Tight-space Dimpler
From Matronics
< Tools < Home-made Tools
This dimpling tool -- made from a normal, hardware-store C-clamp -- works well in tight locations, such as the tips of the rudder top and bottom ribs. The "foot" that comes with the clamp has been removed and replaced with a hole drilled to fit the shank of a dimple die. Use of a washer on the shank of the dimple die will help prevent the dimple die from rotating and burnishing the workpiece. A matching "die" has been machined in the boss of the clamp, using simple tools found in most RV workshops.
Modify the Jackscrew
Remove the "foot" that comes with the clamp, using whatever means are at hand. Clamping the jackscrew in a soft-jawed vice and hitting the "foot" with a hammer works well. Be careful not to bend the jackscrew. Another method, that works quite well, is to place a slotted spacer (think of a fat tuning fork) over the jackscrew, between the foot and the threaded end of the frame. Then, simply unscrew the jackscrew. This will force the foot off the end of the jackscrew. This method avoids bending forces on the jackscrew.
Saw off the end of the jackscrew that the "foot" was crimped to. File the butt end flat and perpendicular to the jackscrew axis.
Drill a 3/16" hole in the end of the jackscrew, to hold the dimple die. To find the center of the shaft, place the jackscrew in a drill press, spin it at low RPM (500 or less), and find the center with an auto-center punch. Hold the center punch lightly and allow it to "find" the spot where it doesn't wobble. Then make a punch mark while it's still turning. Next, drill the hole, starting with a small bit and working out in stages, while the shaft is still turning in the drill press. In effect, you are using the drill press as a vertical lathe.
To get the jackscrew into a drill-press chuck you will probably have to remove the "T" bar. Do this by cutting off one of the flared ends. When you are finished machining the shaft you can put the "T" bar back in and re-flare the cut-off end by squashing it in a vice.
Machine the Matching Die in the Clamp
To make the dimple countersink in the clamp body you will need a way to extend the countersink bit to get a straight shot through the jackscrew hole. One way to do this is to drill and tap a hole in the end of an exacto-knife handle, and use this to extend the bit. Drill the hole in the end of the handle using the method described above.
To machine the clamp body, insert the tapped extender through the jackscrew hole and thread the countersink bit onto the end. Clamp the C-clamp into a vice. Now you can drill a countersunk hole in the boss of the C-clamp using a hand drill.
