill the space between the masking tape arbors with glue so that I have a solid glue line running from the blank to the grip and to the reel seat. As a result, I have never had a grip or a reel seat fail using this method.

Dan
An excellent alternative to masking tape for arbors is using fiberglass drywall tape. Several advantages are; it is impervious to water should it ever get under the cork unlike paper on making tape. It is porous so depending on the depth of the tape the epoxy can penetrate all the way to the blank offering a super strong bond. It also transmits vibration better from the blank should that be a concern which is why I use it on reel seats for the most part.

The only downside I can see is that it is thicker than masking tape and if you need a very thin arbor it could be harder to obtain that diameter.

Tom

You can use tape But 1/4" Also if you need to wrap the tape more then 8 - 10 turns over the blank I would go the arbors Glue in the seat them ream to fit the blank
The tape can be used with about 1 - 1 1/2" spacing in between them The blank SHOULD BE SANDED for adhesion of the seat to the blank

Bill - willierods.com