Well, I'm going to have a crack at these. I have access to a pretty decent metal lathe, and want to try and turn some tapered steel rods, to which I'll epoxy the abrasive strip. I suppose I'll probably end up with a lot of them, considering that I'm looking for diameter overlaps and different tapers, which I hope will closely match future projects. These will be easy to chuck up without fear of damage.

The machine time and steel will be in exchange for help in teaching the engineering students work on the lathes. Appreciate any input from everyone here, as I'll be looking into what length to make them, and also tapers. Even if I do have to pay more, I look at it as a one off investment, like mandrels.

Assuming the butt taper is pretty even over, say 18", it's easy to calculate the blank taper by measuring the butt outer diameter, and the outer diameter of the blank a set distance up, say 12". Probably only applies to lighter rods.

Tangent of taper angle = (D1 - D2)/2 * taper length.

So, anyone willing to help can send me those measurements so I can get an idea of what I may be getting myself into. Maybe a range from UL (1-4 lb) to 15 lb class blanks. This'll really keep me busy for the next couple of months!!

Ted,
I have some steel reamers that are naturally tapered and basically have teeth that run the length of the reamer rather than across like a file or saw. In a lathe they will ream cork very, very fast, sometimes too fast. You might want to consider something like them. If you want a more detailed description send me an e-mail.

Ted: Tangent of taper angle = 0.500 * (D1 - D2) / (taper length).
Tangent = (opposite) / (adjacent).

All your rod taper angles will likely be well below 1 degrees.
One moderate-taper surf rod I just checked was ~ 0.25 degrees.
One fast-taper boat rod was ~ 0.30 degrees.
One moderate-taper spinning rod was ~ 0.15 degrees.

I know very little about lathes. But such small angles and such tiny variations between one rod and the other may allow you to use a "one-taper-fits-all" approach. Or some kind of cushioned wrap for adjustment. Check your own stock of rods for confirmation.
LOL, -Cliff Hall-.

Yes Cliff, I noted the same on my meagre few rods. Rods close to one another in power/action tend to vary not by very much. That's why lots of input would help determine whether to just use one taper very close to the average, or use 2 or 3. I don't think being off by 0.5 degrees would greatly affect the concentricity of the handle. So my initial thought was a set in 0.1, 0.2, 0.3 degrees, of length appropriate to allow reasonable expansion of the hole without having to change reamer too many times.

Emory, metal tapered reamers don't do very well on softer materials like cork or EVA/Hypalon. To my knowledge they also aren't available in the lengths most useful for grips (most are too short). I have used them on a couple of wood insert experiments quite recently and must admit they work pretty good. However, they are made to a standard taper, which would necessitate Cliff's adjustments.

Maybe I'll just make a set like the commercial reamers and make do with those.

A series of reamers from 0.00 degrees (no taper) to 0.50 degrees (stand-up, extra-fast taper tuna stick) would cover the absolute extremes of the spectrum. Using 0.05 degree or 0.10 degree increments would allow some very close fitting.

If you play with the numbers and make limit assumptions for OD(butt) and OD(tip), you can assume: [for maximum taper scenario]
Tangent of the Taper angle = F(D1, D2) = 0.500 * OD(butt) / (rod length)

Probably 90% of your rods would fall within the your initial selection for a set of reamers: 0.10; 0.20; 0.30 degrees, of length appropriate to allow reasonable expansion of the hole without having to change reamer too many times. I think you've got it nailed, Ted, if the lathe can create so fine a selection of angle and increments.
Slow tapers = ~ (0.10 degrees)
Moderate-Fast = ~ (0.20 - 0.30 degrees)
Extra-Fast = ~ (0.40 degrees)

If you manage to refine it any more than that, Ted, you'll have removed all the guesswork, and then, where would the fun be? LOL, -Cliff Hall-

Oh, that's right ! Now that you know the taper angles, you can multiply that array times the array of RANGE of BLANK DIAMETERS !
From 0.300 inches up to 1.300 inches, in 0.100 increments. More fun !

And a ton more work. Since I started doing wood handles the whole boring/reaming thing has become a real pain. I just don't particularly like shimming up the blank under grips/seat inserts, and avoid it if I can.

Had a really good design on the handle of the sneaky pete, but ruined it when it came time to ream.

Anyway, thanks for the extra math. I came up with pretty much the same stuff. Funnily, 0.32 degrees came up A LOT!! Blank tapers and commercial reamer tapers. Are they trying to tell me something?

I would also hate to see the size of the steel reamer to ream 1.3 inches. LOL.