Sunday, March 20, 2011

Part 8 - Regulator and CNC Switch Mount

The original plan was to mount the oil filter and regulator on a nicely chromed dual mount (see Parts blog). It didn't fit on this frame most likely due to the single down pipe.

The alternative was to fabricate a mounting bracket for the regulator and purchase a new oil filter mount that attaches to the EVO motor in traditional Harley fashion.

Alternator and voltage regulator

To create the mount, a heavy duty aluminum angle extrusion left over from a previous project was used. Cutting it to size was the usual death defying feat involving a chop saw and a huge amount of luck. Not recommended.

Regulator mounting bracket - front view

Regulator mounting bracket - rear view
The regulator is mounted to the bracket with 2x 1/4-20 SHCS. The bracket was tapped so eliminate nuts.  The other 2 holes are 3/8 clearance holes for the front motor mount bolts. The bracket is bolted to the underside of the frame and held in place by the the front motor mount bolts.

Regulator mounted

The ignition switch was next. There are a number of switch mounts available but decided to fabricate a custom part from 1/4" 6061-T6 aluminum plate. The switch mount also serves as a spacer for mounting the ignition coil to the top motor mount. Without the spacer, the ignition coil would be resting on the cooling fins of the cylinder.

The basic design was sketched on a piece of paper taking measurements directly from the top motor mount and the ignition switch. The paper sketch was then detailed using a CAD program - Alibre Design.

After messing around with a number of different designs, the basic design shown above was as far as my creativity would stretch. The vertical slots were added to create visual interest and serve no practical purpose whatsoever. After the CAD model was completed, a 2-D drawing was created and exported to a CAM (Computer Aided Manufacturing) program. 

Toolpaths for cutting the part
The toolpaths were created and downloaded to a CNC controller (Mach 3) which controls a homebuilt CNC machine that profile routes the part. The CNC machine was built from scratch a couple of years ago. 

Going from paper, to CAD to CAM to CNC Controller may seem like a lot of steps to get to the end product but the accuracy and finish of the part makes the process worth while. Cutting the part out by hand would take significantly longer and the slots would be a real challenge to keep straight using hand tools.
CNC Machined switch mount

Switch mounted
The switch mount still needs to be polished to match the shine of the primary.  


  1. Hey,
    First of all let me say thank you and the project looks great so far. Also, you've give me some ideals about my prostreet build. I wanted to ask which coil cover are you going to go with? Also, what are you doing about the 5th mounting stud on the RSD 6-speed trans? Do you have a five hole transmission plate, or will you just leave it hanging?
    thanks and good luck.

  2. Hey Lex, the coil cover hasn't been decided yet. I am going to see about making my own.
    The advice I got from the frame guy is that they cut the 5th stud off if the transmission mounting plate is welded to the frame. In my case it is, but I'm still thinking about adding a bracket to the right side tube to support the 5th stud. There is a big moment force due to the distance between the 5th stud and the other studs which I'd like to eliminate.