Conical Washer Forming

All this wood work going on around the shop lately motivated me to install a set of double doors between the art studio and the metal working shop. We found some interesting solid semi Moroccan style doors on Craigslist a few months ago that we set aside for the project. Meanwhile I squirreled away all the lumber and fittings we would need when the moment of truth came to hang the doors. These were bare doors without a jamb. I have installed a few doors with pre-made jambs which is pretty easy. This is the first set of double doors sans jamb that I have done. To complicate things slightly the folks that built the wall added some extra thickness to the wall for shear strength which forced me to make a custom jamb set for the doors.

One of my construction buddies gave me a good tip for hanging heavy solid doors. He mentioned that the hinge screws should go all the way through the door jam and into the trimmer stud if possible. It makes perfect sense when you lift the dead heavy doors even once. Each one weighs maybe sixty or eighty pounds all of which is screwed to some flimsy jam lumber with #10 screws. I took his advice and used long screws where I could.

My problem was the countersink in the mortise hinge. The screws I used have a spline drive on them to make it less likely to cam out when installing them to high torque levels driving them deep into the trimmer stud. Unfortunately the heads were a whisker too small and just passed through the stock holes in the hinges. What to do. I could get new hinges or new screws all of which require a trip to the store on a holiday.

What was needed were some custom conical washers. At least that's how I decided to fix my current dilemma.

You can see in this picture the head just passes through the hinge countersink. These screws are 3.5 long with a spline drive.

A quick forming die made from some steel flat bar. This was just drilled clearance for the screw and countersunk 82 degrees to match the screw head. The countersink top diameter is the before forming washer OD.

I did have some nice #10 stainless AN washers in stock. They just sit on the top edge of the countersink helping to center them.

The screw is the punch used to form the washer. I pulled down from underneath the vise so the screw and washer didn't move when I smacked it.

A few love taps with a small hammer and now I have some special washers.

The screw fully seated with the formed washer.

You can even see the imprint in the washers of the small splines and text from under the head of the screw.

I deepened the hinge countersink to accept the screw with the new washer. It acts like a small spherical washer and allows the screw to center itself in the hole. It saved me a trip to the store and allowed me to use the heavy duty screws driven into the stud.

A simple job but worth sharing here. It keeps you all guessing as to what will come next around the shop.

Thanks for looking.