#270 For today's post I made the adjustable 1" carrier disc for the hall sensor, and the 1" carrier disc for the magnet that will rotate with the crank and trip the sensor. In the picture I'm cutting off one of the rotating discs that will carry a magnet.
#271 On the left are the blanks that will become the discs for the hall sensors, and on the right are the blanks that will become the carrier discs for the magnets.
#272 The first step on the sensor disc was to drill and ream a hole for a rod that will be used for fine adjustments. A temporary rod will be inserted and used to fixture the discs in the next machining steps.
#273 I made a simple fixture to locate and rotate the sensor disc to mill out a slot for a captive screw that will allow movement of the disc for adjustments while the engine is running.
#274 The temporary rod is used to rotate the disc back and forth while the end mill is lowered slowly to a depth of the thickness of a cap screw head plus .020" for a .010 spring steel washer. The second step (not shown) was to use a smaller end mill and go all the way through for the threaded part of the cap screw.
#275 I used the same fixture with the aid of space blocks to center a shallow milled slot for the hall sensor. I milled it the thickness of the sensor plus .004" so that when its glued in place it will be just below the surface and out of harms way.
#276 I got lucky and a 5/32" end mill made a perfect width slot for the sensor. The sensors I'm using are HAL506UA-A from Symmetry Electronics, Corp.
#277 I made another simple fixture by drilling and tapping a hole for a cap screw that fit the bore of the carrier disc for the magnet. This made it easier to drill and ream all of the .125" holes for the .1245" cylindrical magnets.
#278 I tapped the hub on the magnet carrier disc for a 4-40 set screw. The location was not important so I offset it by 90* from the magnet to avoid fighting with the hex wrench during the initial adjustment since these are very powerfull little magnets.
#279 The magnets I'm using on this project are cylindrical 1/8" x 1/8" D22-N52 from K&J Magnetics.
#280 This is the position the hall sensor will be mounted in. All of the engine side frames will have to come off to drill and tap for the mounting/adjusting screws.
#281 The magnet carrier is being installed to give a better idea of how the system will go together and look.
#282 Here's another view of my set up. The gap between the discs will be set at about .030". I might just machine up some .030" spacers to eliminate the spacing issue during the initial set up.
-MB