A Better Height Adjustment
Height Adjustments. Heavy, bulky, hard to do. More parts to buy and keep in stock. Man I hate doin' those things. There must be a better way.
Forget about what you think height adjustments should look like and think about what it is you really want to accomplish. The ability to easily raise and lower the uprights in relation to the plastic cuffs. Easy right? The only problem really is that in doing so you will increase the thickness of the uprights at the adjustment area and increase the overall weight by as much as a full pound. And when you do want to adjust the height, you must re-contour the uprights and hope that the holes still line up. Well, there is a better way.
The first step is to make some key cast modifications. At the sagital midline where the uprights will be attached (lay down an upright and trace it in position on the cast) carve a small flat area that does not alter the shape of the cast too much. Just take off the apex of the cast and make it about 3/4" to an inch wide. To be sure that it's straight, cut a length of bar stock and set it on the spot to check it and carve it flat as needed. This is very easy at the thigh but is a little more tricky on the calf section. Here, you will need to half and half the flat by carving a little and adding a little. After you have carved a small flat spot on the calf, put some plaster just above and just below it. Set the bar stock over it to make the build up flat and straight. After the plaster hardens remove the bar stock and carve, sand or fill as needed (Fig. 1). The idea here is to make a nice flat area at the attachment points so that the uprights may slide along them with a minimum of re-bending. Pull the plastic and bend the uprights as usual. There should be very little in the way of contouring the bars at the cuff area. It should be pretty flat.
Once the bars are contoured you need to drill the adjustment holes in them. Dunlap Machine Products in Arizona sells a good height adjustment fixture (part # 10301, $35.00 each) that makes the job real easy. It will give you 1/2" adjustments, and is very easy to use. Lay the bars back in place on the plastic and mark three holes on the cuff. Pick one at the middle of the height adjustments and one at each end . The ones on the end should not be the last holes, but one or two holes in to allow for more adjustment (Fig. 2). Finish out the uprights and plastic as usual. Drill the holes in the plastic cuff and countersink the inside. Countersinking the inside of the cuff can be accomplished by chucking a countersunk screw into a drill press (high speed) with the head of the screw facing the inside of the plastic cuff (Fig. 3). Clean off any burrs with a razor blade. Attach uprights and finish brace as usual.
The thickness of the uprights is the same as on a brace without height adjustments and it doesn't weigh any more either. Also notice how your uprights just slide up and down and line right up with the holes. When you make any adjustments to the height, the advantages will be easily recognized.