I mentioned above that the horn should be shaped, not to finished but close, if nothing more than rough shaped before it is pressed. The one thing I do not do is cut it to its final length. I leave it an inch or so longer than I want it finished. The reason, I have had them split once the wedges are driven in and the final tightening done. That way if it does crack the crack can be trimmed off and the horn saved. If the crack is to long the horn can still be saved by using staples and a piece of rawhide or leather inside the horn. Without the base the staples can easily be bent over.
I hope the press, it is made of Beach, Pix are self-explanatory. The small wedge is to really tighten things up. You want 1 & 5, which have their outer edges rounded, to press into the horn so the ends come out as round as possible. Square will work too but is not as strong as rounded, more likely to split..
For shaping after the horn is flattered using a Jig makes it easy to hold. Rough cut the two sides based on the shape of the horn, they should be a bit thinner than the horn so you don't hit them while filing of scraping. Lay the horn on a piece of wood and screw one side down, put the other side tightly against the horn and screw it down. Screw a small piece at the end, a piece of it can actually go into the horn to help hold it down if needed. Do one side than turn the horn and the sides over. If you want to work the edges of the horn, the thin sides, just shape a piece of wood that will fit inside it and hold it in a vice, I clamp the horn and the piece of wood. The bottom of the jig has a keel on it so it can be clamped in a vice. The jig is useful when carving the horn too.
Hope this helps.
Tim
The Jig:
In Use, with a scraper:
