Tightbond is a standard in wool glues. Any hardware will stock it.

As for "Drying epoxy hard", I'm not sure what you are getting at. From a hardness standpoint, epoxy isn't all that hard. It is tough and bonds to wook well. Some epoxies dry rather rubbery, but still have good bonding strength. The slower it dries, the better penetration into the soft wood.

Tightbond is a glue that you can clean up with water before it drys. After, it is near water proof. It will sand some what easier than epoxy so that is a plus for it. I mix up a small bottle using about 7/8 ths Tightbond and 1/8th distilled watter. This gives a better penetration for the balsa. 3/4 to 1/4 is a little wetter than I like. Some applications, IE cap strips on ribs, I use straight tightbond as it is less likely to run.

I just finished a 60" wing for my Ruperts Dad, using only tighbond. There were a couple areas where it was slower that squirting CA, but in the end, it has turned our very well. The D tube sheets were left to dry overnight, but most of the other joints were ready to be moved in a couple hours. If you plan your work ahead, it doesn't really slow you down any. You also gain in the end as there is little dried glue cleanup required.

I have also heard the argument that it gives a much lighter weight as a great precentage of the volume evaporates of as it cures, where epoxy retains all of it's wet weight and CA keeps a high precentage. From a structural stand point, there are places for all three on your bench.

Doing the Ruperts Dad wing, I cracked the light LE sheeting and repairing it, I used thin CA as it would penetrate the wood better. THe down side is any CA that hardens external to the wood that needs to be sanded smooth. I made a pleasent discovery. If you you wet or dry 320 grit paper glued onto craft sticks (popcile sticks) it is abrasive enough to cut the hardened CA, but fine enoght not to be agressive on the soft balsa. I found that you can sand the CA right down to the balsa with minimual cutting of the wood. Garnet paper will not do this.

Don