I don't remember how I stumbled upon the idea (edit; it was described in
"Recreating the American Longrifle" by Buchele, Shumway and Alexander), but I fab'd a Drilling Jig in College Machine Shop Class in the early 90's.
Even though I made different sizes of guides I mostly created it to more accurately drill for Tang Bolts and Lock Nails (1/8" guide holes), I never really used it for smaller RR Pipe and Bbl Cross Pins, preferring an x-y vise in my Drill Press for that task.
In the mid 90's, I was in Harbor Freight and saw 2 1/2" 3-way edging clamps on sale cheap, so I picked up a few (impulse buy
).
Later, when using my college-made clamp, I recalled the 3-way clamp and thought "hmmmmmm, that could work, too"
I removed all the screws, ground the former center screw to a point and screwed it into one side. Then, I tapped the other end for a 8-32 thumb screw and put in a 5/16(?) x 1/8" drill guide bushing. “Voilà!” an inexpensive tool I christened the "C-Straight" Drilling Jig.
I brought some with me to Conner Prairie in '97 and sold a few and offered it for sale in Muzzle Blasts Magazine, but never really promoted it much.
The hard part was finding inexpensive drill guide bushings.
A year or two later, I noticed Mountain-State Muzzleloading Supply offering a variation of it. Now, many others have jumped in with their versions.
So, for you fellow CABs (Cheap Arse B****ds) out there, here is a way to have one with just a little work and $.
I don't see HF currently offering the 3-way clamps but they shouldn't be too hard to find. Drill guide bushings may be a little more of a challenge, but the hole can be resized to accommodate what ever.
Rotsa ruck, G.I.!