So far I have made 5 slip joints that worked great. I recently decided to cut out ten of the same design and make them at the same time. I'm having the same problem with all ten of them that I did not have with the first three. When the blade is opened that liners bow inwards at the bolster binding on the knife. It bows inward at the top of the bolster or the open side. I've double checked my double check of the squareness of my drill press and can't find any fault there. On 3 or 4 of the knives the liners bow inward when closing the blade also. It's no just a slight bow that I could scrape out or mill out like the How to Make Multiblade folers and How to Make Folding Knives talk about. Does anyone have an idea on what else could cause the problem? Any help would be appreciated. Ryan Minchew

Flatness of blade or spring maybe ?

Sounds like the spring may not be flat, either that or the blade tang is not square to the pivot on the liners. If the pivot holes on the liners are not exactly square to the blade when you peen them togather this will happen. Sometimes if the spring tension is to tight the liners will shift while being peened togather, This happend quite often if you are not carefull. Each slip joint will be different when you build them even if off of the same pattern. As Elmer says Be Very Very Quite, What I am saying peen them very slowly. If you did that then the canches are that it is the spring tension causing a shift when peened, either that or the liners pin holes are off, and it wont take but a few thousands to do this.
Curtis Wilson

Lighten up the tention on the springs , and make sure your handle material is Flat and reaches the bolsters all the way snug ,

Sorry for the time getting back to this thread. I try to respond quickly thanking everyone that helped. I may have made a bigger mistake now. I changed too many things at once. I'm not far enough along to tell if they helped though. I went to a thicker liner material. I changed the tension on the spring, and I also clamped the piece flat while the slabs were drying on the liner. I'm hoping something in that has fixed it. I check my drill press again and the spring and both show to be where I want them, but We'll see. Thanks for the help.